SHORT-TERM EFFECT OF CINNAMON ON BLOOD
PRESSURE IN MIDDLE-AGED OBESE ADULTS
A THESIS SUBMITTED TO THE GRADUATE SCHOOL
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE
MASTER OF SCIENCE
BY
SAMANTHA R. TICKLE, RD, LD
ADVISOR- JO CAROL CHEZEM, PHD, RD
BALL STATE UNIVERSITY
MUNCIE, INDIANA
MAY 2013
ABSTRACT
THESIS:
Short-Term Effect of Cinnamon on Blood Pressure in Middle-Aged Obese
Adults
STUDENT:
Samantha R. Tickle
DEGREE:
Master of Science
COLLEGE:
Applied Sciences and Technology
DATE:
May 2013
PAGES:
77
The purpose of this study was to determine the short-term effect of cinnamon on blood
pressure in middle-aged obese adults. Subjects consumed a beverage with (experimental)
and without (control) 6 g ground cassia cinnamon. Blood pressure was assessed at
baseline, and then at 30, 60, 90, 120, 180 and 240 minutes. A food frequency
questionnaire was administered to estimate usual dietary intake. Twenty-six adults (9
males and 17 females), aged 40-65 years, completed the study. There was no significant
difference in blood pressure at any time point between the two conditions (p>0.05).
Multiple regression analysis evaluated the relationship between usual intake of diet
components and control baseline blood pressure. The diet components studied did not
significantly predict systolic blood pressure or diastolic blood pressure at baseline. The
results of this study suggest 6 g cinnamon does not exert a short-term beneficial effect on
blood pressure in middle-aged obese adults.
ii
ACKNOWLEDGEMENTS
I would like to thank my thesis committee, Dr. Carol Friesen, Dr. Jocelyn Holden,
and Mrs. Rhonda Murr for their time and expertise that was contributed to make this
thesis possible. A special thanks goes out to my major professor, Dr. Jo Carol Chezem,
who has always been there to provide support and guidance for which I am grateful. Dr.
Jo Carol Chezem has been a wealth of knowledge and I am thankful for the time and
dedication she was able to provide. I would also like to thank Dr. Nicolle Fernandez who
was a great asset to making this research possible. A thank you goes out to the research
assistants that were available to devote their time and energy to help carry out this
research. Thank you to my family, friends, and professors at Ball State University for
their support, guidance and encouragement throughout my thesis and master’s degree.
iii
TABLE OF CONTENTS
PAGE
ABSTRACT ........................................................................................................................ ii
ACKNOWLEDGEMENTS ............................................................................................... iii
TABLE OF CONTENTS ................................................................................................... iv
CHAPTER 1: INTRODUCTION .......................................................................................1
Problem Statement ...................................................................................................2
Purpose Statement ....................................................................................................3
Research Questions ..................................................................................................3
Rationale ..................................................................................................................3
Assumptions.............................................................................................................4
Definitions................................................................................................................4
Summary ..................................................................................................................5
CHAPTER 2: REVIEW OF LITERATURE ......................................................................6
Introduction
..........................................................................................................6
Background
..........................................................................................................6
Obesity .........................................................................................................7
Increasing Aging Population........................................................................7
Hypertension ................................................................................................8
Diet and Blood Pressure...............................................................................9
Medicinal Effects of Cinnamon ...............................................................................9
Impact on Blood Glucose and HbA1c .......................................................10
Impact on Serum Lipids (Total Cholesterol, TG, LDL, HDL) ..................11
iv
PAGE
Pathophysiology of Hypertension in Older Adults ................................................11
Changes in Vascular System with Aging...................................................11
Normal vs. Uncontrolled Blood Pressure ..................................................12
Risks Associated with Uncontrolled Blood Pressure.................................12
Effects of Cinnamon on Blood Pressure ................................................................13
Animal Studies ...........................................................................................13
Human Studies ...........................................................................................15
Quantity and Duration of Cinnamon Supplementation in Human Studies ............16
Quantity of Cinnamon Supplementation ...................................................17
Duration of Cinnamon Supplementation ...................................................17
Summary ................................................................................................................17
CHAPTER 3: METHODOLOGY ....................................................................................18
Institutional Review Board ....................................................................................18
Consent Form ........................................................................................................18
Subjects ..................................................................................................................19
Methods..................................................................................................................20
Instruments .............................................................................................................20
Data Analysis ........................................................................................................21
Summary ................................................................................................................22
CHAPTER 4: RESULTS ..................................................................................................24
Subjects
........................................................................................................24
Blood Pressure Control vs. Cinnamon ...................................................................26
v
PAGE
Blood Pressure and Correlations between Diet Components ................................31
Diet Components Effect on Blood Pressure ..........................................................32
Summary
........................................................................................................35
CHAPTER 5: DISCUSSION ............................................................................................36
Limitations
........................................................................................................36
Timing
........................................................................................................37
Mechanism of Action ............................................................................................38
Amount of Cinnamon ............................................................................................39
Form of Cinnamon .................................................................................................39
Participants’ Health Conditions .............................................................................40
Diet and Blood Pressure.........................................................................................41
Strengths
........................................................................................................42
Summary
........................................................................................................42
CHAPTER 6: CONCLUSION AND RECOMMENDATIONS ......................................44
Conclusions
........................................................................................................44
Recommendations for Future Research .................................................................44
REFERENCES ..................................................................................................................46
vi
LIST OF APPENDICES
PAGE
Appendix A: Institutional Review Board Documents ..........................................53
A-1: Letter from Ball State IRB................................................................54
A-2: CITI Completion Certificate .............................................................55
Appendix B: Screening Form ...............................................................................56
Appendix C: Participant Letter of Consent ...........................................................60
Appendix D: General Survey .................................................................................65
Appendix E: Data Collection Instrument ...............................................................67
vii
LIST OF TABLES
PAGE
Table 1
Demographics, Activity Level, and Family Hypertension Rate In Study
Participants .................................................................................................25
Table 2
Mean Systolic Blood Pressure During 4 Hours Post Prandial Period
Without and With 6 g Cinnamon ...............................................................28
Table 3
Mean Diastolic Blood Pressure During 4 Hours Post Prandial Period
Without and With Cinnamon .....................................................................30
Table 4
Correlations between Blood Pressure and Diet Components ....................32
Table 5
Diet Components Prediction of Baseline Systolic Blood Pressure ............33
Table 6
Diet Components Prediction of Baseline Diastolic Blood Pressure ..........34
viii
LIST OF FIGURES
PAGE
Figure 1
Systolic Blood Pressure During 4 Hour Post Prandial Period Without and
With 6 g Cinnamon ....................................................................................27
Figure 2
Diastolic Blood Pressure During 4 Hour Post Prandial Period Without and
With 6 g Cinnamon ....................................................................................29
ix
CHAPTER 1
INTRODUCTION
Obesity has reached epidemic proportions in the United States, with an estimated
97 million adults being overweight or obese (Flegal, Carroll, Ogden, & Curtin, 2010).
The increasing prevalence of obesity has coincided with an increase in diabetes as well;
from 1980 through 2009, the number of adults aged 18 years or older with diabetes in the
United States more than tripled, increasing from 5.5 to 19.6 million individuals over this
30 year period (Pleis, Ward & Lucas, 2010).
Concomitant with the increase in diabetes seen in this country, hypertension
affects approximately one in three adults in the United States (CDC, 2011). According to
National Health and Nutrition Examination Survey (NHANES) data there are
approximately 68 million U.S. adults living with hypertension, and this prevalence has
shown no improvement in the last decade (CDC, 2011). Many studies closely associate
diabetes, insulin resistance, and hypertension. Hypertension contributes to the leading
causes of morbidity and mortality in people with diabetes, including coronary heart
disease (CHD), stroke, peripheral vascular disease, lower extremity amputations, and
end-stage renal disease (Tocci, Sciarretta, & Volpe, 2008; Flack & Sowers, 1991).
Research has shown positive effects of cinnamon on glucose regulation
(Ziegenfuss, Hofheins, Mendel, Landis, & Anderson, 2006; Akilen, Tsiami, Devendra, &
Robinson, 2010). More recently, several studies have suggested there may be a
beneficial impact of cinnamon on blood pressure (Preuss, Echard, Polansky, & Anderson,
2006; Ziegenfuss et al., 2006). Research investigating the mechanism of cinnamon
suggests it affects the nitric oxide pathway and inhibits Ca2+ influx to relax blood vessels
(Xue, Shi, Murad, & Bian 2011; Nyadjeu, Nguelefack-Mbuyo, Atsamo, Nguelefack,
Dongmo, & Kamanyi 2013). Additional research is needed to develop an accessible
treatment option for hypertension that’s economical with limited side effects.
Problem
The prevalence of obesity continues to rise in the United States, exceeding 30
percent in most sex and age groups (Flegal et al., 2010). All overweight and obese adults
are at an increased risk for hypertension and type 2 diabetes (National Institutes of
Health, 1998; Holecki, Dulawa, & Chudek, 2012). Hypertension and diabetes are
interrelated diseases that, if untreated, strongly predispose to atherosclerotic
cardiovascular disease (CVD) (The National High Blood Pressure Education Program
Working Group, 1994; Gu, Burt, Paulose-Ram, Yoon, & Gillum, 2008). The addition of
cinnamon has been shown in preliminary studies to reduce blood glucose (Khan, Safdar,
Khan, Khattak, & Anderson, 2003; Ziegenfuss et al., 2006). Animal and human studies
have indicated it may reduce blood pressure (Akilen et al., 2010; Preuss et al., 2006;
Nyadjeu et al., 2013; Xue et al., 2011; Ziegenfuss et al., 2006). It is important to further
investigate the effect cinnamon has on blood pressure in humans.
2
Purpose
The purpose of this study was to determine the effect of a breakfast beverage
containing 6 g ground cinnamon on blood pressure at baseline 30, 60, 90, 120, 180 and
240 minutes in adults 40-65 years of age who are obese and at an increased risk for
developing hypertension. Usual diet intake was also studied because of the known
relationship between diet and blood pressure.
Research Questions
The following primary research question was examined in this study:
1.) What impact, if any, did drinking the beverage with and without 6 g cinnamon
have on the systolic and diastolic blood pressure measurements of obese adults
aged 40-65 years?
The following exploratory research question was examined in this study:
2.) What influence did usual intakes of sodium, potassium, calcium, and fruit and
vegetable have on systolic and diastolic baseline blood pressure measurements in
obese adults aged 40-65 years?
Rationale
Determining if cinnamon has an effect on systolic blood pressure (SBP) and
diastolic blood pressure (DBP) could be influential in developing a low cost, convenient
treatment for hypertension. More human trials need to be done to test the effect that
cinnamon has on blood pressure. This population of middle-aged obese adults is at risk
of hypertension and might be an appropriate target for this type of intervention.
3
Assumptions
The following assumptions were made in the development, implementation and
analysis of this study:
1. Subjects consumed the breakfast beverage after an 8 hour fast.
2. Participants accurately recalled information on the food frequency
questionnaire.
3. The food frequency questionnaire was representative of subjects’ usual intake.
4. Participants were honest about medications or herbal supplements they
consumed.
Definitions
For the purpose of this study, the following definitions were used:

Type 2 diabetes. A type of diabetes mellitus that is non-insulin-dependent and is
characterized by hyperglycemia resulting from impaired insulin utilization
combined with the body’s inability to compensate with increased insulin
production (ADA, 2004).

Hypertension. An adult systolic blood pressure of 140 mm Hg or greater or a
diastolic blood pressure of 90 mm Hg or greater (AHA, 2011).

Systolic blood pressure. The top number of a blood pressure reading, which is
also the higher of the two numbers, measures the pressure in the arteries when the
heart beats (when the heart muscle contracts) (AHA, 2011).
4

Diastolic blood pressure. The bottom number, which is also the lower of the two
numbers, measures the pressure in the arteries between heartbeats (when the heart
muscle is resting between beats and refilling with blood) (AHA, 2011).

Insulin resistance. The body's inability to respond to and use the insulin it
produces. Insulin resistance may be linked to obesity, hypertension, and high
levels of fat in the blood (ADA, 2012).

Impaired glucose tolerance. A condition in which blood glucose levels are higher
than normal but are not high enough for a diagnosis of diabetes. IGT, also called
pre-diabetes, is a blood glucose level of 140 mg/dL to 199 mg/dL 2 hours after the
start of an oral glucose tolerance test (ADA, 2012).

Cardiovascular disease (CVD). Diseases of the heart and blood vessel system.
Diseases included are heart disease, stroke, high blood pressure, angina (chest
pain), and rheumatic heart disease (National Heart, Lung, and Blood Institute,
2012).
Summary
Through this study, the researcher examined the effects of 6 g cinnamon on blood
pressure in obese middle-aged adults at an increased risk for hypertension. By answering
the research questions, this study contributed to the knowledge base regarding the use of
cinnamon as a treatment for hypertension. A review of the literature follows in chapter
two, chapter three illustrates methods used when conducting this study, chapter four
reviews the results, chapter five presents a discussion, and chapter six offers conclusions
and recommendations for future research.
5
CHAPTER 2
REVIEW OF LITERATURE
The purpose of this study was to determine the effect of a breakfast beverage
containing 6 g ground cinnamon on blood pressure at baseline and 30, 60, 90, 120, 180
and 240 minutes after consuming the beverage in adults 40-65 years of age who are obese
and at an increased risk for developing hypertension. This chapter will provide general
information about the prevalence of obesity, aging and hypertension, and the impact of
dietary intake on blood pressure. A review of the literature will describe the medicinal
effects of cinnamon on blood glucose, HbA1c, serum lipids and hypertension in humans
and animals; the pathophysiology of hypertension in older adults and vascular changes
that occur; the effect of cinnamon on blood pressure in humans and animals as well as the
proposed mechanisms of cinnamon; and a review of methods in human studies focusing
on quantity and duration of cinnamon supplementation in individuals with type 2
diabetes.
Background
Many factors contribute to the development of hypertension, including age and
obesity. This section of the literature review highlights the prevalence of obesity, aging,
and hypertension in the United States; as well as reviews the impact diet has on blood
pressure.
Obesity
In 2007-2008, the prevalence of obesity was 32.2 percent among adult men and
35.5 percent among adult women in the United States (Flegal et al., 2010). All
overweight and obese adults are considered at risk for developing associated morbidities
or diseases such as hypertension, high blood cholesterol, type 2 diabetes, coronary heart
disease, among other conditions (National Heart, Lung, and Blood Institute, 1998;
Holecki et al., 2012). Diabetes and hypertension often coexist, with obesity being a
contributing factor to both health problems (American Diabetes Association [ADA],
2008). Obesity has been found to be associated with several abnormalities that contribute
to the development of hypertension (Rahmouni, Correia, Haynes, & Mark, 2005).
Weight control or reduction is important in the treatment of those with hypertension
(Rahmouni et al., 2005; ADA, 2008). Interventions to decrease the prevalence of obesity
will lower health care costs, and may decrease the prevalence of hypertension and type 2
diabetes (The National High Blood Pressure Education Program Working Group, 1994;
Blumenthal et al., 2010).
Increasing Aging Population
The U.S. population has continued to grow older, with much of the population
reaching a median age of over 40 years (U.S. Census Bureau, 2011). Due primarily to
the aging of the Baby Boom population, the population aged 45 to 64 years grew at a rate
7
of 31.5 percent from 2000 to 2010 (U.S. Census Bureau, 2011). Between 2000 and 2010,
the population 65 years and over increased at a faster rate (15.1 percent) than the total
U.S. population (9.7 percent) (U.S. Census Bureau, 2011). The Framingham Heart Study
determined the residual lifetime risk of developing hypertension was 90 percent in men
and women aged 55-65 years old with normal blood pressure (Vasan et al., 2002). As the
population of older adults rises, the importance of finding a treatment for hypertension
also increases (Fields, Burt, Cutler, Hughes, Roccella, & Sorlie, 2004).
Hypertension
The Joint National Committee’s seventh report identifies hypertension as an adult
systolic blood pressure of 140 mm Hg or greater or a diastolic blood pressure of 90 mm
Hg or greater (Chobanian et al., 2003). Data from the National Health and Nutrition
Examination Survey (NHANES) during 2005-2008 indicated that approximately 68
million Americans had hypertension and only 31 million had their condition controlled
(CDC, 2011). Elevated blood pressure is strongly associated with obesity and is listed as
a risk factor for metabolic syndrome; which is associated with an increased risk for CVD
and type 2 diabetes (Grundy, Brewer, Cleeman, Smith, & Lenfant, 2004; Wilson,
D’Agostino, Parise, Sullivan & Meigs, 2005). Every year, hypertension contributes to
one out of every seven deaths in the United States and to nearly half of all cardiovascular
disease-related deaths, including stroke (Chobanian et al., 2003). NHANES data from
2005-2008 indicated the prevalence of hypertension was 69.7% among persons aged ≥65
years (CDC, 2011). If the rise in blood pressure with age could be prevented or
diminished, much of hypertension, cardiovascular disease and stroke might be prevented
8
(Chobanian et al., 2003). One controllable solution to hypertension may lie in dietary
intake. Recent research suggests the reduction of sodium intake to 2,300 mg per day may
reduce cases of hypertension by 11 million (Palar & Sturm, 2009). Diet has the potential
to influence blood pressure and can be the etiology of hypertension in some individuals
(Sacks et al., 2001; Sarkkinen et al., 2011; Whelton & He,1999; Wang, Manson, Buring,
Lee, & Sesso, 2008; Blumenthal et al., 2010).
Diet and Blood Pressure
Research has shown usual dietary intake of sodium, potassium, calcium, and fruits
and vegetables can affect blood pressure. Increased sodium intake has been linked to
hypertension in many studies (Sacks et al., 2001; Pimenta et al., 2009). Several studies
have found an inverse relationship between potassium and blood pressure, supporting a
higher potassium intake for lower blood pressure (Whelton et al., 1999; Sarkkinen et al.,
2011). A higher intake of dietary calcium has been associated with a decreased risk of
hypertension in middle-aged and older women (Wang et al., 2008). High fruit and
vegetable intake has been associated with preventing and lowering blood pressure (AlSolaiman, Jesri, Mountford, Lackland, Zhao, & Egan, 2010; Tsubota-Utsugi et al., 2011).
Usual dietary intake should be evaluated when analyzing blood pressure.
Medicinal Effects of Cinnamon
The positive health benefits of cinnamon have been demonstrated in numerous
studies. This section of the literature review highlights the positive effect cinnamon
supplementation has on blood glucose, hemoglobin A1c (HbA1c), and serum lipids.
9
Impact on Blood Glucose and HbA1c
Ziegenfuss and colleagues (2006) studied the effect of 500 mg/d (equal to 10 g
cinnamon powder) water-soluble cinnamon extract (Cinnulin PF®) on fasting blood
glucose, systolic blood pressure and body composition. Twenty-two subjects from
northeastern Ohio, aged 30-60 years with prediabetes and metabolic syndrome, were
randomly assigned to supplement their diet with Cinnulin PF® or a placebo for 12 weeks.
These researchers found that supplementation of 250 mg Cinnulin PF® twice daily for 12
weeks produced a significant decrease of 8.4% in fasting blood glucose (Ziegenfuss et al.,
2006).
Khan et al. (2003) reported that a daily intake of cinnamomum cassia for 40 days
caused a decrease in serum glucose, triglyceride, LDL cholesterol, and total cholesterol.
A total of 60 subjects from Pakistan, aged 40 years and older with type 2 diabetes, were
included in the study. Three experimental groups given 1, 3 or 6 g of cinnamon daily
were compared with three groups given placebo capsules. Results of the study concluded
that the addition of 1, 3 or 6 g of cinnamon to the diet may help lower serum glucose and
lipids in individuals with type 2 diabetes.
Cinnamon supplementation has been shown to significantly reduce HbA1c in type
2 diabetes patients (Akilen et al., 2010; Crawford, 2009). Akilen and colleagues (2010)
studied the effects of 2 g cinnamon for 12 weeks in 58 type 2 diabetic patients aged
54.9±9.8 years. The study aimed to determine if cinnamon had an effect on HbA1c,
blood pressure, and lipid profiles. After the intervention, the mean HbA1c was
significantly decreased in the cinnamon group from 8.22% to 7.86% (Akilen et al., 2010).
10
Impact on Serum Lipids (Total Cholesterol, TG, HDL, LDL)
Khan et al. (2003) studied the effect of cinnamomum cassia for 40 days in type 2
diabetic subjects and found the addition of 1, 3 or 6 g of cinnamon to the diet may help
control serum lipid values. In comparison, Mang et al. (2006) conducted a study in
Hannover, Germany on 79 patients diagnosed with type 2 diabetes. Patients were
supplemented 112 mg capsulated aqueous cinnamon extract (equivalent to 1 g cinnamon)
or placebo three times a day for 4 months and found no significant difference in lipid
profiles.
Pathophysiology of Hypertension in Older Adults
The pathophysiology of aging is characterized by increasing arterial stiffness
caused by arterial wall thickening and increased collagen content (Cohen & Townsend,
2011). This section of the literature review reviews the changes as the vascular system
ages and the effects of these changes, as well as the differences between controlled and
uncontrolled blood pressure.
Changes in Vascular System with Aging
Cardiovascular complications of aging are related to vascular structure and
function and may be due to changes at the cellular and molecular level (Basso, Cini,
Pietrelli, Ferder, Terragno, & Inserra, 2007; Fields et al., 2004). Evidence suggests aging
is associated with arterial stiffness and an increase in systolic blood pressure (Stehouwer,
Henry, & Ferreira, 2008). At the cellular level, angiotensin II and nitric oxide are
particularly important in the process of vascular aging (Fyhrquist, Metsärinne, &
11
Tikkanen, 1995; Basso et al.,2007; Bosc, Kurnjek, Müller, Terragno, & Basso, 2001).
Long-term angiotensin II inhibition has been shown to induce a protective effect on the
process of aging on the cardiovascular system by increasing nitric oxide synthase and
reducing oxidative stress (Basso et al.,2007; Bosc et al., 2001). Bosc (2001) and
colleagues discovered by inhibiting angiotensin II, nitric oxide synthase activity
increased and exhibited a protective effect against aging. Due to the pathophysiology of
vascular damage that occurs with aging, it is important to focus attention to the aging
population as the prevalence of hypertension increases.
Normal vs. Uncontrolled Blood Pressure
The Joint National Committee’s (JNC) seventh report identifies optimal blood
pressure as <120 mmHg systolic and 80 mmHg diastolic (Chobanian et al., 2003).
Individuals with diabetes mellitus are recommended to have a systolic blood pressure
lower than 130 mmHg and a diastolic blood pressure lower than 80 mmHg (Khan et al.,
2009). Hypertension is defined by the JNC 7 report as a systolic blood pressure of 140
mmHg or above and a diastolic blood pressure of 90 mmHg or above (Chobanian et al.,
2003).
Risks Associated With Uncontrolled Blood Pressure
Hypertensive individuals have an increased risk for heart attack, heart failure,
stroke, and kidney diseases, decreasing life expectancy (Chobanian et al., 2003). Franco
and colleagues concluded that total life expectancy was 5.1 years longer for normotensive
men and 4.9 years longer for normotensive women than for hypertensive individuals of
12
the same sex at 50 years of age (Franco, Peeters, Bonneux, & de Laet, 2005). Mortality
and morbidity are also heightened in diabetes patients who do not achieve blood pressure
control (Campbell et al., 2011). Hypertension exacerbates all of the vascular
complications of diabetes; including renal disease, coronary heart disease, stroke,
peripheral vascular disease, lower extremity amputations and retinopathy (Bakris et al.,
2000). By preventing hypertension related complications in diabetes, other complications
can be avoided (El-Bassossy, Fahmy, & Badawy, 2011).
Effects of Cinnamon on Blood Pressure
Cinnamon has been studied for its beneficial effects on blood pressure in animals
and humans (Preuss et al., 2006; Ziegenfuss et al., 2006; Akilen et al., 2010; Xue et al.,
2011; Nyadjeu, Dongmo, Nguelefack, & Kamanyi, 2011; Nyadjeu et al., 2013). This
section of the literature review highlights previous studies examining the association of
cinnamon and blood pressure in animals and humans, as well as the physiological effects
cinnamon has on blood pressure.
Animal Studies
Research in rodents has found cinnamon to work at the vascular level to decrease
blood pressure (Xue et al., 2011). Xue and colleagues (2011) used isolated rings of rat
aorta to discover cinnamaldehyde, a key component of cinnamon, relaxes blood vessels
by the inhibition of vasoconstrictors such as angiotensin II, a hormone implicated in
sodium-sensitive hypertension (Xue et al., 2011). Pretreatment of aorta rings with
cinnamaldehyde also produced vasodilatory effects when exposed to vasoconstrictors
13
phenylephrine and KCl (Xue et al., 2011). The vasodilatory effect of cinnamaldehyde
has the ability to dilate smooth muscle by its ability to interfere with Ca2+ influx and Ca2+
release (Xue et al., 2011).
The acute and chronic antihypertensive effects of Cinnamomum zeylanicum stem
bark (MECZ) has been observed in L-NAME induced hypertensive rats (Nyadjeu et al.,
2013). Immediately following MECZ administration, a significant decrease (p<0.001) in
mean arterial blood pressure occurred. Blood pressure lowering effects of MECZ were
observed for more than an hour after administration at doses 5, 10, and 20 mg/kg,
decreasing blood pressure by 12.5%, 26.6%, and 30.6% respectively. MECZ increased
nitric oxide (NO) production in the aorta and heart by 47.7% and 38.4% respectively
compared to the control group. This study identified the antihypertensive mechanism of
cinnamon to be the production of NO via the nitric oxide pathway.
The vasodilatory effects of cinnamon are like those of medications used today.
Sung et al. (1999) found that the vasodilator effects of the insulin sensitizing drug
troglitazone reduced blood pressure in 22 type 2 diabetes patients with normal to highnormal blood pressure. Specifically, systolic blood pressure and diastolic blood pressure
decreased significantly by 9 mm Hg and 6 mm Hg, respectively. The implicated
vasodilatory effects found in cinnamon could reduce blood pressure by relaxing blood
vessels, similar to antihypertensive medications used today (Xue et al., 2011; Nyadjeu et
al., 2013, Sung, Izzo, Dandona, & Wilson, 1999).
Preuss and colleagues (2006) studied the effect of dietary cinnamon on SBP in
spontaneously hypertensive rats (SHR). Three experiments were done with sucrose and
non-sucrose containing diets with the addition of various amounts of cinnamon,
14
cinnamon extracts or chromium. Results from the first experiment found the addition of
8.0% w/w cinnamon to the starch or sucrose diets caused a significant decrease in SBP.
The second experiment found the addition of 4 and 8.0% w/w cinnamon resulted in
significant changes in SBP by the second week. The third experiment found the addition
of 2 and 6% w/w cinnamon extract prevented a significant elevation of SBP in the
sucrose diet group. In conclusion, varying amounts of whole cinnamon and cinnamon
extracts were found to work similarly to decrease SBP in SHR.
A study by El-Bassossy et al. (2011) investigated the effects of cinnamaldehyde
on diabetes-induced hypertension in rats. Rats were divided into two models; insulin
deficiency and insulin resistance. Insulin deficiency and insulin resistance were induced
by fructose and streptozotocin, respectively. In the last six weeks of the study, rats were
given 20 mg kg-1 day-1 of cinnamaldehyde. Results from the study concluded that
cinnamaldehyde reduced hyperglycemia and reduced insulin resistance in insulin
deficient rats at a comparable level to that of the antihyperglycemic drug gliclazide. In
addition, cinnamaldehyde administration completely prevented the Ca2+ influx, which
leads to vasoconstriction of blood vessels resulting in hypertension (El-Bassossy et al.,
2011). In conclusion, cinnamaldehyde prevented the development of hypertension in
insulin deficiency and insulin resistance through normalization of vascular contractility
and the stimulation of insulin in insulin deficiency.
Human Studies
Cinnamon has been shown to have a positive effect on blood pressure in humans
(Ziegenfuss et al., 2006; Akilen et al., 2010). Ziegenfuss and colleagues (2006) studied
15
the effect of 500 mg/d Cinnulin PF® (equivalent to 10 g whole cinnamon powder) on
fasting blood glucose, systolic blood pressure and body composition. Systolic blood
pressure and diastolic blood pressure were taken at baseline, six weeks, and 12 weeks.
These researchers found that supplementation of 250 mg Cinnulin PF® twice daily for 12
weeks reduced systolic blood pressure significantly by 3.8% (p<0.001) compared to
subjects in the placebo group. Cinnamon had a greater effect on subjects with a higher
baseline systolic blood pressure.
Akilen and colleagues (2010) studied the effects of 2 g cinnamon for 12 weeks in
58 type 2 diabetic patients aged 54.9±9.8 years. Mean systolic and diastolic blood
pressures in the experimental group were significantly reduced compared to the placebo
group (SBP: 129 mmHg vs. 135 mmHg, DBP: 81 mmHg vs. 86 mmHg). Similar to
Ziegenfuss et al. (2006), the effect of cinnamon was greater with higher baseline systolic
blood pressure. Conclusions from the study suggest that cinnamon is independently
associated with blood pressure levels (Akilen et al., 2010).
Quantity and Duration of Cinnamon Supplementation in Human Studies
The beneficial effects of cinnamon have been demonstrated primarily with
individuals who have type 2 diabetes. Few studies have exclusively examined metabolic
markers of diabetes, such as blood pressure (Khan et al., 2003; Crawford, 2009;
Wainstein, Stern, Heller, & Boaz, 2011). This section of the literature review will review
methods for quantity of cinnamon and duration of supplementation in studies shown to
reduce blood pressure.
16
Quantity of Cinnamon Supplementation
Ziegenfuss et al. (2006) discovered a significant reduction in systolic blood
pressure (-3.8%) in subjects with prediabetes and metabolic syndrome following
500mg/d supplementation of Cinnulin PF® (equal to 10 g cinnamon powder) for 12
weeks. Akilen et al. (2010) studied 58 patients with type 2 diabetes given 2 g cinnamon
powder daily for 12 weeks. Reductions in systolic blood pressure (132.6 mm Hg to 129.2
mm Hg) and diastolic blood pressure (85.2 mm Hg to 80.2 mm Hg) were reported. These
studies illustrate that therapeutic effects of cinnamon can be seen even with 2 g daily
cinnamon supplementation.
Duration of Cinnamon Supplementation
Treatment periods for cinnamon supplementation associated with a reduction in
blood pressure have been weeks long in all of the human studies published to date
(Akilen et al., 2010; Ziegenfuss et al., 2006). Currently, no studies documenting the
immediate effect of cinnamon supplementation on blood pressure in humans have been
identified in the literature.
Summary
The prevalence of obesity and an aging population are increasing, both of which
are risk factors for developing hypertension. There is sufficient evidence to suggest
cinnamon has beneficial effects on blood pressure. Additional research is necessary to
determine how the use of cinnamon, a naturally-occurring, low cost spice, could help
develop strategies to prevent and treat hypertension.
17
CHAPTER THREE
METHODOLOGY
The purpose of this study was to determine the effect of a breakfast beverage
containing 6 g ground cinnamon on blood pressure before and 30, 60, 90, 120, 180 and
240 minutes after consuming the beverage in adults 40-65 years of age who are obese and
at an increased risk for developing hypertension. This chapter will describe the methods
used to conduct the study.
Institutional Review Board
This study was approved as expedited by the Institutional Review Board at Ball
State University on February 15, 2012 (Appendix A-1). The researcher completed the
Collaborative Institutional Training Initiative (CITI) prior to conducting this study
(Appendix A-2).
Consent Form
Individuals interested in participating in this study were asked to contact the
primary investigator by phone or e-mail to schedule a one-on-one appointment which
allowed for a review of the study and an opportunity to ask questions. If the individual
was interested, they were asked to complete a consent form (Appendix C). Once the
consent form was signed, eligibility was determined via a screening form (Appendix B).
Individuals who met eligibility criteria were asked to provide contact information and
were fitted for a blood pressure cuff (with cuff bladder encircling about 80 percent of the
arm) (Chobanian et al., 2003).
Subjects
Twenty-six subjects were recruited through print advertisements and online
announcement/bulletin boards. An a priori power analysis was done to determine sample
size. With a 5 percent type 1 error (alpha), and a 20 percent type 2 error (beta), 15
subjects were needed to observe a large effect (.8) on blood pressure (Faul, Erdfelder,
Lang, & Buchner, 2007). A power analysis was not accomplished for the exploratory
research question (diet components’ influence on baseline blood pressure). Subjects
served as their own control. Individuals willing to participate in this study were
determined to be eligible via a screening form. Only obese subjects between the ages of
40-65 years were eligible for inclusion due to increases in blood glucose and blood
pressure that commonly occur with age during adulthood and due to the increased risk of
hypertension with increasing adiposity. Exclusion criteria include: known allergies to
cinnamon or any ingredient in foods served during the study, current use of cinnamon or
other herbal supplements, current use of hypoglycemic or antihypertensive medications,
previous diagnosis of diabetes mellitus (type 1, type 2 or gestational) or hypertension,
severe health conditions (e.g., kidney disease, liver disease or cancer), pregnancy or
lactation.
19
Methods
This study was conducted in collaboration with a larger study that explored the
effects of cinnamon on blood glucose and appetite. Subjects completed two study visits,
at least five days apart, following an eight hour fast. After baseline blood pressure was
measured, subjects were given a breakfast drink containing 50 g available carbohydrate
that was prepared from whole milk, dextrose, vanilla and ice. The breakfast drink was
served plain during one visit and with the addition of 6 g ground cinnamon during one
visit. The order of the two breakfast drinks was randomly assigned for each subject using
an online randomizer (Urbaniak & Plous, 2011). Blood pressure was evaluated at
baseline and at 30, 60, 90, 120, 180 and 240 minutes following consumption of the
breakfast drink. During the study visit, subjects could read, listen to music and/or use
their computers. During the first visit, subjects completed a general survey to collect
information on demographics, physical activity, and diabetes risk factors. During the
second visit, in the second hour of the study visit, subjects completed a VioScreen webbased self-administered graphical FFQ to assess usual food and nutrient intake (Kristal &
Kolar, 2011).
Instruments
Blood pressure was obtained using the method described by the National
Institutes of Health in the Seventh Report of the Join National Committee on Prevention,
Detection, Evaluation and Treatment of High Blood Pressure using an automatic blood
pressure monitor (Chobanian et al., 2003). Subjects were seated quietly for at least 5
minutes with the left arm supported at heart level. An appropriately sized cuff
20
(determined at screening visit) was used to ensure accuracy. Two measurements were
recorded, and the average was used for data analysis and recorded on the Data Collection
Instrument (Appendix E). To collect information on demographics, physical activity, and
diabetes risk factors, a general survey was given (Appendix D).
The VioScreen web-based self-administered graphical FFQ was administered to
obtain an estimate of usual dietary intake (Kristal et al., 2011). FFQs have been used in
major epidemiological studies to examine usual nutrient intake (Thompson, Kipnis,
Midthune, Freedman, Carroll, 2008; Tsubota-Utsugi et al., 2011). The FFQ collects data
on the use of 156 food items in the past three months and takes approximately 26.7 ±10
minutes to complete (Kristal et al., 2011). The VioScreen graphical Food Frequency
Questionnaire (FFQ) has been shown to be a convenient, valid and reliable screening tool
(Kristal et al., 2011). When compared to multiple 24 hr recalls, inter-method reliability
was higher in the VioScreen than in the paper FFQ (Kristal et al., 2011). Test-retest
reliability was found to be comparable to other screening tools. One drawback of using
the FFQ is nutrient consumption is often difficult to measure due to underreporting
(Neuhouser et al., 2008). The FFQ assessed usual sodium, potassium, calcium, and fruit
and vegetable intake; all of which have been shown to affect blood pressure (Sacks et al.,
2001; Pimenta et al., 2009; Whelton et al., 1999; Sarkkinen et al., 2011;Wang et al.,
2008; Al-Solaiman et al., 2010; Tsubota-Utsugi et al., 2011).
Data Analysis
Blood pressure data were entered into Excel and uploaded into Statistical Package
for the Social Sciences (SPSS) v.19.0 for statistical analysis. Descriptive statistics were
21
run on all variables. Data was presented as means ± standard deviations. Paired t-tests
were used to assess differences in systolic and diastolic blood pressure at baseline and at
30, 60, 90, 120, 180 and 240 minutes after consuming the beverage with and without
cinnamon. Bonferroni corrected alpha level was p<.0083 to correct for the 6 tests
performed. Effect size in the present study was measured using Cohen’s d. Cohen’s d
was calculated using University of Colorado Springs online calculator (Becker, 2000).
Correlations were done to look for relationships between blood pressure and diet
components. Multiple regression analysis was performed to examine the relationship of
sodium, potassium, calcium and fruit and vegetable consumption on baseline blood
pressure.
The dietary intake information from the FFQ was downloaded into an Excel
spreadsheet and then uploaded into SPSS for analysis. Multiple regression analysis was
used to determine if the intake of sodium (mg), potassium (mg), calcium (mg), and
number of ½ cup servings of fruit and vegetables (excluding juices and potatoes)
predicted blood pressure at baseline. Regression analysis was done on placebo baseline
systolic and diastolic blood pressure. Statistical significance was set at p ≤ 0.05.
Summary
Through the methods previously described, the researcher studied the effect of 6 g
cinnamon on blood pressure in middle-aged obese individuals at risk for hypertension.
Using a crossover design, subjects consumed a drink with and without 6 g cinnamon.
Data were analyzed using paired t-tests, Cohen’s d to determine effect size, regression
22
analysis, and correlations. This study adds to the body of knowledge capable of
providing a treatment option for individuals with hypertension.
23
CHAPTER FOUR
RESULTS
Subjects
The baseline characteristics of the participants are shown in Table 1. This study
had a minimal dropout rate. A total of 28 participants were recruited, however one
participant withdrew from the study before the first study visit due to personal reasons,
and one was excused during the first visit due to low blood glucose. A total of 26
participants met inclusion criteria and completed the study. The average age of
participants was 52.5 years (SD = 7.1), and average BMI was 35.7 (SD = 5.0). The
subjects were primarily Caucasian (96%). The proportion of females to males was
considerably larger, 65% vs. 35% respectively. Most subjects reported their activity level
to be active (35%) or low active (35%). More than half of the subjects (58%) had a
family history of hypertension.
Table 1.
Demographics, Activity Level, and Family Hypertension Rate In Study
Participants
N
26
Age (years)
52.5±7.1
BMI (kg/m2)
35.7±5.0
Race
Caucasian
African American
25 (96%)
1 (4%)
Gender
Female
Male
17 (65%)
9 (35%)
Activity Level
Extremely Active
Very Active
Active
Low Active
Sedentary
1 (4%)
2 (7%)
9 (35%)
9 (35%)
5 (19%)
Family history of hypertension
Yes
15 (58%)
No
10 (38%)
No Answer
1 (4%)
Data presented as mean ± SD and n (%)
25
Blood Pressure Control vs. Cinnamon
Paired t-tests used to examine SBP over a period of four hours post prandial
without (control) and with (experimental) 6 g cinnamon are shown in Figure 1 and Table
2. Results revealed no significant differences in SBP at any time point between control
and cinnamon conditions (p>0.05). Cohen’s d indicated a small effect size at all time
intervals for SBP (0.02-0.18). For all time intervals systolic blood pressure did not differ
significantly in men and women, p>0.05.
Paired t-tests used to examine DBP over a period of four hours post prandial
without (control) and with (experimental) 6 g cinnamon are shown in Figure 2 and Table
3. There were no significant differences in DBP at any time point between control and
cinnamon conditions (p>0.05). Cohen’s d indicated a small effect size at all time
intervals for DBP (0.00-0.26). For all time intervals diastolic blood pressure did not
differ significantly in men and women, p>0.05.
26
Figure 1.
Systolic Blood Pressure During 4 Hour Post Prandial Period Without and
With 6 g Cinnamon
27
Table 2.
Mean Systolic Blood Pressure During 4 Hour Post Prandial Period
Without and With 6 g Cinnamon
Time
(minutes)
Control Blood
Pressure (mm
Hg)
Cinnamon
Blood Pressure
(mm Hg)
p
Cohen’s d
0
119.1±14.0
118.5±14.2
.762
0.04
30
116.7±11.7
115.8±12.4
.612
0.07
60
115.8±11.6
116.6±14.3
.708
0.06
90
118.8±12.2
117.2±14.2
.488
0.12
120
118.4±12.7
118.1±13.9
.891
0.02
180
120.6±13.7
118.4±12.2
.311
0.18
240
123.0±11.5
120.9±14.5
.312
0.16
Values are expressed as mean ± SD
28
Figure 2.
Diastolic Blood Pressure During 4 Hour Post Prandial Period Without and
With 6 g Cinnamon
29
Table 3.
Mean Diastolic Blood Pressure During 4 Hour Post Prandial Period
Without and With Cinnamon
Time
(minutes)
Control Blood
Pressure (mm
Hg)
Cinnamon
Blood Pressure
(mm Hg)
p
Cohen’s d
0
77.8±9.9
77.4±10.2
.716
0.04
30
74.9±9.4
74.9±9.5
.985
0.00
60
76.8±12.5
74.7±10.4
.284
0.19
90
79.6±13.5
77.4±10.7
.246
0.19
120
80.2±12.6
78.2±11.1
.292
0.17
180
81.1±12.7
78.1±9.4
.126
0.26
240
81.4±11.1
79.3±9.3
.158
0.21
Values are expressed as mean± SD
30
Blood Pressure and Correlations between Diet Components
Table 4 represents correlations among baseline control blood pressure and
sodium, potassium, calcium and fruit and vegetable intake. There were no significant
correlations between baseline diastolic blood pressure and sodium r(24) = .218, p>0 .05,
potassium r(24) = 0.26, p>0.05, calcium r(24) = .332, p >0.05, and fruit and vegetable
intake r(24) = .107, p>0.05. There were no significant correlations between systolic
blood pressure and sodium r(24) = .187, p>0.05, potassium r(24) = .338, p>0.05 and fruit
and vegetable intake r(24) = .132, p>0.05. Systolic baseline blood pressure and calcium
intake were moderately correlated, r(24) =.441, p<0.05. There were significant
correlations between diet components. Sodium and potassium were moderately
correlated, r(24) =.702, p<0.01, sodium and calcium were moderately correlated, r(24)
=.519, p<0.01, potassium and calcium were moderately correlated, r(24) =.705, p<0.01,
and potassium and fruit and vegetable intake were moderately correlated, r(24) =.616,
p<0.01.
31
Table 4.
Correlations between Blood Pressure and Diet Components
Variable
Sodium
Potassium
Calcium
Fruit and
Vegetable
SBP
.187
.338
.441*
.132
DBP
.218
.260
.332
.107
.702**
.519**
.373
.705**
.616**
Sodium
Potassium
.293
Calcium
*p<0.05,**p<0.01
Diet Components’ Effect on Blood Pressure
Table 5 and Table 6 represent multiple regression analysis that was used to
determine if diet components (sodium, potassium, calcium and fruit and vegetable intake)
significantly predicted control baseline blood pressure. The results of the regression
indicated that none of the dietary components significantly affected baseline systolic
blood pressure, R2=.20, F(4,21) = 1.35, p>0.05, or baseline diastolic blood pressure,
R2=.11, F(4,21) = 0.67, p>0.05.
32
Table 5.
Diet Components Prediction of Baseline Systolic Blood Pressure
β
B
p
107.81
Constant
Sodium
-.123
-.001
.659
Potassium
.172
.002
.673
Calcium
.397
.009
.177
Fruit and Vegetable
-.044
-.202
.866
R2=.204, F(4,21)=1.35, p>0.05
33
Table 6.
Diet Components Prediction of Baseline Diastolic Blood Pressure
β
B
p
70.87
Constant
Sodium
.056
.000
.849
Potassium
.025
.000
.954
Calcium
.289
.005
.345
Fruits & Vegetables
-.014
-.044
.960
R2=.113, F (4,21)=0.67, p>0.05
34
Summary
Twenty-six middle-aged obese adults completed the study. Paired t-tests found
no differences in blood pressure between the control and experimental conditions at any
time point. Although there were multiple correlations between diet components, the only
significant correlation between diet and blood pressure was a positive correlation
between calcium and SBP. Multiple regression analysis found usual intake of sodium,
potassium, calcium, and fruits and vegetables did not predict baseline blood pressure.
These results indicate no effect of 6 g cinnamon on blood pressure in middle-aged obese
adults.
35
CHAPTER FIVE
DISCUSSION
The purpose of this study was to examine the short-term effect of 6 g
ground cinnamon on blood pressure in middle-aged obese adults at increased risk for
developing hypertension. This chapter discusses the findings of the current study in
comparison to previous research that has been conducted on cinnamon and its effects on
blood pressure. The present study suggests 6 g cinnamon does not exert a significant
short-term antihypertensive effect on systolic or diastolic blood pressure. In addition, this
study investigated the relationship between diet components sodium, potassium, calcium
fruit and vegetable intake and blood pressure. The results of this study found no
relationship between diet components and baseline blood pressure. A discussion of the
results are presented in this chapter.
Limitations
Several limitations of this study should be addressed. First, the results from this
study are not representative of the general population due to the homogeneity of the
subjects. Additionally, this study did not represent genders equally; the majority of study
participants were female. Furthermore, this study did not incorporate individuals with a
history of hypertension or type 2 diabetes, two conditions that are present in human
subjects participating in research observing the effects of cinnamon on blood pressure
(Akilen et al., 2010; Ziegenfuss et al., 2006). Another potential limitation in this study
was sample size. Although sample size was adequate for assessing the effects of
cinnamon on blood pressure, it was not adequate for predicting baseline blood pressure
from usual diet intake. The current study used cinnamon incorporated into a beverage.
This differs from other studies which use cinnamon capsules. A related potential
weakness is 6 g cinnamon is the maximum amount that can be incorporated into food,
whereas other studies have used up to the equivalent of 10 g cinnamon in an extract. For
these reasons, the results of this study should be interpreted with care.
Timing
Several studies in humans indicate daily cinnamon supplementation for 12 weeks
has beneficial effects on blood pressure (Akilen et al., 2010, Ziegenfuss et al., 2006).
This is the first study in humans to our knowledge to study the immediate effects of
cinnamon on blood pressure. In spontaneously hypertensive rats, significant changes in
SBP were observed by the second week of 4% and 8% w/w cinnamon supplementation
(Preuss et al., 2006). In vitro and in vivo studies in animals have observed immediate
decreases in blood pressure induced by cinnamon (Xue et al. 2011; Nyadjeu et al., 2013;
Nyadjeu et al., 2011). It is of interest that all of these studies induced
hypertension/vasoconstriction before the administration of cinnamon. This evidence
suggests the immediate effects of cinnamon to lower blood pressure may only be seen in
hypertensive individuals. The possible mechanisms include blocking vasoconstrictors
37
(angiotensin II and phenylephrine) and inducing vasodilators (nitric oxide) (Xue et al.,
2011; Nyadjeu et al., 2013). Findings from the current study indicate no immediate
beneficial effect on blood pressure on individuals that had no prior diagnosis of
hypertension.
Mechanism of Action
The potential blood pressure lowering effects of cinnamon have been identified in
vivo and in vitro animal studies. A study by Xue et al. (2011) proposes the vasodilatory
effects of cinnamaldehyde may be due to its ability to interfere with both Ca2+ influx and
Ca2+ release. El-Bassossy and colleagues (2011) propose the effect of cinnamaldehyde
on diabetes-induced hypertension is its antihyperglycemic effect via a role in Ca2+ influx.
The vasodilatory effects of cinnamon identified in previous research suggest the blood
pressure lowering effects may have a larger effect in individuals with insulin resistance
(El-Bassossy et al., 2011). Type 2 diabetes decreases vascular structure and function; if
cinnamon can help prevent hyperglycemia, it can then help slow vascular degradation.
Intravenous administration of the methanol extract of Cinnamomum zeylanicum stem
bark was found to lower blood pressure via the nitric oxide pathway by producing the
vasodilator nitric oxide in hypertensive rats (Nyadjeu et al., 2013). Nitric oxide induced
vasodilation may have the potential to affect the mobilization of Ca2+, thus lowering
blood pressure (Van Hove, Van der Donckt, Herman, Bult, & Fransen, 2009).
Cinnamon extracts and cinnamon polyphenols have been researched for their
potential to increase the GLUT4 protein, (a protein often decreased in insulin resistance),
therefore acting like insulin (Cao, Polansky, & Anderson, 2007; Leguisamo, Lehnen,
38
Machado, Okamoto, Markoski, Pinto, & Schaan, 2012). GLUT4 is a transport protein
initiated by insulin that catalyzes the uptake of glucose into adipose and muscle cells
(Watson, Kanzaki, & Pessin, 2004). The activation of GLUT4 by cinnamon works to
regulate blood glucose in type 2 diabetes which could also prevent the development of
metabolic syndrome, CVD, and hypertension. The present study did not examine the
mechanism of cinnamon on blood pressure; more research needs to be done to fully
understand the underlying mechanism of cinnamon.
Amount of Cinnamon
The reduction of blood pressure has been observed with various doses of
cinnamon. The effect of cinnamon supplementation on blood pressure can be seen with
as little as 2 g cinnamon, reported by Akilen et al. (2010). However, it should be noted
that individuals in the study done by Akilen and colleagues had type 2 diabetes and
consumed the 2 g cinnamon daily over a period of 12 weeks. The effects of cinnamon
can also be seen with the equivalent of 10 g cinnamon supplementation as reported by
Ziegenfuss et al. (2006). When studying the immediate effects of cinnamon, findings
from the current study suggest 6 g of cinnamon does not significantly impact blood
pressure. The amount of cinnamon to see an immediate effect on blood pressure is
uncertain and needs to be investigated further.
Form of Cinnamon
Research suggests cinnamon is a spice that has the potential to lower blood
pressure. Several forms of cinnamon have been used to determine optimal benefits of
39
this spice. In rats, blood pressure lowering effects of cinnamon extracts have
demonstrated significant decreases in blood pressure similar to those of whole cinnamon
(Preuss et al., 2006; Nyadjeu et al., 2013). In humans, cinnamon extracts and cinnamon
powder (made from species Cinnamomum cassia) supplementation have shown blood
pressure lowering effects (Ziegenfuss et al., 2006; Akilen et al., 2010).
Ziegenfuss and colleagues (2006) found Cinnulin PF® (a specific aqueous extract
of cinnamon) exhibited blood pressure lowering effects in humans. The action of
Cinnulin PF® may be due to procyanidin type-A polymer, a polymer found in cinnamon
that enhances insulin activity (Ziegenfuss et al., 2006; Anderson et al., 2004). In vitro,
the polyphenolic compounds of cinnamon have been studied for their ability to enhance
the activity of insulin (Anderson et al., 2004). In humans, cinnamon extracts have shown
the ability to decrease oxidative stress and improve impaired fasting glucose (Roussel,
Hininger, Benaraba, Ziegenfuss, & Anderson 2009). The antioxidant effects of cinnamon
extracts to reduce oxidative stress and improve impaired fasting glycemia, suggests
cinnamon has the potential to protect against vascular complications (Roussel et al.,
2009; Ortiz, Manriquez, Romero, & Juncos, 2001). Ground cassia cinnamon was used in
the present study due to its studied potential to lower blood pressure. Experimenting
further with different forms of cinnamon may help to develop a strategy to ameliorate the
effects of chronic diseases.
Participants’ Health Conditions
Previous studies supporting the positive effects of cinnamon on blood pressure
have included subjects with underlying conditions such as type 2 diabetes, prediabetes,
40
and metabolic syndrome (Akilen et al., 2010; Ziegenfuss et al., 2006). None of the
previous studies to date have investigated the effect of cinnamon on blood pressure in
subjects without prediabetes, type 2 diabetes or hypertension. Previous research suggests
cinnamon has a greater effect on blood pressure in individuals with a higher baseline
systolic blood pressure (Ziegenfuss et al., 2006; Akilen et al., 2010). Wainstein and
colleagues (2011) included subjects with type 2 diabetes and found no significant effect
of cinnamon on blood pressure. Cinnamon may only have the ability to reduce blood
pressure in individuals with preexisting conditions, like hypertension. The present study
found no significant effects of cinnamon on blood pressure in subjects with no prior
diagnosis of hypertension or diabetes mellitus.
Diet and Blood Pressure
Despite research suggesting beneficial effects of sodium, calcium, potassium, and
fruit and vegetable intake on blood pressure, this study found no significant relationship
between these diet components and control baseline blood pressure (Sacks et al., 2001;
Pimenta et al., 2009; Whelton et al., 1999; Sarkkinen et al., 2011; Wang et al., 2008; AlSolaiman et al., 2010; Tsubota-Utsugi et al., 2011). Sample size for this study was too
small to significantly predict control baseline blood pressure. As evidenced by small
proportions of variance (20%, 11%), we suggest a larger sample size to detect a
significant impact of usual diet intake on blood pressure.
The reason no relationships were observed may have been due to the tool used for
evaluating dietary intake. The FFQ has the potential for error due to under or over
reporting by the participants (Neuhouser et al., 2008). Diet components such as sodium
41
and potassium are often more difficult to measure in study participants. The
measurement of biological samples, such as urine, to determine intake of certain nutrients
would account for the underestimation that may occur with self-reporting. Methods for
diet analysis should be considered when evaluating usual food and nutrient intake of
subjects.
Strengths
Strengths of this study include a low dropout rate. Although a relatively small,
homogeneous subject sample was used, cinnamon powder appeared to be safe at the
dosage and duration studied. All individuals tolerated the breakfast beverage without and
with cinnamon. This study was adequately powered to detect differences in blood
pressure.
Summary
Although there were limitations to this study, most notably sample size and
subject health history, this study had a low dropout rate and was adequately powered to
detect differences in blood pressure. This study differed in the amount and type of
cinnamon compared to other human studies. Several studies have hypothesized the
underlying mechanism of cinnamon on blood pressure; however, the present study did
not investigate the mechanism of action of cinnamon. The current study recruited
subjects with no prior history of hypertension or diabetes mellitus, differing from
previous research studying the effect of cinnamon on blood pressure in humans. To our
knowledge, this is the first study to examine the immediate effect of cinnamon on blood
42
pressure. Although previous research suggests diet components affect blood pressure,
diet did not predict baseline blood pressure. While this study suggests no beneficial
impact of cinnamon on blood pressure, it adds to the pool of research data to continue
examining the effects of cinnamon on blood pressure.
43
CHAPTER SIX
CONCLUSIONS AND RECOMMENDATIONS
Conclusions
The purpose of this study was to examine the short-term effect of 6 g ground
cinnamon on blood pressure in middle-aged obese adults at an increased risk for
developing hypertension. The results of this study suggest 6 g cinnamon does not exert a
short-term beneficial effect on blood pressure. The current research does not indicate
ground cinnamon should be consumed to lower blood pressure in individuals with no
previous history of hypertension or type 2 diabetes. Although some week long studies
support the efficacy of cinnamon supplementation on reducing blood pressure, the current
study does not support the use of cinnamon for immediate reduction of blood pressure.
Recommendations for Future Research
Additional research is required to examine the effects cinnamon has on blood
pressure. Based on the results of this study, the following recommendations for future
research are made:
1. Future research should recruit subjects with type 2 diabetes mellitus. Due to the
mechanisms previously studied, cinnamon may only have the potential to lower
blood pressure in individuals with type 2 diabetes.
2. Future research in humans should use cinnamaldehyde or cinnamon extracts to
determine immediate effects of cinnamon on blood pressure similar to Xue et al.
(2011) and Nyadjen et al. (2013).
3. WHO considers a 24-hour urine collection to be the “gold standard” for
measuring sodium intake (World Health Organization, 2007). This being said,
there are limitations for using this measurement tool such as a high cost and high
participant burden. The use of a 24-hour urine collection to measure sodium
could improve accuracy of estimating an important diet component that affects
blood pressure.
4. Recruitment of a more diverse sample will better represent the general population.
45
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Appendix A
Institutional Review Board Materials
A-1
Letter from Ball State IRB
A-2
CITI Letter of Completion
53
Appendix A-1
Letter from Ball State Institutional Review Board
54
Appendix A-2
CITI Collaborative Institutional Training Initiative Certificate
55
Appendix B
Screening Form
56
Impact of a Cinnamon-Rich Breakfast Drink on Blood Glucose, Blood Pressure
and Appetite
Screening Form
Age: ________
Gender:
M/ F
Height: ____________
Weight: ____________
BMI: ____________
1. Are you currently pregnant?
____ No
____Yes
2. Do you have any known food allergies?
____ No
____Yes (Please describe below)
___________________________________________________________
___________________________________________________________
3. Do you currently take any herbal supplements?
____ No
____Yes (Please describe below)
___________________________________________________________
___________________________________________________________
4. Are you currently following a weight reduction diet?
____ No
____Yes (Please describe below)
___________________________________________________________
___________________________________________________________
57
5. Have you previously been diagnosed by your doctor or other health professional with
diabetes mellitus (type 1, type 2 or gestational)?
____ No
____Yes (Please describe below)
___________________________________________________________
___________________________________________________________
6. Are you currently taking medication that lowers your blood glucose? See examples
on next page.
____ No
____Yes (Please identify below)
___________________________________________________________
___________________________________________________________
7. Have you previously been diagnosed by your doctor or other health professional with
high blood pressure?
____ No
____Yes (Please describe below)
___________________________________________________________
___________________________________________________________
8. Are you currently taking medication that lowers your blood pressure? See examples
on next page.
____ No
____Yes (Please identify below)
___________________________________________________________
58
___________________________________________________________
9. Are you comfortable providing blood samples by capillary finger prick?
____ No
____Yes
10. Are you willing and able to eat the following foods during the study: rice milk-based
breakfast drink with cinnamon, peanut butter and strawberry jelly sandwiches on
wheat bread, turkey and American cheese sandwiches with salad dressing on wheat
bread, potato chips and blueberry muffins?
____ No
____Yes
Examples of Medications that Lower Blood Glucose:
Drug Class
Generic Drug Names/Brand Names
Sulfonylureas
Chlorpropamide (Diabinese)
Glipizide (Glucotrol and Glucotrol XL)
Metformin (Glucophage)
Rosiglitazone (Avandia)
Acarbonse (Precose)
Repaglinide (Prandin)
Sitagliptin (Januvia)
Biguanides
Thiazolidinediones
Alpha-Glucosidase Inhibitors
Meglitinides
Dipepitdyl peptidase IV
Examples of Medications that Lower Blood Pressure:
Drug Class
Diuretics
Angiotensin-Converting (ACE) Inhibitors
Angiotensin II Receptor Blockers
Beta Blockers
Calcium Channel Blockers
Renin Inhibitors
Generic Drug Names/Brand Names
Captopril (Capoten)
Iosartan (Cozaar)
Metoprolol (Lopressor, Toprol XL)
Diltiazem (Cardizem, Dilacore XR)
Nifedipine (Adalat, Procardia)
Aliskiren (Tekturna)
59
Appendix C
Participant Letter of Consent
60
Study Purpose and Rationale
Previous research has shown beneficial effects of ground cinnamon on blood glucose
levels in healthy adults. However, there is conflicting evidence on the influence of
cinnamon on blood pressure and appetite.
The purpose of this study is to describe the effects of a breakfast beverage containing 6 g
cinnamon on blood glucose, blood pressure and appetite.
Inclusion/Exclusion Criteria
To be eligible to participate in this research, you must be between the ages of 40-65,
carry extra body fat (BMI of at least 30), willing to provide blood samples via finger
prick, willing and able to consume study foods and beverages, not previously diagnosed
with diabetes or high blood pressure, not pregnant, not currently on medication to lower
blood glucose or blood pressure, not currently on a weight loss diet, not taking herbal
supplements and not allergic to foods/ingredients used in the study.
Participation Procedures and Duration
You will be asked to meet with the researcher for 10-15 minutes to sign an informed
consent document, complete a screening form, and discuss and answer questions about
the study. You will be excluded from the study after the initial screening if you do not
meet the inclusion criteria.
Once enrolled, you will be asked to visit the Nutrition Assessment Lab at Ball State
University for 4 ½ hours on two different occasions, at least 5 days apart. During each
visit, you will consume a breakfast drink with or without cinnamon. Your blood glucose,
blood pressure, and appetite levels will be assessed over the next 4 hours, then you will
be fed lunch. During the study, you will be asked questions regarding demographic
information, physical activity, food allergies, usual food intake, and family history of
type 2 diabetes. The total participation time for the entire study will be 9 hours.
During each visit, you will be asked to drink a breakfast beverage with or without 6 g
cinnamon in a 15 minute period. You will complete 9 assessments of blood glucose,
blood pressure and appetite over a 4-hour period. Then you will be fed lunch. The total
participation time for the entire study will be 9 hours.
Capillary finger prick will be used to collect blood for analysis of blood glucose levels.
An electronic blood pressure instrument will be used to evaluate your blood pressure. A
paper survey will assess your appetite.
Upon arrival at the lab, you will be asked to sit at an assigned station. Once you are
comfortable, a blood sample will be obtained by capillary finger prick to assess fasting
61
blood glucose, your blood pressure will be evaluated and you will be asked to describe
your appetite using the paper survey.. You will then be asked to drink the breakfast
beverage within a 15-minute period. You will also be given 16 oz of water that you may
drink, if you like, during the first 3 hours of the study visit. Additional evaluation of
blood glucose, blood pressure, and appetite will be completed at 15, 30, 45, 60, 90, 120,
180 and 240 minutes. At 240 minutes (4 hours) from the start of the study visit, you will
be fed a buffet lunch of sandwiches (peanut butter and jelly sandwiches on wheat bread
and turkey and American cheese sandwiches with salad dressing on wheat bread), potato
chips and blueberry muffins.
During the study visit, you may read, listen to music and/or use your computer. Subjects
may also have conversations with research staff or other subjects, as long as they are not
related to food, appetite or other study-related topics. With the exception of restroom
breaks, you must remain seated and sedentary during the study visit.
Data Confidentiality or Anonymity
All data will be maintained as confidential and no identifying information such as names
will appear in any publication or presentation of the data. Once the informed consent
document has been signed, you will be assigned a unique identifier. This unique identifier
or study number, not your name, will be used for all study related forms, including
screening forms and data collection forms.
Storage of Data
The master list containing your name and study number will be stored in the primary
investigator’s locked office in a locked file cabinet. This master list will be destroyed
after data collection has been concluded and compensation has been distributed. All
study forms, including completed screening and data collection forms, will also be stored
in the primary investigator’s locked office in a locked file cabinet for three years and will
then be shredded. The de-identified data will be entered into an Excel spreadsheet; this
electronic data will be stored on the primary investigator’s password-protected computer
with a backup copy on iLocker. Data will be presented only in aggregate; no individual
data will ever be released. Only members of the research team will have access to the
data.
Risks or Discomforts
The research is of minimal risk to you. You may experience mild discomfort from the
pricking of your finger to determine your blood glucose level. In the unlikely event of an
adverse reaction, emergency medical treatment will be available to you if you become
injured or ill during participation in this research. You will be responsible for the costs of
any medical care that is provided. If any injury or illness occurs in the course of your
participation in this research project, please seek treatment as appropriate and notify the
62
research staff as soon as possible. The research staff will immediately contact 911 for
emergency care if emergency care is needed.
There is a possibility that having your finger pricked to determine your blood glucose
level may result in discomfort. If you experience discomfort, report it to the research
staff; they can provide cooling packs for topical relief. In addition, you can choose to
stop your participation at any time.
It is understood that in the unlikely event that treatment is necessary as a result of your
participation in this research project that Ball State University, its agents and employees
will assume whatever responsibility is required by law.
Benefits and Incentives
By participating in this study, you may benefit by learning more about your blood
glucose and blood pressure levels. You will be given general information about blood
glucose and blood pressure, as well as specific information about your blood glucose and
blood pressure levels during the study.
In addition, you will receive up to $50 in compensation for your time. Because the study
includes two study visits, the compensation will be prorated to $25 if you choose to
complete only one study visit.
Voluntary Participation
Your participation in this study is completely voluntary, and you are free to withdraw
your permission at anytime for any reason without penalty or prejudice from the study
staff. Please feel free to ask any questions of the primary investigator before signing this
form and at any time during the study.
Additional Information
There is information related to this research that cannot be explained prior to the
beginning of the study. This information will be provided once you complete your
participation.
IRB Contact Information
For your rights as a research subject, you may contact the following: Office of Research
Integrity, Ball State University, Muncie, IN 47306, (765) 285-5070, irb@bsu.edu.
63
Consent
I, _______________________________, agree to participate in this research project
entitled, “Impact of a Cinnamon-Rich Breakfast Drink on Blood Glucose, Blood Pressure
and Appetite.” I have had the study explained to me, and my questions have been
answered to my satisfaction. I have read the description of this project and give my
consent to participate. I understand that I will receive a copy of this informed consent
form to keep for future reference.
To the best of my knowledge, I meet the inclusion/exclusion criteria for participation
(described on the first page) in this study.
________________________________
_________________
Participant’s Signature
Date
Researcher Contact Information
Primary Investigator:
Co-Investigator:
Jo Carol Chezem, PhD, RD
Associate Professor
Family and Consumer Science
Ball State University
Muncie, IN 47306
Telephone: (765)285-5959
Email: 00jcchezem@bsu.edu
Nicolle Fernandes, PhD, RD
Assistant Professor
Family and Consumer Sciences
Ball State University
Muncie, IN 47306
Telephone: (765)285-5956
Email: nvfernandes@bsu.edu
64
Appendix D
General Survey
65
General Survey
1. In a typical week, how often do you take part in physical activities? (Examples:
walking, jogging, bike riding or anything that increases your heart rate).
_____ None
_____ 1 day/week
_____ 2 days/week
_____ 3 days/week
_____ 4 days/week
_____ 5 days/week
_____6 days/week
_____7 days/week
2. On days when you take part in physical activity, how many minutes do you
usually spend in this activity?
_____ Minutes
3. Compared with most men or women your age, you are ____.*
____ More active
____ Less active
____ About the same
4. Does anyone in your immediate family (mother, father, brother and/or sister) have
diabetes?*
_____ Yes
_____No
5. Does anyone in your immediate family (mother, father, brother and/or sister) have
hypertension/high blood pressure?
_____ Yes
_____ No
6. What race or ethnicity best describes you?*
___ White/Caucasian ___ Black/African American
___ Hispanic
___ Native American
___ Asian
___ Other
* From http://www.diabetes.org/diabetes-basics/prevention/diabetes-risk-test/
66
Appendix E
Data Collection Instrument
67
68