The media article called Blueberries could cut your risk of heart disease ‘by a FIFTH’ (but
you'd have to eat a punnet per day for a month) by Peter Lloyd claims that blueberries are a
significant source of certain chemical compounds that may possibly reduce risks of cardiovascular
diseases. Researchers have narrowed down and deduced that a particular group of polyphenols
called anthocyanins are the reason behind the beneficial effects of blueberries. Anthocyanins are
the reason why blueberries have a deep indigo colour. For this specific research article, it states
that consuming 200g of blueberries can help lower levels of blood pressure and improve
functioning of blood vessels. The key points in the article include conclusions about anthocyanins
improving endothelial functioning which would directly affect the possible pliability of the lining
of blood vessels. Blood vessel diameter was measured through flow mediated dilation. Stiffness
of arteries is a genuine concern in cardiovascular health. Effects of blueberries on blood vessels
were found to be instantaneous. Blood vessel condition improved in just a mere of 2 hours. Doctor
Ana Rodriguez-Mateos claims that by consuming blueberries every single day, it can reduce an
individual’s risk of developing a cardiovascular disease by 20%. A study was done with 40
participants who were given a 200g drink everyday that was either a blueberry drink or a placebo
drink. In order to measure effects of blueberries, tests for blood pressure, blood as well as urine
was also conducted. Flow mediated dilation which is a measure of blood flow on artery size was
also another way for researchers to calculate results. Unfortunately, in order to fully receive the
full benefits of anthocyanins from blueberries, a minimum of 200g of blueberries is required to be
consume daily. Other nutrients derived from blueberries that may have a factor in altering blood
pressure are procyanidins, flavonols and phenolic acids. Blueberries have a smaller and less
significant amount of these vitamins in comparison to anthocyanin. In the end, the article still
claims that consuming at least 200g of blueberries a day can significantly reduce the risk of
developing a cardiovascular disease and that the reduction is linked to the anthocyanins in
blueberries. The credibility of the media article is high as King's College London where the
research was conducted at is a reputable public research university. Research on anthocyanin
effects were duplicated/ replicated and the results were found to be similar to results found in other
studies.
When analyzing this media article, we wanted to find out the credentials of the researchers
and publishers involved. Doctor Ana Rodriguez-Mateos who is the lead researcher of this study
is currently a lecturer at King’s London College. The author of this media article is Peter Lloyd
who has written this article has been nominated for two awards in journalism. These two facts
highly increase the credibility of our article. Blueberries have also been well known to be a super
food that is extremely beneficial for health so it is not out of the ordinary to state that blueberries
have a positive effect on cardiovascular health. The journal that the study was published in was
also a reputable journal that was published in the Journal of Gerontology Series A by Oxford
Academia. Oxford journals are said to all be peer reviewed. Oxford is also a highly reputable and
well- known university so any articles published under their name would be well written. Factors
that may have influenced results were controlled for as much as possible such as consumption time
as well as consistent measuring of blood pressure, blood, and urine. The control and experimental
groups were allowed the same amount of liquid to control for any outlying variables. Participants
were not subject to any memory bias or recall bias as data collected is quantitative and not
qualitative. Another concern from the media article may be that the sample size for the research
was relatively small since there were less than 100 people that were selected and studied. In order
to achieve better results in the future, a bigger sample size would allow for a higher confidence
level in finding statistically significant data. As well, the blood pressure was also lowered by 5
mmhg. 5 mmhg is a relatively small amount to decrease by. Other lifestyle factors could have
contributed to this.
The first journal article we chose to support the media article is Diets containing blueberry
extract lower blood pressure in spontaneously hypertensive stroke-prone rats by Kevin S.
Shaughnessy, Ian A. Boswalla , Adam P. Scanlana,b, Katherine T. Gottschall-Passb, and Marva
I. Sweeney. A study was done on rats to see how consuming blueberries can prevent the rats from
developing hypertension. The definition of hypertension is described as having a blood pressure
level of 140/90 mm Hg or more which can lead to the risk of developing myocardial infarction and
a stroke. The article hypothesized that consuming blueberries regularly will slow down the process
of a rat from developing hypertension due to the antioxidants in blueberries. In the study, there
were a total of 24 male rats that were divided into 2 groups, where the first 12 rats were considered
as the control group while the other 12 rats were considered as the ‘spontaneously hypertensive
stroke-prone rats’ (SHSPR) group. Both groups had the same variables when it comes to the cage
they were staying in, the temperature of the cage, and the light/ dark cycle. The only difference
was that the rats were randomly assigned to 1 out of the 2 diet groups where one group contained
3% more in freeze dried blueberries and as well for every diet of 100g, about 3g of cornstarch was
removed from the blueberry diet. This was ongoing for 8 weeks where the rats were consistently
being monitored and weighed. The results came out and researchers noticed that the systolic blood
pressure in SHSPR rats who had a normal diet had an elevated blood pressure of 206 to 216 mm
HG while for SHSPR rats who were on the blueberry diet, had a lower blood pressure level which
went down to 19%. A problem with this study is the duration of how long these rats were analyzed
for when it came to their diets. Researchers in this study has mentioned that when the rats
consumed the blueberries, it definitely reduced the risk of developing hypertension. As well,
researchers did state that although blueberries did slow down the process of rats developing
hypertension, 8 weeks is generally not enough time to see the full picture of how consuming
blueberries can truly have an effect on slowing down/ preventing cardiovascular diseases.
The second journal article Blueberries Decrease Cardiovascular Risk Factors in Obese
Men and Women with Metabolic Syndrome by Arpita Basu, Mei Du Misti J. Leyva, Karah
Sanchez, Nancy M. Betts, Mingyuan Wu, Christopher E. Aston, and Timothy J. Lyons states that
systolic and diastolic blood pressure are two very important measurements in determining risk
factors for cardiovascular diseases. In a single blinded control study published in the Oxford
Journal of Medicine, 34 test subjects were studied on the effects of blueberries on cardiovascular
health for 8 weeks. In this particular study, all 66 participants were suffering from metabolic
syndrome. Participants were also a mix of both men and women who were medically diagnosed
to be obese. This means that cardiovascular risk was extremely high. Wild freeze dried blueberries
were chosen for this experiment as wild blueberries were found to contain the highest amount of
anthocyanins. The freeze drying method of preservation was also proven to be most effective in
retaining optimal anthocyanin levels. Breed of blueberries used were lowbush or wild blueberry
which contains both high levels of anthocyanin as well as a higher level of antioxidant capacity.
Blueberries were administered in a rehydrated form from freeze dried blueberries. Tifblue and
Rubel wild blueberries were blended together and given to participants in 50g doses reconstituted
in 480 mL water. Half of this blueberry blend was consumed in the morning and the other half was
consumed at night with at least a 6-8 hour gap in consumption. In order to control for variables,
participants from both control and experimental groups drank the same amount of liquids per dose
of blueberries or placebo. The control group consumed 950mL of water. No other factors in the
participants’ life was affected besides the addition of blueberries into their diet. This meant that
factors such as their typical lifestyle, diet, and physical activity were also kept the same. Results
corroborate with our media article’s claim.
In conclusion with this journal article, blueberries were found to have a positive effect on
cardiovascular health. This experiment also found that blueberries had an effect on endothelial
lining. Systolic and diastolic blood pressure in participants were also found to be lower than at the
beginning. In comparison to the control group, participants in the experimental group showed
greater decreases in systolic and diastolic blood pressure as well. In this second article there was
reported to be a decrease in both vasoconstriction as well as renal oxidative stress which was said
to directly affect systolic blood pressure. With these results, researcher were able to successfully
conclude that blueberries had an antihypertensive effect on participants with metabolic syndrome.
The last journal article we analyzed was called Habitual intake of anthocyanins and
flavanones and risk of cardiovascular disease in men by Aedín Cassidy, Monica Bertoia,
Stephanie Chiuve, Alan Flint, John Forman, and Eric B Rimm. Researchers also categorized
anthocyanins as flavonoids. In the last study we analyzed, researchers were interested in finding
out the correlation between the cardio-protective effects of a anthocyanin rich diet on coronary
artery disease long- term study that focused on blueberries that were extraordinarily rich in
anthocyanins. In this particular prospective cohort study, 51,529 males were studied for 24 years
worth of follow up. In conclusion, researchers were able to successfully repeat the results of
previous studies done. The effectiveness of the anthocyanin rich blueberries were proven again.
Participants who were found to have consumed higher amounts of anthocyanin rich blueberries
were also found to have lead healthier lifestyles. This included high levels of physical activity as
well as a more balanced diet full of fibre. Alcohol and smoking were abstained. This study differs
from other studies in that blueberries were not directly administered to participants. Instead, this
study takes on a more natural approach and simply documents the relationship between strokes
and anthocyanin and flavonoid intake. Anthocyanins were calculated to show a 14% decrease in
risk of nonfatal myocardial infarctions. Factors such as lifestyle and diet were also factored into
this calculation in order to exclude other factors that may have contributed to differences in
cardiovascular health.
In conclusion, all three of the journal articles states that anthocyanins were found to
significantly affect cardiovascular health. Anthocyanins were able to positively influence
endothelial functioning as well as blood pressure. As one researcher from our journal articles
noted, this also expands possibilities for cardiovascular health beyond just blueberries. The article
states that the effects of blueberries mimic the effects of hypertension medicine. Anthocyanins can
possibly be marketed as a more natural and tastier option for improving cardiovascular health.
Blueberries are also a source of micronutrients and fibre which may contribute to helping reduce
blood pressure levels. By comparing the three journal articles with the media article, we are able
to conclude that the media article had demonstrated the effectiveness of blueberries on prevention
in the risk of developing a cardiovascular disease. Media articles have the tendency to
sensationalize certain aspects of research in order to attract a wider audience and increase shock
factor. Some media articles may also state claims without any scientific evidence to provide
credibility. While our media article was fortunately supported by numerous other research articles,
it is in our best interests to always critically analyze media articles and their claims.
References
Basu, A., Du, M., Leyva, M. J., Sanchez, K., Betts, N. M., Wu, M., . . . Lyons, T. J. (2010). Blueberries
Decrease Cardiovascular Risk Factors in Obese Men and Women with Metabolic Syndrome. The
Journal of Nutrition, 140(9), 1582-1587. doi:10.3945/jn.110.124701
Cassidy, A., Bertoia, M., Chiuve, S., Flint, A., Forman, J., & Rimm, E. B. (2016). Habitual intake of
anthocyanins and flavanones and risk of cardiovascular disease in men. The American Journal of
Clinical Nutrition, 104(3), 587-594. doi:10.3945/ajcn.116.133132
MailOnline, P. L. (2019, February 21). Blueberries cuts your risk of heart disease 'by a FIFTH' (but
you'd have to eat a punnet a day) . Retrieved April 2, 2019, from
https://www.dailymail.co.uk/health/article-6729019/Blueberries-cuts-risk-heart-disease-FIFTHyoud-eat-punnet-day.html
Shaughnessy, K. S., Boswall, I. A., Scanlan, A. P., Gottschall-Pass, K. T., & Sweeney, M. I. (2009).
Diets containing blueberry extract lower blood pressure in spontaneously hypertensive strokeprone rats. Nutrition Research, 29(2), 130-138. doi:10.1016/j.nutres.2009.01.001