Melissa Vigdor - NUTR6101 Final Exam
Title
Vitamin B-12 Injection Intervention for Weight Loss in an Overweight/Obese Population of
Adult Males and Females – a randomized crossover pilot study
Problem
The popularity of vitamin B-12 injections for weight loss has been increasing recently. However,
there is no existing evidence that shows a cause and effect relationship between vitamin B-12
injections and increased weight loss.
Brief History
Vitamin B-12 is a water-soluble vitamin necessary for various functions in the body one of
which is red blood cell production (1). Red blood cells are responsible for carrying oxygen
through the body. It is possible that with fewer RBC’s an individual may not be able to carry out
normal metabolic functions, which could be connected with the inability to lose weight. Many
studies have been conducted on vitamin B-12 deficiency; these studies focus on at-risk
populations such as the elderly (2) or people who consume vegetarian diets (3). There is one
case-control study that links low vitamin B-12 levels with obesity and overweight and
establishes a negative correlation between body mass index (BMI) and vitamin B-12. However,
this study was not a randomized control trial and did not demonstrate causation between low
vitamin B-12 and these variables (4). A gap exists in the research surrounding B-12 injections
and increased weight loss; although weight-loss clinics continue to offer injections as a weightloss treatment.
Study Goal and Aims
Primary Goal: The purpose of this study is to determine if weekly B-12 injections of 1,000 mcg
increases weight loss in a population of overweight/obese adult males and females ages 25-50
years old.
Study Aims:
 To determine if there is a relationship between vitamin B-12 injections and weight loss in
an overweight/obese adult population of males and females ages 25-50.
 To collect initial data on the effect of vitamin B-12 injections on weight loss in a
population of overweight/obese adult males and females ages 25-50.
Hypothesis
Hypothesis: Weekly Vitamin B-12 injections (1,000mcg) will not increase weight loss in an
overweight/obese population of adult males and females ages 25-50.
Null Hypothesis: Weekly Vitamin B-12 injections (1,000mcg) will increase weight loss in an
overweight/obese population of adult males and females ages 25-50.
Methods
Study Design
This is a randomized control crossover pilot study that may serve as the foundation for a future
intervention study. 30 participants will be recruited using flyers posted at weight loss clinics. All
participants will be required to sign consent forms. They will be randomly assigned into one of
two treatment groups (Group 1: 1,000 mcg B-12 injection or Group 2: placebo saline injection).
The random assignment will be made using a random number table to select participants and
randomize them. Each group will have 15 subjects and subjects will be blinded to which
intervention group they are in. This study will take place over a 14-week period. There will be a
6-week intervention period followed by a 2-week washout; an additional 6-week intervention
period will follow. Once randomized, all subjects will visit the same testing clinic and
anthropometric measurements will be taken (height, weight, and BMI). Baseline B-12 levels will
be obtained via blood tests. All participants will then receive their first injection (B-12 or
placebo) intramuscularly. Participants will be instructed to engage in no more than moderate
exercise daily, and track weekly food intake and exercise using validated food frequency
questionnaires (FFQ) and physical activity logs provided by primary investigators (PIs). The
FFQ is necessary to collect data on the amount of B-12 consumed from food. Participants will
return to the clinic each week to receive their injection. Weight and BMI will be taken at each
visit and FFQs and activity logs will be collected for analysis. The participants will return to the
clinic after the 2-week washout and switch treatment groups. The study will repeat in the same
manner as the first 6-weeks except participants will receive the other treatment that they had not
previously received.
Study Population
Inclusion Criteria: Males and females ages 25-50 years old with BMI 25 and above.
Exclusion Criteria: BMI below 25, people with conditions such as Cushing's syndrome or
Hypothyroidism that may prevent weight loss, males and females under 25 years old or over 50
years old, individuals taking weight-loss medications or consuming weight-loss diets. Individuals
taking antibiotics or folic acid supplements greater than 1mg/day and people with pernicious
anemia.
Subject Safety Strategy
This study presents a low level of risk to the sample population since B-12 is a water-soluble
vitamin. However, weekly injections of vitamin B-12 or placebo may cause irritation, bruising or
bleeding. A physician will have oversight of injections to ensure they are administered properly
and a registered nurse will perform them.
To protect the confidentiality of study participants, each subject will be assigned a random
identifier number. This information will only be available to primary investigators. It will be kept
in a locked filing cabinet at all times except when in use.
This study will require full IRB approval because it requires participants to receive B-12 or
placebo injections and have blood taken for analysis. This falls outside of routine office visits
and lab work.
Internal Validity
 Selection bias – the use of random selection will decrease selection bias and allow the
research findings to be generalized to a larger population of overweight/obese adult males
and females between the ages of 25 – 50 years.
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Selection-Maturation Interaction – does not apply since this study is not quasiexperimental
History – Outside factors that may contribute to B-12 levels and/or weight loss cannot be
fully controlled. However, FFQs and physical activity logs will allow me to collect data
to monitor factors that may contribute.
Instrumentation – validated FFQs and physical activity logs will be used. Standard
protocol will be used for blood work and all blood samples will be taken at the same
facility using the same instruments.
Maturation – weight may naturally change over time. This will be controlled for by
requiring weekly FFQs and activity logs for analysis.
Repeated testing – Participants will not be able to see weight lost during the study
Experimenter bias – Participants will be blinded to the treatment they are receiving
during the entire study.
External Validity
 Multiple-treatment interference – Each subject will only receive the intervention
treatment during one 6-week period.
 Reactive effects of Experimental arrangements – This is difficult to avoid since subjects
will know they are participating in an experiment
 Reactive or Interactive effect of testing – There will not be a pre-test in this study.
Statistical Testing
Data will be analyzed using SPSS software. The alpha score will be set at P<0.05 for all tests. If
the data is normally distributed, a t-test will be performed to compare the means of the two
treatment groups. This test will either accept or reject the hypothesis and show if weight loss is
significantly higher in the B-12 injection treatment group than in the placebo group.
I would also run a Pearson’s correlation if the data was normally distributed to see if a
relationship exists between B-12 injections and weight loss. This relationship is not causal, but
will provide enough information to allow PIs to decide if this pilot study warrants a larger
intervention study.
Finally, I would perform a multiple regression analysis to see if the fixed amount of B-12
provided (independent variable) in the weekly injections explains a significant variance in weight
loss (dependent variable). I would also look at activity level, and B-12 from the diet as
independent variables to see if they are associated with weight loss.
Independent variables – B-12 injection (mcg), activity level (hrs per day), B-12 from FFQ (mcg)
Dependent variable – Weight loss (kg)
Summary
After this study is complete, I believe we will see that there is no significant cause and effect
relationship between weekly B-12 injections and increased weight loss. If the findings support
this belief, weight loss clinics should no longer be able to tell their clients that B-12 injections
will aid in weight loss. If the data shows that B-12 injections do increase weight loss, a follow-up
study with a larger population should be conducted over a longer period of time.
References
1. Langan R, Zawitoski K. Update on Vitamin B12 Deficiency. Am. Fam. Physician.
2011;83(12):1425–1430.
2. Elzen W, van der Weele G, Westendorp R, Assendelft W. Research article Subnormal vitamin
B12 concentrations and anaemia in older people: a systematic review. BMC Geriatr.
2010;10(42):1–11.
3. Pawlak R, Parrott S, Raj S, Cullum-Dugan D, Lucus D. How prevalent is vitamin B12
deficiency among vegetarians? Nutr. Rev. 71(2):110–117.
4. Kutlucan B, I K. Association of vitamin B12 with obesity, overweight, insulin resistance and
metabolic syndrome, and body fat composition; primary care-based study. Med. Glas. Ser.
Online. 2013;10(2):203–210.