Does vitamin B12 help with weight loss?

Basic answer, no.  

Here's why:

1.   Anemia:  Vitamin B12 deficiency can cause a condition called megaloblastic anemia, which is characterized by extreme tiredness.  Once this deficiency is corrrected via vitamin B12 supplementation, these people will have more energy and be less tired.  And since they have more energy, they are able to be more active.  Studies have not supported this level of improvement in those who do not have anemia and take vitamin B12 supplements.

2.  Accountability:  Weight loss clinics that recommend vitamin B12 injections along with their program (which usually has a nutrition plan as well) often are recommending weekly injections, in addition to weekly weigh-ins.  What this suggests is that people know they are getting weighed, and are more likely to adhere to the recommended diet plan.  Thus, the misconception that the injections are directly causing some of their weight loss.

3.  Metabolism:  Vitamin B12 helps make enzymes that are needed to break down food and convert this food into energy.  There is no scientific evidence to show that increased vitamin B12 consumption will increase the break down or metabolism of food (i.e. it will not speed up your metabolism).


So, what is vitamin B12?

Vitamin B12 is a water soluble B vitamin, made by bacteria (i.e. our bodies cannot make it – we have to get it from our diet).  The majority of vitamin B12 will come from animal products, which is why vegetarians are more likely to be deficient.  


What does vitamin B12 do for our bodies?

-Optimize nerve health

-Help with red blood cell production 

-DNA synthesis

-Makes the enzymes that help our body produce energy (i.e. help covert the food we eat into energy) and maintain balanced metabolism

-Regulation of homocysteine (high homocysteine has been associated with cardiovascular disease and poor memory/cognition)

-Mood/memory stabilization


How can you tell if you are deficient?

A basic lab test can show you if you have low vitamin B12, or if you poorly absorb vitamin B12.   Ask a knowledgeable integrative healthcare provider if your levels are "optimal" (i.e. within lab ranges does not mean levels are optimal).


People at risk for deficiency:

1.       Vegetarians/vegans

2.       Elderly

3.       Anyone who has undergone surgery for weight reduction

4.       People afflicted with Crohn’s or celiac (gluten-intolerance) disease

5.       Anyone taking the prescription metformin

6.       Women who are pregnant

7.       Anyone taking an acid-reducer for gastrointestinal reflux disease (i.e. heartburn)


Where do you get vitamin B12?

1. Supplementation (best option), in pill form or injectable.  Best form (most active form) of vitamin B12 is methylcobalamin.

2. Clams

3. Beef liver

4. Trout

5. Salmon


There are different names found in supplements when it comes to vitamin B12.  How do you know which type of vitamin B12 is the best to take?

1. Cyanocobalamin: this is the most readily available on the market, is the only type approved by the FDA for treatment of vitamin B12 deficiency, and is inexpensive.  However this is synthetic, and the body has to convert it to the active form (methylcobalamin) to be able to use it.

2. Methylcobalamin: Most active form of vitamin B12 (thus, best form to take).  Studies have shown this to be beneficial in patients with autism and patients with dementia, as well as multiple sclerosis.

3. Hydroxocobalamin:  A natural form of vitamin B12, and the only type recommended by the World Health Organization for treatment of vitamin B12 deficiency.  Difficult to put in supplements without adding "stabilizers", so often obtained from a compound pharmacy.

4. Adenosylcobalamin: The type of vitamin B12 found within the mitochondria of our cells (mitochondria = energy producers).  Best when used in combination with methylcobalamin.


For more information on the details of vitamin B12, and some studies that look into vitamin B12, click the following link: