To B or Not to B: Vitamin B12 and Folic Acid in Mental and Physical Health

Everyone seems to be talking about the Bs lately. Specifically, B12 and folic acid (or folate) are making headlines for their roles in mental health and illness. Both of these vitamins play an essential role in a number of key bodily processes.

Symptoms of a Deficiency

A deficiency in B12 or folate may take months or years to become evident, and may lead to symptoms such as fatigue, muscle weakness, diarrhea, difficulty concentrating, forgetfulness, sleeplessness, irritability, and mood swings. In more severe cases, deficiency can result in seizures, dementia, or parathesia (burning, prickling, tingling, numbness, or a crawling sensation in the extremities or elsewhere in the body).

Low levels of B12 and folate are associated with having higher levels of homocysteine, an amino acid found in the blood; when levels are too high, the risk of cardiovascular disease and cognitive problems increase. What is particularly interesting about this relationship is that over the past several years, more research has emerged showing a link between depression, and to lesser extents, anxiety, hostility, and increased likelihood of cardiovascular problems. Additionally, people who have heart disease have higher rates of depression than what is seen in the general population. It is unclear if the sole or definitive link between heart disease and B-vitamins is homocysteine levels, but the relationship is intriguing.

Who is at Risk?

Risk factors for B12 or folate deficiencies include following a vegan diet ( B12 is only found in animal products), being elderly, having an inflammatory bowel disease, being malnourished, having liver problems, being pregnant, using proton pump inhibitors regularly (medications that reduce stomach acid), and alcoholism. In addition, certain medications may interfere with the absorption of B12 or folate.

What’s the Evidence?

Recent research has investigated whether supplementation with B12 or folate could yield observable improvements in cognitive functioning or mood. A 2012 study examined the effects of supplementation on cognitive functioning in 700 elderly adults who had symptoms of depression but did not meet full criteria for a depressive disorder. Improvements in some aspects of memory (immediate and delayed recall) were significant, if not modest, but were only seen after two years of daily use. Supplementation did result in significantly higher blood levels of B12 and folate, and significantly lower increases in levels of homocysteine over time, as compared to taking a placebo.

Other research has found that approximately one third of depressed patients have low levels of folate and elevated levels of homocysteine. Treatment with antidepressants may be less effective in those with low levels of B12. Adequate levels of folate and B12 are also important for those taking the supplement SAM-e (S-adenosyl-methionine). SAM-e is a popular over-the-counter supplement typically used to treat depressive symptoms or pain due to osteoarthritis or fibromyalgia. SAM-e is sometimes used in conjunction with conventional antidepressants to boost their effectiveness in those who don’t respond sufficiently to antidepressants alone.

Finally, a 2010 paper discussed two case reports in which depressed patients had failed to respond to three different trials of antidepressant therapies. In each case, the patient was a male vegetarian with low levels of B12. One of the men had sleep difficulties that progressed to complete insomnia, as well as cognitive symptoms (slowness in thinking, difficulty performing calculations, and forgetting names of objects and people). The other experienced problems with attention-concentration, learning new information, and immediate and visual recall of information. In both cases, supplementation resulted in an improved response to medication and reduction in depressive, sleep, and other cognitive symptoms.

Although recent headlines and some of the study findings suggest a link, it is important to note that more research needs to be done to definitively state whether B-vitamin supplementation can reduce, prevent, or reverse cognitive or mood problems in healthy or ill people.


  • Strive for a healthy diet comprised of adequate amounts of high-quality food. This should include whole grains, vegetables and fruits, beans/legumes, as well as fish, dairy, and other lean proteins if you eat animal foods.
  • B12 and folic acid supplements are water soluble and tend to be safe in moderate doses. If you do choose to take supplements, be aware that when taken without B12, folate can mask a B12 deficiency. Thus, it is typically recommended to add B12 if you are already taking a folic acid supplement.
  • If you fall into one or more of the higher-risk categories mentioned above, it is worth consulting with your physician and/or a registered dietician regarding whether supplementation is warranted or to adjust your diet appropriately.
  • If you have any of the cognitive, psychological, or physical symptoms mentioned above, consult a health care provider immediately.
  • Learn more about dietary supplements at the National Institutes of Health’s Office of Dietary Supplement’s page


  1. Kate, N, Grover, S, and Agarwal, M. (2010). Does B12 deficiency lead to lack of treatment response to conventional antidepressants? Psychiatry, 7(11), 42-44.
  2. Stanger O, Fowler B, Piertzik K, Huemer M, Haschke-Becher E, Semmler A, Lorenzl S, & Linnebank M (2009). Homocysteine, folate and vitamin B12 in neuropsychiatric diseases: review and treatment recommendations. Expert Rev Neurother, 9(9), 1393-412.
  3. Walker, JG, Batterham, PJ, Mackinnon, AJ, Jorm, AF, Hickie, I, Fenech, M, et al. (2012). Oral folic acid and vitamin B-12 supplementation to prevent cognitive decline in community-dwelling older adults with depressive symptoms—the Beyond Ageing Project: a randomized controlled trial.  American Journal of Clinical Nutrition, 95(1), 194-203.


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The preceding article was solely written by the author named above. Any views and opinions expressed are not necessarily shared by Questions or concerns about the preceding article can be directed to the author or posted as a comment below.

  • Leave a Comment
  • Cameron

    January 10th, 2012 at 3:37 PM

    Well I religiously get a b12 shot once a month and it makes a marked improvement in my energy level and just how good I feel on a daily basis. The months when I go without one, no matter who well I eat or exercise, I never have the same amoun t of energy and stamina that I feel when I am getting the shots like I should. I know that there are going to be nay sayers, who will say that this is all in my head and I guess that maybe that could be true. But if it is something that makes me feel better and it is not doing any harm then I am definitely going to keep the shots as a part of my regimen.


    January 11th, 2012 at 4:30 PM

    Personally I would rather get vitamins from my diet instead of having to rely on injections. Something about doing it that way seems healthier than having to rely on a needle in my arm.

  • T.Vincent

    January 12th, 2012 at 12:01 AM

    Interesting information. I don’t think any one food compound has been shown to impact mental health to this extent before. Anyway, the advice on a healthy diet is much better than saying have a vitamin rich diet alone. It’s like a universal thing you know- eat right and you will do fine- and still so many people get into trouble due to poor eating habits and a poor diet. :|

  • Traci Stein

    January 12th, 2012 at 4:55 PM

    Hi All, and thanks for sharing your thoughts. Dakota and T., although I understand your feelings regarding it being best to aim for a healthy diet, there are definitely times when diet alone is not enough, particularly in cases where someone is in a high risk group like the ones mentioned above. In cases of malabsorption, it may not be possible to take in enough of B12 (or another important vitamin or mineral) through diet alone – even if eating large quantities of food (which can be problematic on its own). In these types of situations, it’s especially important to consult with a health care provider who can help determine the best way to address the deficiency. Of course, taking supplements when necessary should not preclude eating a good diet anyway. And a registered dietician can assist with coming up with a nutritious (and tasty) meal plan.

  • Chris

    May 27th, 2015 at 7:47 AM

    I recently heard about a new oral prescription alternative to the injections called Eligen B12. I recently read that it works even if you don’t have intrinsic factor (so even if you don’t have normal gut absorption). Apparently it came out a month or two ago. Has anyone heard of it or tried it??

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