There is a new health trend popping up online: Vitamin B12. Vitamin B12 deficiency would be the forgotten and often overlooked cause of many (mental) health issues, such as depression. I encounter many articles entitled “Vitamin B12 can be sneaky and harmful” or “10 signs you might suffer from vitamin B12 deficiency without even knowing it”. These titles elicit anxiety in readers and offer few actual insights or sources. It clearly works though; I have noticed an increasing number of vitamin B12 ‘preachers’ on the Internet. When reading comments on Facebook I encounter more and more self-proclaimed vitamin B12 experts preach about possible B12 deficiency.
The other day I read an article about whether or not Albert Einstein had ADHD. Someone in the comments started a discussion that he clearly did not have ADHD, but vitamin B12 deficiency because that causes concentration issues too. Clearly. Poor Albert already had Asperger, ADHD, giftedness, depression, and now also B12 deficiency.
The problem with vitamin B12 deficiency is that many of the symptoms linked to it, are also symptoms of many other disorders/diseases and, more importantly, are pretty vague. According to the NIH government website they include fatigue, anxiety, diarrhea, loss of appetite, etc. All very common symptoms, related to many other underlying causes. The fact that there is an official website from NIH about the symptoms of Vitamin B12 deficiency does suggest that this is a serious health issue. However, what evidence exists for its link with depression? Work to do for ScienceChecker!
I looked up some recent research papers about Vitamin B12. Good start: lots of papers available on the topic! After a closer look, however, more articles are about Vitamin D. Especially those linked to depression. There seems to be a clear link between vitamin D deficiency and depression, found in multiple studies (e.g., Anglin et al., 2013 for meta-analyses).
When looking more closely to Vitamin B12, it became clear that the investigation started because low levels of Vitamin B12 were found in depressed patients. Vitamin B12 (and other B vitamins) play a role in producing brain chemicals that affect mood and other brain functions. This suggests that there may be a link between mood and Vitamin B12 deficiency.
Nevertheless, I could not find a paper stating clear evidence for an association between Vitamin B12 deficiency and depression in the general population. More importantly, evidence for Vitamin B12 supplementation and alleviation in mood is called “weak” (Mitchell, Conus, & Kaput, 2014). This indicates that, if a link between the two exists, taking supplements for it does not seem to work. Official websites, such as from the Mayo clinic, warn patients that taking supplements does not replace proven depression treatments. Interestingly, there seemed to be some studies that suggested that the link between Vitamin B12 and mood disorders could be stronger in elderly (Lachner, Steinle, & Regenold, 2012), however. More research seems to be necessary, including randomized controlled trails, before clear conclusions can be drawn.
To conclude, Vitamin B12 preachers are annoying, but they could be right (in some cases). Vitamin B12 has been linked to serious issues, but this does not mean that you have Vitamin B12 deficiency if you experience fatigue, depression or anxiety. There are many, many other potential underlying causes. In any case, if it continues, visit your doctor. Also, there is much more evidence for a link between Vitamin D and depression.
Conclusion: WEAK evidence.
Vitamin B12 & Depression:
Mitchell, Conus, & Kaput. (2014). B vitamin polymorphisms and behavior: Evidence of associations with neurodevelopment, depression, schizophrenia, bipolar disorder and cognitive decline. Neuroscience & Biobehavioral Reviews, 47, 2014, 307-320.
Lachner, Steinle, & Regenold. (2012). The Neuropsychiatry of Vitamin B12 Deficiency in Elderly Patients. The Journal of Neuropsychiatry and Clinical Neurosciences, 24(1), 5-15.
Vitamin D & Depression:
Anglin, Samaan, Walter & McDonald. (2013) Vitamin D deficiency and depression in adults: systematic review and meta-analysis. British Journal of Psychiatry, 202, 100-107. PDF available online: http://bjp.rcpsych.org/content/bjprcpsych/202/2/100.full.pdf
Parker, Brotchie, & Graham. (2017) Vitamin D and depression, Journal of Affective Disorders, 208, 2017, 56-61.