Vitamin B12 and health

Milly Ryan-Harshman; Walid Aldoori

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Re: Response to Vitamin B12 and Health Article
Walid Aldoori

Published on: 04 May 2008
Response to Vitamin B12 and Health Article
Edward Leyton

Published on: 23 April 2008

Published on: (4 May 2008)

Re: Response to Vitamin B12 and Health Article
Walid Aldoori, Medical Director
Other Contributors:
Reply to Dr. Edward Leyton:
We would like to thank Dr. Leyton for his interest in our review article about vitamin B12 and health (1). Dr. Leyton is drawing our attention and the readers to a review article by Coppen and Bolander- Gouaille (2) that we did not cite in our article. This article is advocating that folic acid and B12 should be considered for the treatment of depression. Dr. Leyton is objecting that...
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Reply to Dr. Edward Leyton:
We would like to thank Dr. Leyton for his interest in our review article about vitamin B12 and health (1). Dr. Leyton is drawing our attention and the readers to a review article by Coppen and Bolander- Gouaille (2) that we did not cite in our article. This article is advocating that folic acid and B12 should be considered for the treatment of depression. Dr. Leyton is objecting that we have stated in our review that this benefit is inconclusive when it comes to depression. The article by Coppen and Bolander-Gouaille which was cited by Dr. Leyton is a testament that this clinical practice might not be widely accepted by all. Furthermore, we would like to emphasize that our clinical reviews should not be interpreted as making clinical guidelines or recommendations. Dr. Leyton might feel convinced with the benefit of B12 and folic acid in the treatment of depression, but to our knowledge this benefit is not yet part of clinical practice to treat depression.
Another objection by Dr. Leyton is that we have reviewed vitamin B12 on health instead of looking at the synergistic effect of multiple nutrients on health. I think that Dr. Leyton appreciates that to understand whether there is synergy, one need to look at the individual nutrients and gather as much scientific knowledge as could be gathered, before exploring whether other nutrients are also involved. Studying the effects of multiple nutrients on health is the biggest challenge in nutritional epidemiology. As our understanding grows about the associations between one nutrient and several health outcomes, one can gather such information to look at the synergy between multiple nutrients on one or more health outcomes. We can assure Dr. Leyton that in future articles, we will look at a specific disease and the micronutrients and/or lifestyle characteristics associated with it. In fact, we have published several articles in this journal utilizing this approach (3-5) Once again; we would like to thank Dr. Leyton for his letter and for giving us the opportunity to reply.
Walid Aldoori, M.D., M.P.A, Sc.D. Medical Director, Wyeth Consumer Healthcare, CANADA
Milly Ryan-Harshman. PhD, RD. FEAST Enterprises, Oshawa, CANADA.
1) Ryan-Harshman M, Aldoori W. Vitamin B12 and health. Can FAM Physician 2008; 54:536-541.
2) Coppen A, Bolander-Gouaille. Treatment of depression: time to consider folic acid and vitamin B12 [Review]. J Psychopharmacol 2005; 19; 59-65.
3) Ryan-Harshman M, Aldoori WH. Diet and Colorectal Cancer: Review of the Evidence. Can Fam Physician 2007; 53:1913-1920.
4) Ryan-Harshman M, Aldoori WH. How diet and lifestyle affect duodenal ulcers. Review of the evidence. Can Fam Physician 2004; 50:727-732.
5) Aldoori WH, Ryan-Harshman M. Preventing Diverticular Disease. Review of Recent Evidence on High-fiber Diets. Can Fam Physician 2002; 48:1632-1637.
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Competing Interests: None declared.
Published on: (23 April 2008)

Response to Vitamin B12 and Health Article
Edward Leyton, MD FCFP CGPP
The clinical review by Milly Ryan-Harshman and Walid Aldoori in Canadian Family Physician Volume 54 April 2008 requires comment. While I appreciate the efforts of the authors to review such a huge unwieldy topic, I think one of the several dangers in doing so is that certain key elements are not covered. I particularly refer to the section on B12 and mental health. It appears that there is a huge volume of literature th...
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The clinical review by Milly Ryan-Harshman and Walid Aldoori in Canadian Family Physician Volume 54 April 2008 requires comment. While I appreciate the efforts of the authors to review such a huge unwieldy topic, I think one of the several dangers in doing so is that certain key elements are not covered. I particularly refer to the section on B12 and mental health. It appears that there is a huge volume of literature that has not been researched by the authors regarding this topic, and I note that prolific authors such as Coppen and Bottiglieri are not even mentioned in the bibliography. Their contributions to the literature on vitamin B12, folic acid, S-adenosylmethionine, homocysteine and depression are of paramount importance. I therefore think that Harshman and Aldoori’s conclusion that B12 is “unlikely to substantially alter cognitive function or depression” is both inaccurate and unfair.
The other issue that I take with review articles such as this regarding vitamins and essential nutrients is that an attempt to single out one particular element as having a beneficial effect is both inappropriate and unlikely to produce valid results. Vitamins and minerals work in concert. They work synergistically, and nowhere is this more important than in the 1-carbon methylation cycle that involves folic acid, vitamin B12, and homocysteine. This cycle, in and of itself, requires no less than 6 or 7 cofactors that must act together in concert for appropriate methylation of neurotransmitters and other important intermediates, as well as removal of toxic by-products. In fact, I would suggest that it is impossible to even consider vitamin B12 in relation to the treatment of depression without considering folic acid, S-adenosylmethionine and vitamin B6 as well tetrahydrobiopterin. This is notwithstanding the contribution that the MTHFR polymorphism would make.
In future clinical reviews where nutrients are being considered as possible factors, I think it would be worthwhile for both the editors and the authors to consider synergistic aspects and to direct themselves away from the outdated concept that there is one specific treatment for one disease.
For an excellent recent review of depression, folic acid and vitamin B12, I would refer the readers to the paper by Coppen and Bolander Gouaille entitled "Treatment of depression: time to consider folic acid and vitamin B12" in Journal of Psychopharmacology 2005; 19 (1): 59-65.
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Competing Interests: None declared.