Folic Acid Supplementation in Canada: What is the Right Dose?

Robyn MacQuarrie comments on the appearance of industry influence on the Joint SOGC-Motherisk clinical practice guideline on folic acid supplementation.

In an era of evidence-based medicine, healthcare providers generally rely on clinical practice guidelines to help them provide their patients with the highest standards of care. These guidelines are often produced by committees and sometimes one or more committee members will have a conflict of interest as when, for example, a clinical practice guideline concerns a product in which the committee member has a financial interest.  In modern times, it is expected that clinicians will be made aware of such conflicts and also be informed as to how these conflicts were mitigated.

The Canadian Medical Association has published guidelines for physicians in interactions with industry, which state that “physicians with ties to industry have an obligation to disclose those ties in any situation where they could reasonably be perceived as having the potential to influence their judgement.” Unfortunately, all too often, such conflicts are under-reported. A current Canadian example of this problem is the Joint SOGC-Motherisk clinical practice guideline on folic acid supplementation.

Irises, Vincent Van Gogh, J. Paul Getty Museum

Irises, Vincent Van Gogh, J. Paul Getty Museum

Folic acid supplementation is standard prenatal care – a simple way to reduce the incidence of neural tube defects and to improve prenatal outcomes.  In 1989, Canada began fortifying a large variety of cereal and grain products with folic acid. This alone led to nearly a 50 percent decrease in neural tube defects.

In addition, some women who are planning to become pregnant take a daily multivitamin that has 0.4 to 1mg of folic acid. However, more is not always better and women are generally warned not to increase the dose of folic acid beyond 1mg without first talking to their physician. High doses of folic acid have been associated with an increase in the incidence of bowel cancer, cervical cancer, and lung cancers. What then is the optimal dose of folic acid supplementation?

Separate guidelines issued by Health Canada and by the Public Health Agency of Canada, developed by a multidisciplinary team of physicians, dieticians, and other experts, recommend that most Canadian women take 0.4 mg of folic acid supplementation. The guidelines also specify that women should only take doses of folic acid greater than 1 mg under the care of a physician.  Women who might be counselled to take higher doses of folic acid include women who have had a fetus with a neural tube defect and women with pre-existing diabetes.

By contrast, the current Joint SOGC-Motherisk clinical practice guideline, developed by members of the SOGC Genetics Committee and members of Motherisk, do not limit high dose supplementation to a small group. This guideline, on the basis of expert opinion and not clinical trial data, recommends high dose supplementation for a much larger group of women. This group includes women without an underlying health problem, but perhaps only a history of poor compliance with prescription medication, no consistent birth control, or variable diet – categories that surely capture more women than would need to have high dose folic acid supplementation.

Motherisk is a private organization based out of the Sick Kids hospital in Toronto.  It has received a considerable amount of industry funding for clinical trials from Duchesnay and Apotex, each of which produce a 5 mg folic acid supplement.  Around the time that the Joint SOGC-Motherisk guideline was issued, Duchesnay was heavily promoting PregVit5, a multivitamin that contains 5 mg of folic acid. All of the research supporting the PregVit5 product on the Duchesnay website was conducted by members of the Motherisk team.

Given this clear relationship with industry, one would expect the Joint SOGC-Motherisk guideline to disclose the financial relationship between Motherisk and Duchesnay and Apotex. When I raised this concern with SOGC more than a year ago, I was told not to worry about this apparent conflict, as a new guideline for folic acid supplementation was being drafted.  Since then, no new guideline has been issued by SOGC, but the current Joint SOGC-Motherisk guideline has been “archived” such that it is no longer available to the general public.

By archiving the ethically questionable clinical practice guideline on folic acid supplementation, without at the same time issuing a replacement guideline based on clinical trial evidence (not expert opinion), SOGC fails to serve the interests of Canadian women.

Robyn MacQuarrie is a PhD candidate in the interdisciplinary PhD program at Dalhousie University, with a focus on bioethics. She is also a practicing obstetrician/gynaecologist in Amherst, Nova Scotia. @robynmacquarrie

One comment

  1. Robyn MacQuarrie · · Reply

    Despite claims that a new document is being produced, the SOGC has just launched a new patient directed website aimed at informing patients about issues surrounding pregnancy. The expanded patient population is once again described as potentially needing 5 mg doses of folic acid, despite the previously described lack of evidence to support this. This can be accessed at

    Although this resource does not tell patients they must take 5 mg, it suggests that they might, and refers them to their physicians to discuss it. Once again, if no guidelines with good evidence are available, these physicians will once again refer to the Joint SOCG – Motherisk guidelines, and prescribe high-dose (5mg) treatment.

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