Latimer: Best to believe research science

Conflicting advice abounds about what dietary supplements or medicines we should take in order to maintain optimal health.

One vitamin supplement that has received a lot of attention over the past 10 years is vitamin D.

We have long been advised of the importance of this vitamin for the body’s absorption of calcium and have also heard of many other health benefits associated with vitamin D consumption, such as lower rates of chronic diseases like cancer, diabetes and more.

Dozens of studies seem to support the idea that vitamin D is critically important. What’s more, we’ve been told that most people living in our part of the world do not get enough of this vital nutrient from our diets or sun exposure.

So it was a bit confusing for many people when the U.S. Institute of Medicine reported a few months ago that vitamin D supplements were unnecessary for most people and potentially harmful.

This announcement shed some light on a disparity between what is often touted in the media and what scientific research is held by governments and physicians as evidence of the effectiveness of a given substance.

Most scientists believe the randomized clinical trial is the only acceptable way to prove the effectiveness of a treatment—whether pharmaceutical or a dietary supplement such as vitamin D. Typically these involve comparing the effects of a treatment against those of a placebo.

Health Canada makes its recommendations for Canadians based on the existing body of evidence for any given treatment.

In the case of many dietary supplements including vitamin D, the majority of the evidence currently available comes not from randomized clinical trials but from observational studies of the health of populations who get high levels of a particular substance.

These studies observe in the real world and although thought to be inferior to a controlled clinical trial, they try to make up for that by using very large sample sizes—some following up to 50,000 people—and then applying statistical techniques to figure out results.

According to these studies, high levels of vitamin D are thought to be beneficial. To date, the data collected in controlled trials has been a little more inconclusive and more research is needed before the scientific community or the governing health agencies are willing to make a stronger recommendation.

I agree with the science. The clinical trial is the only real way to prove the effectiveness of a treatment. That said, if a clinical trial for a given treatment is impossible or delayed due to lack of funding or interest, we still have to act on the information that is available. That is and always has been the nature of medicine.

In the case of vitamin D—the current Health Canada recommendations are 400 IU/day for children aged 0-1, 600 IU/day for children and adults aged 1-70 and 800 IU/day for people over age 70. Adults should not get more than 4000 IU/day. The upper intake levels for children can be found on the Health Canada website at www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php

Paul Latimer is a psychiatrist and president of Okanagan Clinical Trials.




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