Vitamin D: dietary supplements do not prolong life or prevent fractures

Two recent clinical trials suggest that the popular belief that vitamin D supplementation protects against fractures and extends life expectancy, rooted in the biochemical mechanisms in which vitamin D is involved, is not clinically substantiated. .

The dietary supplement market is trying to meet a need of our time: people want to take care of their health, even if they are well. They want to maximize their well-being, reduce their risk of disease, sometimes emancipate themselves from medical authority, so many reasons that make food supplements an attractive technical solution. Indeed, medical knowledge is always situated: it is generally only pronounced for a specific group of patients (the problem of the external validity of clinical trials that multicenter trials attempt to resolve) and for particular judgment criteria (a pathologya marker, a symptom, etc.). No miracle solution for the new health objectives of part of the population.

The dietary supplement market is rarely encumbered with these considerations. Mechanistic reasoning, based on the biochemical knowledge of our organism or isolated clinical trials, lacking statistical power, is sufficient for it. Indeed, thanks to this, supplement sellers can attest to a pseudo-efficacy by using complex scientific language or by suggesting that the efficacy is clinically demonstrated by weak trials that they themselves have financed. most of the time. From then on, we find ourselves in a cacophony, with products that boast of booster your immunity, to silence your digestive disorders or to make you losing weight. It’s a bit like the vitamin D whose merits are praised on immunity, fractures, mortality, etc. Two clinical trials come straight challenger these common beliefs.

Robust clinical trials

These two trials lasted a long time: five years for the first, five years and three months for the second.

The first is a randomized trial double-blind against placebo and attempts to assess the effect of taking 60,000 IU of vitamin D per month on mortality in Australians over the age of 60, not screened for a deficiency in vitamin D. As a result, taking vitamin D had no significant effect on matter of mortality.

The second is a randomized ancillary trial (with randomization factorial) triple-blind versus placebo. The main trial (VITAL) aimed to determine the effect of takingOmega 3 on one side and vitamin D on the other on the prevention of the cardiovascular illnesses and cancer. The ancillary trial discussed focused on self-reported fracture risk as an outcome. In more than 25,000 US patients not screened for vitamin D deficiency, fracture risk was not reduced by taking vitamin D.

What should we conclude from this?

Taking vitamin D does not seem to have an effect on mortality or on the risk of fracture in people over 60 without diagnostic of deficiency. It is then advisable to be careful with the taking of food supplements devoid of certain benefits, because the risks can sometimes be badly assessed, as suggested by the recent investigation opened on turmeric. Obviously, these trials say nothing about the effectiveness of vitamin D in other indications and in other types of patients.