A Western-led study has added further evidence to the growing understanding that not only do most nutritional supplements not prevent chronic disease or increase longevity, but their widespread use should be avoided. There are no shortcuts, the study contends, that can replace a healthy lifestyle.
“We always look for a shortcuts in addressing the fundamental roots of our problems,” explained Saverio Stranges, a Schulich School of Medicine & Dentistry professor. “As health professionals and scientists, we have a responsibility to convey clearly the evidence around the use of supplements, at least around the expectation of chronic disease or longevity because a great number of people take supplements with that expectation.”
Almost half of Canadians regularly take micronutrients or nutritional supplement – things like vitamins, minerals, fibre supplements or fish oils. Over-the-counter sales of drugs, vitamins, herbal remedies and other health supplements in Canada top $5 billion annually, according to Stats Canada.
Problem is, they are not necessary for the majority of the population.
Stranges has been involved in several studies and clinical trials examining the benefits and risks of micronutrients and nutritional supplements across North America and Europe. His work has focused on selenium, a nutrient used by many as an anti-oxidant for cardiovascular disease and cancer prevention.
“Most of these micronutrients have a very narrow physiological range and window of benefit,” he said. “When you take more selenium than your body needs, you may have adverse effects. In North America, 90 per cent or more of the population already have enough selenium just from the natural foods they eat because of the amount of selenium in the soil is extremely high in North America.”
In a previous randomized clinical trial conducted in the United States, Stranges said high doses of selenium supplements, in areas where it is already plentiful in the diet, actually increased the risk of Type 2 diabetes.
In his most recent study, Stranges and his colleagues looked at the effects of selenium supplements in a population from Europe, where levels of natural selenium are much lower than in North America. While no adverse effects were discovered, researchers also did not uncover any benefits from taking the supplements, even in a population with low levels of selenium.
“If we convey the idea that supplements can replace healthy lifestyle, then not only are we giving something which is unlikely to help, but we are also taking these people away from what they should be doing in term of living a healthy life,” Stranges said.
Increasing physical activity, a healthy diet, better sleep, meaningful social interaction and minimizing stress are just some of the ways individuals can improve their well-being, added Stranges.
“We need to honest and not raise the expectation of people. The scientific message around the role of these supplements for chronic disease prevention is quite limited,” he said. “People need to be aware that the scientific evidence around the potential role of these supplements in chronic disease prevention is basically zero or very limited in the general healthy population.”
This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent the majority of supplement users in North America. More than 90 per cent of this population already have enough selenium just from natural foods, such as beef, fish and poultry, along with the high amount of selenium in the soil.
Stranges said there may be some groups which may benefit from these supplements, but even those micronutrients have a very narrow physiological range and window of benefit.
“I’ve become quite skeptical about using supplements for chronic disease prevention. These are very complex and multi-factorial diseases. So, unless you are having very obvious and clear deficiencies of these micronutrients, thinking that one single micronutrient may have an impact on your heart is not the case,” he said. “There is really no physiological rationale for supplementation in the vast majority of the cases.”
Stranges added from a public-health perspective, funding should be allocated to policies, campaigns and interventions that improve dietary patterns in the general public and disadvantaged population subgroups – interventions that increase consumption of plant foods containing the required vitamins and minerals for optimal health.
The study, Effect of selenium supplementation on changes in HbA1c: Results from a multiple‐dose, randomized controlled trial, was recently published in the Diabetes, Obesity and Metabolism.
