According to a recent study, most dietary supplements and diets have no effect on health status and mortality rate.
Do dieting and taking dietary supplements really serve something? Perhaps not, according to a study conducted by researcher Safi Khan of West Virginia Universiy (USA) and published in the journal Annals of Internal Medicine. The latter analyzed the results of 277 randomized studies, involving more than one million participants, to understand how dietary supplements and diets affect mortality rates and cardiovascular health.
Folic Acid and Omega 3
"We started this study because millions of people in the US and around the world are using dietary supplements or following certain diet models, but there was no evidence that these behaviors had any effect on the protection against heart disease, "says Safi Khan. Of the 16 dietary supplements studied, only two seem to be beneficial: folic acid and omega 3, two long-chain fatty acids. The first would protect against strokes and the second would reduce the risk of heart attacks and coronary heart disease.
The study also examined the impact of these supplements and regimens on the all-cause mortality rate, the cardiovascular mortality rate, the risk of heart attack, cardiovascular accident and coronary heart disease.
Result: consuming calcium and vitamin D at the same time can be dangerous and increase the risk of stroke. However, taking calcium or vitamin D separately would have no effect on health. This is also the case for all the other supplements analyzed by the study, such as multivitamin supplements, iron, folic acid, beta-carotene and antioxidants.
More or less solid results
For diets, eating less salt, for example, increases the risk of all-cause mortality in people who do not have high blood pressure, but lowers the risk of death from heart disease in people with high blood pressure. The low sodium diet is the only one that would have a significant effect.
The other seven diets studied, such as eating less or eating a diet that focused on different types of fat, had no effect on health. Regarding that of a diet with less sodium, it is supported by logic and by sufficient data from other studies. But the evidence on which folic acid and omega 3 results are based is less robust.
"Randomized studies are unclear," explains Khan, "they're problematic in terms of methodology, target populations, and construction, so the results have to be tweaked."