Vitamin and mineral supplements, consumed by millions of people, could potentially cause more harm than good, even increasing the risk of heart disease and premature death, according to a study.
In the UK, 46 percent of individuals take vitamins and minerals daily, contributing to an industry valued at over £500 million annually. However, most are deemed useless by US scientists, providing no protection against illness.
For example, combining vitamin D with a calcium pill was found to increase the likelihood of a stroke rather than decrease it as reported by Surrey Live.
The research, published in the Annals of Internal Medicine, analysed 277 previous randomised trials involving nearly one million participants. It examined the effects of 16 different nutritional supplements and eight dietary interventions on mortality and cardiovascular outcomes in adult participants.
Dr Safi Khan, the lead author from the University of West Virginia in the US, stated: “We found out only a few of the 16 nutritional supplements and one of the eight dietary interventions evaluated had some protective effect in cardiovascular risk reduction.
“In our study the fish oil supplementation we found to be protective against heart attacks and folic acid supplementation was found to be protective against strokes.”
However, he warned that some were linked with significant harms. Dr Khan added: “A combination of calcium and vitamin D was associated with a higher risk of stroke.” He concluded: “Other supplements did not seem to have significant effect on mortality or cardiovascular outcomes.”
These supplements included multivitamins, as well as vitamins A, B6, C, D and E, and iron tablets. In terms of specific diets, the researchers also examined the benefits of reduced fat and reduced saturated fat intake, but were unable to find any positive impact on heart health.
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Dr Khan stated: “We examined Mediterranean diet, reduced dietary fat, modified dietary fat and reduced saturated fat intake. We found none of these dietary modifications had any effect on cardiovascular risk.”
There were only two diets that showed some protective effects – a reduced salt diet lowered risk of death from any cause in those with normal blood pressure, while a diet rich in omega-3 fats from fish protected against heart attack and coronary heart disease.
Despite US health guidelines recommending the Mediterranean diet and vegetarian diets, they do not advise taking supplements for cardiovascular health, highlighting the confusion over the benefits of diet and supplements.
In response to the study, researcher Dr Eric Topol noted: “For example, geographic considerations among the studies need to be considered.”
“The reported benefit of folate seems to be largely driven by the inclusion of one study from China, where a folate-rich diet is not routine. In addition, most studies rely on food diaries, which are based on a person’s memory of what they consumed and therefore are not wholly reliable.”
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