In a new study, researchers found that the nutritional supplements people take or the diets they eat may not actually protect them against heart problems and death.
In the study, the team analyzed 277 published studies, in which nearly 1 million adults participated.
They wanted to find out how nutritional supplements and diets influenced mortality rates and heart disease risk.
The researchers examined whether supplements and diets changed the rates of all-cause mortality, cardiovascular mortality, heart attack, stroke, and coronary heart disease.
They also evaluated the quality of the evidence that underpinned the trials’ findings.
They found that among the 16 nutritional supplements considered, only two seemed beneficial: folic acid and omega-3, long-chain fatty acids.
Taking folic acid may protect against stroke, and taking omega-3s may reduce the risk of heart attack and coronary heart disease.
In addition, the team found that taking both calcium and vitamin may actually be harmful.
The result showed that taking a combination of calcium and vitamin D may increase the risk of stroke.
But taking calcium or vitamin D alone seemed to have no effect on mortality or heart disease whatsoever.
Neither did any of the other supplements, such as multivitamins, iron, folic acid, beta-carotene, and antioxidants.
The researchers then examined the health effects of diets and that eating less salt improved all-cause mortality rates in people with normal blood pressure.
It also made heart disease deaths rarer among people with high blood pressure.
But reducing sodium was the only diet that demonstrated any benefit.
The other seven—which included eating less or different types of fat, adopting a Mediterranean diet and increasing fish-oil intake—had no effect.
The researchers say that future work needs to confirm the findings, including the benefits of folic acid and omega-3s and the detriment of combining calcium and vitamin D supplements.
The lead author of the study is Safi Khan, an assistant professor in the West Virginia University School of Medicine.
The study is published in the Annals of Internal Medicine.
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