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Study Warns Supplements Not Always Safe; Calcium, Vitamin May Become Harmful

Analyzing data of nearly one million people, a new study debunks claims that all nutritional supplements can protect people or support healthy diet. Researchers even warned that taking both calcium and vitamin D can actually be harmful and increase the risk of stroke.

The findings, published in the Annals of Internal Medicine, analyzed data from 277 trials that explored the effects of various nutritional supplements and diets. The analysis also covered mortality rates and prevalence of cardiovascular diseases.

“The reason we conducted this study was that millions of people in the United States and across the world consume supplements or follow certain dietary patterns,” Safi Khan, an assistant professor in the West Virginia University School of Medicine, said in a statement. “But there was no good-quality evidence to suggest that these interventions have any effect on cardiovascular protection.”

Results show that among all supplements studied, only folic acid and omega-3 appeared effective to promote better health. Taking folic acid has been linked to lower risk for stroke, while omega-3s could reduce the chances of heart attack and coronary heart disease, according to the study. 

However, taking calcium, vitamin D, multivitamins, iron, beta-carotene and antioxidants have no effect on mortality or cardiovascular outcomes. For the analysis, the researchers looked at the effects of supplements and diets on all-cause mortality, cardiovascular mortality, heart attack, stroke and coronary heart disease. 

The Impact Of Diet

The research team also analyzed how common diets contribute to heart health. Eating less salt was found effective to improve all-cause mortality rates and to reduce cardiovascular-related deaths.

However, low-salt diet was the only approach that appeared with benefits during the study. The other diets, including low-fat diet, a Mediterranean diet and high fish-oil intake, had no effect.

“Reduced salt intake was associated with improving overall survival and cardiovascular mortality,” Khan said. “This is something that can be backed up with logic because there is a sufficient amount of data, in various studies, that shows low salt intake basically improves hypertension, which directly influences cardiovascular outcome.”

He noted that most studies that promoted the health benefits of supplements and diets “lacked precision.” His team found issues in methodology, the target population and the timing and location of studies. 

pills A survey by the Council for Responsible Nutrition (CRN) showed that 75 percent of U.S. individuals showed strong confidence in dietary supplements in 2018 Pixabay

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