TORONTO, May 28, 2018 - The most commonly consumed vitamin and mineral supplements provide no consistent health benefit or harm, suggests a new study led by researchers at St. Michael's Hospital and the University of Toronto.
Published today in the Journal of the American College of Cardiology, the systematic review of existing data and single randomized control trials published in English from January 2012 to October 2017 found that multivitamins, vitamin D, calcium and vitamin C - the most common supplements - showed no advantage or added risk in the prevention of cardiovascular disease, heart attack, stroke or premature death. Generally, vitamin and mineral supplements are taken to add to nutrients that are found in food.
"We were surprised to find so few positive effects of the most common supplements that people consume," said Dr. David Jenkins*, the study's lead author. "Our review found that if you want to use multivitamins, vitamin D, calcium or vitamin C, it does no harm - but there is no apparent advantage either."
The study found folic acid alone and B-vitamins with folic acid may reduce cardiovascular disease and stroke. Meanwhile, niacin and antioxidants showed a very small effect that might signify an increased risk of death from any cause.
"These findings suggest that people should be conscious of the supplements they're taking and ensure they're applicable to the specific vitamin or mineral deficiencies they have been advised of by their healthcare provider," Dr. Jenkins said.
His team reviewed supplement data that included A, B1, B2, B3 (niacin), B6, B9 (folic acid), C, D and E; and β-carotene; calcium; iron; zinc; magnesium; and selenium. The term 'multivitamin' in this review was used to describe supplements that include most vitamins and minerals, rather than a select few.
"In the absence of significant positive data - apart from folic acid's potential reduction in the risk of stroke and heart disease - it's most beneficial to rely on a healthy diet to get your fill of vitamins and minerals," Dr. Jenkins said. "So far, no research on supplements has shown us anything better than healthy servings of less processed plant foods including vegetables, fruits and nuts."
*David Jenkins is Director of the Clinical Nutrition and Risk Factor Modification Centre, scientist at the Li Ka Shing Knowledge Institute of St. Michael's Hospital and university professor in the Department of Nutrition Sciences and Medicine at the University of Toronto.
This study was funded by the Canada Research Chair Endorsement, Loblaw Cos. Ltd., and the Canadian Institutes for Health Research (CIHR).
About St. Michael's Hospital
St. Michael's Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 29 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the Hospital's recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.
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