No risk but no benefits, study finds
St. Michael's Hospital
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 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 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."