Do you take general vitamin and mineral supplements each day? You may not need to, according to a new study led by St. Michael’s Hospital and the University of Toronto.  

The researchers found that the most commonly used vitamin and mineral supplements, including multivitamins, vitamin D, calcium and vitamin C, don’t provide any consistent health benefit, particularly in the case of cardiovascular disease (CVD) prevention.

The study is published in the Journal of the American College of Cardiology.

The study

To conduct the study, the researchers reviewed existing data and single randomized control trials that were published in English from January 2012 to October 2017.

“We reviewed 1,496 papers and accepted 179 RCTs (randomized control trials) for analysis of the effects of vitamins, minerals and multivitamins on CVD outcomes and all cause mortality,” said Dr. David Jenkins, a scientist at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital and a professor in the Departments of Nutritional Sciences and Medicine at the University of Toronto. “Studies were generally carried out in healthy individuals or those at risk of CVD.”

The researchers reviewed data that included information on vitamins A, B1, B2, B3 (niacin), B6, B9 (folic acid), C, D, and E; as well as β-carotene; calcium; iron; zinc; magnesium; and selenium.

The term “multivitamin” was used to describe supplements that included most vitamins and minerals.  

The findings

The researchers found that multivitamins, vitamin D, calcium and vitamin C showed no advantage or added risk in the prevention of cardiovascular disease, heart attack, stroke, or premature death.

“We were surprised to find so few positive effects of the most common supplements that people consume,” Jenkins said in a statement. “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.”

However, the researchers did find that folic acid and B-vitamins with folic acid may be effective in reducing CVD and stroke.

“Folic acid reduced stroke risk by about 20 percent largely as a result of a large Chinese study, a country with no folate food fortification,” said Jenkins.

Additionally, the researchers found that niacin and antioxidants showed a small effect that could signify an increased risk of death from any cause.

“The very small signal for an adverse effect on longevity for pharmacologic doses of Niacin to reduce cholesterol when taken with a statin and also for antioxidant mixtures, was somewhat of a surprise,” said Jenkins. “However these effects are very small.”

Vitamin intake in U.S.

According to a 2015 CRN consumer survey, vitamins are ubiquitous in the U.S., with 68 percent of Americans taking dietary supplements.

That same year, in a study of dietary supplements use by college students, researchers found that they are more likely to take them than the general population. Sixty-six percent of college students used dietary supplements at least once each week, while 12 percent consumed five or more supplements a week. Forty-two percent of students used multivitamins/multiminerals at least once a week, with 18 percent using vitamin C, 17 percent protein/amino acids, and 13 percent using calcium.

The students reported that they used supplements to promote general health, provide more energy, increase muscle strength, and enhance performance.

But based on these results, is that necessary?

According to Jenkins, vitamin intake cannot necessarily be generalized, but people should be more conscious of what vitamins they’re taking, and why.

“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,” Jenkins said in a statement.

Vitamins or a healthy diet?

Since vitamins and mineral supplements are generally taken to add nutrients that are found in food, it’s generally better to simply rely on a healthy diet.

“Supplements should not be a substitute for a good diet,” said Jenkins. “I would advise people to take a healthy, less processed plant-based diet with generous servings of fruit, veggies, whole grain cereals, beans, peas, lentils, nuts and seeds that are rich in the nutrients you need. Vegans may take B12 based on regular blood checks. Here and in older people a supplement may be useful based on regular blood checks and physician consultation.”