Vitamin supplements may do more harm than good

Nutritional supplements are big business, with one recent survey finding that 29 per cent of Australians take at least one dietary supplement. So how much could these supplements be helping or hurting the nation’s health? That was the big question a recent study that aimed to examine the benefits of vitamin and mineral supplements for prevention of heart disease, stroke and premature death.

The systematic review and meta-analysis collated all relevant research papers that explored supplement use and disease and mortality outcomes. All up, 179 studies were included. The supplements examined included vitamin A, thiamin, riboflavin, niacin, vitamin B6, and folic acid along with vitamins C, D, E, beta-carotene, and the minerals calcium, iron, zinc, magnesium and selenium.

What the study found

In studies that tested the four most common supplements of multivitamins, vitamin D, calcium and vitamin C, there was no decrease in the risk of heart disease, stroke or premature death. Fortunately, there was no increase in harm seen either with these supplements meaning their overall effect was nil.

Of the less common supplements studied, folic acid did show a reduction in heart disease and stroke. The magnitude of benefit though small. In order to prevent one case of heart disease or stroke, 111 people needed to be taking a folic acid supplement. And for stroke, that number rose to 167 people needing to take it to prevent one case of stroke.

On the negative side of the ledger, for people taking niacin along with a statin medication used to lower cholesterol, there was a rise in the risk of early death by 10 per cent. For studies that used an antioxidant supplement, a marginally significant increased risk of early death was also seen.

Implications

The findings of this review show that people should be turning first to supplementing their diet with ‘healthy food’ rather than supplements. Focussing on one vitamin or mineral supplement means missing out on a range of beneficial nutrients found in food that go along with that particular nutrient that contribute to overall health. If supplements are taken, it should be done so as being relevant to an identified deficiency of that nutrient.

References

Jenkins D et al. Supplemental vitamins and minerals for CVD prevention and Treatment. Journal of the American College of Cardiology 2018;71:2570.