According to a recent nutrition survey in Australia, 29 percent of the population are taking at least one dietary supplement a day. In the United States, at least 52 percent are taking a dietary supplement a day. The study attempted to look at the long term benefits offered by regular intake of vitamin and mineral supplements for the prevention of diseases such as heart disease and stroke as well as premature death.
Results revealed that not all types of vitamins and mineral supplements are helpful in preventing premature deaths due to any cause or all-cause mortality and some of them are actually harmful.
The study was published in the latest issue of Journal of the American College of Cardiology released this week (29th May 2018).
This was a systematic review looking at a total of 179 studies that looked at benefits of vitamin and mineral supplements on long term health. Some of these supplements included vitamins A, beta carotene, B1 (thiamin), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B9 (folic acid), C, D, and E. Mineral supplements included calcium, iron, zinc, magnesium and selenium. Multivitamin supplements contained a combination of these vitamins and minerals.
The studies that the team analysed included the use of vitamin D, calcium and vitamin C and multivitamins. Results showed that these did not provide any benefit in preventing due to heart disease, strokes and premature deaths due to any of these. No harm was noted with the use of any of these supplements either. They also looked at the benefits of folic acid supplements and saw that regular intake of folic acid supplements can reduce the incidence of heart disease and stroke. They noted that 111 people needed to take regular supplements of folic acid in order to prevent one case of heart disease or stroke. This number is called “number needed to treat” in order to see a benefit. To prevent one case of stroke, 167 people need to take folic acid supplements regularly and 250 people would need to take supplements containing B complex vitamins and folic acid to prevent one case of stroke. They also found that excess folic acid in daily supplements can also be linked to prostate cancer. This association however was not proven. There were in all seven large studies that looked at folic acid supplementation and prevention of stroke of which only two showed a protective effect. Of these one was a Chinese study involving over 20000 people.
Lead author of the study Dr David Jenkins, professor of nutrition science and medicine at St Michael's Hospital in Toronto said that it was surprising that nutritional supplements has so few benefits and yet were consumed by so many people.
The researchers found that patients who were taking statins to reduce their cholesterol showed harm caused by taking niacin or vitamin B3 supplementation. Taking these two together raised the risk of death by 10 percent. Statistically 200 people would need to take a combination of niacin and statin to see a single case of premature death. This number is called “number needed to harm”. Antioxidant supplements on the other hand raised the risk of early death with number needed to harm being 250.
One of the new trends of supplementation include vitamin D. The team looked at the benefits of vitamin D on prevention of stroke and heart disease and found no benefits seen with the supplementation. No benefits were seen with vitamin D in preventing early deaths. More studies of longer durations are needed to prove this said researchers.
The study concluded that there is a low or moderate quality proof that folic acid and B complex vitamins prevents heart disease and stroke. University of Newcastle nutrition professor Clare Collins explained that nutritional supplements were not an “insurance policy” against a poor diet and they did not work. The authors advise that whole foods rich in nutrients such as vegetables, fruits, whole grains, eggs, poultry, nuts, seeds, citrus fruits etc. would be a better eating choice that regular vitamin supplements.