Do supplements increase risk of death?

Contrary to the headlines, this recent paper, published in the journal Annals of Internal Medicine, analysed the risk of mortality of those taking various supplements versus non-users and found that supplement takers had a reduced risk of death. To quote the study “self-reported use of vitamin B complex; vitamins C, D, and E; and calcium had significantly lower risk of total mortality compared with non-use; copper was associated with higher risk.” They found statistically significant health benefits for many supplements, with calcium being the strongest positive, and copper being the strongest negative.
When they looked at the pattern of risk over the three decades they reported that, for many nutrients the mortality risk was less in supplement takers and further reduced the longer people had been taking the supplements. This was true for multivitamins, magnesium, selenium, vitamin D, vitamin E. Vitamin C and B vitamins were associated with reduced risk in each of the three survey points.
The most negative association was seen with iron, with increasing mortality risk the longer a person had taken it. Copper went from a negative in the first survey point, to a positive result in the last.
They also found that “compared with nonusers, supplement users had a lower prevalence of diabetes mellitus, high blood pressure, and smoking status”. Generally, they were a bit more physically active and less likely to be on HRT.

Source  - Patrick Holford