Do vitamins and supplements increase mortality rate in older women? The headlines in USA Today sure make it look like they do.
The only clear associations shown in this study were that supplemental iron was found to increase the risk of mortality and the higher the dose of iron, the higher the risk. Calcium was shown to reduce the risk of mortality.
Calcium and Iron were the only supplements where the authors listed the doses that were studied.
First, it is already known that excess iron seen with high levels of ferritin (iron stores) increase the risk of cardiovascular disease in several studies (Circulation, 1992 and NEJM 1994). For this reason many multivitamins for adults and non-menstruating women exclude the use of iron. In my practice I asses ferritin levels and do not prescribe iron in patients where it is unwarranted based on adequate levels of ferritin and red blood cell counts.
Second, the lower risk of death with calcium intake is actually reassuring in light of recent research pointing to calcium supplementation possibly causing an increase risk of cardiovascular disease (CVD).
If you read the study, in their initial analysis, multiple different vitamins were actually found to be beneficial including vitamin B complex, C, D, E and calcium. After several adjustments in the data they were able to show weak negative associations. Most of the associations reported in USA Today did not even reach statistical significance. In a scientific paper, if it did not reach statistical significance, then it did not happen, essentially.
There are 2 other issues to consider here which are frequently not considered when scientific research on vitamins is carried out. The first issue is that very frequently the doses that have been shown to be beneficial in prior studies are not used and then the authors conclude that whichever vitamin or supplement is not beneficial. Well if they don’t use the beneficial doses then of course that is what they will find. Secondly, and importantly, they frequently don’t use the proper form of the vitamin that is shown to be more efficacious. For example, in the current study, they do not distinguish between the use of cholecalciferol and ergocalciferol – 2 different types of vitamin D. The former has been shown to be more effective than the latter but if you don’t distinguish, you are less likely to see a beneficial effect. This mistake has been made in many studies that look at the benefits of supplemental nutrients.
As Dr. Pappo (quoted in the USA Today article) states, “very few people eat the required amount of fruits and vegetables a day” and “I wouldn’t conclude from this that you stop taking a standard multivitamin”.
Further, consider that a standard multivitamin may not be enough both in dose and quality to protect your health. In summary, avoid iron unless your tests show you need it and make sure you are getting high quality supplements from a reputable, pharmaceutical grade supplement maker to assure yourself that you are getting the best benefits from vitamins.