This study about woman who take supplements dying younger a good example of why it’s important to be research literate. This study does not show a casual link to taking supplements and early death. All it shows is a correlative link between woman who take supplements and die earlier. That’s like saying ice cream causes summer because more people eat ice cream in summer.
In this study, being trumpeted all over the web today, WebMB reports that “In a new study, multivitamins, folic acid, iron, copper, magnesium, zinc, and vitamin B6 supplements all increased an older woman’s risk of dying from any cause. The greatest risk was seen with iron supplements. Calcium supplements, however, seemed to reduce a woman’s risk of dying. The study, which appears in the Archives of Internal Medicine, was an observational trial, not a cause-and-effect trial. So it can’t say how, or even if, these supplements actually increase a woman’s chance of dying.”
The results were gathered by woman filling out surveys. No actual medical examinations were done. And self reporting is known to be fairly inaccurate. Do you recall what you ate last Wednesday for lunch? If someone asked you to fill out a survey about your eating habits, would you be able to be 100% accurate? So why would an older woman answering a survey about taking vitamins. Many commenters have asked if the study considered whether woman taking supplements already had health issues. Science Daily does a better job of reporting the story. Their headline reads “Certain Dietary Supplements Associated With Increased Risk of Death in Older Women, Study Suggests” while WebMD’s headlines reads “Can Supplements Increase a Woman’s Risk of Dying?”
In reviewing the actual study, it appears that what the researchers did was simply compare the woman who took vitamins and woman who did not and determined who died earlier. No other data was taken into consideration. Like overall health of the woman. The study did not take into account any other factors that may have caused earlier death. Like genetic predisposition to disease. Link to the actual study results here. At the same time, if fat ssoluable vitamins are taken in high doses, there can be adverse health effects. But this study didn’t mention that.
Citation: J. Mursu, K. Robien, L. J. Harnack, K. Park, D. R. Jacobs. Dietary Supplements and Mortality Rate in Older Women: The Iowa Women’s Health Study. Archives of Internal Medicine, 2011; 171 (18): 1625 DOI:
Look at How Different Media Spin These Correlative Research Results:
- Can Supplements Increase a Woman’s Risk of Dying? (webmd.com)
- Vitamins May Increase Women’s Risk of Dying, Research Finds (livescience.com)
- Daily Vitamins Tied to Early Deaths (abcnews.go.com)
- Vitamin pills ‘may shorten life’ (bbc.co.uk)
- Vitamins Could Lead To Higher Death Rates In Women [Study] (inquisitr.com)
- Study: Vitamins may boost death risk in older women – USA Today (news.google.com)