Americans spend more than $36 billion a year on vitamins and nutritional supplements – all in the hopes for leading healthier lives. More than half of Americans take at least one vitamin a day, and millions take more than that. But do vitamins actually improve your health?
Researchers from Harvard University’s School of Public Health reviewed the large body of evidence on vitamins and nutritional supplements to make some broad recommendations about when they are helpful.
The basic take-home message: most people do not benefit from taking vitamin supplements.
Dr. JoAnn Manson, the study’s lead author and the chief of preventive medicine at Brigham and Women's Hospital, explains that it’s best to get nutrients from a healthy diet because people absorb vitamins of minerals from food more easily and are more likely to consume nutrients in the proper ratios.
In fact, research clearly demonstrates positive health outcomes are more strongly related to healthy diets and specific foods compared to supplements.
According to the evidence, there are some clear cases where taking vitamins is helpful and even medically-necessary:
Pregnancy: There is clear evidence that taking folic acid early in pregnancy helps to prevent neural tube defects. In addition, iron and calcium can be beneficial to pregnant women and their babies. Research shows it’s best to get these with prenatal vitamins.
Infants and children: Infants and children who are breastfed should take a vitamin D supplement until weaning. In addition, infants should take an iron supplement from the ages of 4 to 6 months. Beyond that, there is no evidence that vitamins help improve children’s health.
Midlife and older adults: Multivitamins are not recommended for middle-aged and older adults, but there are some cases where a supplement may help. Adults over 50 years old may benefit from supplemental vitamin B12. There is some evidence that vitamin D and calcium can help prevent bone loss in older adults. But too much calcium is associated with kidney stones and a higher risk of heart disease, so it’s best to get calcium through diet.
In addition to these general categories, there are medical conditions and medications that interfere with vitamin absorption. In these cases, it’s best to work with your doctor to determine what your body needs.
The review also notes that the U.S. Food and Drug Administration does not review dietary supplements for safety or efficacy.
There are independent testing labs – including ConsumerLab.com, US Pharmacopeia, and NSF International – that certify supplements do not contain microbes or toxins. If you do need a supplement, it’s best to use one certified by one of these labs.
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References
Manson, JoAnn E. , and Shari S. Bussuk. “Vitamin and Mineral Supplements: What Clinicians Need to Know.” JAMA, 5 Feb. 2017, doi:doi:10.1001/jama.2017.21012.
