Heart disease is a buildup of plaque in blood vessels that leads to poor blood flow to the heart. This can lead to heart attack and early death. Changes to lifestyle habits, such as eating a heart-healthy diet, have been shown to promote heart health. Some adults turn to dietary supplements and special diets to further promote heart health and life longevity. In fact, studies show that more than half of all Americans take dietary supplements.
Researchers wanted to examine the evidence about the effects of nutritional supplements and dietary interventions on mortality and cardiovascular outcomes in adults. The study, published in Annals of Internal Medicine, found that most dietary supplements cannot be linked to life longevity or protection from heart disease.
The researchers included 277 randomized controlled trials using 16 supplements and 8 dietary interventions for their association with mortality or heart disease, stroke, and heart attack. The studies had a combined number of 992,129 participants worldwide. Researchers found that nutritional supplements, such as vitamin B6, vitamin A, multivitamins, antioxidants, and iron, did not affect mortality or cardiovascular disease outcomes. Likewise, dietary interventions, such as reduced fat intake, also did not have an affect.
The interventions that did show promise include:
Researchers found that most of the supplements and diets did not cause harm with the exception of combining calcium and vitamin D. This combination may increase the risk of stroke.
A meta-analysis combines many studies to create a larger pool of participants. The larger the pool the more sound the results are. However, the review is only as sound as the studies that are in it. The 277 studies used differing interventions and controls, making it harder to pool and compare data. Long term supplements and dietary studies are difficult to do as controlled studies. That type of study would require intentionally giving someone a harmful diet to see difference and that would not be ethical. This is why it is hard to make direct links between foods or supplements and health. It also results in inconsistent and sometimes frustrating results.
Supplements are readily accessible at most stores and diets are easily found on the internet. However, this ease makes it crucial that consumers educate themselves about the benefits and risks. Talk to your doctor about any supplements or diets that you use or plan to use. Your overall health and current treatment may be an important factor in deciding supplements. Some interventions may be no more than an added expense in the family budget. Work with your doctor to make shared decisions about the role that supplements and diet changes may play in your health.
American Heart Association
Centers for Disease Control and Prevention
Khan SU, Khan MU, et al. Effects of nutritional supplements and dietary interventions on cardiovascular outcomes: an umbrella review and evidence map. Ann Intern Med. 2019 Jul 9. doi: 10.7326/M-190341.
Using dietary supplements wisely. National Center for Complementary and Integrative Health website. Available at: https://nccih.nih.gov/health/supplements/wiseuse.htm. Updated January 2019. Accessed July 29, 2019.
Last reviewed July 2019 by EBSCO Medical Review Board