Do Multivitamins Really Work?

​Cassandra Gong

Early in my adolescent years, my pediatrician noticed that the iron levels in my blood tests were low, so she prescribed me an iron supplement to take once a day. My new anemia diagnosis scared my mother into buying expensive multivitamins in bulk, and she encouraged me to take two multivitamins every morning because they would “stop diseases from happening”. While these multivitamins did provide the iron I needed, I wondered if taking these broad multivitamins was necessary since I wasn’t deficient in nutrients other than iron. There is a common misconception that taking vitamins and supplements will prevent chronic diseases and improve health outcomes. However, research does not support these wide-ranging health claims. 

Many studies have looked at the relationship between multivitamins and health outcomes. For example, a comprehensive study done on 2 million adults revealed that multivitamins use did not improve cardiovascular outcomes in the general population. In a longitudinal study for up to 55 months on 1,708 heart attack survivors, researchers at Johns Hopkins Medicine found that heart health is also not improved by taking multivitamins. Additionally, taking multivitamins did not reduce risk for mental decline, like memory loss. While the evidence does not support some of the positive health claims made about daily multivitamin use, it does indicate that there may be adverse side effects associated with regular use, which can occur at higher rates if taken right before surgery or with other drugs. For example, taking Vitamin K supplements is associated with a reduction in the efficacy of blood thinners.
 
Meanwhile, studies done on the effects of vitamins and supplements on cancer incidence are conflicting. For example, a study done with 35,000 men at the National Institute of Health found that taking Vitamin E supplements is associated with a higher risk of developing prostate cancer, contrary to earlier research hypotheses. However, a different study done on daily low-dose multivitamin supplementation has been potentially linked to reduced incidence of cancer among men. Further research on the side effects of multivitamins on different demographic groups is needed to understand the effects of vitamin and supplement intake on our health.
 
Although taking a multivitamin does not improve general health outcomes we do have evidence that a balanced diet can supply all the nutrients necessary for a healthy life. Experts recommend using trusted sources to make sure the foods you eat contain a variety of vitamins and minerals you need, like omega-3 fatty acids from fish, and calcium, magnesium, and potassium from low-fat dairy. A healthy diet that encompasses a variety of vitamins and minerals is also possible when following diets like vegetarianism or veganism. For example, tofu provides the necessary amount of vitamin B-6 and leafy green vegetables provide adequate calcium. To support families in identifying how to consume a balanced diet, The National Institutes of Health (NIH) released a dietary supplement fact sheet to provide information about dietary supplements, their ingredients, and how each can affect your health.
 
While research doesn’t support the case for general multivitamin consumption as a path to disease prevention or improved health outcomes, people with vitamin deficiencies should consult with their healthcare provider to appropriately address their specific need. However, in most cases, the data shows that we should prioritize improving our diets by eating a variety of healthy foods, including fruits and vegetables, rather than relying on supplements and multivitamins as a blanket fix.

​About the Author:
Casandra Gong is a rising third-year undergraduate student at The University of Massachusetts, Amherst studying Microbiology with a minor in Sociology. She plans to pursue a career in public health and healthcare. In her free time, Casandra is an instrumentalist and coordinator for UMass Amherst Lion Dance (UMassALD), an East-Asian cultural lion dance performance group.