- Evidence from a large U.S. study indicates that multivitamin supplements do not improve mortality risk.
- Individuals taking a multivitamin supplement actually had a slightly higher mortality risk than those who did not.
- Multivitamins are taken by roughly one in three US adults, but their health benefits are not well established.
Daily multivitamins are some of the most popular supplements in the United States, but they may not actually make you healthier.
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However, evidence, or, more accurately, a lack of evidence, has been mounting for some time that daily multivitamins may not provide consumers with any real protective benefit when it comes to chronic conditions like heart disease and cancer.
In fact, for healthy individuals, a multivitamin may provide no benefit at all.
In a large study involving nearly 400,000 US adults without a history of chronic diseases over a follow-up period of more than 20 years, those taking a daily multivitamin showed no improvement in mortality risk compared to those who did not.
In fact, those who were taking the supplement demonstrated a slightly increased (4%) mortality risk. The average age of participants was 61.5.
The findings, from researchers at the National Cancer Institute, were published in
Loftfield and her team utilized three separate cohorts for their study, totaling 390,124 generally healthy US adults, with follow-up data of about 20 years.
The study’s size and length are two of its greatest strengths. However, it is observational in nature, meaning that, unlike a controlled trial, it does not demonstrate causality between two events — in this case, taking a multivitamin and death. Instead, it helps to form a picture of any associations between these events at a large scale in the real world.
Part of the difficulty of conducting a study of this nature is the sheer volume of data to sort through and the potential for confounding. For example, the study discusses two distinct problems they had to control for in their data: the “sick user effect” and the “healthy user effect.”
There is a concern that health outcomes related to multivitamin use are misleading because of the demographics using them. The “sick user effect” refers to the possibility that individuals who are sick may more frequently use multivitamins due to their health condition.
On the other hand, the “healthy user effect” is the opposite: individuals who already live a healthy lifestyle may be more inclined to use a multivitamin as part of their routine than those who are less health conscious. Without proper controls in place, these effects could lead a researcher to two opposing conclusions about the effects of multivitamins on mortality risk.
Loftfield told Healthline that they were able to control for these distinct effects, by adjusting for lifestyle factors like smoking, diet, and physical activity. They also excluded individuals with major chronic diseases, including cancer, at baseline to account for the “sick user effect.”
Ultimately, after controlling for all these factors, they found that those taking a multivitamin did not have a lower risk of all-cause mortality than those who did not. Nor did they observe any benefits related to specific health outcomes, including cancer, heart disease, and stroke.
The findings are in line with prior research, including recommendations made by the
Dr. Parul M. Goyal, MD, an Associate Professor of Medicine and Director of Medicine for Seniors at Vanderbilt University Medical Center who wasn’t affiliated with the study, told Healthline the results were not surprising.
“The patients that they enrolled are all patients without any chronic medical conditions. Essentially, they’re all healthy patients. Typically, if you are a healthy individual, and you are exercising, you’re eating a regular diet, you’re consuming your fruits and vegetables, you are getting your regular intake of vitamins and supplements,” she said.
Goyal notes that there are some individuals who would likely benefit from a multivitamin supplement, including those with anemia, diabetes, and postmenopausal women. She encourages patients to speak with their healthcare professional before taking a multivitamin.
Healthline spoke to two registered dietitians to hear their recommendations about eating a healthy diet and taking multivitamin supplements.
“My recommendations for patients are always personalized. In my practice at the Cleveland Clinic, a recommendation to take or skip a multivitamin is based on many factors, including the patient’s current health, dietary pattern, other supplements being taken, and personal health goals. An MVI is not insurance [from] an unhealthy dietary pattern,” said Kristin Kirkpatrick, MS RD, a registered dietitian at the Cleveland Clinic and co-author of Regenerative Health.
Alyssa Kwan, MS, RD, a Clinical Dietitian in Cardiology at Stanford Medicine, told Healthline, “I do not generally recommend a multivitamin for those following a healthy diet and eating well-balanced meals…I will only recommend one if patients are not nutritionally meeting their nutrient needs or have a poor diet at baseline. Maybe their appetite is really poor or they are just not able to meet everything via diet alone, then I would recommend supplementing with a multivitamin.”
Like Kirkpatrick, Kwan also cautions that a multivitamin should not be taken to cover unhealthy “choices of foods that are not nutritionally dense.”
In a large observational study involving nearly 400,000 US adults over 20 years, taking a daily multivitamin did not lower mortality risk overall, nor for specific chronic conditions like cardiovascular disease and cancer.
Multivitamins are among the most popular supplements on the market, taken by roughly one in three US adults. Despite their popularity, their health benefits are not well established.
Experts interviewed by Healthline say that if you eat a healthy diet, taking a multivitamin is not recommended. Always speak with your healthcare provider before starting or stopping taking a nutritional supplement.