- Evidence from a large US study shows that multivitamin supplements do not improve the risk of death.
- In fact, people who took multivitamin supplements had a slightly higher risk of death than those who did not.
- Multivitamins are taken by approximately one in three American adults, yet their health benefits are not well established.
Daily multivitamins are one of the most popular supplements in the United States, but they may not actually improve your health.
Estimation
However, when it comes to chronic diseases like heart disease and cancer, evidence — or, more accurately, a lack of evidence — has been building for some time now that taking a daily multivitamin may not provide consumers with any substantial preventative benefit.
In fact, for healthy people, multivitamins may not be effective at all.
A large study that followed nearly 400,000 American adults with no history of chronic disease for more than 20 years found that people who took a daily multivitamin did not have a better risk of death than those who did not.
In fact, there was a slightly increased risk of death (4%) in people who took the supplements. The average age of the participants was 61.5 years.
The findings of the study by researchers at the National Cancer Institute:
Loftfield and her team used three separate cohorts of a total of 390,124 healthy U.S. adults with nearly 20 years of follow-up data.
The size and duration of this study are two of its greatest strengths. However, because it is an observational study, unlike a controlled trial, it does not prove a causal relationship between two events (in this case, taking multivitamins and death). Instead, it helps us understand the association between these events on a large scale in the real world.
One of the challenges in conducting this kind of study is the sheer amount of data to sort through and the potential for confounding. For example, the study describes two different issues that needed to be controlled for in the data: the effect of sick users and the effect of healthy users.
There is concern that health outcomes associated with multivitamin use may be misleading due to the demographics of those who take them: the “sick user effect” refers to the fact that sicker people may use multivitamins more frequently due to their health conditions.
On the other hand, the “healthy user effect” is the opposite: people who already lead a healthy lifestyle may be more likely to use multivitamins on a daily basis than those who are less concerned about their health. Without proper controls, these effects may lead researchers to two opposing conclusions about the impact of multivitamins on mortality risk.
Loftfield told Healthline that they were able to control for these distinct effects by adjusting for lifestyle factors such as smoking, diet and physical activity, and they also excluded individuals with serious chronic diseases, including cancer, from the baseline to account for “disease user effects.”
Ultimately, after controlling for all these factors, the study found that people who took multivitamins did not have a lower risk of all-cause mortality than those who did not, and no benefits were observed related to specific health outcomes, such as cancer, heart disease, or stroke.
The results of this study are in line with previous studies and
Parul M. Goyal, MD, associate professor of medicine and chief of geriatric medicine at Vanderbilt University Medical Center, who was not involved in the study, told Healthline that the results were not surprising.
“All of the patients enrolled are patients without any chronic diseases. Essentially, they are all healthy patients. Typically, if you’re a healthy person, you exercise, you eat a regular diet, you eat fruits and vegetables, you take vitamins and supplements regularly,” she said.
Goyal noted that some people may benefit from multivitamin supplements, including those with anemia, diabetes and postmenopausal women, and urged patients to consult with a medical professional before taking a multivitamin.
Healthline interviewed two registered dietitians to get their advice on eating a healthy diet and taking a multivitamin supplement.
“My advice to patients is always individualized. In my practice at Cleveland Clinic, the recommendation to take or not take a multivitamin is based on many factors, including a patient’s current health status, dietary patterns, other supplements they are taking, and their personal health goals. An MVI is not insurance. [from] unhealthy eating patterns,” says Dr. Regenerative Medicine.
Dr. Alyssa Kwan, a cardiology clinical nutritionist at the Stanford University School of Medicine, told Healthline, “I don’t generally recommend multivitamins for people who are eating a healthy, balanced diet. I only recommend them if my patients are not meeting their nutritional needs nutritionally or if their baseline diet is inadequate. If they have a very poor appetite or are unable to meet all their needs through food alone, I would recommend a multivitamin supplement.”
Like Kirkpatrick, Kwan warns that multivitamins shouldn’t be taken to compensate for unhealthy “non-nutritious food choices.”
A large observational study conducted over 20 years in nearly 400,000 US adults found that taking a daily multivitamin did not reduce the risk of death overall or from any specific chronic disease, such as cardiovascular disease or cancer.
Multivitamins are one of the most popular supplements on the market, taken by approximately one in three adults in the U.S. Despite their popularity, their health benefits are not well established.
Experts interviewed by Healthline said that if you’re following a healthy diet, taking a multivitamin is not recommended. Always consult with your healthcare provider before starting or stopping any dietary supplements.
