Major study reveals if multivitamins actually help you live longer

Multivitamin supplements have become a routine addition to many Americans' diets, with as many as 1 in 3 U.S. adults consuming them regularly, but are these daily doses improving overall health and longevity?

A study from the National Institutes of Health (NIH) published Wednesday found that multivitamins won't help extend your life, with researchers reporting, "multivitamin use to improve longevity is not supported."

The study analyzed data from nearly 400,000 adults over 20 years. Participants had a median age of 61.5 years old and were generally healthy, with no history of chronic diseases, according to the study published in JAMA Network Open.

The study found no evidence that daily multivitamin consumption reduced the risk of death from conditions such as heart disease or cancer.

Rather than living longer, otherwise healthy people who took daily multivitamins were slightly more likely (4%) than non-users to die in the study period, according to researchers.

Researchers reported nearly 165,000 deaths occurring during the follow-up period of the study, out of the initial group of 390,000 participants.

The study, however, did not analyze data from people with pre-existing vitamin deficiencies.

"What this study shows is that, generally, multivitamins aren't going to help you live longer," Dr. Jade A Cobern, MD, MPH, board-certified physician in pediatrics and general preventive medicine, told ABC News.

"Even though the cost of many multivitamins isn't high, this is still an expense that many people can be spared from," Cobern said.

Cobern explained that, when possible, it's best to get vitamins and minerals from your diet, focusing on increasing vegetable intake and limiting red meat consumption, rather than relying solely on a supplement.

"We can all likely benefit from adding more vegetables and whole grains or legumes into our diets, reducing red meat intake, decreasing our sedentary time and reducing alcohol intake," Cobern suggested.

While taking a multivitamin supplement does not increase longevity, Cobern said it's important for people to ask their doctor to know if a multivitamin or specific vitamin supplement would be helpful in their case, based on their health history and diet.

"If a doctor prescribes a vitamin for someone, it's important to take that medication," Cobern said, adding, "I recommend everyone get routine health checkups and to talk to doctors about your dietary history and disclose any supplements you're taking in those appointments."