Vitamin D, which you can generate from sunlight exposure, or get through certain foods like salmon or fortified milk, helps keep the body’s immune system, bones, muscles, and heart healthy. 

A new long-term study published Wednesday finds that vitamin D supplementation may also play a significant role in aging.

The study, which appears in The American Journal of Clinical Nutrition, found that those who took vitamin D supplements over four years slowed the shortening of their telomeres. Telomeres are the protective ends of chromosomes that shrink with age. “The finding that these telomeres seem to be protected against shortening, and that their length was being preserved by vitamin D supplementation, suggested that vitamin D may have a role in slowing biological aging,” says Dr. JoAnn Manson, coauthor of the study and chief of the Division of Preventive Medicine at Brigham and Women’s Hospital. 

Like the plastic end of shoelaces that help protect the string from fraying, the telomeres have a similar role in keeping the chromosomes healthy, Manson explains. The randomized clinical trial included about 1,000 people aged 50 and over who had a baseline telomere length at the start and were analyzed via white blood cell tests at years two and four in either the vitamin D group taking 2,000 IU per day or a placebo group. 

“The vitamin D group had the amount of telomere shortening that you would expect with about one year of aging,” Manson tells Fortune, who claims this is the first large-scale randomized trial looking into the benefits of vitamin D supplementation on biological aging. “It appeared that close to three years of aging were being eliminated with the vitamin D supplementation.” 

In the parent study that Manson was a lead investigator on, which included nearly 26,000 participants, researchers found that Vitamin D supplementation was associated with decreased inflammation, autoimmune diseases, and advanced cancers, all of which play a role in aging. Other research found that Vitamin D may improve brain health and memory.

While the findings show a link between biological aging and vitamin D supplementation, Manson says further studies are needed. At this point, she does not call for universal use of vitamin D supplementation for the sole purpose of slowing telomere shortening, which is but one biological process of aging. 

High-risk groups, like those 75 and older or those with osteoporosis or who get little sunlight, may benefit from vitamin D supplementation. You should speak with your doctor before taking it. 

As for the average healthy individual, Manson hopes it’s clear that adequate vitamin D is essential to taking care of your health. First and foremost, ensure you’re getting enough through your lifestyle, like going outdoors and eating foods rich in the vitamin. 

Though the study found that between 1,000 and 2,000 IU can be safe, the recommended dietary allowance of vitamin D is 600 IU per day for those between ages 1 and 70, and 800 IU for those over 70.

Manson warns that there is danger in overdoing it on supplements or “mega dosing,” which can lead to toxicity and adverse side effects. “Having a healthy diet and time outdoors, being physically active, will be enough for the majority of the population to have adequate vitamin D status,” she says.

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• An expert says don’t waste your money on beetroot supplements—try this instead
• Some dietary supplements you think are improving your health may be damaging your liver, research warns