A large new study suggests that vitamin D supplements may help slow one of the body’s basic aging processes. Researchers found that people who took vitamin D every day showed less shortening of telomeres, which are small protective parts of our DNA that naturally become shorter as we get older.
The research comes from the VITAL study, a major long‑term clinical trial carried out in the United States. The findings were published in The American Journal of Clinical Nutrition.
Telomeres are often compared to the plastic tips at the ends of shoelaces. Just as those tips stop the shoelaces from fraying, telomeres protect the ends of chromosomes, which carry our genetic information.
Every time a cell divides, telomeres become a little shorter. Over time, when telomeres become too short, cells can no longer work properly. This process is considered an important part of biological aging.
Scientists have learned that shorter telomeres are linked to a higher risk of several diseases that tend to appear later in life. These include cancer, heart disease, diabetes, and autoimmune disorders.
Because of this, researchers have been trying to understand whether certain lifestyle choices or nutrients might help protect telomeres and slow down their shortening.
Vitamin D has long been known for helping the body absorb calcium and keep bones strong. It also plays an important role in the immune system and inflammation. In recent years, scientists have started to wonder whether vitamin D might also influence aging at the cellular level.
Earlier small studies suggested that vitamin D or omega‑3 fatty acids might help maintain telomere length. However, those studies often involved small numbers of participants and produced mixed results. Researchers wanted stronger evidence from a much larger and more carefully designed study.
The VITAL trial provided an opportunity to investigate this question. This large clinical trial followed more than 25,000 adults across the United States.
Participants were randomly assigned to receive vitamin D supplements, omega‑3 supplements, both, or a placebo. Because it was randomized and followed participants for several years, the study provides strong scientific evidence.
Within the VITAL trial, scientists conducted a special sub‑study focusing on telomere length. This part of the research included 1,054 participants. The group included women aged 55 or older and men aged 50 or older.
Researchers measured the length of telomeres in the participants’ white blood cells at the beginning of the study. They then measured them again after two years and four years.
Participants who took vitamin D3 supplements received 2,000 international units (IU) per day. When researchers compared their results with those who took a placebo, they found an important difference. People taking vitamin D showed significantly less telomere shortening over time.
The researchers estimated that the effect was roughly equal to preventing nearly three years of biological aging over the four‑year study period. This means that vitamin D appeared to help protect the telomeres from shrinking as quickly as they normally would.
Omega‑3 fatty acid supplements were also tested in the study. Participants taking omega‑3 received one gram per day. However, the researchers did not find any meaningful effect of omega‑3 on telomere length.
Dr. JoAnn Manson, one of the senior authors of the study and the principal investigator of the VITAL trial, explained that this is the first large and long‑term randomized trial to show that vitamin D supplementation can help preserve telomere length.
Dr. Manson is chief of the Division of Preventive Medicine at Brigham and Women’s Hospital, part of the Mass General Brigham healthcare system.
The first author of the study, Dr. Haidong Zhu from the Medical College of Georgia at Augusta University, said the results suggest that vitamin D may slow some aspects of aging at the cellular level.
However, he also noted that scientists still need to learn more about how vitamin D produces this effect and whether it can reduce the risk of age‑related diseases over many years.
These findings add to earlier results from the VITAL trial. Previous reports from the same large study showed that vitamin D supplementation may reduce inflammation and lower the risk of certain chronic diseases, including advanced cancers and autoimmune conditions.
Although vitamin D supplements are widely used and generally considered safe when taken at recommended levels, experts still advise people to speak with a healthcare professional before starting a supplement routine. Individual needs for vitamin D can vary depending on factors such as age, health status, sun exposure, and diet.
Overall, this research highlights a new possible benefit of vitamin D beyond its well‑known role in bone health and immunity. By helping protect telomeres, vitamin D may influence one of the fundamental processes that drive aging.
Scientists say more research is needed, but the findings suggest vitamin D could play an important role in future strategies aimed at healthy aging and disease prevention.
If you care about nutrition, please read studies about how Mediterranean diet could protect your brain health, and this plant nutrient could help reduce high blood pressure.
For more information about nutrition, please see recent studies that olive oil may help you live longer, and vitamin D could help lower the risk of autoimmune diseases.
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