A groundbreaking study has revealed that vitamin D3 may play a key role in slowing the process of biological ageing by protecting DNA from age-related damage.
The four-year study, conducted by researchers at Harvard University, involved 1,031 participants. Half of the group received a daily supplement of 2,000 IU (international units) of vitamin D3, while the other half was given a placebo.
After analysing blood samples, the researchers found that the participants who took vitamin D3 experienced significantly slower shortening of telomeres—the protective caps at the ends of DNA strands that serve as biological markers of ageing.
According to the findings, telomere length in the vitamin D group decreased by only 5% in the first two years, compared to a 12% reduction in the placebo group. After four years, the telomere reduction in the vitamin D group was limited to 7%, while the placebo group saw a 28% decline. This difference is estimated to represent a biological ageing delay of approximately three years.
Dr. JoAnn Manson, Chief of Preventive Medicine at Brigham and Women’s Hospital and a co-author of the study, noted that this is the first large-scale randomised trial to demonstrate that vitamin D supplementation may help preserve telomere length. She added that the findings support previous research suggesting that vitamin D reduces inflammation and lowers the risk of chronic age-related diseases such as cancer and autoimmune disorders.
The study suggests that vitamin D helps protect DNA by reducing oxidative stress—an imbalance between harmful free radicals and antioxidants in the body—as well as by enhancing the activity of Telomerase, the enzyme responsible for maintaining telomere integrity.
Despite these promising results, the researchers cautioned against unsupervised high-dose supplementation. The study used a dosage of 2,000 IU per day, which exceeds the commonly recommended daily intake of 600 to 800 IU but remains within the safe upper limit of 4,000 IU.
Excessive intake of vitamin D can lead to calcium buildup in the blood, potentially causing nausea, vomiting, and kidney stones. As such, medical guidance is advised before beginning high-dose vitamin D supplementation.
