Vitamin D May Slow Cells\u2019 Aging<\/p>\n
Vitamin D supplements may help prevent the loss of telomeres, DNA sequences that shrink with aging, a large study shows. But the health effects aren\u2019t yet clear<\/p>\n<\/div>\n
By Stephanie Pappas<\/a> edited by Jeanna Bryner<\/a><\/span><\/p>\n A new study suggests vitamin D supplements might slow cellular aging by protecting telomeres.<\/p>\n<\/div>\n Olga Pankova\/Getty Images<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/div>\n Vitamin D supplements might slow cellular aging<\/a> by preventing the loss of telomeres, DNA sequences at the ends of chromosomes that shorten in old age, a new study suggests. The health effects of these findings aren\u2019t yet clear.<\/p>\n Vitamin D had been touted as a panacea for a number of health conditions<\/a>, from cardiovascular disease to bone loss. In 2020 a large randomized controlled trial of supplementation<\/a> instead found benefits only in a few conditions, particularly autoimmune disease and advanced cases of cancer, says the new study\u2019s co-author JoAnn Manson, a professor of medicine at Harvard Medical School and a principal investigator of that large trial, called the VITamin D and OmegA-3 TriaL (VITAL). The new study is an analysis of data from VITAL. Its finding could explain the protective effect of vitamin D supplements on these specific aging-related diseases<\/a>, Manson says.<\/p>\n \u201cIf is replicated in another randomized trial of vitamin D supplements<\/a>, I think this could translate into clinical effects for chronic diseases of aging,\u201d she says. \u201cWe\u2019re already seeing that vitamin D does reduce inflammation<\/a>; it reduces advanced cancers and cancer deaths, as well as autoimmune diseases. This could provide a biological mechanism.\u201d<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing<\/a>. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n In the VITAL project, researchers enrolled nearly 26,000 women aged 55 or older and men aged 50 or older, and they randomly assigned participants to take vitamin D supplements, fish oil supplements, a combination of both or a placebo. For the new study, published today in the American Journal of Clinical Nutrition,<\/i> the scientists looked at a subset of 1,054 participants who lived close enough to Harvard\u2019s Clinical and Translational Science Center in Boston to have their blood drawn three times over four years so researchers could measure their telomeres.<\/p>\n Inside the nuclei of most cells in the human body<\/a> reside 46 chromosomes<\/a>, where our DNA is neatly packed. Each time a cell divides, these chromosomes unravel and copy themselves, and the copies coil back into the nuclei of the new cells. Telomeres are repetitive DNA sequences that cap the ends of chromosomes. They stabilize the chromosomes during cell division, though they get shorter each time cells divide. When the telomeres<\/a> get very short, the cells stop dividing and die. Over time, as more and more of our cells die, the body ages and ultimately stops functioning. Telomeres aren\u2019t a perfect clock for health\u2014very long telomeres can increase cancer risk<\/a> by stabilizing mutated cells\u2014but they\u2019re often used as a biomarker for aging.<\/p>\n Participants in the placebo and supplement groups had similar telomere lengths at the beginning of the study, the researchers found. But over the four years of follow-up, people assigned to take 2,000 international units of vitamin D per day showed less shortening of their telomeres compared with people in the placebo group. Fish oil had no significant effect.<\/p>\n \u201cVitamin D supplementation is able to slow down the telomere shortening process, at least during the four-year period,\u201d says the study\u2019s first author Haidong Zhu, a molecular geneticist at the Medical College of Georgia at Augusta University.<\/p>\n Participants started out with an average of 8,700 base pairs of DNA telomere length, and vitamin D supplementation slowed the loss of length by about 140 base pairs over four years, the study found.<\/p>\n The health implications of that number aren\u2019t clear. \u201cIt\u2019s only at the extremes that telomere length really matters in terms of aging,\u201d cautions Mary Armanios, a professor of oncology and director of the Telomere Center at Johns Hopkins University, who was not involved in the research. The magnitude of difference seen in the vitamin D trial is within the normal range of human variation, meaning it may not equate with aging or youthfulness in any clinical sense.<\/p>\n \u201cMost of us are going to be within this normal range, and there is a wide buffer for how much telomere length can change,\u201d Armanios says.<\/p>\n In addition, Armanios says, the study used a method called quantitative polymerase chain reaction (qPCR) to assess telomere length, and this method can be very sensitive to factors such as when samples were collected and what time elapsed between collection and testing. \u201cThe methodology for telomere length measurement has been compared to others and found to be the least reproducible<\/a>,\u201d she says.<\/p>\n![\"Golden](\"https:\/\/static.scientificamerican.com\/dam\/m\/666c49904844c4e9\/original\/vitamin-d-pills.jpg?m=1747851417.134&w=600\")
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