How Vitamin D Stops Your Telomeres Shortening | Dr JoAnn Manson

[00:08] this year, right? 2026 2025. >> 2025. So, it came out in May of 2025. It was published in the American Journal of Clinical Nutrition. >> And can you talk about the headline result, which was that the telomere

[00:23] length was would would not reduced the the level of reduction was like almost it was only like 12% of the placebo. But anyway, could you talk about how about

[00:37] the telomere length and how it compares to the placebo? to the placebo? >> The vitamin D supplement did protect the >> The vitamin D supplement did protect the telomeres in that over 4 years of

[00:51] telomeres in that over 4 years of treatment, there was only 1 year of telomere shortening in the vitamin D randomized group, the group that received the the vitamin D in comparison to the placebo group that had

[01:08] comparison to the placebo group that had 4 years of telomere shortening over that 4 years of telomere shortening over that 4-year follow-up period. So, there was protection of the telomeres by the vitamin D

[01:23] >> Could we talk a little bit about how the telomeres were measured? So, which telomeres were measured? So, which telomeres were measured in which cells? >> So, this was a peripheral blood sample measured in leukocytes or white blood

[01:39] measured in leukocytes or white blood cells. And um cells. And um it is a technically complicated measurement. However, we we collaborated with an outstanding lab. And also, I I

[01:55] just want to clarify for the audience. I I know many of them may fully understand what telomeres are. But one way to think about the telomeres is that they're the

[02:07] protective caps at the end of the chromosome similar to the protective caps on shoelaces that keep the shoelace from unraveling and degrading. Um the telomere cap which

[02:26] and degrading. Um the telomere cap which is a repeated sequence of DNA at the end of each telomere. This protects the telomere the um Excuse me. It protects the chromosome from degrading, um unraveling, damage uh

[02:43] from degrading, um unraveling, damage uh to the chromosome. So we we found that to the chromosome. So we we found that the amount of telomere shortening that the amount of telomere shortening that would normally take place over 4 years

[02:55] would normally take place over 4 years as we saw in the placebo group had only about 1 year of shortening in the vitamin D randomized group. >> Right. And just for reference, what causes the telomeres to to shorten?

[03:12] what causes the telomeres to to shorten? >> It's a biological pathway of aging. The >> It's a biological pathway of aging. The These cells are constantly replicating. There's a lot of turnover of cells. Um and it is a marker of biological

[03:29] Um and it is a marker of biological aging. Over our lifespan, we have a substantial shortening of the telomeres in cells. And it's one of the um you

[03:41] in cells. And it's one of the um you know, uh hopes in trying to extend know, uh hopes in trying to extend health span and and slow biological health span and and slow biological aging to find ways to um

[03:54] protect telomeres, prevent the telomere shortening that occurs with biological aging, as well as some of these affect some of these other biological pathways such as DNA methylation, epigenetic aging. That's a separate biological

[04:10] aging. That's a separate biological pathway, but telomere shortening is one pathway, but telomere shortening is one of the biological pathways of aging. >> Some years ago, I I mean 10 years or so, it it was like one of the major markers

[04:25] for aging, and it seems to have not to be to be viewed more nuanced recently, but it's still definitely correlated. Longer telomeres are correlated with younger organisms, I guess.

[04:39] >> Right. And also the shortening of the telomeres has been linked to some chronic diseases of aging. The The evidence in the literature is not

[04:51] entirely consistent, but overall, there is a pattern of shorter telomeres being is a pattern of shorter telomeres being predictive of higher risk of cardiovascular disease, of type 2 diabetes, of some cancers. Though with

[05:07] diabetes, of some cancers. Though with cancer, it's a very complex relationship where for some cancers, actually shorter telomeres are are are predictive of of lower risk. So, it's it's an inconsistent

[05:23] picture with cancer. But cardiovascular disease, type 2 diabetes, um osteoporosis fractures, most aging-related diseases, there there is an association between shorter telomeres and higher

[05:39] between shorter telomeres and higher risk of aging-related chronic diseases.