Higher dietary selenium intakes linked to younger ‘biological age’: Telomere study

Every 1 microgram increase in dietary selenium intake in women with diabetes was associated with telomeres that were 1.84 base pairs longer, according to an analysis of data from the National Health and Nutrition Examination Survey (NHANES) in 1999–2000 and 2001–2002.

However, no such association was observed for men with diabetes, according to the paper published in the British Journal of Nutrition.​

The data show correlation and not causation but could have implications for our understanding of healthy aging.

“The present study demonstrates that dietary selenium intake is significantly associated with telomere length only present in the female population with diabetes in the United States.,” ​reported scientists from Ganan Medical University and Jinggangshan University (both in Jiangxi province)

Telomeres​

The aging and lifespan of normal, healthy cells are linked to the so-called telomerase shortening mechanism, which limits cells to a fixed number of divisions. During cell replication, the telomeres function by ensuring the cell's chromosomes do not fuse with each other or rearrange, which can lead to cancer.

Elizabeth Blackburn, a telomere pioneer at the University of California San Francisco, likened telomeres to the ends of shoelaces, without which the lace would unravel.

With each replication the telomeres shorten, and when the telomeres are totally consumed, the cells are destroyed (apoptosis). Previous studies have also reported that telomeres are highly susceptible to oxidative stress and inflammation. Some experts have noted that telomere length may be a marker of biological aging.

Consumption of foods with antioxidant and anti-inflammatory properties have previously been linked with longer telomere length, and since selenium participates in antioxidant and anti-inflammatory effects in the form of selenoproteins, increases in dietary selenium intake may be related to longer telomere length.

This is not the first time that dietary selenium intake has been linked to telomere length, with a 2020 paper in Clinical Nutrition​​ reporting that that the increased dietary selenium intake was associated with longer telomere length among middle-aged and older adults in America. However, the new study is reportedly the first to examine any potential associations in diabetics.

Study details​

NHANES data for 878 people with diabetes (average age 61) indicated that

After controlling for the confounders, 1 microgram increase in dietary selenium intake in female patients with diabetes, and telomere length increased by 1.84 base pairs, and the relationship was found to be linear in the range 0-250 micrograms.

Men did not show the same associations, said the researchers.

“Changes in telomere length in women may be influenced by estrogen levels in their bodies,”​ explained the researchers. “Estrogen stimulates telomerase production and may prevent reactive oxygen species damage. ​

“In addition, women have better antioxidant and physiological properties of selenoproteins, which may reduce telomere attrition. Previous animal experiments have shown that female rats have a lower demand for selenium than male rats, which is related to sex differences in telomere attrition. ​

“However, the mechanism of action of sex on dietary selenium intake and telomere length among diabetes remains unclear, and further studies are needed for confirmation.”​

Selenium ​

Selenium is an essential micronutrient, and is considered to be an antioxidant. The mineral is included in 25 selenoproteins in the body, with diverse roles including immune support, thyroid function and healthy sperm. The issue for selenium, as for other nutrients, is that you can get too much of a good thing.

Mean dietary selenium intakes in the US range from 93 micrograms in women to 134 micrograms in men, compared to only 40 micrograms per day in Europe (the recommended daily amount for US adults is 55 micrograms per day​).

Data from prospective studies have reported potential risk reductions for a number of cancers for selenium, and it is the only mineral that qualifies for a Food and Drug Administration (FDA)-approved qualified health claim for general cancer reduction incidence.

A review paper by Joyce McCann and Bruce Ames​ from the Nutrition and Metabolism Center at Children’s Hospital Oakland Research Institute in Oakland (CHORI) indicated that moderate deficiency in selenium may have long-term detrimental effects (FASEB Journal​, 2011, Vol. 25, pp. 1793-1814).

Source: British Journal of Nutrition​
Published online ahead of print, doi: 10.1017/S000711452200174X​
‘The relationship between dietary selenium intake and telomere length among diabetes”​
Authors: H. Gong et al.