LAUSR

Objectives DNA damage induced by oxidative stress is implicated in accelerated telomere shortening, a biomarker of biological aging. Although selenium has antioxidant properties, its impact on telomere length is largely unknown. This study aimed to examine the association between dietary selenium intake and leukocyte telomere length in a nationally representative sample of US adults. Methods We included 7409 adults aged 20 years or older who participated in the National Health and Nutrition Examination Survey (NHANES) 1999-2002. Dietary selenium intake was calculated using data collected in the 24-hour dietary recall. Leukocyte telomere length was assayed using the quantitative polymerase chain reaction method. The association between selenium intake and telomere length was estimated by weighted linear regression models adjusting for demographic, socioeconomic and lifestyle factors, body mass index, supplements intake, and leukocyte cell type composition. Results The average dietary selenium intake was 109.1 mg/d (standard error [SE] 1.15). We didn't find a significant association between dietary selenium intake and telomere length in US adults. The average telomere length (SE) was 1.01 (0.02), 1.01 (0.01), and 1.04 (0.01) across increasing tertiles of dietary selenium intake. However, a significant interaction was observed for age (P = 0.02). Among individuals aged 20-44 years, the β coefficient of log-transformed telomere length, compared to lowest tertile of dietary selenium intake, was -0.041 (SE 0.012, P = 0.002) and -0.033 (SE 0.018, P = 0.07) for middle tertile and the highest tertile of selenium intake, respectively. The corresponding β coefficient was 0.009 (SE 0.016, P = 0.59) and -0.001 (SE 0.012, P = 0.95), respectively, for adults 45-64 years old, and 0.017 (SE 0.015, P = 0.28) and 0.059 (SE 0.021, P = 0.01), respectively, for those aged 65 years or older. The results were not appreciably changed even after additionally adjustment for dietary intake of vitamin A, vitamin E, and zinc. Conclusions The association between dietary selenium intake and telomere length differed significantly by age groups, indicating that higher selenium intake may prevent telomere shortening in older adults but not in younger or middle-aged adults. Further studies about the underlying mechanisms are warranted. Funding Sources NA.