Abstract
Folate and vitamin B12 are essential for a variety of metabolic processes. Both micronutrients have been shown to reduce oxidative stress significantly. The present cross-sectional investigation evaluated the association between serum and dietary folate and vitamin B12 levels and leukocyte telomere length, an index of cellular aging influenced by oxidative stress. The study included 5581 adults from the National Health and Nutrition Examination Survey (NHANES). Because participants were randomly selected, results are generalizable to all civilian, noninstitutionalized U.S. adults. A blood draw provided DNA and serum folate and B12 information. The quantitative polymerase chain reaction method was used to measure telomere length. The Bio-Rad Quantaphase II folate and vitamin B12 radioassay kit was used to quantify levels of folate and vitamin B12. Dietary folate and vitamin B12 were assessed using a multipass 24 h recall. In some models, age, race, smoking pack-years, alcohol use, body mass index, total physical activity, hours fasted before the blood draw, and diabetes status were employed as covariates to minimize their influence. Findings showed that for each additional year of chronological age, telomeres were 15.6 base pairs shorter, on average (F = 378.8, p < 0.0001). Men had shorter telomeres than women after adjusting for all the covariates (F = 6.8, p = 0.0146). Serum (F = 10.5, p = 0.0030) and dietary (F = 5.0, p = 0.0325) folate concentrations were each linearly related to telomere length in women, but not in men, after controlling for age and race. Serum vitamin B12 and telomere length had a nonsignificant, inverse relationship in women, with age and race controlled (F = 2.8, p = 0.1056), but no relation in men. Dietary vitamin B12 was linearly related to telomere length in women, after adjusting for age and race (F = 4.3, p = 0.0468), but not in men. Overall, evidence indicates that folate and vitamin B12 levels, especially folate, account for meaningful differences in cell aging in women, but not in men.
Highlights
A good measure of DNA stability, cellular integrity, and biologic aging is the length of telomeres
After adjusting for differences in age, race, smoking, alcohol use, body mass index (BMI), total physical activity, hours fasted, diabetes status, and pregnancy status, for each 10% increase in serum vitamin B12, telomeres were 5.59 base pairs longer, on average (F = 3:1, p = 0:0867)
The observed relationship in women could be a function of low concentrations of folate and vitamin B12 resulting in higher oxidative stress levels, leading to accelerated cell aging and shorter telomeres
Summary
A good measure of DNA stability, cellular integrity, and biologic aging is the length of telomeres. Telomeres are nucleoprotein structures that cap the ends of chromosomes. Because the ends of telomeres cannot be completely replicated when cells divide, telomeric DNA is used to safeguard genetic code, so it is not lost from the ends of chromosomes. Telomeres naturally shorten during each cell division. The loss of telomere base pairs is sometimes called “the end replication problem,” but other factors can cause telomere shortening. Telomeres become critically short and senescence and cell death occur. Morbidity and mortality associated with several disorders are higher in adults with shorter telomeres [1,2,3]
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