Aging, though natural, is a gloomy prospect. It heralds end of life but scientists at Guangdong Medical University, China, have discovered a dietary protector that can preserve youth and delay aging and associated chronic diseases. The protector is selenium and its increased intake has shown to be associated with longer telomere length among middle-aged adults.
Yanling Shu et al conducted this study in Wuhan, China, to determine the association of dietary selenium with telomere length. This is the first study of its kind and the results show that dietary selenium was associated with prominent telomere length in women and non-obese participants.
The fact that telomeres protect our DNA was discovered in the 1930s. Telomeres are an important part of our cells and they affect how our cells age. Like aglets (little plastic or metal sheath) at the end of a shoelace, they cover the end of the DNA strand and protect chromosomes, they cover the ends of DNA stands. Telomere gets shortened as we grow older but they can also be shortened by stress, smoking, obesity, lack of physical activity and malnutrition. Telomere represents our biological age. Without their protection, our cells age and die. The 2009 Nobel Prize was awarded to three scientists who discovered that telomerase is an enzyme that plays major in the length of the telomere.
This study aimed to find the link of telomere with aging among middle-aged and older adults in the USA. 3,194 adults older than 45 were selected from the National Health and Nutrition Examination Survey (NHANES) in 1999-2000 and 2001-2002. With the help of polymerase chain reaction, leukocyte telomere length was measured. Generalized linear models were performed to check the link of selenium with telomere length. Restricted cubic spine analysis was used to measure the nonlinear dose-response relationship between selenium and telomere.
The results showed that 20ug increase intake of selenium increased the telomere length by 0.42%. In subgroup analysis longer telomere length was related to increased selenium intake in female and non-obese participants but not in males and obese patients. Restricted cubic spine analysis revealed a linear association between selenium intake and telomere length.
Selenium is a trace mineral that plays a major role in reproduction, thyroid hormone metabolism, DNA synthesis, infection and oxidative damage. It has two forms, organic and inorganic, both of which are good sources of selenium. It is present in the form of selenomethionine in human and animal tissue. It can be measured in plasma and serum selenium concentrations.
Recommended dietary allowance of selenium for 1-3 years old children is 20mcg, for 4-8 year children it is 30 mcg, for 9-13 years 40mcg, for 14-18 years 55mcg and for 18+ it is 55mcg.
Best sources of selenium include brazil nuts, cashew nuts, tuna, sardines, shrimp, turkey, beef, chicken, cottage cheese, brown rice, egg, whole wheat, milk, yogurt, lentils, green peas, banana, potato, peaches, carrots, spinach and lettuce.
Its deficiency may lead to cardiomyopathy, male infertility, osteoarthritis and cretinism in people. People with hemodialysis and HIV are prone to develop selenium deficiency because the constant loss of selenium occurs through dialysis, diarrhea and malabsorption.