Effect of various dietary factors on the deposition of selenium in the hair and nails of rats.

Noninvasive techniques to monitor selenium (Se) status at higher intake levels should be developed if Se supplements are to be given to human subjects as possible anti-cancer agents. Hair and nails have been suggested as indices of Se status because they are easily obtained, transported and stored. However, there has been little research on the potential influence of such factors as dietary Se intake or nutritional status on the levels of Se in hair and nails. Here we report the effects of chemical form of dietary Se and of methionine (Met) status on the Se content of rat hair and nails. Rats were fed diets containing 0.5, 1.5 or 2.5 micrograms/g of Se as sodium selenate (Na2SeO4) or L-selenomethionine (SeMet) for 8 wk. Hair and nail Se retention was two- to threefold greater when dietary SeMet was fed. Hair and nail Se levels increased as liver and muscle Se retention increased in rats fed SeMet, whereas in rats fed Na2SeO4, hair, nails and liver accumulated Se but muscle Se levels remained relatively unchanged. In a second experiment, rats were fed diets containing 0.1, 0.5 or 2.5 micrograms/g of Se as Na2SeO4 or SeMet, +/- added Met (0.3%) for 6 (+Met) or 7 (-Met) wk. Hair and nail Se retention was greater when Met was deficient than when this amino acid was not limiting. These results suggest that factors other than dietary Se intake affect hair and nail Se content and that these tissues should be used with caution for Se status assessment purposes.