Effect of selenium status and supplementation with high‐selenium yeast on plasma homocysteine and B vitamin concentrations in the UK elderly

Abstract

The level of plasma total homocysteine (tHcy), long known to be B vitamin dependent, has recently been shown to be inversely associated with plasma selenium (Se) concentration in human subjects. We therefore, chose to investigate the interaction between Se, tHcy and B vitamins in a double-blind, placebo-controlled trial where 501 healthy UK elderly volunteers were randomly allocated to receive 100, 200, or 300 microg Se/day as high-Se-yeast, or placebo-yeast for 6 months. Plasma Se, tHcy, folate, vitamin B-12, pyridoxal-5'-phosphate (PLP) and its catabolite, 4-pyridoxic acid, were measured in all participants at baseline and in samples from the placebo, 100 and 300 microg Se/day groups, at follow-up. At baseline, Se was inversely correlated with tHcy but only in males (p < 0.001). Before supplementation, tHcy concentration was significantly lower in the highest compared to the lowest Se tertile in males (p < 0.05), and in females when folate concentrations were also in the top tertile (p < 0.05). The effect of folate, PLP and vitamin B-12 concentrations on plasma tHcy correlated with Se concentration at baseline. After 6 months of Se supplementation, only Se concentration had changed significantly. Supplementation with Se does not affect tHcy concentration in the UK elderly population.

Frequent Consumption of Selenium-Enriched Chicken Meat by Adults Causes Weight Loss and Maintains Their Antioxidant Status

“…Many studies have assessed the efficacy of selenium supplements intake on antioxidant status and general health parameters of different populations, with pharmacological levels, ranging from 100 to 480 μg/day [21,24,25,28,32,33], while in the present trial the dose employed was of 36.4 μg/day (22 additional daily microgram compared with non-enriched chicken), and as novelty it was not consumed as a supplement, but it was provided with chicken breast. One of the aims of supplying a selenium supplement was to avoid the tachyphylactic process concerning antioxidant status after weight loss [10].…”

“…Indeed, almost all the research performed in relation to selenium intake has been carried out by administering high selenium concentrations as dietary supplements [21,24,25,28,32,33], while the effect of consumption of functional foods with a moderately higher content in selenium, within the recommended dietary allowance, has not yet been apparently assessed.…”

Epigenetic effects of selenium and their implications for health

“…Se supplementation in form of daily doses of 100 or 300 mg Se as high-Se yeast for 6 months increased plasma Se but had no effect on HCys levels. 60 This lack of effect supported an earlier intervention study where 200 mg Se (as SelMet) given daily for 20 weeks failed to change plasma HCys levels; yet a possible association of Se and HCys at baseline was not assessed in that study. 68 Animal experiments allow greater flexibility in the design of supplementation studies, a better control for confounding factors, and more options for end point detections.…”

“…Removal of the adenosyl group gives homocysteine (HCys). The concentration of HCys in blood or plasma is of clinical importance, as it has been associated with a multitude of complex diseases like cardiovascular and neurodegenerative diseases 60 (and references therein). Clearance of HCys occurs through its remethylation to methionine, in turn serving as a substrate for the formation of SAM, or otherwise via metabolism in the transsulfuration pathway.…”

“…60 Plasma Se was calculated to account for 1.8% of HCys variance by linear regression analyses. In line with this, serum Se predicted 5.8% variance in HCys in a Spanish population independently of folate and vitamin B 12 , and individuals within the highest versus lowest Se tertile had a 63% reduced risk of being in the top HCys tertile.…”