2009 Annual Report
We found dietary selenomethionine increases biomarkers of selenium status, but that this effect is dependent on genotype with respect to two selenoenzymes, glutathione peroxidase (GPX1) and selenoprotein P (SePP1). GPX1 genotype is a determinant of baseline plasma selenium level, and SePP1 genotype is a determinant of selenium balance and urinary selenium losses. IMPACT: This finding relates the metabolism of a nutrient (selenium) show capable of reducing cancer risk to a GPX1 genotype associated with increased (lung) cancer risk. We found a high meat-protein diet with high potential acid load does not impair calcium retention in women. IMPACT: This study confirms previous work at the Center; it shows that diets high in meat protein do not impair the use of dietary calcium in healthy adults and refutes previous results with purified proteins in rats. We conducted a randomized clinical trial to determine whether low magnesium status contributes to the high prevalence of sleep disturbances in older adults. We randomized subject (>51 y) to a supplemented of magnesium citrate or a placebo of sodium citrate. We found sleep quality (Pittsburg Sleep Quality Index) and red blood cell magnesium to increase in both groups, with the latter increase 70% greater in the magnesium-supplemented group. Magnesium supplementation significantly reduced C-reactive protein (CRP) in subjects whose baseline values were higher than 3.0 (indicating inflammatory stress). Subjects with baseline serum magnesium concentrations <1.8 mg/mL responded to magnesium supplementation with increases in both serum magnesium and calcium. The findings indicate that a significant number of older individuals are of low magnesium status, and that magnesium supplementation may alleviate some chronic low-grade inflammation, which has been associated with poor sleep quality.
Because the study was performed in-house, the ADODR actively participated in the research by conducting information meetings, assessing the validity of the procedures followed, and addressing problems with equipment, forms and procedures occurring during the study. Progress completed.