Coffee consumption and skeletal muscle mass: WASEDA'S Health Study.

Few studies have examined the association between coffee consumption and muscle mass; their results are conflicting. Therefore, we examined the association between coffee consumption and low muscle mass prevalence. We also performed an exploratory investigation of the potential effect modification by demographic, health status-related and physical activity-related covariates. This cross-sectional study included 2085 adults aged 40-87 years. The frequency of coffee consumption was assessed using a self-administered questionnaire. Muscle mass was assessed as appendicular skeletal muscle mass/height2 using a multifrequency bioelectrical impedance analyser. We defined low muscle mass using cut-offs recommended by the Asian Working Group for Sarcopenia. Multivariable-adjusted OR for low muscle mass prevalence were estimated using a logistic regression model. The prevalence of low muscle mass was 5·4 % (n 113). Compared with the lowest coffee consumption group (< 1 cup/week), the multivariable-adjusted OR (95 % CI) of low muscle mass prevalence were 0·62 (0·30, 1·29) for 1-3 cups/week, 0·53 (0·29, 0·96) for 4-6 cups/week or 1 cup/d and 0·28 (0·15, 0·53) for ≥ 2 cups/d (P for trend < 0·001). There were no significant interactions among the various covariates after Bonferroni correction. In conclusion, coffee consumption may be inversely associated with low muscle mass prevalence.

Effect of Vitamin D Supplementation on Body Composition and Physical Fitness in Healthy Adults: A Double-Blind, Randomized Controlled Trial.

INTRODUCTION: This study aimed to clarify whether 1 year of vitamin D3 supplementation has a direct effect on body composition and physical fitness in healthy adults. METHODS: Ninety-five participants randomly received either 420 IU vitamin D3 per day (n = 48) or placebo (n = 47) in a double-blind manner for 1 year. Lean body mass and percentage body fat were determined. Physical fitness including hand grip strength, leg extension power and cardiorespiratory fitness (CRF) were assessed. Serum 25-hydroxyvitamin D (25[OH]D) and 1,25-dihydroxyvitamin D (1,25[OH]2D) concentrations were assessed using ELISA kits. RESULTS: Serum 25(OH)D and (1,25[OH]2D) concentrations significantly increased by approximately 11.2 ± 9.2 ng/mL (pinteraction <0.001)and 7.0 ± 7.8 pg/mL (pinteraction <0.001) after 1 year of vitamin D3 supplementation respectively. Lean body mass significantly increased from 43.8 ± 9.6 to 44.3 ± 9.8 kg in vitamin D group, while no change was observed in placebo group (from 42.6 ± 8.9 to 42.4± 8.9 kg) after 1 year intervention. Furthermore, no treatment effects on other indicators of body composition and physical fitness were observed. CONCLUSIONS: One year of vitamin D supplementation effectively improves lean body mass, but not muscle strength and CRF in healthy adults.

Vitamin D supplementation reduces insulin resistance in Japanese adults: a secondary analysis of a double-blind, randomized, placebo-controlled trial.

Higher circulating 25-hydroxyvitamin D (25[OH]D) concentration has been linked to a lower prevalence of insulin resistance and type 2 diabetes mellitus. However, randomized controlled trials have not clarified the effect of vitamin D supplementation on insulin resistance in healthy adults. The objective of this study was to assess the effect of vitamin D supplementation for 1 year on insulin resistance; the study was a secondary analysis of a clinical trial. We hypothesized that increased 25(OH)D concentration after vitamin D supplementation for 1 year would significantly improve insulin resistance. Ninety-six healthy adults participated in this study, of whom 81 completed the study. The participants randomly received daily either 420 IU vitamin D3 or placebo in a double-blind manner for 1 year. The levels of fasting insulin, glucose, and other parameters were assessed at baseline and after 1 year of intervention. Homeostasis model assessment of insulin resistance index was calculated from insulin and glucose levels. Visceral fat area and physical activity were also investigated. Serum 25(OH)D and 1,25-dihydroxyvitamin D concentrations were significantly increased by approximately 29.5 nmol/L and 7.0 pg/mL, respectively, after 1-year vitamin D supplementation. After vitamin D supplementation, fasting glucose levels and values of homeostasis model assessment of insulin resistance index significantly decreased from 88.3 to 85.3 mg/dL (P < .01) and 1.17 to 0.84 (P < .01), respectively, and the results were independent of physical activity and visceral fat accumulation. In conclusion, the present study showed that vitamin D supplementation for 1 year effectively improves fasting glucose level and insulin resistance in healthy Japanese adults.

Mitochondrial gene in the nuclear genome induces reproductive barrier in rice.

Hybrid incompatibility in F(1) hybrids or later generations is often observed as sterility or inviability. This incompatibility acts as postzygotic reproductive isolation, which results in the irreversible divergence of species. Here, we show that the reciprocal loss of duplicated genes encoding mitochondrial ribosomal protein L27 causes hybrid pollen sterility in F(1) hybrids of the cultivated rice Oryza sativa and its wild relative O. glumaepatula. Functional analysis revealed that this gene is essential for the later stage of pollen development, and distribution analysis suggests that the gene duplication occurred before the divergence of the AA genome species. On the basis of these results, we discuss the possible contribution of the "founder effect" in establishing this reproductive barrier.