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Background To investigate the association between green tea consumption and the annual rate of change of gray matter (GM), white matter (WM), and hippocampal volumes in middle-aged and older Japanese community-dwellers. Methods A prospective cohort study with two years of follow-up was conducted with 1693 participants (aged 40–89 years). Green tea consumption (mL/day) data were collected with a 3-day dietary record. Volumes of GM, WM, and the hippocampus were estimated by T1-weighted brain magnetic resonance imaging and FreeSurfer software. The GM ratio, WM ratio, and hippocampal ratio (HR) were calculated as the percentages of total intracranial volume, respectively. Results The mean (SD) annual rate of change of hippocampal volume [(HR at baseline - HR at follow-up)/HR at baseline/follow-up years×100%] was 0.499 (1.128) (%). In the multivariable-adjusted general linear model, green tea consumption at baseline was negatively associated only with the annual rate of change of hippocampal volume (%) [β (95% CI) for each 1 mL/day increase in green tea consumption = -20.2E-5 (-35.0E-5 to -5.3E-5); P-value = 0.008]. No associations were observed for the annual rate of change of GM or WM volumes. The results remained significant when the analysis was limited to those with stable green tea consumption and were especially evident among individuals aged 65 years and older and among women. Conclusions In this study, each additional 100 mL/day of green tea intake was related to a reduction of approximately 5% in annual hippocampal atrophy. This association was especially evident among older individuals and among women. Key messages A negative association between green tea consumption and brain atrophy has been suggested; however, this relationship has not yet been investigated in humans. In this study, for the first time, a negative association between green tea consumption and annual hippocampal atrophy was observed in community-dwelling middle-aged and older individuals.

Background Serum uric acid (SUA) is related not only to an increased risk of gout, but also to an increased risk of cardiovascular diseases. However, real age-related changes in SUA remain unknown. Methods Longitudinal population-based study of epidemiological follow-up data of SUA, body mass index (BMI), and alcohol intake was conducted at a health examination center between 1989 and 1998. The subjects were 80,506 Japanese office workers or their families (50,157 men and 30,349 women) with an average age of 44.5 years for the men and 43.7 years for the women. Results SUA increased with age in all birth cohorts examined in men, and in women except for the youngest birth cohort (1960-1969). BMI and alcohol consumption positively contributed to the longitudinal changes of SUA. However, SUA also increased with age in the model controlled for BMI and alcohol consumption. There were birth cohort effects of SUA; at most ages, there were higher SUA levels in younger cohorts in men and lower SUA levels in younger cohorts in women, respectively. Conclusions SUA levels in men and women increased with advancing age, despite changes in drinking and in the BMI. There are birth cohort effects for SUA levels in the Japanese population.

The present study assesses the effects of dietary diversity on information processing speed among 1,766 men and women aged 40 to 79 years who participated in the first and follow up (second to seventh) waves of the National Institute for Longevity Sciences-Longitudinal Study of Aging at least once. Information processing speed was assessed using a component of the Wechsler Adult Intelligence Scale-Revised at all waves. Dietary diversity was determined using the Quantitative Index for Dietary Diversity based on a three-day dietary record at the first wave. Sex- and age decade-stratified, general linear, mixed models comprised fixed effects of dietary diversity (high/low groups), age at the first wave, years of follow-up, interactions, and covariates (education, living alone, family income, smoking, body mass index, energy intake, and medical history). The results indicated that the effects of dietary diversity were marginally significant for males aged in their 40s, 50s, and 70s (p < 0.06), suggesting that more dietary diversity was associated with better information processing speed. Regardless of dietary diversity (high/low groups), information processing speed increased with aging during the 40s and decreased in 60s and 70s in both sexes (p < 0.05). Interaction between dietary diversity and follow-up years revealed a significant interaction effect only among females aged in their 70s (p = 0.04), and information processing speed decreased less in groups with high than low diversity (-0.34 vs. -0.58 points/year). In conclusion, daily intake of various foods might help to protect information processing speed decline in females aged in their 70s.

Although smoking is a well-known risk factor of sarcopenia, the mechanism remains unclear. If inflammation or hyper-oxidants influences the etiology, anti-oxidants such as carotenoids might have preventive effects on sarcopenia. The aim of this study is to clarify the effects of carotenoids on muscle mass decline with aging, and whether there are some interactive effects between carotenoids and smoking.