Cancer mortality and serum levels of carotenoids, retinol, and tocopherol: a population-based follow-up study of inhabitants of a rural area of Japan.

A total of 3,182 subjects (1,239 males and 1,943 females) aged from 39y to 79y, were recruited from the inhabitants of a rural area in Japan who participated in health check-up programs from 1988 to 1995. During the 10.5 year follow-up, 287 deaths (175 males and 112 females) from all causes, 134 (81 males and 53 females) from cancer of all sites, 31 from lung cancer, 21 from colorectal cancer, 20 from stomach cancer, and 62 from other cancers, were identified among the cohort subjects. Fasting serum samples were taken at the time of the health check-ups, and serum levels of carotenoids, retinol and tocopherols were separately determined by HPLC. Statistical analyses were performed using Cox's proportional hazard model after adjusting for sex, age, and other confounding factors. High serum levels of alpha- and beta- carotenes and lycopene were found to marginally significantly or significantly reduce the risk for mortality rates of cancer of all sites and of colorectal cancers. High serum levels of beta-cryptoxanthin also showed an inversely relation with the risk of mortality from lung and stomach cancers, but this was not statistically significant. High intake of green-yellow vegetables contributing to serum levels of alpha- and beta- carotenes, as well as lycopene, may reduce the risk of cancer mortality, especially from colorectal cancer, in rural Japanese.

Relationship between obesity and serum markers of oxidative stress and inflammation in Japanese.

The present study was conducted to assess the relationship between obesity and serum levels of C-reactive protein (CRP), carotenoids, oxidized LDL (oxLDL), oxidized LDL antibodies (oLAB), and leptin in Japanese residents. The subjects were 158 males and 158 females aged 40-79 years, and living in Hokkaido, Japan, who attended a health examination screening. Serum levels of CRP, oxLDL, oLAB, and leptin were measured by enzyme-linked immunosorbent assay (ELISA) and serum carotenoid levels were measured by high-performance liquid chromatography (HPLC). Body mass index (BMI) was calculated as body weight (kg) divided by height (m) squared and obesity was defined as BMI of 25 or more (kg/m2). Serum levels of CRP and leptin were significantly higher in the obese group than in their non-obese counterparts in both genders. Serum levels of beta-carotene and beta-cryptoxanthin were lower in the obese individuals, especially in females. While values for oxLDL and oLAB did not significantly vary. BMI was positively correlated with log-transformed serum levels of CRP and leptin in both genders (males: r=0.231, p<0.05; females: r=0.305, p<0.001). In females, moreover, BMI was negatively correlated with log-transformed serum levels of beta-carotene, zeaxanthin/lutein, and beta-cryptoxanthin (r=-0.244, p<0.01; r=-0.200, p<0.05; r=-0.207, p<0.01, respectively). Significantly higher odds ratios (ORs) for high serum levels of CRP (males: OR=2.12; females: OR=3.96) and leptin (males: OR=3.83; females: OR=9.07) were observed in obese versus non-obese men and women, after adjusting for various confounding factors. Significantly lower adjusted odds ratios for high serum levels of alpha- and beta-carotenes (males: OR=0.23, 0.33; females: OR=0.35, 0.39, respectively) were also observed in the obese as compared to the non-obese group. In conclusion, obesity is highly associated with states of oxidative stress and low-grade inflammation in Japanese residents, suggesting that these latter might play an important role in the association between a high BMI and certain cancers as well as coronary heart disease (CHD).