Sex and seasonal variations of plasma retinol, alpha-tocopherol, and carotenoid concentrations in Japanese dietitians.

AIM: To clarify sex and seasonal variations of plasma antioxidant concentrations among middle-aged Japanese. SUBJECTS AND METHODS: We investigated sex and seasonal variations of plasma antioxidant concentrations, including retinol, alpha-tocopherol, and carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein and lycopene), in 55 middle-aged dietitians (46 women and 9 men) in Aichi Prefecture, Central Japan, who took no supplements from autumn 1996 to summer 1997. Reversed-phase high performance liquid chromatography was used to measure plasma antioxidant concentrations in overnight-fasting blood samples. RESULTS: Plasma levels of alpha-tocopherol, alpha-/beta-carotene, b-cryptoxanthin and lutein were significantly influenced by sex, being significantly higher for women than men in each corresponding season; retinol and lycopene, however, showed no such difference. For women, winter values of alpha-tocopherol, alpha-/beta-carotene, lutein and lycopene were significantly lower than corresponding summer values, and had reached their annual lowest. Retinol failed to show any significant seasonal variation, whereas the winter value of beta-cryptoxanthin had reached its annual highest. For men, beta-cryptoxanthin exhibited significant seasonal changes and was also highest in winter. Winter values of alpha-tocopherol, alpha-/beta-carotene and lycopene were lower compared with other seasons, but not statistically significant, probably due to the small sample size. CONCLUSIONS: The findings indicate that sex and seasonal variations of plasma antioxidant concentrations should be taken into account in nutritional epidemiologic studies.

Serum concentrations of fatty acids and colorectal adenoma risk: a case-control study in Japan.

BACKGROUND: Epidemiologic studies of n-3 fatty acids (FAs) and risk of colorectal cancer have generated inconsistent results, and relations with precursor colorectal adenomas (CRA) have not been evaluated in detail. We here focused on possible associations of serum FAs with CRA in the Japanese population. METHODS: We conducted a case-control study of 203 asymptomatic CRA cases (148 men, 55 women) and 179 healthy controls (67 men, 112 women) during 1997-2003 in Nagoya, Japan. Baseline information was obtained using a lifestyle questionnaire and serum FA levels were measured by gas chromatography. RESULTS: A non-significant inverse association with CRA was observed for eicosapentaenoic acid (EPA) among women. Moreover, the concentrations of docosahexaenoeic acid (DHA), a major component of n-3 highly-unsaturated FAs (HUFAs), were significantly lower in cases in both sexes. In addition, serum concentrations of total FAs, saturated FAs (SFAs) and mono-unsaturated FAs (MUFAs) had strong positive links with CRA risk. In contrast, arachidonic acid (AA) and DHA were inversely related, with 66% and 59% risk reduction, respectively. Ratios of SFAs/n-3 PUFAs and SFAs/n-3 HUFAs exhibited significant positive relations with CRA risk but there was no clear link with n-6 PUFAs/n-3 PUFAs. CONCLUSIONS: Our findings suggest a promoting influence of SFAs and MUFAs along with a protective effect of DHA on CRA risk. However, further research is needed to investigate the observed discrepancy with the generally accepted roles of the AA cascade in carcinogenesis.

The increasing incidence of colorectal cancer and the preventive strategy in Japan.

BACKGROUND: In Japan, the westernization of lifestyle, especially dietary habits, has progressed remarkably since 1950 and is presumably directly related to the increasing incidence of colorectal cancer (CRC). The aim of this epidemiology note was to summarize the most recent trends in CRC incidence and predictions until 2020 for suggesting the preventive strategies in Japanese. METHODS: Using the newest published data in Japan, the most recent trends in CRC incidence and the predicted numbers of incident cases of CRC until 2020 were summarized. RESULTS: Dietary intake of milk, meat, eggs and fat/oil demonstrated remarkable increment through 1950 to 1970, and since then has remained relatively constant. Compared with values for 1975, age-adjusted incidence rates for colon and rectal cancers were estimated to be 3.7 and 1.9 times higher among men and 2.9 and 1.3 times higher among women by 1995 or 2000, respectively, and then to plateau. Considering progression of aging of the society, numbers of incident cases for colon cancer among men and women have been predicted to increase 9.5 and 7.5 times by 2005 and 12.3 and 10.5 times by 2020, respectively, from the 1975 baseline. Likewise, the figures for rectal cancer have been predicted to increase. CONCLUSION: The increment of CRC incidence is assumed to coincide with such changes in dietary intake after approximately 20-years lag. Concrete programs for lifestyle modification and more emphasis of early cancer screening are now needed for prevention purposes.

Comparison of Japanese, American-Whites and African-Americans--pointers to risk factors to underlying distribution of tumours in the colorectum.

Relative incidence rates for colon and rectal cancer vary greatly between populations in the world. While Japanese have historically had low prevalence, immigration to the United States has now resulted in equal if not higher rates than in Caucasian- or African-Americans. Furthermore, recent data from some population-based registries in Japan itself are also pointing to particularly high susceptibility. Of particular interest is the fact that Japanese in both the home country and the US in fact have far higher rates for rectal cancer than the other two ethnic groups. An intriguing question is whether they might also demonstrate variation from Caucasian- and African-Americans in the relative incidence rates for proximal and distal colon cancers, given the clear differences in risk factors like diabetes, physical exercise, smoking, alcohol consumption, meat and fish intake and calcium exposure which have been shown to operate in these two sites. A comprehensive epidemiological research exercise is here proposed to elucidate ethnic variation in colorectal cancer development, based on cross-cancer registry descriptive and case control approaches. It is envisaged that additional emphasis on screened populations should further provide important insights into causal factors and how primary and secondary prevention efforts can be optimized.

Relation of the CD36 gene A52C polymorphism to the risk of colorectal cancer among Japanese, with reference to with the aldehyde dehydrogenase 2 gene Glu487Lys polymorphism and drinking habit.

High consumption of white meat (or saturated fatty acids) and alcohol has been demonstrated to have a tendency to increase the risk of colorectal cancer, according to the level of malondialdehyde-deoxyguanosine adducts derived from lipid per-oxidation in the colorectal mucosa. CD36 plays important roles as a long-chain fatty acid translocase and oxidized low-density lipoprotein (LDL) scavenger, while alcohol is metabolized by aldehyde dehydrogenase 2 (ALDH2) and decreases transiently metabolism of dietary fat and serum lipids. To examine associations between the risk of colorectal cancer and the CD36 gene A52C polymorphism according to the ALDH2 gene Glu487Lys polymorphism and drinking habit, a hospital-based case-control study was conducted with 128 colorectal cancer cases and 238 cancer-free controls. Odds ratios (ORs) for the C/C genotype relative to the A/A genotype were 1.70 [95% confidence interval (CI), 0.76-4.11] and 4.24 (95% CI, 1.42-22.66) for men and women, respectively, with the low-activity (Glu/Lys + Lys/Lys) ALDH2 genotype. The high-activity (Glu/Glu) genotype for men and women had no associations. On the other hand, the OR for the C/C genotype with high frequency of drinking habit relative to the A/A genotype with low frequency of drinking habit among men was 3.63 (95% CI, 1.29-13.15). The number of women with a high frequency drinking habit was too small for any corresponding analyses. Our findings suggest a significant interaction between alcohol consumption and the CD36 gene A52C polymorphism related to the metabolism of long-chain fatty acids and oxidized LDL in the etiology of colorectal cancer.

An epidemiological study of HBV, HCV and HTLV-I in Sherpas of Nepal.

An epidemiological study of hepatitis viruses type B (HBV) and type C (HCV) and human T-cell leukemia virus type I (HTLV-I) was carried out among 103 residents (male:female=61:42) regarded as Sherpas, at Lukla (Solukhumbu district), Nepal in 2004. Blood was drawn from apparently healthy volunteers at ages of 28.8+12.3 (range 15-66) years. HBsAg, HBsAb, HBcAb, and HCV Ab were measured by microparticle enzyme-immunoassay, and HTLV-I Ab was measured by particle agglutination. Prevalence of HBsAg(+), HBsAb(+), HBcAb(+), and HBsAb(+) or HBcAb(+) were 1.9% 22.3%, 24.3%, and 28.2%, respectively. For HCV Ab, only a borderline reaction was observed in one sample, and for HTLV-I Ab all samples were negative. Nucleotide sequencing of the PreS1, PreS2, and S genes revealed that HBV among Sherpas to be of the A' (or Aa) genotype, which is prevalent among Nepalese but rare in native Tibetans, suggesting transmission within Nepal rather than association with ancestors' migration from Tibet as the origin. This is the first report of Himalayan Sherpas' state of infection with HBV, HCV, and HTLV-I.

Association between type II diabetes and colon cancer among Japanese with reference to changes in food intake.

Many epidemiological studies have provided support for the hypothesis that type II diabetes can increase the risk of colorectal cancer, but time trends, geographical distributions and host factors for the two diseases remain largely to be clarified. To address these issues, we investigated the epidemic pattern of colon cancer and type II diabetes among Japanese in Japan (J-Japanese), with consideration of the westernization of dietary habits. Over the last three decades, the increase in crude mortality rates of colon cancer from the Vital Statistics has closely paralleled the increment in prevalence rates (PRs) from hospital based surveys of diabetes. Age-standardized incidence rates (ASIRs) for colon cancer among Japanese in the United States (US-Japanese) were higher than those among J-Japanese and almost the same as those among US-Whites, while PRs for type II diabetes among US-Japanese were the highest in the three populations. Correlation analysis showed that PRs for type II diabetes had a positive association with ASIRs for colon cancer among the combination of Japanese and US-Japanese (r=0.79, p<0.01). Since 1950, intake of milk, meat, eggs and fat/oil has increased, while that of rice and potatoes has gradually decreased. Our findings indicate that the increment of ASIRs for colon cancer among J-Japanese might be closely associated with the increment of PRs for type II diabetes, reflecting the westernization of food intake.