Dietary n-3/long-chain n-3 polyunsaturated fatty acids for prevention of sporadic colorectal tumors: a randomized controlled trial in polypectomized participants.

To address preventive effects of n-3 PUFAs/LC n-3 PUFAs on CRTs, a randomized controlled trial was conducted. One-hundred four experimental group participants were advised to increase intake of n-3 PUFAs, including fish/shell fish, fish oil supplements and perilla oils, and to decrease consumption of n-6 PUFAs and fats/oils as a whole for 24 months. One-hundred one control group participants were only cautioned to reduce consumption of fats/oils as a whole. Random allocation was satisfactorily attained, and participants sufficiently complied with our regimen. Intakes, plasma concentrations, and compositions of the RBC and sigmoid colon membranes of n-3 PUFAs, LC n-3 PUFAs, EPA and DHA increased, and the ratios of n-6 PUFAs/n-3 PUFAs and AA/LC n-3 PUFAs decreased without any adverse response. Twenty-four months after the intervention, the multivariate-adjusted hazard ratio (95% confidence intervals) was estimated to be 0.805 (0.536-1.209) with a signal towards the reduced CRT incidence.

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.

Contribution of specific foods to fat, fatty acids, and cholesterol in the development of a food frequency questionnaire in Koreans.

The present study identified dietary sources of fat, fatty acids, and cholesterol in Koreans residing in and near Seoul. The study also identified foods to be included in a food frequency questionnaire (FFQ) by both contribution analysis (CA) and multiple regression analysis (MRA). Three-day dietary records were collected from 224 subjects (107 men and 117 women) aged 30 to 85 years. Pork was the main source of total fat and the largest contributor to saturated fatty acids (SFA) was beef. MRA identified animal food as the primary source of between-person variance for SFA. Arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid originated primarily from marine products. About a fourth of the total cholesterol intake was derived from chickens' eggs by CA, while chickens' eggs accounted for 46% of the cholesterol intake for between-person variance by MRA. With 10 food items, the FFQ could explain more than half of total intakes except for total fat and n-3 polyunsaturated fatty acids (PUFA), and at least 65% of between-person variances. The percentage coverage in the FFQ ranged from 61% for n-6 PUFA and linoleic acid and to 90% for arachidonic acid. The value of this FFQ is that it can estimate usual dietary food patterns and nutrient intake in Koreans for epidemiological studies. It can also potentially be used to study the relationship between specific diseases and nutrient intakes of interest.

Plasma concentrations of (n-3) highly unsaturated fatty acids are good biomarkers of relative dietary fatty acid intakes: a cross-sectional study.

A cross-sectional study was conducted to clarify the associations of lifestyle factors (habitual exercise, alcohol intake and smoking habit) and plasma fatty acid (FA) concentrations as biomarkers of dietary FA intakes. We collected 7-d weighed diet records, lifestyle information and blood samples from 15 male and 79 female Japanese dietitians, and estimated dietary FA intakes and analyzed plasma FA concentrations. Plasma concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and (n-3) highly unsaturated FA (HUFA) derived from marine foods, but not linoleic and alpha-linolenic acid from plant origins, demonstrated positive correlations with dietary intakes (r = 0.303-0.602, P < 0.05) in both genders. Multiple linear regression analyses adjusted for age, BMI, total energy intake, fat (or respective FA) consumption and lifestyle factors showed that dietary intakes of EPA, DHA and (n-3) HUFA were positively associated with age in men (P < 0.05) and negatively associated with BMI in women [P < 0.01 for DHA and (n-3) HUFA]. The plasma concentrations of EPA, DHA and (n-3) HUFA in women were found to be positively associated with age and marine oil (or respective FA) intake (P < 0.01), and negatively associated with total energy intake [P < 0.05 for EPA and (n-3) HUFA]. Lifestyle factors were not associated with dietary FA intakes and plasma FA concentrations. These findings suggest that the plasma concentrations of EPA, DHA and (n-3) HUFA might be useful biomarkers for the assessment of relative FA intakes without considering associations with habitual exercise, alcohol intake and smoking habit.