Shoichiro Tsugane

Food consumption and gastric cancer mortality in five regions of Japan

To explore the causes of the threefold variation in mortality rate from gastric cancer in Japan, we studied the geographic correlations between food consumption and age-adjusted mortality rates in five regions, which covered the areas with the highest and lowest mortality rates in the country. Six hundred thirty-four men and wives of 373 of the men sampled from the general populations in these districts were interviewed about intake frequency of 38 food items. Age-adjusted mean frequencies of food intake differed markedly among the regions, in which 32 food items for men and 28 for women showed a significant difference (p < 0.05). Rank correlation coefficients between the average frequencies and the mortality rates with adjustment for sex and prevalence of current smokers were 0.49, 0.32, 0.36, -0.88, and -0.57 for rice, bean paste soup, pickled vegetables, green vegetables, and yellow vegetables, respectively. These results suggest that the regional differences in consumption of these foods may account partly for the geographic variation in gastric cancer mortality in Japan.

Green tea intake in relation to serum lipid levels in middle-aged Japanese men and women

PURPOSEnThe relationship between green tea intake and serum concentrations of total cholesterol, triglycerides, and high density lipoprotein cholesterol was examined.nnnMETHODSnThe subjects were 630 middle-aged men and their 370 wives sampled from five regions of Japan during 1989-1991. Consumption frequency of 38 foods, including green tea, was determined by interview. Three-day food records were collected from 207 of the men and 164 of the wives. The mean serum concentrations of the three lipids were compared according to the three levels of daily green tea intake (< 1 cup, 1-4 cups, and > 4 cups), with adjustments for various health habits, food frequencies, and nutrient intakes.nnnRESULTSnAfter extensive multivariate adjustments for nondietary and dietary covariates, green tea was not associated with any of the lipid levels.nnnCONCLUSIONSnThe results of this cross-sectional study do not support the beneficial effects of green tea on serum lipid levels.

Differential Effects of Cigarette Smoking and Alcohol Consumption on the Plasma Levels of Carotenoids in Middle-aged Japanese Men

Although several studies have reported that cigarette smoking and alcohol consumption are inversely associated with the plasma level of beta‐carotene even after adjustment for dietary carotene intake, their effects on other carotenoids have not been examined extensively. The authors examined the associations of smoking and alcohol with plasma levels of the five principal carotenoids (beta‐carotene, alpha‐carotene, lutein, lycopene, and zeaxanthin). The subjects were 634 apparently healthy men aged 40–49 years who were sampled randomly from five areas in Japan with varying rates of mortality from gastric cancer. Multiple linear regression analysis controlling for age, serum total cholesterol, serum triglycerides, body mass index, and consumption frequencies of green vegetables, yellow vegetables and fruit, showed that both smoking and alcohol had a significant inverse association with the plasma levels of beta‐carotene and alpha‐carotene; only smoking reduced the level of lutein, and neither smoking nor alcohol significantly affected the level of lycopene or zeaxanthin. With regard to the reduction of beta‐carotene and alpha‐carotene, the effect of smoking was smaller in drinkers than in nondrinkers, and the effect of alcohol was smaller in smokers than in nonsmokers, and significant interactions between smoking and alcohol were observed (P=0.034 for beta‐carotene and 0.026 for alpha‐carotene). The results indicate that the differential effects of smoking and alcohol should be considered when the health effects of plasma carotenoids are examined.

Nutrient consumption and gastric cancer mortality in five regions of Japan

To explore the causes of the threefold variation in mortality rate from gastric cancer in Japan, we studied the geographic correlations between nutrient consumption and the disease in five Public Health Center districts including the regions with the highest and lowest mortality rates in the country. In the winters of 1989-1991, a three-day weighed food record was collected from 207 men and the wives of 165 of the men sampled from the five districts. The average daily consumption of selected nutrients was computed and correlated with the age-adjusted mortality rates from gastric cancer. Partial rank correlation coefficients adjusted for sex and other nutrients were 0.45, -0.80, -0.20, and -0.07 for sodium, carotene, ascorbic acid, and retinol, respectively. The results suggest that variation in gastric cancer mortality in Japan may be partly accounted for by the regional differences in consumption of sodium, carotene, and possibly ascorbic acid.

Interpopulation and intrapopulation variability of nutrient intake in five regions of Japan

Objectives: To determine the extent to which interpopulation (between-population) variance, relative to intrapopulation (within-population) variance, contribute to the total variability in nutrient intakes.Design: Cross-sectional study.Setting: Five Public Health Center districts in Japan.Subjects: Two hundred and seven men and 183 spouses.Interventions: A three-day weighed food record.Main outcome measures: The total variance in the consumption of 17 nutrient variables was partitioned by analysis of variance into its inter- and intrapopulation components separately for men and women.Results: The percentage contribution of the interpopulation to total variance differed according to the nutrient; it was notable (8–17%) for total energy, carbohydrates, phosphorus, and sodium in both men and women, but was negligible (less than 4%) for micronutrients such as retinol, carotene, thiamin, riboflavin, niacin and ascorbic acid. The ratio of intra- to interpopulation variance was estimated for 31 nutrients (17 in men and 14 in women). The point estimates of the ratio were larger than unity in all nutrients, and the lower limit of the 95% confidence intervals exceeded unity for all but 5 nutrients. Of the two sources of intrapopulation variation, intraindividual variance was larger than interindividual variance in most of the nutrient.Conclusions: The relative magnitude of interpopulation variation in dietary data can be used to quantify the range of exposure in ecological studies and to examine the heterogeneity of populations pooled for individual-based analysis.Sponsorship: This study was supported in part by Grants-in-Aid for Cancer Research from the Ministry of Health and Welfare, and for Scientific Research from the Ministry of Education, Science and Culture of Japan.

Four Food-Frequency Categories of Fruit Intake as a Predictor of Plasma Ascorbic Acid Level in Middle-Aged Japanese Men

PURPOSEnPlasma levels of ascorbic acid are assumed to be determined not only by dietary amount of ingested vitamin C, but also by other dietary and nondietary factors. To assess the predictability of plasma ascorbic acid level in Japanese men, we examined its association with dietary sources of vitamin C and other lifestyle factors.nnnMETHODSnIn a cross-sectional study of 621 healthy men aged 40-49 years who were sampled randomly from five areas in Japan, the weekly intake frequency of foods rich in vitamin C (< 1, 1-2, 3-4, > or = 5 days/week), alcohol consumption per week, use of vitamin C supplements, and smoking were assessed by use of a food-frequency questionnaire (FFQ) (all subjects) and a 3-day weighed dietary record (DR) from 203 volunteers.nnnRESULTSnIn univariate analyses of FFQ data, the intake frequency of fruit (R2 = 0.12), pickled vegetables (R2 = 0.03), potatoes (R2 = 0.01), and alcohol consumption (R2 = 0.02) were significant determinants of plasma ascorbic acid in addition to supplement use and study area. In a multivariate analysis, four FFQ categories of fruit intake accounted for 19% of the variation in plasma ascorbic acid among nonsupplement users after adjustment for study area and alcohol intake. The association between plasma ascorbic acid level and quartile of dietary vitamin C intake (mg/day) measured by DR was weaker (R2 = 0.04) than the association between plasma ascorbic acid level and dietary intake of fresh fruit (g/day) (R2 = 0.09).nnnCONCLUSIONnThe predictability of plasma ascorbic acid by a four-category FFQ assessment of fruit intake was superior to calculated vitamin C or fruit intake assessed by detailed DR.

Within‐ and between‐person variations in portion sizes of foods consumed by the Japanese population

There has been considerable controversy about the utility of asking separate questions on portion sizes in addition to items on consumption frequencies in food frequency questionnaires. One argument against this type of inquiry is that, for most foods, within-person variation of portion size is greater than between-person variation, making it difficult to characterize usual or long-term average serving sizes. The authors studied the relative effects of within- and between-person variances in portion sizes of 69 food items using three-day food record data collected from 335 Japanese men and women. Total variance in the portion size for each food was partitioned into within- and between-person components by analysis of variance. Although the ratios of within- to between-person variances in log(e)-transformed portion sizes were > 1.0 for the majority of foods (50 of 69 items, median = 1.7), they were smaller than or close to unity for subgroups of foods that were the major sources of nutrient variables of relevance to diet-cancer associations, such as total energy (rice, calcium (milk), sodium (pickled vegetables), and alcohol (beer, shochu, whiskey). These results indicate that the relative contributions of within- and between-person variations in portion size may vary among foods, and therefore investigators should consider the balance between the advantages and disadvantages of obtaining portion size data separately from intake frequencies when designing food frequency questionnaires.

A Pilot Study for a Randomized Controlled Trial to Prevent Gastric Cancer in High‐risk Japanese Population: Study Design and Feasibility Evaluation

Observational epidemiological studies suggest that some nutrients reduce the risk of gastric cancer and that individuals with atrophic gastritis are at high risk of developing gastric cancer. One possible measure for gastric cancer prevention is therefore nutritional supplementation for the high risk group. Before recommending this strategy for the general public, however, a randomized controlled trial (RCT) is necessary. To evaluate the feasibility of an RCT, the authors conducted a pilot study using recipients of a health check‐up program in a general hospital in Japan. The subjects who were asked to participate in the trial had been diagnosed as having atrophic gastritis on the basis of serum pepsinogen I <70 ng/ml and the ratio of pepsinogen I to II <3.0. They were requested to ingest double‐blinded capsules containing different levels of vitamin C and β‐carotene every day. Out of the 219 subjects (118 males, 101 females) who were eligible for the study and had the required pepsinogen measurement, 90 (41%) met the criteria for atrophic gastritis. Among them, 55 (61%) (35 males, 20 females) gave their informed consent to participate in the RCT. Fifty‐four participants completed a 3‐month course of supplementation, and all of them agreed to a 5‐year supplementation period. The authors concluded that an RCT using double‐blinded nutritional supplements and targeting apparently healthy individuals is feasible in an intervention study for cancer prevention in Japan.

Effects of human diets of two different Japanese populations on cancer incidence in rat hepatic drug-metabolizing and antioxidant enzyme systems

Hepatic enzyme systems of drug metabolism and antioxidation were investigated in rats fed the complete human diets consumed in the two Japanese prefectures, Akita and Okinawa, where the incidence of cancers was quite different: Okinawa had the lowest and Akita the highest age-adjusted mortality rate. In rats fed the human diet consumed in Okinawa, hepatic glutathione S-transferase activity was higher and lipid peroxide content was lower than in rats fed the diet consumed in Akita. These data might indicate that the number and/or quantity of the dietary components attributed to the detoxification of carcinogens and the scavenging reactive carcinogen species was much higher in the foods consumed in the population having lower cancer mortality rate.

Perceptions of change in diet have limited utility for improving estimates of past food frequency of individuals

Accuracy of methods to assess past diet in retrospective studies is of concern. Adjustment of current intake for subjects perceptions of change is one alternative to estimate past intake. The authors studied the potential utility of perceived change in diet in residents of a rural Japanese community who participated in three sequential surveys with self-administered questionnaires. Frequencies of consumption for 27 foods were investigated in the first and second questionnaires administered in 1988 and 1993 (n = 451), and perceived changes in their frequencies during this period were asked in the second and third questionnaires surveyed within two weeks (n = 214). Perceptions of change in diet were highly reproducible. At a group-level analysis, they were consistent with the changes in food frequencies in 21 of the 27 items. Nevertheless, whereas current diet adjusted for perceived change correlated better with past intake than did current intake alone in 17 foods, improvement in Pearsons correlations was only marginal (median = 0.02). Perceptions of change in diet would therefore be of limited utility in improving estimate of past intake among individuals in retrospective studies.