No association between fruit or vegetable consumption and the risk of colorectal cancer in Japan

Abstract

In a pooled analysis of two prospective studies with 88 658 Japanese men and women, fruit and vegetable consumptions, were not associated with a lower risk of colorectal cancer (705 cases); multivariate relative risk (95% confidence interval) for the highest vs the lowest quartile of intake being 0.92 (0.70 -1.19) and 1.00 (0.79 -1.27), respectively. (Michels et al, 2000;Voorrips et al, 2000). In Japan, mortality from colorectal cancer increased during 1950 -2000, especially in men (age-adjusted rate per 100 000 of 2.9 -14.4 for colon and 5.6 -9.3 for rectum in men; 3.3 -9.5 for colon and 4.2 -4.1 for rectum in women) (Statistics and Information Department, Minister's Secretariat, Ministry of Health, Labor, and Welfare of Japan, 2003). Dietary factors may play a part in this increase, but the role of fruit and vegetables remains unclear. We therefore examined the association between fruit and vegetable consumption and the risk of colorectal cancer in the Japan Public Health Center (JPHC) prospective study on cancer and cardiovascular disease. MATERIALS AND METHODSThe JPHC study has two population-based cohorts, and study designs are described in detail elsewhere (Otani et al, 2003). Briefly, Cohort I started in 1990 and included 40 106 subjects (19 345 men and 20 761 women) who were 40 -59 years of age, lived in four Public Health Center districts, responded sufficiently to a self-administered questionnaire, and had no history of cancer (73.7% of the eligible subjects). Cohort II started in 1993 and included 48 552 subjects (23 180 men and 25 372 women) who were 40 -69 years of age, lived in five Public Health Center districts, responded sufficiently to a self-administered questionnaire, and had no history of cancer (77.9% of the eligible subjects).Cohort I questionnaire asked about the average consumption during the previous month of 44 food items including two fruit (fruit and fruit juice) and five vegetables (green leafy vegetables, yellow vegetables, white vegetables, pickled vegetables, and vegetable juice). Cohort II questionnaire asked about the average consumption during the previous month of 52 food items including three fruit (apples, oranges, and fruit juice) and six vegetables (green vegetables, carrot, tomatoes, green pickled vegetables, other pickled vegetables, and vegetable juice). The questionnaires had six frequency categories for fruit juice and vegetable juice that ranged from 'rarely' to '5 glasses day À1 ', and four (Cohort I) or five (Cohort II) categories for other items that ranged from 'never' or 'rarely' to 'almost everyday'. The amount of consumption of total fruit and total vegetables (g day À1 ) were calculated from these responses. We documented the questionnaire assessment of fruit and vegetable consumption to be reasonably valid (Kobayashi et al, 2002).We followed up vital and residential status of subjects and incidence of cancer until the end of 1999. During 694 074 personyears of follow-up from the two cohorts, 705 cases of histologically confirmed colorectal cancer (456 col...

Physical activity and risk of colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study

“…Further adjustment was made for intake of energy-adjusted dietary fiber (in quartiles), total folate (in quartiles) and red meat (in quartiles). These variables are either known or suspected risk or preventive factors for colorectal cancer [20,[23][24][25][26][27][28][29][30]. Additional adjustment for intake of energy-adjusted total calcium and vitamin D produced no appreciable change in the results and these variables were excluded from the final model.…”

“…However, the characteristics of subjects with and without missing information did not differ. Although unmeasured confounders may not have been controlled in this study, lifestyle factors and dietary habits identified as potential confounding factors possibly associated with colorectal cancer in previous reports were accounted for [20,[23][24][25][26][27][28][29][30], with the expectation that statistical adjustment might be to some degree possible if information on associated variables were available.…”

Dietary Flavonoids and the Risk of Colorectal Cancer

“…5 This questionnaire was developed for use in a wide range of studies of diet and health in Scotland, and the validity for ranking macronutrients and micronutrients in younger adults have been previously described (31). In particular, it has been validated against serum phytoestrogen concentrations (ref.…”

“…Results from more recent cohort studies are inconclusive. Some cohort studies reported no or little effect of vegetable or fruit intake on colorectal cancer risk (5)(6)(7). However, in the Nurses' Health study, an inverse association between fruit consumption and colorectal adenomas was identified (8), and in a population-based prospective study of women in central Sweden, individuals who consumed very low amounts of fruit and vegetables had the greatest risk of colorectal cancer (9).…”

Plasma Isoflavones and the Risk of Lung Cancer in Women: A Nested Case–Control Study in Japan

“…The questionnaires had 6 frequency categories for beverages, ranging from 'rarely' to '5 glasses per day', and 4 (Cohort I) or 5 (Cohort II) categories for other items, ranging from 'never' or 'rarely' to 'almost daily'. The intakes of total energy, vegetables, fruit, and fish were calculated from these responses (26,27), and portion sizes were estimated using data from a validation study (28).…”