Dietary fiber, vitamins A, C, and E, and risk of breast cancer: a cohort study

Abstract

Risk of breast cancer was examined in relation to intake of dietary fiber and vitamins A, C, and E, and food groups which are sources of these dietary constituents, in a cohort of 56,837 women enrolled in the Canadian National Breast Screening Study. Between 1982 and 1987, 519 incident, histologically confirmed cases of breast cancer were identified among women who previously had completed self-administered dietary questionnaires. Their nutrient and food intake was compared with that of 1,182 women who had not developed breast cancer during the follow-up period. Women at the uppermost quintile level of dietary fiber intake had a 30 percent reduction in risk of breast cancer relative to that for women at the lowest quintile level (adjusted odds ratio = 0.68, 95 percent confidence interval = 0.46-1.00), and the reduction in risk persisted after adjustment (separately) for total vitamin A, beta-carotene, vitamin C, and alpha-tocopherol. Inverse associations of similar magnitude were observed in association with consumption of pasta, cereals (the trend for which was statistically significant), and vegetables rich in vitamins A and C. Smaller, statistically nonsignificant reductions in risk were observed with increasing intake of dietary retinol, beta-carotene, and vitamin C, but the magnitude of these associations was reduced after adjustment for other dietary factors. Vitamin E intake was not associated with altered risk of breast cancer.

Lifelong vegetarianism and risk of breast cancer: A population‐based case‐control study among South Asian migrant women living in England

“…40 No association between total dietary fibre intake and subsequent incidence of breast cancer was reported by 2 prospective studies conducted in the US, 41,42 but a weak protective effect was found in a prospective study conducted in Canada. 43 Intake of vegetables in Western countries is lower than in South Asian populations. The median intake of total vegetables, including pulses, among the controls in our study was 355 g/day, much higher than in the cohorts included in the pooled analysis (range: 77-226 g/day 32 ).…”

Vitamins C and E, retinol, beta-carotene and dietary fibre in relation to breast cancer risk: a prospective cohort study

“…Rohan et al (1993) reported a 40-50% increase in the risk of breast cancer in association with the intake of more than 250 mg day-' vitamin C supplements. It is suggested that diets rich in PUFAs promote mammary tumour growth by generating lipid peroxy radicals and/or oxygen radicals (Welsch, 1987).…”

“…Some case-control studies showed a decrease in breast cancer risk with increased intake of the (pro)vitamins (Katsouyanni et al, 1988;Howe et al, 1990; Graham et al, 1991;Lee et al, 1991;Zaridze et al, 1991) and fibre (Iscovich et al, 1989;Howe et al, 1990;Van 't Veer et al, 1990; Graham et al, 1991;Baghurst and Rohan, 1994), whereas other case-control studies showed the opposite for (pro)vitamins (Toniolo et al, 1989;Ewertz and Gill, 1990;Richardson et al, 1991) and fibre (Katsouyanni et al, 1988;Ingram et al, 1991). Mostly negative non-significant associations between (pro)vitamin intake and the risk of breast cancer have been found in the few prospective cohort studies that have been conducted so far (Paganini-Hill et al, 1987;Graham et al, 1992;Hunter et al, 1993;Rohan et al, 1993). Of the three prospective cohort studies of dietary fibre intake and breast cancer risk, one found a non-significant negative association (Rohan et al, 1993) and two no association (Graham et al, 1992;Willett et al, 1992).…”

“…Mostly negative non-significant associations between (pro)vitamin intake and the risk of breast cancer have been found in the few prospective cohort studies that have been conducted so far (Paganini-Hill et al, 1987;Graham et al, 1992;Hunter et al, 1993;Rohan et al, 1993). Of the three prospective cohort studies of dietary fibre intake and breast cancer risk, one found a non-significant negative association (Rohan et al, 1993) and two no association (Graham et al, 1992;Willett et al, 1992). Therefore, we prospectively investigated the relation between the intake of 1-carotene, retinol, For data analysis the case-cohort approach is used: cases are enumerated for the entire cohort, whereas the person-years at risk of the entire cohort are estimated using a random subcohort sample.…”

Glycemic index in chronic disease: a review

“…High-GI foods as white bread and crackers are the main starch consumed by the Italian population representing 39% of total starch intake, followed by pasta and rice which together account for 25% . Starch identified as a food group (eg white bread or refined cereal dishes) has also been found to increase risk of breast cancer in most epidemiological studies (Iscovich et al, 1989;Franceschi et al, 1995;Favero et al, 1998), although some have found no association (Toniolo et al, 1989;Rohan et al, 1993) and in one study from the Netherlands an inverse association emerged (van't Veer et al, 1990). However, in this study the cereal products represented also the main source of dietary fiber suggesting these were not refined cereals.…”