PLANT FOODS AND COLON-CANCER - AN ASSESSMENT OF SPECIFIC FOODS AND THEIR RELATED NUTRIENTS (UNITED-STATES)

Plant foods have been associated inversely with colon cancer. Since a major focus of this study was to identify components of plant foods wh ich may account for their association with colon cancer, nutrients whi ch are commonly found in plant foods also were evaluated. A population -based case-control study was conducted in Northern California, Utah, and the 'Twin Cities' area of Minnesota (United States). Complete data were available from interviewer-administered questionnaires on 1,993 cases and 2,410 controls. Higher intakes of vegetables (for highest re lative to lowest quintile of intake) were associated inversely with co lon cancer risk: the odds ratio (OR) was 0.7 for both men (95 percent [CI] confidence interval = 0.5-0.9) and women (CI = 0.5-1.0). Associat ions were stronger among those with proximal tumors. Total fruit intak e was not associated with colon cancer risk although, among men, highe r levels of whole grain intake were associated with a decreased risk ( OR = 0.6, CI = 0.4-0.9 for older men); high intakes of refined grains were associated with an increased risk (OR = 1.5, CI = 1.1-2.1). Dieta ry fiber intake was associated with a decreased risk, of colon cancer: OR = 0.5 (CI = 0.3-0.9) for older men; OR = 0.7 (CI = 0.4-1.2) for ol der women; OR = 0.6 (CI = 0.4-1.0) for men with proximal tumors; OR = 0.5 (CI = 0.3-0.9) for women with proximal tumors. Other nutrients, fo r which plant foods were the major contributor - such as vitamin B-6, thiamin, and niacin (women only)- also were associated inversely with colon cancer. Neither beta-carotene nor vitamin C was protective for c olon cancer. Adjustment of plant foods for nutrients found in plant fo ods or for supplement use did not appreciably alter the observed assoc iations between plant foods and colon cancer.