Elevations of blood pressure are a strong independent risk factor for end-stage renal disease; interventions to prevent the disease need to emphasize the prevention and control of both high-normal and high blood pressure.

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Although fruits and vegetables have been evaluated in numerous epidemiologic studies, few validation studies have examined fruits and vegetables. We examined the reproducibility and comparability of fruit and vegetable intakes estimated by diet records, food frequency questionnaires, and modules (brief food frequency questionnaires) in 101 control participants of a 1-year diet intervention trial. For each method, mean intakes at baseline and 3 months were generally within 0.3 serving per day for juice, fruits, vegetables, and total fruits and vegetables. In addition, Pearson correlations for the two time periods generally exceeded 0.55 for these four groups for each method. We evaluated comparability of intakes for 15 days of diet records, 1-year food frequency questionnaires, and modules, respectively. Mean total fruit and vegetable intakes were 6.3, 6.5, and 3.8 servings per day for diet records, food frequency questionnaires, and modules. For each pair-wise combination of methods, Pearson correlations exceeded 0.45 for juice, fruits, and total fruits and vegetables; correlations were lower for vegetables. Exact agreement in quintile assignment was less than 45%, however. These results indicate that estimates of fruit and vegetable intakes and disease associations may differ depending on the method used to assess fruit and vegetable intake.

Although high vegetable intakes have been associated with a lower risk of colorectal cancer, this relation is less well established for the precursor lesions, adenomatous polyps. With a case-control design involving adenomatous polyp cases (n = 564), colonoscopy-negative controls who were polyp free at colonoscopy (n = 682), and community controls (n = 535), this 1991-1994 Minnesota Cancer Prevention Research Unit study investigated the relation between fruit and vegetable consumption and first incident adenomatous polyps. Dietary intake was assessed using a food frequency questionnaire. For women, adenoma risk was approximately halved in the highest versus lowest quintile of juice consumption (cases vs. colonoscopy-negative controls: odds ratio (OR) = 0.50, 95% confidence interval (CI): 0.27, 0.92; cases vs. community controls: OR = 0.56, 95% CI: 0.30, 1.06). The association was stronger for adenomas with moderate or severe dysplasia compared with mild dysplasia. Juice was not associated with adenoma risk in men. The results for fruits, vegetables, total fruits and vegetables, green leafy vegetables, and several botanically and phytochemically defined subgroups generally were not statistically significant. Because elevated vegetable consumption has been associated with a lower risk of colorectal cancer, vegetables may have a stronger role in preventing the progression of adenomas to carcinomas rather than in preventing the initial appearance of adenomas.