Increasing vegetable and fruit intake: randomized intervention and monitoring in an at-risk population.

High vegetable and fruit (V&F) consumption has been associated with a lower risk of several cancers. However, little is known about the ability of individuals to increase their intakes markedly. In this 1-year randomized, controlled diet intervention study of men and women with a recent history of adenomas, the intervention group (n = 100) was asked to increase V&F intake to at least eight servings per day; the control group (n = 101) continued eating their usual diet. End-point measures included V&F intake assessed by 3-day diet records, plasma carotenoids, serum lipids, urinary sodium and potassium, and body weight. The intervention group increased their daily V&F intake an average of 5.5 servings over 1 year; the control group had an average decrease of 0.5 servings per day (P < 0.001). Plasma total carotenoids, alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein/zeaxanthin were each statistically significantly elevated over baseline (11-54%) in the intervention group compared with the control group over the duration of follow-up (P < 0.001). Urinary potassium excretion was elevated 14% over baseline in the intervention group compared with no change in the control group (P < 0.001). Modest decreases in the intervention but not the control group were observed for total and low-density lipoprotein cholesterol. Plasma lycopene, triglycerides, high-density lipoprotein cholesterol, body weight, and urinary sodium were not affected by the intervention. V&F intake was significantly increased in this motivated population at higher risk of colon cancer and maintained for at least 12 months, as assessed using diet records and an ensemble of biomarkers.

Reliability and comparability of three dietary assessment methods for estimating fruit and vegetable intakes.

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.

Videotape dietary assessment: validity, reliability, and comparison of results with 24-hour dietary recalls from elderly women in a retirement home.

The validity and reliability of a videotape method for quantifying food intake were tested, and results of the method were compared with results obtained from 24-hour dietary recalls. Participants were 37 elderly Catholic nuns (aged 81.8 +/- 4.1 years) who were ambulatory and living in a retirement home. The videotape method of dietary assessment consisted of videotaping food trays of each participant for three meals during 1 day and the subsequent identification of food types and amounts from the videotapes. Estimates of food amounts obtained were used in the calculation of energy and nutrient intake. Correlation coefficients between values for energy and 14 nutrients obtained by direct measurement of food and estimates from the videotape method were high (r = 0.86 to 1.0). Compared with measured food amounts, the videotape method underestimated food quantities by an average of 6%. The reliability test indicated that mean nutrient values obtained from the videotape method by two research assistants differed by an average of 3.7% and were highly correlated (r = 0.84 to 0.98). Comparison of the videotape method with 24-hour dietary recalls revealed differences between mean values that were greater than 10% for energy and 6 of the 14 nutrients and correlations that ranged from 0.09 to 0.82. These results suggest that use of 24-hour dietary recalls among the elderly may result in a high percentage of error.