Increasing Vegetable and Fruit Intake: Randomized Intervention and Monitoring in an At-Risk Population

Increasing Vegetable and Fruit Intake: Randomized Intervention and Monitoring in an At-Risk Population

Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455 [S. A. S-W., P. J. E., T. M. T., M. G., J. D. P.]; Now, Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115 [S. A. S-W.]; Now, Center for Health Research, Kaiser Permanente, Portland, Oregon 97227 [P. J. E.]; Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455 [L. F., B. R.]; Now, Boston Scientific Scimed, Inc., Maple Grove, Minnesota 55311 [B. R.]; and Digestive Healthcare P.A., Minneapolis, Minnesota 55404 [J. W.]; and Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024 [J. D. P.]

Abstract

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, α-carotene, β-carotene, β-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.

Footnotes

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↵1 To whom requests for reprints should be addressed, at Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, MP 702, Seattle, WA 98109-1024.
↵2 The abbreviations used are: V&F, vegetable and fruit; CPRU, Cancer Prevention Research Unit; DH, Digestive Healthcare, P.A.; NDS, Nutrition Data System; HDL, high-density lipoprotein.
- Accepted December 23, 1999.
- Received September 8, 1999.
- Revision received December 15, 1999.