A Prospective Study of Fruit and Vegetable Intake and the Risk of Type 2 Diabetes in Women

  1. Simin Liu, MD12,
  2. Mary Serdula, MD3,
  3. Sok-Ja Janket, DMD1,
  4. Nancy R. Cook, SCD1,
  5. Howard D. Sesso, SCD1,
  6. Walter C. Willett, MD24,
  7. JoAnn E. Manson, MD124 and
  8. Julie E. Buring, SCD125
  1. 1Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
  2. 2Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts
  3. 3Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, Atlanta, Georgia
  4. 4Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
  5. 5Department of Ambulatory Care and Prevention, Harvard Medical School, Boston, Massachusetts
  1. Address correspondence and reprint requests to Dr. Simin Liu, Division of Preventive Medicine, BrighamWomen’s Hospital, 900 Commonwealth Ave. East, Boston, MA 02215. E-mail: siminliu{at}hsph.harvard.edu

Fruits and vegetables contain many beneficial nutrients and phytochemicals that are thought to protect against cardiovascular disease (1,2) and diabetes (3–5). Further, different types of vegetables and fruits may differ in their contents of carbohydrates, antioxidants, vitamins, minerals, and other unidentified phytochemicals. However, epidemiologic data on fruit and vegetable intake and type 2 diabetes are very limited. To evaluate the hypothesis that a high intake of fruits and vegetables protects against the incidence of type 2 diabetes and to explore whether specific subgroups of fruits and vegetables differentially affect diabetes risk, we analyzed prospective data from the Women’s Health Study (WHS) from 1993 to 2003.

RESEARCH DESIGN AND METHODS

The WHS comprised 39,876 female health professionals aged ≥45 years who were free of heart disease, stroke, or cancer at baseline. Detailed diet information was provided by 38,018 (95%) of the participants without previously diagnosed diabetes at baseline and who completed a 131-item semiquantitative food frequency questionnaire (6).

This semiquantitative food frequency questionnaire, including 28 vegetable and 16 fruit items, has demonstrated reasonably good validity as a measure of long-term dietary intakes in women (6). The average daily intakes of individual fruits and vegetables were calculated by multiplying the intake frequency by the portion size of the specific items. Intake of total fruits and vegetables was then computed by summing over the intake of individual items. We divided the vegetables into groups, including cruciferous (broccoli, …

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