Low-fat, increased fruit, vegetable, and grain dietary pattern, fractures, and bone mineral density: the Women's Health Initiative Dietary Modification Trial

Abstract

Background: The effects of dietary changes on osteoporosis, low bone density, and frequent falls are unestablished.

Objective: We assessed the effect of the Women's Health Initiative Dietary Modification low-fat and increased fruit, vegetable, and grain intervention on incident hip, total, and site-specific fractures and self-reported falls, and, in a subset, on bone mineral density (BMD).

Design: Postmenopausal women (n = 48,835) aged 50-79 y (18.6% of minority race-ethnicity) were randomly assigned to receive the Dietary Modification intervention (40%, n = 19,541) (daily goal: < or =20% of energy as fat, > or =5 servings of vegetables and fruit, and > or =6 servings of grains) or to a comparison group that received no dietary changes (60%; n = 29,294).

Results: After a mean 8.1 y of follow-up, 215 women in the intervention group and 285 women in the comparison group (annualized rate: 0.14% and 0.12%, respectively) experienced a hip fracture (hazard ratio: 1.12; 95% CI: 0.94, 1.34; P = 0.21). The intervention group (n = 5423; annualized rate: 3.44%) had a lower rate of reporting > or =2 falls than did the comparison group (n = 8695; annualized rate: 3.67%) (HR: 0.92; 95% CI: 0.89, 0.96; P < 0.01). There was a significant interaction according to hormone therapy use; those in the comparison group receiving hormone therapy had the lowest incidence of hip fracture. In a subset of 3951 women, hip BMD at years 3, 6, and 9 was 0.4-0.5% lower in the intervention group than in the comparison group (P = 0.003).

Conclusions: A low-fat and increased fruit, vegetable, and grain diet intervention modestly reduced the risk of multiple falls and slightly lowered hip BMD but did not change the risk of osteoporotic fractures. This trial was registered at clinicaltrials.gov as NCT00000611.

FIGURE 1

Participant screening and randomization.

FIGURE 2

Mean (±SE) percentage changes from baseline in hip bone mineral density (BMD), spine BMD, and total-body BMD in a subset of participants in the Women's Health Initiative Dietary Modification trial from 3 clinical centers who were randomly assigned to the Dietary Modification intervention group (n = 1580) or to a comparison group (n = 2371). Generalized estimating equations were used to compare the mean percentage changes in BMD from baseline by visit, with adjustment for clinical center, race-ethnicity, and weight (kg) at the corresponding visit. Mean (±SD) change in hip BMD from baseline: 0.87 ± 0.14 in the intervention group and 0.88 ± 0.14% in the comparison group. Mean (±SD) change in spine BMD from baseline: 0.99 ± 0.17 in the intervention group and 0.99 ± 0.17% in the comparison group. Mean (±SD) change in total-body BMD from baseline: 1.02 ± 0.11% in the intervention group and 1.03 ± 0.11 in the comparison group.