Plant-based dietary patterns and peak bone mass in healthy young adult women

Fifty percent of women over the age of 50 experience osteoporotic fractures. However, peak bone mass is achieved in young adulthood. Recent research suggests that plant-based dietary patterns may be associated with lower bone mineral density and greater fracture risk in older adults. Limited evidence exists among younger populations, particularly studies assessing overall diet quality using index-based dietary measures. We examined associations between plant-based dietary patterns and bone density in a cross-sectional sample of 260 healthy women aged 18-30 participating in the UMass Vitamin D Status Study. Dietary intake was assessed using a modified Harvard Food Frequency Questionnaire, also used to determine vegetarian status and to calculate multiple versions of the Plant-Based Diet Index (PDI). Bone mineral density was measured using dual-energy X-ray absorptiometry. We examined associations between dietary patterns and continuous BMAD using multivariable linear regression models. In unadjusted models, higher unhealthy PDI scores were weakly and inversely associated with body bone mineral apparent density (BMAD) (β = -0.088; P = 0.16), while higher healthy PDI scores were weakly and positively associated with BMAD (β =0.077; P = 0.21). These associations were further attenuated following adjustment for overall diet quality, body fat percentage, and physical activity. Our findings indicate that plant-based dietary patterns are not independently associated with bone density in young adult women. These results provide reassurance that well-planned, plant-based diets in young adulthood are unlikely to compromise peak bone mass development. Longitudinal studies are needed to confirm these findings and evaluate potential long-term implications for bone health.