Consequences of a Plant-Based Diet with Low Dairy Consumption on Intake of Bone-Relevant Nutrients

Objective: This study examines the extent to which a plant-based dietary intervention that discourages consumption of dairy products and meat influences bone-relevant nutrients. Methods: A randomized controlled study design was used to evaluate the Coronary Health Improvement Project. The Project is a heart disease prevention intervention administered in an intensive 40-hour educational course delivered over a 4-week period. Participants were evaluated at baseline, 6 weeks, and 6 months. Results: After 6 weeks, participants in the intervention group compared with the control group experienced significant increases in magnesium and daily intake of fruit, vegetables, and grains but significant decreases in dairy servings per day and calcium and vitamin D from food. After 6 months, those in the intervention group showed significant increases in daily intake of fruit, vegetables, and grains and significant decreases in dairy servings per day, daily meat consumption, and protein, phosphorous, calcium, total calcium, and vitamin D from food. Serum calcium levels are the primary determinant of parathyroid hormone (PTH) release, and within 6 weeks, the intervention group's PTH levels were elevated from baseline and significantly different from the control group's PTH levels. At 6 months, urinary type I collagen N-telopeptide (NTx) levels were significantly greater in the intervention group compared with the control group. Conclusions: The Coronary Health Improvement Project increases the intake of important food items but decreases calcium and vitamin D consumption. There is also some evidence of an increase in NTx biomarkers, consistent with increased bone resorption.