Fortification of yogurts with vitamin D and calcium enhances the inhibition of serum parathyroid hormone and bone resorption markers: A double blind randomized controlled trial in women over 60 living in a community dwelling home

To evaluate whether fortification of yogurts with vitamin D and calcium exerts an additional lowering effect on serum parathyroid hormone (PTH) and bone resorption markers (BRM) as compared to iso-caloric and iso-protein dairy products in aged white women at risk of fragility fractures. A randomized double-blind controlled trial. A community dwelling home. Forty-eight women over 60 years (mean age 73.4). Consumption during 84 days of two 125 g servings of either vitamin D and calcium-fortified yogurts (FY) at supplemental levels of 10 A mu g vitamin D3/d and 520 mg/d of calcium (total=800 mg/d), or non fortified control yogurts (CY) providing 280 mg/d of calcium. Serum changes from baseline (D0) to D28, D56 and D84 in 25OHD, PTH and in two BRM: Tartrate-resistant-acid-phosphatase-isoform-5b (TRAP5b) and carboxy-terminal-cross-linked-telopeptide of type-I-collagen (CTX). The 10 years risk of major and hip fractures were 13.1 and 5.0%, and 12.9 and 4.2 %, in FY and CY groups, respectively. From D0 to D84, serum 25OHD increased (mean +/- SE) from 34.3 +/- 2.4 to 56.3 +/- 2.4 nmol/L in FY (n=24) and from 35.0 +/- 2.5 to 41.3 +/- 3.0 nmol/L in CY (n=24), (P=0.00001). The corresponding changes in PTH were from 64.1 +/- 5.1 to 47.4 +/- 3.8 ng/L in FY and from 63.5 +/- 4.6 to 60.7 +/- 4.2 ng/L in CY (P=0.0011). After D84, TRAP5b was reduced significantly (P=0.0228) and CTX fell though not significantly (P=0.0773) in FY compared to CY. This trial in aged white women living in a community dwelling home at risk for osteoporotic fractures confirms that fortification of dairy products with vitamin D3 and calcium should provide a greater prevention of secondary hyperparathyroidism and accelerated bone resorption as compared to non-fortified equivalent foods.