The Effect of a Whey Protein Supplement on Bone Mass in Older Caucasian Adults.

Randomized, controlled, two-center trial in healthy older Caucasian men and women from Connecticut. Women were older than 60 years and men older than 70 years, with BMI 19 to 32 kg/m2 and self-reported protein intake of 0.6 to 1.0 g/kg/day; in the protein arm, 106 participants were randomized and 61 were treatment completers at 18 months.

Participants in the active arm were asked to incorporate 45 g/day of whey protein isolate (40 g protein; Pro-von 290) into their usual diet for 18 months. The protein supplement was compared with an isocaloric maltodextrin control and was taken daily by oral dietary incorporation.

Whey protein did not improve bone mineral density at the lumbar spine or other skeletal sites over 18 months. In the DXA completer subset, femoral neck BMD differed at 9 months (-1.31 ± 0.43 vs 0.14 ± 0.43; between-group difference -1.5 ± 0.6%, P = .019), but this was not sustained at 18 months. The intervention helped preserve fat-free mass, with truncal lean mass significantly higher at 18 months (p = 0.048) and total lean mass trending higher (P = .069). Renal function was not adversely affected: eGFR was unchanged at 18 months, although urinary urea remained higher and IGF-1, CTX, and urinary calcium showed increases during follow-up.

Attrition and completer-based secondary analyses reduce confidence in some findings, with only 61 protein-arm participants completing 18 months. The cohort was healthy, mostly Caucasian, and recruited from two Connecticut centers, which limits generalizability. Several favorable signals were transient or emerged in subset analyses rather than for the primary bone outcome.