In a meta-analysis of randomised trials in resistance-training adults with a mean age of at least 60 years, 10-15 g of milk protein was sufficient to augment gains in lean body mass, while four out of five studies of whey protein at the same or higher doses showed a negative effect versus control supplementation (-0.49 kg, 95% CI -0.69 to -0.29). Improvements in muscle strength appeared only at protein doses of 22 g or more.
What it shows: Twenty studies were reviewed and 17 pooled, all in resistance-training older adults with a mean age of at least 60; the striking whey result rests on just five studies, the review is a between-study comparison rather than a head-to-head trial, and the authors note that adequate daily protein intake dilutes any supplement effect.Meta-analysis · Nutrients