Milk protein beat whey for older lifters' lean mass

Losing muscle with age is one of the more consequential things that happens to a body, and the standard countermeasure is resistance training plus extra protein — very often whey, which dominates the supplement aisle on the strength of its leucine content and rapid absorption. Whether that reputation holds specifically in older adults, and at what amount, is less settled than the marketing implies. There is also a persistent question of whether supplements add anything when someone is already eating enough protein. This review set out to test milk-based protein supplementation against control supplements for training-induced changes in muscle in people aged 60 and over.

The authors systematically searched PubMed, Scopus and EBSCOhost/SPORTDiscus for randomised controlled trials comparing any type of milk-based protein supplement against a control supplement in older adults undertaking resistance training, with a mean participant age of at least 60 years. Outcomes were resistance-training-induced gains in lean body mass or fat free mass and in muscle strength. Twenty studies were carried into the qualitative synthesis and 17 into the quantitative synthesis. Results were pooled by dose band, allowing the authors to ask not only whether supplementation helped but at what amount, and to separate whey-specific trials from other milk-based products.

A dose of 10-15 g of milk protein supplementation was sufficient to augment resistance-training-induced gains in lean body mass or fat free mass. The unexpected result concerned whey specifically: four out of five studies showed a negative effect of whey supplementation compared with control supplementation at the same dose range or higher, pooling to -0.49 kg with a 95% confidence interval of -0.69 to -0.29 and low heterogeneity. Muscle strength told a different story again, with resistance-training improvements from milk-based protein observed only when doses reached 22 g or more, at +0.66 kg with a 95% confidence interval of 0.07 to 1.25. The authors also concluded that optimal daily protein intake can dilute the effect of supplementation.

This cuts against the widespread assumption that whey is simply the best-value protein for muscle at any age, at least when the comparison is against a control supplement in older trainees. It also separates two outcomes that are usually bundled together, suggesting the amount needed to add lean mass is not the amount associated with strength gains. The whey finding rests on five studies and is a comparison across trials rather than a direct head-to-head, so it should be treated as a signal that warrants a dedicated trial rather than a verdict. The authors' point about background protein intake diluting supplement effects is a reminder that these results depend heavily on what participants were already eating.

The most useful idea here is that the source and amount of a protein supplement may matter differently for size and for strength in older trainees, and that whey's dominance in the supplement aisle is not automatically justified by the trials in this age group. It is also a reason to look first at total daily protein from food, since the review concludes that adequate intake dilutes whatever a supplement adds. This is a between-study comparison, not a controlled test of milk against whey in the same people, so the whey result should be held loosely. Resistance training itself was the constant across every trial pooled.