Can peptides contribute to muscle growth or recovery in older adults?
Peptides, especially in combination with resistance training, can make a measurable contribution to muscle mass and strength in older adults. The strongest evidence applies to collagen peptides and plant-based protein; ideally combine them with exercise for the greatest effect.
Collagen peptides (15 g per day) on top of resistance training gave sarcopenic men with an average age of 72 years significantly more muscle mass after 12 weeks (+4.2 kg versus +2.9 kg in the placebo group) and muscle strength (+16.5 versus +7.3 Nm). That difference was found in a randomised double-blind trial of 53 participants. The combination of peptides with exercise is therefore key here: resistance training without peptides helped too, but noticeably less so.
Plant-based protein and peptide supplementation also helped without a mandatory training programme. In a randomised trial of 124 older adults with sarcopenia and knee osteoarthritis, the muscle mass index increased by 0.66 kg/m², grip strength improved by 2.83 kg, and physical functioning improved measurably after 12 weeks. This is relevant for those who find it difficult to train intensively.
Older muscles respond less sensitively to proteins and peptides than young muscles. This is called anabolic resistance: the threshold for an anabolic response is higher. Higher doses and combining supplementation with physical exercise appear to partially compensate for this, although the exact threshold dose in older adults has not yet been well established. Protein consumed just before sleep increased the synthesis of muscle connective tissue proteins significantly only when exercise had also been performed that evening; protein without training had no measurable additional effect.
Not all peptides are equally well supported by evidence. Egg protein and egg peptides appear in a systematic review of 30 randomised studies to offer no benefit in healthy adults, although they do help kidney patients with low albumin. A garden pea supplement improved recovery after exercise in a small trial, but that study was funded by the manufacturer and was not conducted in older adults, so that result is preliminary. Whey protein has antioxidant properties and soy protein may have anti-inflammatory effects, but their direct muscle effect in older adults with chronic low-grade inflammation has not yet been sufficiently studied.
Evidence based on four randomised trials, one systematic review/meta-analysis of 30 RCTs, and three review articles. Randomised trials vary in population (sarcopenic/non-sarcopenic, different ages). One trial has a conflict of interest (manufacturer co-funded). No large independent meta-analysis specifically on collagen or plant peptides in older adults is available in the supplied sources.