Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial

Zdzieblik D, Oesser S, Baumstark MW, Gollhofer A, König D · British Journal of Nutrition

The primary endpoint was fat-free mass, and it separated: +4.22 kg on collagen against +2.90 kg on placebo (p<0.05), with fat mass falling further (-5.45 kg against -3.51 kg) and isokinetic quadriceps strength rising further (+16.1 Nm against +7.4 Nm), both p<0.05. Three other measures did not separate — bone mass, sensory motor control and body weight all moved alike in the two groups. It is frequently cited as evidence that collagen builds connective tissue, when its endpoint is muscle and body composition, a third distinct claim from either cartilage or tendon.

Population

Men over 65 with class I or II sarcopenia, mean age 72, on a guided 12-week resistance-training programme

Intervention

15 g collagen peptides (BODYBALANCE) daily, taken within an hour of each training session

Comparator

15 g silicon dioxide, same training

Limitations

Muscle and body composition rather than any joint or cartilage endpoint. Part of the costs were paid by GELITA AG, whose product was tested, and the authors declare no conflict of interest. The paper's own first limitation is that the analysis is of completers rather than intention-to-treat: 60 were randomised and 53 finished. The placebo was silica, which carries no calories, so 15 g of collagen is compared against nothing rather than against an equal amount of another protein — the authors raise this and say they know of no data showing that extra calories alone would produce the effects. Randomisation also left the groups differing in fat and fat-free mass at baseline, short of significance. Same Freiburg and Collagen Research Institute group as the bone trials. An erratum was published in 2025 (Br J Nutr 134:440) and a critical comment in 2016 (Br J Nutr 116:569-70).