Do collagen peptides improve strength and body composition? Original paper

To gain muscle from resistance training, you need to consume enough protein. But will any protein do the trick?

While collagen is a protein, it isn’t a complete protein, since it is composed mostly of glycine, proline, and hydroxyproline. Yet although these three nonessential amino acids aren’t thought to contribute very much to muscle protein synthesis, some research suggests that collagen peptides may improve fat-free mass (FFM) in older men undergoing resistance training.^[1]

In this 12-week randomized controlled trial, 97 untrained men aged 30–60 performed three weekly resistance-training sessions. They were divided into three groups:

• 15 grams of collagen per day
• 15 grams of whey protein per day
• 15 grams of silicon dioxide per day (as placebo)

The primary outcome was the difference in FFM between collagen and placebo. The secondary outcomes were the differences in fat mass (FM), body weight, waist circumference, and isometric-leg-press strength between collagen and placebo. The differences between the whey group and the two other groups were considered exploratory outcomes.

Changes in FM and FFM were assessed via DXA.

Leg strength and body composition improved in all three groups. The collagen group experienced a greater increase in FFM and a greater decrease in FM than the placebo group, while there were no differences between the whey group and the other two groups.

While there were no differences between groups with regard to total protein intake, a reduction in caloric and carb intake was observed in the placebo group (and not the two other groups). This may have contributed to the differences in body-composition change.

The authors did not adjust for multiple comparisons, despite assessing a variety of outcomes among multiple groups. This omission increased the likelihood of the trial finding a statistically significant outcome due simply to chance.