People who ate collagen kept more of their body’s protein instead of losing it, compared to those who ate whey.
Scientific Claim
Dietary collagen intake improves whole-body nitrogen balance, indicating reduced net protein catabolism and enhanced protein retention.
Original Statement
“There was a study in the Journal of the Academy of Nutrition and Dietetics and it looked at elderly patients consuming either collagen or whey for 15 days. The collagen group actually had better nitrogen balance which means they were holding on to more total protein rather than breaking it down.”
Context Details
Domain
nutrition
Population
human
Subject
Dietary collagen intake
Action
improves
Target
whole-body nitrogen balance, indicating reduced net protein catabolism
Intervention Details
Evidence from Studies
Supporting (2)
Pigs fed broken-down protein (like collagen) kept more nitrogen in their bodies, meaning they didn’t break down as much of their own muscle — collagen-like proteins help the body hold onto protein.
Technical explanation
This paper directly measures nitrogen retention in pigs fed a hydrolyzed protein supplement (casein hydrolysate), which is structurally similar to hydrolyzed collagen. It shows increased nitrogen retention — the exact outcome in the assertion — confirming that hydrolyzed protein intake enhances protein retention even in low-protein diets.
When rats ate collagen, they grew stronger bones, which means their bodies were holding onto more protein instead of breaking it down — suggesting collagen helps keep protein in the body.
Technical explanation
This study directly tests hydrolyzed collagen intake in a mammalian model and measures nitrogen retention indirectly through bone mass gain and growth, which are downstream indicators of improved protein retention. While nitrogen balance isn't explicitly measured, the context of enhanced growth under collagen supplementation aligns with reduced net protein catabolism.
Contradicting (2)
In a direct test, whey protein helped overweight women lose fat and improve metabolism better than collagen — suggesting collagen doesn’t help the body keep protein as well as other proteins do.
Technical explanation
This study directly compares collagen supplementation to whey protein in humans and finds that collagen did not improve body composition markers as effectively as whey — a high-quality protein known to improve nitrogen balance. This implies collagen may not enhance protein retention as claimed, contradicting the assertion.
Even when scientists tried to stop the body from breaking down protein, it still happened — so just eating collagen might not be enough to stop your body from using up its own muscle.
Technical explanation
Although not testing collagen, this paper shows that inhibiting a specific catabolic pathway (protein breakdown) with a proteinase inhibitor failed to reduce overall protein catabolism. This challenges the assumption that simply adding a protein like collagen will automatically reduce catabolism — suggesting protein intake alone may not override systemic catabolic drivers.