Taking collagen supplements does not help muscles grow larger if you are already consuming enough total protein and vitamin C, because collagen does not contain the right amino acids or biological mechanism to directly stimulate muscle growth.
Evidence from Studies
Supporting (2)
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When people took collagen along with their usual protein shake, they didn’t get stronger or recover better than people who just took the protein shake alone. So collagen didn’t help extra, even though they were both getting the same total protein.
Nutritional Supplements for Muscle Hypertrophy: Mechanisms and Morphology—Focused Evidence
Taking collagen pills won’t make your muscles bigger if you’re already eating enough protein and vitamin C—it just helps your tendons and joints recover better.
Contradicting (1)
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Effects of 12 Weeks of Hypertrophy Resistance Exercise Training Combined with Collagen Peptide Supplementation on the Skeletal Muscle Proteome in Recreationally Active Men
This study found that people who took collagen pills after working out gained more muscle and got stronger than those who didn’t, even though they were already eating enough protein. This contradicts the claim that collagen doesn’t help.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.