No one has set an upper limit for collagen; the trials stop at 35g
Regulators handle hydrolyzed collagen peptides as an ordinary food protein. The largest dose in the trials, 35g, went to ten men on one occasion, as an absorption test.
What the study found
Collagen's highest tested dose was 35g, in a single sitting
No regulator has set a numeric ceiling for hydrolyzed collagen peptides, which are handled as an ordinary food protein. The trials offer no substitute: the largest dose in them, 35g, was several times a typical 2.5 to 15g serving and was run as an absorption test, not a safety one.
The caveat · One dose, ten men, no follow-up
That 35g went to ten men on one occasion, with no long-term follow-up. All ten were men, so nothing here speaks to anyone else. And no formal ceiling means nobody has set one, which is not the same as evidence that any dose is safe indefinitely.