Today I learned : the body stores some protein in the synovial fluid around the joints. (Might be partially why I always “feel better” an hour or two after eating certain proteins like cottage cheese or beef. It also might be related to the body releasing pepsin but I’m not sure).
Oh it doesn’t replace the fluid, just that it’s stored in the same area. I’ve had arthritis since I was a kid; never got worse or better, just the same. My body always did “well” with enough protein. Never sure how to describe the feeling though.