“…Smith et at. (61) have examined and confirmed the relation of riboflavin retention to protein balance [as pointed out by Pollack and Book man (62) and Bro-Rasmussen (56)]. By varying the protein intake in young men, from approximately 0 to 17 gm per day at a constant riboflavin intake, Smith's group was able to show that excessive riboflavin loss occurred concurrently with and roughly proportional to negative nitrogen balance.…”