According to McCarthy, Garrard-Cole and Geddes, we should take 10 grams of collagen a day, but Dr. Skotnicki doesn’t see it so clearly. “Nobody really knows what concentration [to take],” she says. “It's like CBD oil . Everyone's jumping on the bandwagon, but no one knows the right dose, how long does it take it, etc.” Skotnicki also notes that across studies, the range varies from 2.5 grams to 10 grams per day, which she believes is a lot of collagen based on volume alone.