The stuff in beauty creams is appearing in foods, as companies launch pricey snacks and drinks containing collagen—and many consumers are eating it up despite little hard evidence that it works.
Valerie Grogan, a 53-year-old teacher’s aide in Torrance, Calif., three years ago began making a collagen-rich bone broth in her crockpot every week, hoping it would help soothe aches and smooth her skin. Recently, she discovered a vanilla-coconut collagen powder, which she mixes into coffee and smoothies. Then came collagen snack...