"Provides speciﬁc amino acids necessary to replenishing the body’s collagen supply. Helps minimize ﬁne lines & wrinkles, and improves elasticity in the skin. Builds and supports bone matrix. Corrects weak, broken, split and damaged nail beds. Thickens ﬁne hair, adds body and slows down hair loss. Repairs connective tissues for improved elasticity; improves circulation; promotes wound healing. Glycine builds lean muscle to help burn fat while you sleep." (Source: Neocell)The question, of course, is does taking collagen orally lead to these results? Honestly, I had no idea, so I did a literature search in PubMed. There are a fair amount of animal studies looking at oral collagen supplementation, but few human studies. The human studies I did find were small and conducted by the parent companies of the supplements. While that doesn't negate their findings, it does mean there is the potential for bias, and the smallness of the study subject numbers means the results are probably non-significant. Hmm.
"When we consume collagen, usually in the form of food, the long chain proteins are broken down during digestion to their original amino acids. Only then can they be absorbed. Once absorbed, these amino acids are available as building blocks to support collagen synthesis throughout the body. So from a dietary perspective, your body doesn’t care (and can’t tell) if you ate a collagen supplement, cheese, quinoa, beef, or chick peas — they’re all sources of protein, and indistinguishable by the time they hit the bloodstream. The body doesn’t treat amino acids derived from collagen any differently than any other protein source. For this reason, the idea that collagen supplementation can be an effective treatment for joint pain, osteoarthritis, or any other condition, is highly implausible, if not impossible in principle." (Source: Science-based Medicine)
Disclaimer: I purchased these.