Collagen supplementation has increased exponentially in the past few years and sources can be from porcine, bovine, or marine.  Collagen from the diet is digested and broken down into small pieces called amino acids or dipeptides and distributed to  tissues. Some forms of collagen are used best by tendon, ligament,  bone, skin, or cartilage, depending on the source and preparation of the collagen.  Collagen is the most abundant component of the extracellular matrix, comprising 75% of the skin. In a review published last month, researchers demonstrated the efficacy of collagen supplementation for dermatological applications.

This review consisted of 11 studies including 805 patients. Eight studies used collagen hydrolysate (which has a low molecular weight) at doses ranging from 2.5 to 10 grams per day over a period of 8 to 24 weeks for the treatment of pressure ulcers, dry skin, skin aging, and cellulite. These studies resulted in a significantly better pressure ulcer scale for healing, reduction of wrinkle volume, improved skin elasticity, increased skin moisture, and significantly decrease in degree of cellulite. In addition, two studies used collagen tripeptides at 3 grams per day for 4 to 12 weeks, with a noticeable improvement in skin elasticity and hydration. 

Collagen use has also expanded into the treatment of some dermatological conditions such as atopic and allergic contact dermatitis. Thus, this review also included one 12-week study comparing the effect of collagen supplementation in 13 patients with atopic dermatitis using 3.9 grams per day. The patients that supplemented with collagen demonstrated a significant decrease in immune response and inflammation. After 12 weeks, skin eruption areas, disease severity, skin hydration, and itchiness were all significantly improved with collagen supplementation.

This meta analysis demonstrated that collagen peptides taken orally can help with dermatological conditions such as atopic exzema, allergic contact dermatitis, skin ulcers, wound healing, skin elasticity, hydration and dermal collagen density. Collagen peptides have also been shown to help Osteoporosis, and  Osteoarthritis. 
Source: Choi FD, Sung CT, et al. Oral Collagen Supplementation: A Systemic Review of Dermatological Applications. J Drugs Dermatol. 2019 Jan 1;18(1):9-16.