Effects of collagen-based supplements on skin's hydration and elasticity: A systematic review and meta-analysis.

Background Ageing is a degenerative process that affects the entire body. Skin ageing is characterised by a decrease in the levels of collagen, elastin fibre, and hyaluronic acid (HA), resulting in a loss of skin elasticity and hydration. Prior studies suggest that oral collagen supplements can help increase collagen, elastin, and HA levels, ultimately improving skin health. Objective To assess the impact of collagen-based supplements on the signs of skin ageing and determine the effective dosage. Methods This systematic review and meta-analysis utilized PubMed, Clinical Key, ProQuest, and Cochrane Library databases to identify studies published from 2010 to 2021. It includes ten randomised controlled trials (RCTs) with a total of 646 participants. Results The findings indicate that collagen supplements were statistically effective in increasing skin hydration (SMD 1.25 (CI: 0.77-1.74)) and elasticity (SMD 0.61 (CI: 0.21-1.02)). The most commonly administered dose was 4 g/day, with a median dose of 3.5 g/ day. Limitations Most of the studies could not control for weather-related factors. The findings are more applicable to females. Moderate heterogeneity (I2 = 55.5-56.5%) may limit generalisability. The risk of bias was generally unclear, and publication bias could not be assessed due to the small number of studies. Conclusion Oral administration of collagen supplement in a dose ranging from 1-10 g/day was statistically effective in increasing the skin hydration and elasticity.