The effects of collagen hydrolysate and milk protein on knee pain and skin condition among women aged ≥50 years : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatū, New Zealand

Abstract

The global population is aging, and the prevalence of age-related illness is expected to rise. Knee osteoarthritis (KOA) and deteriorating skin condition are common complaints associated with aging, and collagen breakdown is the underlying cause in both instances. Collagen is the main structural protein in humans. Its breakdown in the knee joint leads to pain and inflammation, while the skin becomes thin, dry and loses its viscoelasticity. Estrogen depletion amplifies the events underpinning collagen loss, so peri and postmenopausal women are targets for nutraceuticals such as collagen hydrolysate (CH). They are advertised as effective for joint pain relief and improving skin condition, but such claims are unconvincing from an objective standpoint. Therefore, the Collagen Hydrolysate and Milk Protein (CHAMP) study was prompted as a project.

The CHAMP study evaluated the effect of CH on knee pain (perceptions, functional performance, biomarkers) and skin condition (thickness, hydration, viscoelasticity) among women aged ≥50 years with knee pain not necessarily due to KOA. It was a randomized, double-blind controlled trial (RDBCT) of four months, and the participants consumed either an oral supplement of 15 g protein as CH (from bovine hide) or the comparators of milk protein (matched by protein and energy), or maltodextrin (matched by energy).

There was no evidence of a superior effect from CH in alleviating pain or improving functional performance. The three supplements performed similarly over time, without having any apparent impact on slowing an early stage of cartilage turnover dysregulation among the same cohort of women. The data were inconclusive about any effect on inflammation, but the CH supplement may have increased skin thickness in areas generally protected from sunlight (i.e. inner forearm). Ultimately more research is warranted before conclusions can be made about the effect of CH as a nutraceutical for skin condition or knee joint pain. Future studies would benefit by reevaluating the same outcome measures of the CHAMP study over a longer timeframe, at different doses of CH (with or without other active ingredients such as vitamin C and glucosamine), and with more participants under tightly controlled environmental conditions.