Nutraceuticals: do they represent a new era in the management of osteoarthritis? - a narrative review from the lessons taken with five products

Objectives: The aim of this first global systematic review on selected nutraceuticals was to synthesize and evaluate scientific relevant data available in the literature. Evidences that can support health, physiological or functional benefit on osteoarthritis (OA) were gathered and the level of evidence relative to each of these ingredients was highlighted. Methodology: Relevant scientific data (positive or not) regarding OA were searched for five groups of compounds (avocado/soybean unsaponifiables (ASU), n-3 polyunsaturated fatty acids, collagen hydrosylates (CHs), vitamin D, polyphenols) within preclinical (in vitro and in vivo), epidemiological, and clinical studies. The following criteria were evaluated to assess the methodology quality of each study: (1) study question; (2) study population; (3) primary endpoint; (4) study design (randomization, control, blinding, duration of follow up); (5) data analysis and interpretation. A scientific consensus was determined for all studied nutraceuticals to evaluate their efficacy in OA. Results: The studied compounds demonstrated different potencies in preclinical studies. Most of them have demonstrated anti-catabolic and anti-inflammatory effects by various inhibitory activities on different mediators. Vitamin D showed a pro-catabolic effect in vitro and the polyphenol, Genistein, had only anti-inflammatory potency. The evaluation of the clinical data showed that ASU was the only one of the studied ingredients to present a good evidence of efficacy, but the efficient formulation was considered as a drug in some countries. Pycnogenol showed moderate evidence of efficacy, and vitamin D and collagen hydrolysate demonstrated a suggestive evidence of efficacy, whereas curcumin, epigallocatechin-3-gallate (EGCG) and resveratrol had only preclinical evidence of efficacy due to the lack of clinical data. The literature gathered for n-3 PUFA, nobiletin and genistein was insufficient to conclude for their efficacy in OA. Conclusion: Additional data are needed for most of the studied nutraceuticals. Studies of good quality are needed to draw solid conclusions regarding their efficacy but nutraceuticals could represent good alternates for OA management. Their use should be driven by any recommendations. (C) 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.