Are collagen supplements beneficial for osteoarthritis arthritis or rheumatoid arthritis? Original paper

Two of the most common types of arthritis are osteoarthritis (OA) and rheumatoid arthritis (RA). Both are joint diseases, but they differ in their underlying cause and presentation. OA involves the degradation of articular cartilage, a type of connective tissue that separates certain joints (e.g., those in the knees and hips). RA is an autoimmune disease in which the immune system mistakenly attacks the joints, resulting in inflammation and tissue damage.

For both RA and OA, there are hypothetical ways that supplementing with collagen might reduce pain and improve joint health. For OA, supplementing with collagen could provide amino acids that allow for increased collagen synthesis, thus supporting repair of the articular cartilage (which consists of about two-thirds collagen). Additionally, for both RA and OA, collagen — and specifically undenatured (or “intact”) collagen — may stimulate the immune system in a manner that reduces inflammation. Do these proposed mechanisms translate into observable benefits among people with RA and OA in clinical trials?

This systematic review of 19 randomized controlled trials examined the effect of collagen supplementation among participants with osteoarthritis or rheumatoid arthritis. Of the trials, 10 were conducted in participants with RA, and 9 were conducted in participants with OA.

All 10 trials in participants with RA used intact (undenatured) type II collagen, with dosages ranging from 20 μg to 10 mg per day. Four trials in participants with OA used intact collagen, with dosages ranging from 50 μg to 40 mg per day. Five trials in participants with OA used hydrolyzed collagen, with dosages ranging from 2 to 10 grams per day.

Of the 10 trials in participants with RA, one reported a benefit (reduced anticollagen IgG levels), and 7 reported no clear benefit compared to a placebo. Two trials found that collagen was inferior to methotrexate, a common medication for RA. All 10 trials were judged to be of poor quality.

Summary of studies: Undenatured collagen for rheumatoid arthritis

Of the 4 trials on people with OA testing undenatured collagen, 3 reported benefits and 1 noted benefits but did not specify whether the effects were statistically significant. Of these trials, 3 were judged to be fair quality and 1 of poor quality.

Summary of studies: Undenatured collagen for osteoarthritis

Of the 5 trials on people with OA testing hydrolyzed collagen, 3 reported a benefit, 1 reported no benefit, and 1 reported no effect compared to glucosamine sulfate, a potentially active comparator. Of these, 3 were judged to be of fair quality and 2 of poor quality.

Summary of studies: Hydrolyzed collagen for osteoarthritis

A few of the included trials had potential conflicts of interest (i.e., the investigators received funding from collagen supplement manufacturers or were conducted by researchers employed by a gelatin company).

In McAlindon et al. 2011, the collagen group saw increases in glycosaminoglycan levels around the tibia, potentially indicating increased rates of knee cartilage repair. However, this observation did not correspond with any apparent benefits to knee pain, stiffness, or physical function. Therefore, in the results section, we categorized its results as having no benefit.