High-dose Vitamin C May Worsen Arthritis

DURHAM, N.C.--Vitamin C has been associated with the slowing of osteoarthritis (OA) progression in animal and human studies (Matrix Biol, 21, 2:175-84, 2002); however, a recent in vivo animal study suggests high-dose vitamin C may actually make OA worse (Arthritis Rheum, 50, 6:1822-31, 2004; www.rheumatology.org/publications/ar/index.asp).

Researchers from Duke University Medical Center exposed male guinea pigs with surgically induced OA to low, medium or high doses of ascorbic acid for eight months; the low dose was equivalent to the minimum amount needed to prevent scurvy, the medium dose was equivalent to the amount of a person consuming 200 mg/d (5 fruits and vegetables daily) and the high dose was the dosage shown in a previous guinea pig study to slow OA progression. The researchers found an association between ascorbic acid supplementation and increased cartilage collagen content, but found ascorbic acid worsened the severity of spontaneous OA. They also reported active transforming growth factor beta (TGF beta; prolonged intraarticular exposure to which has been shown to cause OA-like changes) was expressed in marginal osteophytes (small, abnormal bony outgrowths) that increased in size and number with increasing ascorbic acid intake. Researchers concluded the worsening of OA with ascorbic acid supplementation suggests that ascorbic acid intake should not be supplemented above the currently recommended dietary allowance (90 mg/d for men and 75 mg/d for women).