Antioxidants linked to better bone health for osteoarthritis

"Our study suggests a beneficial effect of vitamin C intake on the reduction in bone size and the number of bone marrow lesions, both which are important in the pathogenesis of knee osteoarthritis," wrote lead author Yuanyuan Wang from Monash University.

Osteoarthritis effects about seven million people in the UK alone are reported to have long-term health problems associated with arthritis.

Around 206m working days were lost in the UK in 1999-2000, equal to £18bn (€26bn) of lost productivity.

The new study, published in the Arthritis Research & Therapy , recruited 293 health adults (average age 58) without knee pain or injury, and asked them to complete a 121-item food frequency questionnaire (FFQ) to assess antioxidant intake.

Ten years after the start of the study the researchers measured cartilage volume, bone area, cartilage defects and bone marrow lesions using magnetic resonance imaging (MRI).

Increased intake of vitamin C was associated with a 50 per cent reduced risk of bone marrow lesions, and a smaller bone area.

Fruit intake was also linked to a smaller tibial plateau bone area and a 28 per cent reduction in the risk of bone marrow lesions.

Neither fruit nor vitamin C intake was associated with cartilage measurements.

Increased intake of the carotenoids lutein and zeaxanthin was associated with a 29 per cent reduction in the risk of cartilage defects, while beta-cryptoxanthin intake was linked to smaller tibial plateau bone area.

The researchers stated that the effects of nutrients on knee structure is likely to be complicated.

"Our study suggests that the direct effect of vitamin C is on bone rather than cartilage," they said.

"Although vitamin C and vitamin E are known potent antioxidants, given that different effect of vitamin C and vitamin E was found on bone area in this study, it may be that the mechanism of action in this situation is not via an antioxidant effect."

Indeed, Wang and co-workers suggested that since vitamin C is a cofactor in the hydroxylation of lysine and proline, it could be considered a required nutrient in the cross-linking of collagen fibrils in bone.

"These observations support dietary recommendation for eating more fruit.

While our findings need to be confirmed by larger longitudinal studies, they highlight the potential of diet to modify the risk of osteoarthritis," concluded the researchers.

Source: Arthritis Research & Therapy 2007, 9 :R66, doi:10.1186/

ar2225 "Effect of antioxidants on knee cartilage and bone in healthy, middle-aged subjects: a cross-sectional study" Authors: Y. Wang, A.M. Hodge, A.E. Wluka, D.R. English, G.G. Giles, R. O'Sullivan, A. Forbes and F.M. Cicuttini