Methylsulfonylmethane (MSM), which is one of the popular ingredients of 
so-called health foods in Japan, is expected to relieve inflammation in 
arthritis and allergies. However, there is no scientific evidence to confirm the 
efficacy and safety of MSM in detail. In this study, we examined the effects of 
MSM on cartilage formation in growing rats (G) and cartilage degradation in 
STR/Ort mice (A), an accepted human osteoarthritis (OA) model. For cartilage 
formation study, 6-week-old growing male Wister rats were assigned to four 
groups to receive a control or MSM-containing diet. To examine the efficacy of 
MSM on the cartilage of OA model mouse, 10-week-old male STR/OrtCrlj mice were 
assigned to three groups to receive a control or MSM-containing diet. The 
dosages used were amounts equal to the recommended supplements for humans 
[0.06 g/kg body weight (BW)/day: MSM1G and MSM1A], 10 fold higher (0.6 g/kg 
BW/day: MSM10G and MSM10A), and 100 fold higher (6 g/kg BW/day: MSM100G). Intake 
of MSM for 4 weeks did not affect cartilage formation in the knee joint in 
growing rats. Body, liver, and spleen weight in the MSM100G group were 
significantly lower than those in the control group. Intake of MSM for 13 weeks 
decreased degeneration of the cartilage at the joint surface in the knee joints 
in STR/Ort mice in a dose-dependent manner. These results suggest that 
appropriate intake of MSM is possibly effective in OA model mice; however, 
intake of large amounts of MSM induced atrophy of several organs.