Effects of Equol on Hand Osteoarthritis in Perimenopausal Women: A Pilot Study

Hand pain in women has recently been reported as a symptom of menopause, and the sudden decrease in estrogen levels may be responsible for joint pain in the hand. We therefore hypothesized that intake of the estrogen analog equol (4',7-isoflavandiol) would improve pain resulting from osteoarthritis of the hand in menopausal women. We evaluate the efficacy of equol intake in improving pain and disabilities of daily living caused by hand osteoarthritis in perimenopausal women.

Women aged 45-60 years with hand pain were recruited for provisional registration (n=148). Hand osteoarthritis was diagnosed with radiography according to the Kellgren-Lawrence grading system. Excluded from the study were patients whose laboratory data indicated they had rheumatoid arthritis, thyroid disorders, or naturally possessed equol. Finally, 104 participants were registered for the protocol therapy, and we recorded visual analogue scale (0-100 mm) data on the movement and Disabilities of the Arm, Shoulder, and Hand (DASH) score after 12 weeks of equol intake versus baseline.

Change in visual analogue scale on movement after 12 weeks of equol intake was -34.0 mm relative to baseline (p<0.001) and disability of arm, shoulder, and hands score after 12 weeks of equol intake compared with baseline was -6.6 (p<0.001).

This is the first prospective clinical trial of an equol supplement as a treatment for pain caused by hand osteoarthritis. Visual analogue scale on movement improved with a statistically significant difference. The improvement was observed within 1-3 months after intake of equol. The DASH score also showed significant improvement. Equol is suggested to improve hand pain, upper limb function, and quality of life.