Therapeutic effects of isoflavones on impaired salivary secretion

Dry mouth, which is characterized by decreased salivation, has a number of causes; the involvement of estrogen has been suggested as symptoms typically develop in middle-aged females. However, there is a lack of consensus regarding the treatment of this condition. Soy isoflavones, a subgroup of flavonoids, are abundantly found in the soy germ. They are thought to exert a number of effects by specifically binding to estrogen receptors due to their structural similarity to estrogen. Recently, soy isoflavones have been found to exert antioxidant effects, ameliorating disorders caused by reactive oxygen/free radicals. Based on these observations, the effects of soybean isoflavones on impaired salivary secretion were studied in patients with dry mouth. Soy isoflavone aglycones were administered at 25 mg per day to 15 subjects with an average age of 67.9 ± 8.0 years for 2 months, and salivary secretion was analyzed. The results showed a significant improvement based on the saliva flow rate and self-completed questionnaire, thus suggesting the usefulness of isoflavones in improving the symptoms of salivary gland hypofunction.