Equol production is associated with bone mass in young women

Abstract Background Osteoporosis, a disease characterized by decreased bone strength and increased risk of fracture, represents a significant health concern in older adults. Primary osteoporosis prevention requires increasing bone mass (BM) to its peak at a young age. The estrogen-like effect of equol has been reported to suppress bone loss in postmenopausal women. This study aimed to investigate the relationship between BM, body mass, skeletal muscle mass, exercise habits, menstrual abnormalities, and equol production in younger women. Methods Of a total of 395 female university students recruited, 275 who were not taking any hormonal medications and had no deficiencies in any of the measurement items we evaluated, were included in the analysis. BM was measured in the right calcaneus using an ultrasonic bone densitometer. Body composition was measured via the bioelectrical impedance method, using a multifrequency body composition analyzer. Hormone use, menstrual cycle, current exercise habits, and daily soy intake were assessed using self-administered questionnaires. Equol production was measured using a Soy-Check system. Multiple regression analysis, using the forced-entry method, was performed with BM as the objective variable; and age, body mass index, skeletal muscle mass index, soy intake, exercise habits, menstrual cycle, and equol production as the explanatory variables. Results In our multiple regression analysis with osteo-sonoassessment indexas the objective variable, the significantly associated factors were determined to be the amount of equol production (β = 0.11, p < 0.05), skeletal muscle mass index (β = 0.29, p < 0.01), and current exercise habits (β = 0.31, p < 0.01). By contrast, age, body mass index, soy intake, and menstrual cycle were not found to be significantly associated with osteo-sonoassessment index. Conclusions Young women with higher equol production, exercise habits, and skeletal muscle mass indexshad higher levels of BM. The acquisition of maximal BM at a young age is protective against osteoporosis; therefore, increased equol production at a young age may protect against osteoporosis.