Author(s): IEMITSU, K., FUJIE, S., ITO, R., UCHIDA, M., SHINOHARA, Y., IEMITSU, M., Institution: RITSUMEIKAN UNIVERSITY, Country: JAPAN, Abstract-ID: 1929

INTRODUCTION:
Dioscorea esculenta commonly known as lesser yam, is rich in diosgenin, a plant-derived steroidal saponin with a molecular structure similar to dehydroepiandrosterone (DHEA). Our previous rodent studies have shown that chronic Dioscorea esculenta intake enhances skeletal muscle oxidative phosphorylation and increases muscle mass. However, the effects of chronic Dioscorea esculenta consumption on sarcopenia-related muscle characteristics, including muscle quantity, quality, and function, in middle-aged and older adults remain unclear. Therefore, this study aimed to clarify the effect of Dioscorea esculenta intake on sarcopenia-related muscle characteristics in middle-aged and older adults.
METHODS:
This double-blind trial included 31 volunteers (10 males/21 females; age 53 ± 5 years; body weight 61 ± 13 kg; BMI 23 ± 5 kg/m2) who were randomly assigned to either a placebo (PL) or Dioscorea esculenta (Dio) group. Participants in the Dio group ingested Dioscorea esculenta tablets at a dose of 2,000 mg/day once daily for 12 weeks. Muscle thickness of the anterior and posterior femoris muscles, an index of muscle quantity, and echo intensity of the rectus femoris muscle, an index of quality, were assessed using a B-mode ultrasound device with 3.4–8.0 MHz linear-array probe. Functional performance was evaluated using the five-times sit-to-stand test. Serum C1q concentrations, a potential biomarker of muscle fibrosis, were measured using enzyme-linked immunosorbent assays. Group differences were assessed using analysis of covariance adjusted for age and sex. Statistical significance was set at p<0.05.
RESULTS:
Body weight and BMI did not change significantly in either group following the intervention. Changes in total thickness of the anterior and posterior femoris muscles and performance in five-times sit-to-stand test were greater in the Dio group than in the PL group. Changes in rectus femoris muscle echo intensity (PL: 1.9±4.7 vs Dio: -3.1±6.9 a.u., p<0.05) and serum C1q level (PL: 0.25±0.68 vs Dio: -0.49±1.06 mg/ml, p<0.05) were lower in the Dio group than in the PL group. Muscle echo intensity was positively correlated with serum C1q levels (r=0.46, p=0.001) and anterior femoris muscle thickness (r=0.51, p=0.004). Furthermore, total thickness of the anterior and posterior femoris muscles was negatively correlated with the five-times sit-to-stand test (r=-0.41, p=0.02).
CONCLUSION:
The reduction in serum C1q levels accompanied by lower muscle echo intensity suggests that Dioscorea esculenta intake may be partially associated with improvements in muscle thickness and functional performance. Thus, chronic Dioscorea esculenta intake could influence sarcopenia-related muscle characteristics in healthy middle-aged and older adults.