Estrogenic effect of yam ingestion in healthy postmenopausal women.
OBJECTIVE
Yam (Dioscorea) has been used to treat menopausal symptom folklorically. This study was to investigate the effects of yam ingestion on lipids, antioxidant status, and sex hormones in postmenopausal women.


METHODS
Twenty-four apparently healthy postmenopausal women were recruited to replace their staple food (rice for the most part) with 390 g of yam (Dioscorea alata) in 2 of 3 meals per day for 30 days and 22 completed the study. Fasting blood and first morning urine samples were collected before and after yam intervention for the analyses of blood lipids, sex hormones, urinary estrogen metabolites and oxidant stress biomarker. The design was a one arm, pre-post study. A similar study of postmenopausal women (n = 19) fed 240 g of sweet potato for 41 days was included as a control study. Serum levels of estrone, estradiol and SHBG were analyzed for this control group.


RESULTS
After yam ingestion, there were significant increases in serum concentrations of estrone (26%), sex hormone binding globulin (SHBG) (9.5%), and near significant increase in estradiol (27%). No significant changes were observed in serum concentrations of dehydroepiandrosterone sulfate, androstenedione, testosterone, follicular stimulating hormone, and luteinizing hormone. Free androgen index estimated from the ratio of serum concentrations of total testosterone to SHBG decreased. Urinary concentrations of the genotoxic metabolite of estrogen, 16alpha-hydroxyestrone decreased significantly by 37%. Plasma cholesterol concentration decreased significantly by 5.9%. Lag time of low-density lipoprotein oxidation prolonged significantly by 5.8% and urinary isoprostane levels decreased significantly by 42%. For the control subjects fed with sweet potato, all three hormone parameters measured were not changed after intervention.


CONCLUSIONS
Although the exact mechanism is not clear, replacing two thirds of staple food with yam for 30 days improves the status of sex hormones, lipids, and antioxidants. These effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women.
Wu
Wen-Huey
WH
Graduate Program of Nutrition, Department of Human Development and Family Studies, National Taiwan Normal University, Taipei, 106, Taiwan. t10005@cc.ntnu.edu.tw
Liu
Li-Yun
LY
Chung
Cheng-Jih
CJ
Jou
Hei-Jen
HJ
Wang
Tzong-An
TA
D000368:Aged; D000975:Antioxidants / Q000378:metabolism; D027742:Dioscorea / Q000737:chemistry*; D004967:Estrogens / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004970:Estrone / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008055:Lipids / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood* / Q000502:physiology; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000097:blood
D000975:Antioxidants; D004967:Estrogens; D012739:Gonadal Steroid Hormones; D008055:Lipids; D012738:Sex Hormone-Binding Globulin; D004970:Estrone; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone