Soy Nutrition Institute
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Jul 03, 2015

Soy and luteal phase deficiency (female fertility)

Luteal phase deficiency (LPD) refers to inadequate progesterone secretion by the corpus luteum, which may render the endometrium less receptive to implantation and result in infertility or early pregnancy loss. The prevalence of LPD ranges from 4 to 9% in healthy women of reproductive age. The BioCycle Study (2005-2007) prospectively enrolled 259 women from Western New York state, and followed them for one (n = 9) or two (n = 250) menstrual cycles. Participants completed baseline questionnaires, four 24-h dietary recalls per cycle and daily diaries capturing vigorous exercise, perceived stress and sleep; they also provided up to eight fasting serum samples during clinic visits timed to specific phases of the menstrual cycle using a fertility monitor. Cycles were included for this analysis if the peak serum luteal progesterone was >1 ng/ml and a urine or serum luteinizing hormone surge was detected.


In separate macro- and micronutrient adjusted models, increased fiber and isoflavone intake showed modest positive associations with LPD: fiber (per g), adjusted odds ratio: 1.10 (95% CI: 0.99, 1.23), P = 0.07; and isoflavones (per 10 mg), adjusted odds ratio: 1.38 (95% CI: 0.99, 1.92), P = 0.06. Although this study found an association between isoflavone intake and LPD, the first through fourth quartile isoflavone intake cutoffs were < 0.26 mg/day, >0.26 to 0.57 mg/day, >0.57 to 1.66 mg/day, and >1.66 mg/day, respectively.   Relationships between health outcomes and such low isoflavone intakes almost certainly have no causal basis.


Andrews MA, Schliep KC, Wactawski-Wende J, et al. Dietary factors and luteal phase deficiency in healthy eumenorrheic women. Hum Reprod. (2015).