1. Women with luteal phase deficiency were more likely to have higher Mediterranean diet scores and consume more fiber.
2. Vigorous exercise was negatively associated with luteal phase deficiency.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Infertility is defined as the inability to conceive after 12 months of regular unprotected intercourse or after 6 months in women over the age of 35. Male factors explain a minority of cases; more commonly a female factor or combined male and female factors are involved. Luteal phase deficiency (LPD), or inadequate progesterone secretion by the corpus luteum, is thought to be a rare cause of female infertility. Luteal phase deficiency is thought to result in a sub-optimal endometrial environment for zygote implantation, leading to infertility or early pregnancy loss. Prior work has shown that high fiber, low fat diets are associated with lower progesterone levels. However, studies directly exploring the relationship between diet and LPD have been limited to few nutrients, one ovulatory cycle, and women with documented infertility. Here the authors evaluated diet quality and specific macro- and micro- nutrients in healthy women over 2 ovulatory cycles. They found that diets with higher Mediterranean diet score (MDS) and containing more fiber, fruits and vegetables, and select vitamins were positively associated with LPD. This finding suggests that nutrition impacts normal ovulatory functioning.
Strengths of the study included prospective data collection. Conclusions about causality were limited by the observational nature of this study. Defining luteal phase deficiency as fewer than 10 days duration of luteal phase might create misclassification bias if these women achieve appropriate serum levels of progesterone in this timeframe. Dietary reporting could be affected by recall bias. Further evaluation of diet in randomized controlled trials would help characterize which nutrients are beneficial or detrimental to reproductive function.
In-Depth [prospective cohort]: This study evaluated the impact of diet in LPD. Eumenorrheic (cycle length 21-35 days) women aged 18-44 years (n = 259) were asked to complete daily records of bleeding, exercise, smoking, stress and fertility. Dietary recall and hormone measurements were also made over 1-2 menstrual cycles. The primary outcome of interest was a menstrual cycle exhibiting LPD. LPD was defined as cycles that were ovulatory in which the luteal phase lasted fewer than 10 days.
Higher MDS (p = 0.002) and fiber consumption (p = 0.03) demonstrated a linear relationship with LPD. Younger age and no history of sexual activity were positively associated with LPD (p = 0.04, p=0.002 respectively), while vigorous exercise was negatively associated with LPD (p = 0.02). Selenium intake also trended towards an inverse relationship with LPD (p = 0.05).
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