Dietary fat intake and reproductive hormone concentrations and ovulation in regularly menstruating women.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 26843151 · doi:10.3945/ajcn.115.119321
What was done
In an exploratory analysis of the BioCycle Study, 259 regularly menstruating women were followed for up to 2 menstrual cycles. Endogenous reproductive hormones were measured up to 8 times per cycle, scheduled using fertility monitors. Dietary fat intake was assessed with up to four 24-hour recalls per cycle. Linear mixed models and generalized linear models assessed associations between total and specific fatty acid intakes, reproductive hormone concentrations, and ovulatory status, adjusting for total energy intake, age, BMI, and race.
What was found
Compared with the lowest tertile, the highest tertile of energy from total fat was associated with increased total testosterone (percentage change: 4.0%; 95% CI: 0.7%, 7.3%) and free testosterone (percentage change: 4.1%; 95% CI: 0.5%, 7.7%). The highest tertile of polyunsaturated fatty acid (PUFA) intake was likewise associated with higher total testosterone (3.7%; 95% CI: 0.6%, 6.8%) and free testosterone (4.0%; 95% CI: 0.5%, 7.5%). Docosapentaenoic acid (22:5n-3) intake was not significantly associated with testosterone (P-trend = 0.86), but the highest tertile was associated with increased progesterone and a reduced risk of anovulation compared to the lowest tertile (RR: 0.42; 95% CI: 0.18, 0.95). Other reproductive hormones showed no significant associations with fat intakes.
Why it matters
This study provides prospective evidence that dietary fat composition, particularly specific PUFAs like docosapentaenoic acid, may subtly influence reproductive hormone concentrations and ovulatory function in healthy women.
Limits
The study is observational and exploratory, preventing causal inference. Diet was assessed via self-reported 24-hour recalls, which are subject to measurement error. The cohort was followed for only up to 2 cycles in 259 healthy, regularly menstruating women, which may not generalize to women with irregular cycles or clinical infertility.
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