Iron intake in relation to ovarian reserve among women seeking infertility treatment.

STUDY QUESTION: Is there an association between iron intake and ovarian reserve among women seeking fertility care? SUMMARY ANSWER: Supplemental iron intake above 45 mg/day is associated with lower ovarian reserve among women seeking fertility care. WHAT IS KNOWN ALREADY: Although the literature regarding iron intake in relation to ovarian reserve is scant and inconsistent, some evidence suggests that iron may have gonadotoxic effects. STUDY DESIGN, SIZE, DURATION: This observational study included 582 female participants attending the Massachusetts General Hospital Fertility Center (2007-2019) enrolled in the Environment and Reproductive Health (EARTH) Study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Iron intake was estimated using a validated food frequency questionnaire. Markers of ovarian reserve included antral follicle count (AFC) (assessed via transvaginal ultrasound) and Day 3 FSH, both obtained during the course of an infertility evaluation. MAIN RESULTS AND THE ROLE OF CHANCE: Participants had a median age of 35 years and median total iron intake of 29 mg/day. Total iron intake was inversely related to AFC and this association was driven by intake of supplemental iron. Compared to women with a supplemental iron intake of ≤20 mg/day, women consuming 45-64 mg/day of supplemental iron had a 17% (-35%, 0.3%) lower AFC and women consuming ≥65 mg/day of supplemental iron had a 32% (-54%, -11%) lower AFC after adjusting for potential confounders (P, linear trend = 0.003). Similarly, in a multivariable-adjusted analysis, Day 3 FSH levels were 0.9 (0.5, 1.3) IU/ml higher among women with a supplemental iron intake of ≥65 mg/day when compared to women with a supplemental iron intake of ≤20 mg/day (P, linear trend = 0.02). LIMITATIONS, REASONS FOR CAUTION: Iron intake was estimated using a method that relies on self-report and we had no biomarkers of iron status in our participants; only 36 women consumed ≥45 mg/day of supplemental iron. WIDER IMPLICATIONS OF THE FINDINGS: Since all study participants were seeking fertility treatment, our findings may not apply to women in the general population. Although our findings are consistent with studies of women with iron overload, given the paucity of literature on this topic, it is essential that this question is revisited in studies designed to better understand the dose-response relation of this association across the entire distribution of ovarian reserve and the risk-benefit balance of pre-conceptional iron supplementation given its many positive effects on pregnancy outcomes. STUDY FUNDING/COMPETING INTEREST(S): The project was funded by Grants R01ES022955, R01ES033651, R01ES009718, P30ES000002, and P30DK046200 from the National Institutes of Health. N.J.-C. was supported by a Fulbright Scholarship. N.J.-C., M.M., L.M.-A., E.O.-P., S.W., I.S., and J.E.C. declare no conflict of interest related to the work in the manuscript. R.H. has received grants from the National Institute of Environmental Health Sciences. TRIAL REGISTRATION NUMBER: N/A.

Fruit and vegetable consumption and risk of endometriosis.

STUDY QUESTION: Is there an association between intake of fruits and vegetables and risk of laparoscopically confirmed endometriosis? SUMMARY ANSWER: Higher intake of fruits, particularly citrus fruits, is associated with a lower risk of endometriosis. WHAT IS KNOWN ALREADY: Two case-control studies have examined the associations between fruit and vegetable intake and endometriosis risk with contrasting results. Diets rich in fruits and vegetables include higher levels of pro-vitamin A nutrients (alpha-carotene, beta-carotene, beta-cryptoxanthin) and women with endometriosis have been reported to have lower intake of vitamin A than women without endometriosis. STUDY DESIGN SIZE, DURATION: A prospective cohort study using data collected from 70 835 premenopausal women from 1991 to 2013 as part of the Nurses' Health Study II cohort. PARTICIPANTS/MATERIALS, SETTING, METHODS: Diet was assessed with a validated food frequency questionnaire (FFQ) every 4 years. Cases were restricted to laparoscopically confirmed endometriosis. Cox proportional hazards models were used to calculate rate ratios (RR) and 95% CI. MAIN RESULTS AND THE ROLE OF CHANCE: During 840 012 person-years of follow-up, 2609 incident cases of laparoscopically confirmed endometriosis were reported (incidence rate = 311 per 100 000 person-years). We observed a non-linear inverse association between higher fruit consumption and risk of laparoscopically confirmed endometriosis (Psignificance of the curve = 0.005). This inverse association was particularly evident for citrus fruits. Women consuming ≥1 servings of citrus fruits/day had a 22% lower endometriosis risk (95% CI = 0.69-0.89; Ptrend = 0.004) compared to those consuming <1 serving/week. No association was observed between total vegetable intake and endometriosis risk. However, women consuming ≥1 servings/day cruciferous vegetables had a 13% higher risk of endometriosis (95% CI = 0.95-1.34; Ptrend = 0.03) compared to those consuming <1 serving/week. Of the nutrients examined, only beta-cryptoxanthin intake was significantly associated with lower endometriosis risk (RR fifth quintile = 0.88; 95% CI = 0.78-1.00; Ptrend = 0.02). LIMITATIONS REASONS FOR CAUTION: Some error in the self-reporting of dietary intake is expected, however, use of a validated FFQ and examining diet prospectively across multiple time points, make it unlikely that this non-differential misclassification strongly influenced the results. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that a higher intake of fruits, particularly citrus fruits, is associated with a lower risk of endometriosis, and beta-cryptoxanthin in these foods may partially explain this association. In contrast to what we hypothesized, consumption of some vegetables increased endometriosis risk which may indicate a role of gastrointestinal symptoms in both the presentation and exacerbation of endometriosis-related pain; however, it is not clear what components of these foods might underlie the observed associations. Future studies examining dietary patterns that consider different combinations of food intake may help clarify these associations. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by research grants HD4854, HD52473 and HD57210 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and grant P30 DK046200 from the National Institute of Diabetes and Digestive and Kidney Diseases. The Nurses' Health Study II is supported by the Public Health Service grant UM1 CA176726 from the National Cancer Institute, National Institutes of Health. HRH is supported by the National Cancer Institute, National Institutes of Health (K22 CA193860). No competing interests. TRIAL REGISTRATION NUMBER: n/a.

Serum omega-3 fatty acids and treatment outcomes among women undergoing assisted reproduction.

STUDY QUESTION: Are serum polyunsaturated fatty acids (PUFA) concentrations, including omega-3 (ω3-PUFA) and omega-6 (ω6-PUFA), related to ART outcomes? SUMMARY ANSWER: Serum levels of long-chain ω3-PUFA were positively associated with probability of live birth among women undergoing ART. WHAT IS KNOWN ALREADY: Intake of ω3-PUFA improves oocyte and embryo quality in animal and human studies. However, a recent cohort study found no relation between circulating ω3-PUFA levels and pregnancy rates after ART. STUDY DESIGN SIZE, AND DURATION: This analysis included a random sample of 100 women from a prospective cohort study (EARTH) at the Massachusetts General Hospital Fertility Center who underwent 136 ART cycles within one year of blood collection. PARTICIPANTS/MATERIALS, SETTING, METHODS: Serum fatty acids (expressed as percentage of total fatty acids) were measured by gas chromatography in samples taken between Days 3 and 9 of a stimulated cycle. Primary outcomes included the probability of implantation, clinical pregnancy and live birth per initiated cycle. Cluster-weighted generalized estimating equation (GEE) models were used to analyze the association of total and specific PUFAs with ART outcomes adjusting for age, body mass index, smoking status, physical activity, use of multivitamins and history of live birth. MAIN RESULTS AND ROLE OF CHANCE: The median [25th, 75th percentile] serum level of ω3-PUFA was 4.7% [3.8%, 5.8%] of total fatty acids. Higher levels of serum long-chain ω3-PUFA were associated with higher probability of clinical pregnancy and live birth. Specifically, after multivariable adjustment, the probability of clinical pregnancy and live birth increased by 8% (4%, 11%) and 8% (95% CI: 1%, 16%), respectively, for every 1% increase in serum long-chain ω3-PUFA levels. Intake of long-chain ω3-PUFA was also associated with a higher probability of life birth in these women, with RR of 2.37 (95% CI: 1.02, 5.51) when replacing 1% energy of long-chain ω3-PUFA for 1% energy of saturated fatty acids. Serum ω6-PUFA, ratios of ω6 and ω3-PUFA, and total PUFA were not associated with ART outcomes. LIMITATIONS REASONS FOR CAUTION: The generalizability of the findings to populations not undergoing infertility treatment may be limited. The use of a single measurement of serum fatty acids to characterize exposure may lead to potential misclassification during follow up. WIDER IMPLICATIONS OF THE FINDINGS: Serum ω3-PUFA are considered biomarkers of dietary intake. The association of higher serum long chain ω3-PUFA levels with improved ART outcomes suggests that increased intake of these fats be may be beneficial for women undergoing infertility treatment with ART. STUDY FUNDING/COMPETING INTERESTS: NIH grants R01-ES009718 from the National Institute of Environmental Health Sciences, P30-DK046200 and T32-DK007703-16 from the National Institute of Diabetes and Digestive and Kidney Diseases, and L50-HD085359 from the National Institute of Child Health and Human Development, and the Early Life Nutrition Fund from Danone Nutricia US. Dr Rueda is involved in a patent 9,295,662, methods for enhancing, improving, or increasing fertility or reproductive function (http://patents.com/us-9295662.html). This patent, however, does not lead to financial gain for Dr Rueda, or for Massachusetts General Hospital. Dr Rueda does not own any part of the company nor does he have any equity in any fertility related company. As Dr Rueda is not a physician, he does not evaluate patients or prescribe medications. All other coauthors have no conflicts of interest to declare.

The association between pre-treatment maternal alcohol and caffeine intake and outcomes of assisted reproduction in a prospectively followed cohort.

STUDY QUESTION: Is pre-treatment alcohol and caffeine intake associated with infertility treatment outcomes among women undergoing ART? SUMMARY ANSWER: Low to moderate alcohol and caffeine intakes in the year prior to infertility treatment were not related to ART outcomes. WHAT IS KNOWN ALREADY: Alcohol and caffeine intake have been found to be associated with infertility in some studies. Nevertheless, data on their relation with outcomes of infertility treatments are scarce and inconsistent. STUDY DESIGN, SIZE, DURATION: We included 300 women (493 ART cycles) from the Environment and Reproductive Health Study, an ongoing cohort study (2006-2016). PARTICIPANTS/MATERIALS, SETTING, METHODS: Pre-treatment intakes of alcohol and caffeine were assessed retrospectively using a validated food frequency questionnaire. Intermediate and clinical endpoints of ART were abstracted from electronic medical records. Generalized linear mixed models with random intercepts to account for multiple ART cycles per woman were used to evaluate the association with ART outcomes adjusting for age, BMI, smoking status, infertility diagnosis, protocol type, race, dietary patterns, and calories, vitamin B12 and folate intake. MAIN RESULTS AND THE ROLE OF CHANCE: Median (range) pre-treatment alcohol and caffeine intakes were 5.6 (0.0-85.8) g/day and 124.9 (0.3-642.2) mg/day, respectively. The adjusted percentage of initiated cycles resulting in live birth (95% CI) for women in increasing categories of pre-treatment alcohol intake was 34% (20, 52%) for non-consumers, 46% (36, 57%) for 0.1-6 g/day, 41% (29, 53%) for 6.1-12 g/day, 42% (31, 55%) for 12.1-24 g/day, and 41% (22, 63%) for >24 g/day (P, trend = 0.87). The adjusted percentage of cycles resulting in live birth (95% CI) for women in increasing categories of caffeine intake was 46% (36-57%) for <50 mg/day, 44% (29, 60%) for 50.1-100 mg/day, 42% (31, 53%) for 100.1-200 mg/day, 40% (28, 53%) for 200.1-300 mg/day and 40% (21, 63%) for >300 mg/day (P, trend = 0.34). When specific types of alcoholic and caffeinated beverages were evaluated, no relations with ART treatment outcomes were observed. LIMITATIONS, REASONS FOR CAUTION: Residual confounding by other diet and lifestyle factors cannot be ruled out owing to the observational nature of this study. It is also unclear how generalizable these results are to women who are conceiving without the assistance of ART. WIDER IMPLICATIONS OF THE FINDINGS: Our results provide reassurance that low to moderate intakes of alcohol (e.g. ≤12 g/day) and caffeine (e.g. <200 mg/day) in the year prior to infertility treatment initiation do not have an adverse effect on intermediate or clinical outcomes of ART. STUDY FUNDING/COMPETING INTEREST(S): The authors are supported by National Institutes of Health (NIH) grants ES022955, R01ES009718, R01ES000002, P30DK46200 and L50-HD085359. No conflicts of interest to declare. TRIAL REGISTRATION NUMBER: NCT00011713.

The association of protein intake (amount and type) with ovarian antral follicle counts among infertile women: results from the EARTH prospective study cohort.

OBJECTIVE: To evaluate the association between protein intake (amount and type) and antral follicle count (AFC). DESIGN: Prospective cohort. SETTING: Academic fertility centre. POPULATION: Two hundred and sixty-five women undergoing fertility treatments at an academic fertility centre and participating in an ongoing study on environment and reproductive health. METHODS: We measured AFC in ultrasonographic evaluation among women undergoing infertility treatments. Women completed a previously validated semi-quantitative food frequency questionnaire. We used Poisson regression to evaluate the relation between protein intake and AFC while adjusting for age, body mass index, race, smoking status, and total energy intake. MAIN OUTCOME MEASURES: Antral follicle count. RESULTS: Among 265 women (mean age: 35.0 ± 3.9 years, 85% Caucasian), total protein intake (% energy) was unrelated to AFC. When protein from different food sources was considered separately, we found a negative association between dairy protein intake and AFC. The mean AFC was 14.4% (3.9-23.7%) lower for women in the highest quintile of dairy protein intake than for women in the bottom quintile after adjusting for potential confounders (P-trend = 0.04). This association was stronger among women who had never smoked (P-trend = 0.002) but was not observed among previous smokers (P-trend = 0.36). There were no associations between protein intake from either non-dairy animal or vegetable sources and AFC. CONCLUSION: Higher dairy protein intake (≥5.24% of energy) was associated with lower antral follicle counts among women presenting for infertility treatment. These findings should be further investigated in prospective studies also designed to clarify the biology underlying the observed associations. TWEETABLE ABSTRACT: Higher dairy protein intake was associated with lower antral follicle counts in an infertile population.

Adherence to the Mediterranean dietary pattern and BMI change among US adolescents.

BACKGROUND: Among adults, the Mediterranean dietary pattern (MDP) is inversely related to body mass index (BMI). Data are lacking on adherence to the MDP among youth in the United States and whether the MDP is related to weight change in that group. OBJECTIVE: To assess whether adherence to the MDP was associated with BMI change among adolescents. To examine temporality, we studied the association between baseline and 2-3-year changes in adherence to the MDP with concurrent changes in BMI, as well as subsequent changes in BMI over a 7-year period. METHODS: We prospectively followed 6002 females and 4916 males in the Growing Up Today Study II, aged 8-15 years in 2004, living across United States. Data were collected by questionnaire in 2004, 2006, 2008 and 2011. Dietary intake was assessed by the Youth/Adolescent Questionnaire. The KidMed Index was derived to measure the adherence to the MDP. We used generalized estimating equations with repeated measures within subjects to assess the association between MDP and BMI change. RESULTS: A two-point increment in the KidMed Index was independently associated with a lower gain in BMI (-0.04 kg m(-2); P=0.001). A greater increase in adherence to the KidMed Index was independently related to a lower gain in BMI in both the concurrent (P-for-trend<0.001) and the subsequent period (P-for-trend=0.002). CONCLUSIONS: Adherence to MDP was inversely associated with change in BMI among adolescents. Two-year improvement in adherence to MDP was independently associated with less steep gain in the BMI in both the concurrent and the subsequent period.

Dairy intake in relation to in vitro fertilization outcomes among women from a fertility clinic.

STUDY QUESTION: Is dairy food consumption associated with live birth among women undergoing infertility treatment? SUMMARY ANSWER: There was a positive association between total dairy food consumption and live birth among women ≥35 years of age. WHAT IS KNOWN ALREADY: Dairy food intake has been previously related to infertility risk and measures of fertility potential but its relation to infertility treatment outcomes are unknown. STUDY DESIGN, SIZE, DURATION: Our study population comprised a total of 232 women undergoing 353 in vitro fertilization (IVF) treatment cycles between February 2007 and May 2013, from the Environment and Reproductive Health study, an ongoing prospective cohort. PARTICIPANTS/MATERIALS, SETTING, METHODS: Diet was assessed before assisted reproductive technology (ART) treatment using a validated food frequency questionnaire. Study outcomes included ovarian stimulation outcomes (endometrial thickness, estradiol levels and oocyte yield), fertilization rates, embryo quality measures and clinical outcomes (implantation, clinical pregnancy and live birth rates). We used generalized linear mixed models with random intercepts to account for multiple ART cycles per woman while simultaneously adjusting for age, caloric intake, BMI, race, smoking status, infertility diagnosis, protocol type, alcohol intake and dietary patterns. MAIN RESULTS AND THE ROLE OF CHANCE: The age- and calorie-adjusted difference in live birth between women in the highest (>3.0 servings/day) and lowest (<1.34 servings/day) quartile of dairy intake was 21% (P = 0.02). However, after adjusting for additional covariates, this association was observed only among women ≥35 years (P, interaction = 0.04). The multivariable-adjusted live birth (95% CI) in increasing quartiles of total dairy intake was 23% (11, 42%), 39% (24, 56%), 29% (17, 47%) and 55% (39, 69%) (P, trend = 0.02) among women ≥35 years old, and ranged from 46 to 54% among women <35 years old (P, trend = 0.69). There was no association between dairy intake and any of the intermediate outcomes. LIMITATIONS, REASONS FOR CAUTION: The lack of a known biological mechanism linking dairy intake to infertility treatment outcomes calls for caution when interpreting these results and for additional work to corroborate or refute them. WIDER IMPLICATIONS OF THE FINDINGS: Dairy intake does not appear to harm IVF outcomes and, if anything, is associated with higher chances of live birth. STUDY FUNDING/COMPETING INTERESTS: This work was supported by NIH grants R01-ES009718 and R01ES000002 from NIEHS, P30 DK046200 from NIDDK and T32HD060454 from NICHD. M.C.A. was supported by a Ruth L. Kirschstein National Research Service Award T32 DK 007703-16 from NIDDK. She is currently employed at the Nestlé Research Center, Switzerland and completed this work while at the Harvard School of Public Health. The other authors declare no conflicts of interest.

Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men.

STUDY QUESTION: Is increased consumption of dairy foods associated with lower semen quality? SUMMARY ANSWER: We found that intake of full-fat dairy was inversely related to sperm motility and morphology. These associations were driven primarily by intake of cheese and were independent of overall dietary patterns. WHAT IS KNOWN ALREADY: It has been suggested that environmental estrogens could be responsible for the putative secular decline in sperm counts. Dairy foods contain large amounts of estrogens. While some studies have suggested dairy as a possible contributing factor for decreased semen quality, this finding has not been consistent across studies. STUDY DESIGN, SIZE, DURATION: The Rochester Young Men's Study (n = 189) was a cross-sectional study conducted between 2009 and 2010 at the University of Rochester. PARTICIPANTS/MATERIALS, SETTING, METHODS: Men aged 18-22 years were included in this analysis. Diet was assessed via food frequency questionnaire. Linear regression was used to analyze the relation between dairy intake and conventional semen quality parameters (total sperm count, sperm concentration, progressive motility, morphology and ejaculate volume) adjusting for age, abstinence time, race, smoking status, body mass index, recruitment period, moderate-to-intense exercise, TV watching and total calorie intake. MAIN RESULTS AND THE ROLE OF CHANCE: Total dairy food intake was inversely related to sperm morphology (P-trend = 0.004). This association was mostly driven by intake of full-fat dairy foods. The adjusted difference (95% confidence interval) in normal sperm morphology percent was -3.2% (-4.5 to -1.8) between men in the upper half and those in the lower half of full-fat dairy intake (P < 0.0001), while the equivalent contrast for low-fat dairy intake was less pronounced [-1.3% (-2.7 to -0.07; P= 0.06)]. Full-fat dairy intake was also associated with significantly lower percent progressively motile sperm (P= 0.05). LIMITATIONS, REASONS FOR CAUTION: As it was a cross-sectional study, causal inference is limited. WIDER IMPLICATIONS OF THE FINDINGS: Further research is needed to prove a causal link between a high consumption of full-fat dairy foods and detrimental effects on semen quality. If verified our findings would mean that intake of full-fat dairy foods should be considered in attempts to explain secular trends in semen quality and that men trying to have children should restrict their intake. STUDY FUNDING/COMPETING INTEREST(S): European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

A prospective study of dietary carbohydrate quantity and quality in relation to risk of ovulatory infertility.

OBJECTIVE: To evaluate whether the amount or quality of carbohydrate in diet is associated with ovulatory infertility. SUBJECTS AND METHODS: In total, 18,555 married, premenopausal women without a history of infertility were followed as they attempted a pregnancy or became pregnant during an 8-year period. Diet was assessed two times during follow-up using a validated food-frequency questionnaire and prospectively related to the incidence of infertility due ovulatory disorder. RESULTS: During follow-up, 438 women reported ovulatory infertility. Total carbohydrate intake and dietary glycemic load were positively related to ovulatory infertility in analyses adjusted for age, body mass index, smoking, parity, physical activity, recency of contraception, total energy intake, protein intake and other dietary variables. The multivariable-adjusted risk ratio (RR) (95% confidence interval (CI)) of ovulatory infertility comparing the highest-to-lowest quintile of total carbohydrate intake was 1.91 (1.27-3.02). The corresponding RR (95% CI) for dietary glycemic load was 1.92 (1.26-2.92). Dietary glycemic index was positively related to ovulatory infertility only among nulliparous women. Intakes of fiber from different sources were unrelated to ovulatory infertility risk. CONCLUSIONS: The amount and quality of carbohydrate in diet may be important determinants of ovulation and fertility in healthy women.