A study published in Human Reproduction found that diet around conception, particularly ultra-processed food (UPF) intake, may affect male fertility and early embryonic development through different pathways. The findings further underscore the importance of the preconception window in reproductive health.
The study found clear sex differences in the association between UPF intake and reproductive outcomes: higher intake in men was associated with lower fecundability and a higher risk of infertility, while intake in women was linked to subtle changes in very early embryonic development, particularly at 7 weeks of pregnancy.
Using the prospective Generation R Next Study cohort, researchers included 831 women and 651 male partners and systematically analyzed the effects of periconceptional diet on time to pregnancy, fecundability, and markers of early embryonic development. Dietary data were collected through a food-frequency questionnaire in early pregnancy, at about 12 weeks, and the proportion of UPF intake was identified using the NOVA classification system.
Median UPF intake was 22% (about 563 g/day) in women and 25% (about 643 g/day) in men. Dietary correlation between partners was low, and only 57% of couples showed a clear difference in intake, suggesting that individual dietary behavior may independently affect reproductive health.
Among women, no significant association was observed between UPF intake and fecundability. Only certain intake ranges were associated with a higher risk of infertility, with no clear dose-response relationship. For embryonic development, however, UPF intake was associated with smaller crown-rump length (CRL) and yolk sac volume at 7 weeks, with the effect gradually weakening at 9 and 11 weeks.
The yolk sac is a key structure that nourishes the embryo before the placenta develops, and abnormal yolk sac development has been linked to higher risks of miscarriage and preterm birth. This means that even small changes may be important at the population level.
By contrast, the effect of male UPF intake was more focused on the ability to conceive. Each standard-deviation increase in UPF intake was associated with an approximately 10% reduction in fecundability, and infertility risk increased overall, although no consistent association was found with embryonic development markers.
The research team proposed several possible mechanisms. UPFs are generally nutrient-poor and may trigger oxidative stress, mitochondrial dysfunction, and hormonal changes that impair sperm motility. Endocrine-disrupting chemicals commonly found in food packaging, such as phthalates, may further impair male reproductive function and affect the expression of genes related to yolk sac function.
The health effects also vary among types of UPF. Artificially sweetened beverages and processed meats have more consistently been linked to adverse health outcomes, while processed breads and grain products have not shown similar associations. Bread products were a major source of UPF intake in this study.
These associations persisted after adjustment for confounders including body mass index (BMI), smoking, alcohol use, folic acid supplementation, and socioeconomic factors, suggesting that dietary patterns themselves may have an independent effect.
From a clinical and public health perspective, the findings suggest that reproductive health management should move from the traditional woman-centered model toward joint interventions for both partners, beginning before pregnancy.
The study also had limitations. Participants were mainly healthy, diet was assessed in early pregnancy, and only couples who had conceived were included, creating possible selection bias. As an observational study, it cannot establish causality, and randomized controlled trials and larger population studies are still needed.
Nevertheless, the study offers important clues about how diet may have effects at the earliest stages of life and highlights an underrecognized possibility: reproductive outcomes may be partly shaped before conception.
News | Preconception diet affects fertility: Ultra-processed foods show sex-specific effects
News | Preconception diet affects fertility: ultra-processed foods show sex-specific effects
A study published in Human Reproduction found that diet around conception, particularly ultra-processed food (UPF) intake, may affect male fertility and early embryonic development through different pathways. The findings further underscore the importance of the preconception window in reproductive health.
The study found clear sex differences in the association between UPF intake and reproductive outcomes: higher intake in men was associated with lower fecundability and a higher risk of infertility, while intake in women was linked to subtle changes in very early embryonic development, particularly at 7 weeks of pregnancy.
Using the prospective Generation R Next Study cohort, researchers included 831 women and 651 male partners and systematically analyzed the effects of periconceptional diet on time to pregnancy, fecundability, and markers of early embryonic development. Dietary data were collected through a food-frequency questionnaire in early pregnancy, at about 12 weeks, and the proportion of UPF intake was identified using the NOVA classification system.
Median UPF intake was 22% (about 563 g/day) in women and 25% (about 643 g/day) in men. Dietary correlation between partners was low, and only 57% of couples showed a clear difference in intake, suggesting that individual dietary behavior may independently affect reproductive health.
Among women, no significant association was observed between UPF intake and fecundability. Only certain intake ranges were associated with a higher risk of infertility, with no clear dose-response relationship. For embryonic development, however, UPF intake was associated with smaller crown-rump length (CRL) and yolk sac volume at 7 weeks, with the effect gradually weakening at 9 and 11 weeks.
The yolk sac is a key structure that nourishes the embryo before the placenta develops, and abnormal yolk sac development has been linked to higher risks of miscarriage and preterm birth. This means that even small changes may be important at the population level.
By contrast, the effect of male UPF intake was more focused on the ability to conceive. Each standard-deviation increase in UPF intake was associated with an approximately 10% reduction in fecundability, and infertility risk increased overall, although no consistent association was found with embryonic development markers.
The research team proposed several possible mechanisms. UPFs are generally nutrient-poor and may trigger oxidative stress, mitochondrial dysfunction, and hormonal changes that impair sperm motility. Endocrine-disrupting chemicals commonly found in food packaging, such as phthalates, may further impair male reproductive function and affect the expression of genes related to yolk sac function.
The health effects also vary among types of UPF. Artificially sweetened beverages and processed meats have more consistently been linked to adverse health outcomes, while processed breads and grain products have not shown similar associations. Bread products were a major source of UPF intake in this study.
These associations persisted after adjustment for confounders including body mass index (BMI), smoking, alcohol use, folic acid supplementation, and socioeconomic factors, suggesting that dietary patterns themselves may have an independent effect.
From a clinical and public health perspective, the findings suggest that reproductive health management should move from the traditional woman-centered model toward joint interventions for both partners, beginning before pregnancy.
The study also had limitations. Participants were mainly healthy, diet was assessed in early pregnancy, and only couples who had conceived were included, creating possible selection bias. As an observational study, it cannot establish causality, and randomized controlled trials and larger population studies are still needed.
Nevertheless, the study offers important clues about how diet may have effects at the earliest stages of life and highlights an underrecognized possibility: reproductive outcomes may be partly shaped before conception.
Source:
Compiled from online sources