Research from Erasmus University Medical Center in the Netherlands shows consuming large amounts of ultra-processed foods reduces fertility in men.
The same study, published in the journal Human Reproduction, shows women who consume large amounts of ultra-processed foods have slowed embryonic growth during pregnancy and smaller yolk sac size.
“Even though ultra processed foods are so common in our diets, very little is known about their potential relationship with fertility outcomes, and early human development,” said lead author Romy Gaillard, MD, PhD, a pediatrician and associate professor of developmental epidemiology at Erasmus University Medical Center, in a press statement.
To investigate this further, Gaillard and colleagues carried out a study to assess the impact of these foods on male and female reproduction.
The study included 831 women and 651 male partners from the Generation R Next Study in Rotterdam, with diet assessed via food-frequency questionnaire in the period just before and after conception. Ultra-processed food consumption was calculated as a percentage of a participant’s diet using the NOVA food classification system, which allows an assessment of how processed a given food is.
Across men and women in the study, intake of ultra-processed foods ranged from 15–33% of their diets. The median intake in men and women was 25% and 22%, respectively.
The results for men showed that one standard deviation increase in the proportion of ultra‑processed foods in their diet was associated with about a 10% lower chance of conceiving in a given month. Men who consumed higher amounts of these foods also had a greater chance of having low fertility. Although it impacted fertility, consumption of these foods by men did not significantly impact embryo development in their partners.
Consumption of ultra-processed foods did not appear to impact fertility in women, but it was associated with smaller embryos and a lower yolk sac volume in early pregnancy (around seven weeks). For each standard‑deviation increase in ultra‑processed food intake by women, crown–rump length and yolk sac volume were about 0.13–0.14 standard deviations smaller. These differences became weaker and were no longer clear by nine and 11 weeks.
“Our findings suggest that a diet low in ultra-processed foods would be best for both partners, not only for their own health, but also for their chances of pregnancy and the health of their unborn child,” said Gaillard.
She cautions that although these results are suggestive, “as this is an observational study, our study shows associations, but cannot prove direct causal effects of ultra-processed food consumption on these early life outcomes.”
