Women who consume fewer ultra-processed foods may have higher odds of conceiving, according to new research from McMaster University. The findings, published today in Nutrition and Health, highlight the potential influence of food processing on reproductive health, independent of age, weight, or other lifestyle factors.
The study analyzed dietary and health data from more than 2,500 women participating in the National Health and Nutrition Examination Survey (NHANES), a comprehensive U.S. survey combining interviews, 24-hour dietary recalls, and laboratory tests.
Researchers found that women reporting infertility—defined as not conceiving after one year of trying—consumed more ultra-processed foods, which made up approximately 31% of their daily intake, and had lower adherence to the Mediterranean diet, a pattern rich in fruits, vegetables, whole grains, and healthy fats.
“Most discussions about ultra-processed foods focus on calories and obesity,” said Anthea Christoforou, assistant professor in McMaster’s Department of Kinesiology and senior author of the paper. “Our findings suggest a potentially more complex mechanism—chemical exposures from processed foods may disrupt hormonal pathways and influence fertility.”
Co-author Angelina Baric, a graduate student in Kinesiology, explained:
“Even when nutrient intake appears adequate, ultra-processed foods can expose women to chemicals like phthalates, BPA, and acrylamides from packaging or processing equipment. These compounds are known to affect hormones and may contribute to the observed associations.”
While the Mediterranean diet showed positive associations with fertility, this effect appeared primarily through its role in maintaining healthy weight and metabolism, suggesting that reducing ultra-processed food intake may be a more direct factor.
In fully adjusted models, higher consumption of ultra-processed foods was associated with roughly 60% lower odds of conception. Although the study is cross-sectional and does not establish causation, the findings underscore the importance of dietary guidance for women of reproductive age.
“Few studies have specifically examined how women’s diets influence reproductive outcomes,” Christoforou noted. “These findings indicate that dietary choices—particularly limiting highly processed foods—could be an important and measurable factor affecting fertility.”
The research team emphasizes that even simple shifts toward minimally processed foods, with recognizable ingredients, can reduce exposure to chemicals and support overall reproductive health.
