U.S. study links ultra-processed foods to lower odds of fertility

By Pooja Toshniwal PahariaReviewed by Susha Cheriyedath, M.Sc.Mar 22 2026

A national U.S. study links higher ultra-processed food intake to lower odds of fertility, while suggesting that any Mediterranean diet advantage may depend partly on body weight.

Study: Ultra-processed food intake and Mediterranean diet adherence in relation to fertility status in U.S. women: Findings from NHANES 2013–2018. Image Credit: rafa jodar / Shutterstock

A growing body of evidence increasingly highlights diet as a key factor in reproductive health. In a recent study published in the journal Nutrition and Health, researchers examined associations between ultra-processed food (UPF) intake, Mediterranean diet (MD) adherence, and self-reported fertility status in a nationally representative United States (US) population.

Higher UPF consumption was associated with lower odds of being classified as fertile, whereas greater MD adherence was associated with higher odds of fertility in the initial adjusted models. However, this benefit weakened after accounting for obesity.

Together, the findings underscore the complex interplay between diet, body weight, and self-reported fertility status in women of reproductive age.

Infertility Burden and Role of Diet

Infertility, defined as the inability to conceive after 12 months of unprotected intercourse, remains a significant global health burden with psychological, social, and economic impacts. With limited access to assisted reproductive technologies, attention has shifted to modifiable factors such as diet.

Nutrient-dense, anti-inflammatory dietary patterns, such as the Mediterranean diet, have been linked to improved fertility in prior studies, although evidence in US populations remains limited. At the same time, rising consumption of ultra-processed foods, which are associated with metabolic dysfunction and inflammation, may negatively influence reproductive health.

NHANES Study Design and Population Analysis

In the present study, researchers examined the influence of UPFs and MD adherence on participants' reported fertility status among US females aged 20 to 45 years. The study included 2,582 women from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2018. Fertility status was determined based on self-reported difficulty conceiving after at least 12 months of trying.

Dietary intake was assessed using two 24-hour recalls. UPFs were classified using the Nova system and expressed as a percentage of total daily intake. Mediterranean diet adherence was evaluated using an eight-point scoring system based on food groups, including fruits, vegetables, whole grains, legumes, nuts, fish, and fat composition. Statistical models adjusted for sociodemographic, lifestyle, and health factors, including age, race, physical activity, smoking, and obesity status.

Higher Ultra-Processed Food Intake Linked to Lower Fertility

Among participants, 88% were classified as fertile, while 12% reported infertility. Ultra-processed foods accounted for an average of 27% of daily intake. Women reporting infertility consumed a higher proportion of UPFs (31% vs. 27%) and had lower adherence to the Mediterranean diet compared to fertile participants.

Each 10% increase in UPF intake was associated with significantly lower odds of being classified as fertile, even after adjusting for obesity and total energy intake. These findings suggest that UPFs may negatively affect fertility through mechanisms beyond body weight alone.

Mediterranean Diet Benefits and Obesity Interaction

Greater adherence to the Mediterranean diet was initially associated with higher odds of fertility. However, this relationship lost statistical significance after accounting for obesity, indicating that body weight may partly mediate the benefits of this dietary pattern. This highlights the interconnected roles of diet quality and metabolic health in reproductive outcomes.

Biological Mechanisms Linking Diet and Reproductive Health

Ultra-processed foods are typically low in essential nutrients such as fibre, folate, iron, and antioxidants, which are important for hormonal balance and reproductive function. In addition, industrial processing may alter food structure and increase exposure to endocrine-disrupting chemicals such as phthalates and bisphenols. These compounds have been associated with hormonal dysregulation and impaired fertility.

UPF-rich diets are also linked to chronic inflammation and disruptions in the gut microbiome, which may negatively affect ovarian function, embryo development, and endometrial receptivity. These mechanisms provide plausible explanations for the observed associations between diet and fertility outcomes.

Public Health Implications for Fertility and Nutrition

The findings reinforce the importance of dietary patterns in reproductive health, highlighting ultra-processed food intake as a potential independent risk factor for infertility. Public health strategies may benefit from focusing not only on nutrient intake but also on the level of food processing.

Encouraging consumption of minimally processed, nutrient-dense foods alongside reducing UPF intake may offer a practical approach to supporting fertility, regardless of body weight. Mediterranean-style diets may offer additional benefits by improving metabolic health, though further research is needed to confirm these effects.

Study Limitations and Future Research Directions

While the nationally representative sample strengthens the relevance of the findings, the cross-sectional study design limits the ability to establish causality. Fertility status was self-reported and may not capture all clinical cases of infertility. Future longitudinal and mechanistic studies are needed to better understand causal relationships and underlying biological pathways.