News | U.S. study: Higher ultra-processed food intake linked to lower female fertility; Mediterranean diet benefits may depend on weight
A study using nationally representative U.S. data found that the greater the proportion of ultra-processed foods (UPFs) in a woman’s diet, the less likely she was to be classified as fertile. A Mediterranean diet appeared beneficial in initial analysis, but the advantage weakened substantially after obesity was considered. The study was published in Nutrition and Health.
Using 2013—2018 National Health and Nutrition Examination Survey (NHANES) data, researchers analyzed 2,582 women ages 20 to 45. Infertility was defined by self-report of trying unsuccessfully to conceive for 12 months. About 88% were classified as fertile, while 12% reported infertility.
Ultra-processed food intake significantly associated with lower fertility
About 27% of women’s daily energy intake came from UPFs, rising to 31% among those reporting infertility. For every 10% increase in the proportion of UPFs consumed, women were significantly less likely to be classified as fertile, and the association remained after adjusting for total energy intake and obesity.
This suggests that UPFs may affect fertility through mechanisms beyond weight or obesity, including more complex metabolic and endocrine pathways.
Mediterranean diet: benefits weakened by obesity
Women following a Mediterranean diet rich in fruit, vegetables, whole grains, nuts, and fish initially had a higher probability of fertility. After obesity was included in the model, however, the association was no longer statistically significant.
Researchers said this may mean that some benefits of the Mediterranean diet arise through improved weight and metabolic health rather than an entirely independent effect.
Potential mechanisms: from nutrient deficiencies to endocrine disruption
The study described several links between diet and fertility:
Nutrient deficiencies: UPFs are often low in fiber, folate, iron, and antioxidants, nutrients important for hormonal balance and ovarian function
Exposure to endocrine disruptors: processing and packaging may introduce chemicals such as phthalates and bisphenols, which have been associated with hormonal disruption and lower fertility
Chronic inflammation and gut dysbiosis: high-UPF diets are closely associated with inflammation and disrupted gut microbiota, which may affect egg quality, embryo development, and endometrial receptivity
Together, these mechanisms form a biological basis for the effects of diet on reproductive health.
Public health implications: from “what to eat” to “how food is processed”
The study emphasizes that food processing itself should be considered in reproductive health interventions alongside nutrient intake. Reducing UPFs and increasing whole or minimally processed foods may be more practical than focusing only on calories or nutrient ratios.
It also suggests that the effects of a specific dietary pattern, such as the Mediterranean diet, may depend on an individual’s metabolic status, particularly weight management.
Study limitations and next steps
The team noted that the cross-sectional study cannot establish causation. Fertility status was self-reported and may have underestimated or misclassified some cases of clinical infertility. Long-term follow-up and mechanistic studies are needed to clarify causal pathways between diet and fertility.
News | U.S. study: Higher ultra-processed food intake linked to lower female fertility; Mediterranean diet benefits may depend on weight
News | U.S. study: Higher ultra-processed food intake linked to lower female fertility; Mediterranean diet benefits may depend on weight
A study using nationally representative U.S. data found that the greater the proportion of ultra-processed foods (UPFs) in a woman’s diet, the less likely she was to be classified as fertile. A Mediterranean diet appeared beneficial in initial analysis, but the advantage weakened substantially after obesity was considered. The study was published in Nutrition and Health.
Using 2013—2018 National Health and Nutrition Examination Survey (NHANES) data, researchers analyzed 2,582 women ages 20 to 45. Infertility was defined by self-report of trying unsuccessfully to conceive for 12 months. About 88% were classified as fertile, while 12% reported infertility.
Ultra-processed food intake significantly associated with lower fertility
About 27% of women’s daily energy intake came from UPFs, rising to 31% among those reporting infertility. For every 10% increase in the proportion of UPFs consumed, women were significantly less likely to be classified as fertile, and the association remained after adjusting for total energy intake and obesity.
This suggests that UPFs may affect fertility through mechanisms beyond weight or obesity, including more complex metabolic and endocrine pathways.
Mediterranean diet: benefits weakened by obesity
Women following a Mediterranean diet rich in fruit, vegetables, whole grains, nuts, and fish initially had a higher probability of fertility. After obesity was included in the model, however, the association was no longer statistically significant.
Researchers said this may mean that some benefits of the Mediterranean diet arise through improved weight and metabolic health rather than an entirely independent effect.
Potential mechanisms: from nutrient deficiencies to endocrine disruption
The study described several links between diet and fertility:
Nutrient deficiencies: UPFs are often low in fiber, folate, iron, and antioxidants, nutrients important for hormonal balance and ovarian function
Exposure to endocrine disruptors: processing and packaging may introduce chemicals such as phthalates and bisphenols, which have been associated with hormonal disruption and lower fertility
Chronic inflammation and gut dysbiosis: high-UPF diets are closely associated with inflammation and disrupted gut microbiota, which may affect egg quality, embryo development, and endometrial receptivity
Together, these mechanisms form a biological basis for the effects of diet on reproductive health.
Public health implications: from “what to eat” to “how food is processed”
The study emphasizes that food processing itself should be considered in reproductive health interventions alongside nutrient intake. Reducing UPFs and increasing whole or minimally processed foods may be more practical than focusing only on calories or nutrient ratios.
It also suggests that the effects of a specific dietary pattern, such as the Mediterranean diet, may depend on an individual’s metabolic status, particularly weight management.
Study limitations and next steps
The team noted that the cross-sectional study cannot establish causation. Fertility status was self-reported and may have underestimated or misclassified some cases of clinical infertility. Long-term follow-up and mechanistic studies are needed to clarify causal pathways between diet and fertility.
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