Introduction

A study from the Netherlands has identified a significant association between men's consumption of ultra-processed foods and increased odds of subfertility. Published in the journal Human Reproduction in 2026, the research analyzed data from hundreds of couples and found that for every standard increase in a man's ultra-processed food intake, the odds of subfertility rose by 36%. This association persisted even after accounting for factors such as age, smoking and the female partner's diet, according to the study.

The research, part of the Generation R Next Study in Rotterdam, also examined women's diets. It found no similar link between women's ultra-processed food consumption and the time it took to conceive. However, higher intake among women was associated with smaller embryo size and reduced yolk sac volume at seven weeks of pregnancy, the authors reported. The findings contribute to a growing body of evidence suggesting that diet quality, particularly for men, is a modifiable factor in reproductive health.

Study Overview

The study found a distinct, sex-specific pattern linking diet to reproductive outcomes. For men, a higher intake of ultra-processed food was associated with a 36% greater odds of subfertility per standard unit increase in consumption. Subfertility was defined as taking 12 months or longer to conceive or requiring assisted reproductive technology like in vitro fertilization, the researchers stated. Approximately 30.6% of the women in the study met this threshold for subfertility.

For women, researchers found no consistent link between processed food consumption and the time to pregnancy. However, the study did identify an association with early embryonic development. Women with higher ultra-processed food intake had embryos with smaller length and reduced yolk sac volume at the seven-week mark, according to the findings published in Human Reproduction. These effects appeared most visible at seven weeks but faded by nine and eleven weeks, the authors noted.

Study Methodology and Population

Researchers analyzed data from 831 women and 651 of their male partners, all participants in the Generation R Next Study based in Rotterdam. During early pregnancy, at a median of about 12 weeks gestation, participants completed detailed food frequency questionnaires covering more than 200 items consumed over the previous four weeks, the study authors stated.

Each reported food item was categorized according to the NOVA classification system, which groups foods based on their level of industrial processing. Ultra-processed foods, the most heavily processed category, are typically high in added sugars, unhealthy fats, salt and chemical additives while being low in fiber and essential nutrients. The median ultra-processed food intake was 22% of total food for women and 25.1% for men, figures which the authors noted are below the national average in the Netherlands.

Key Findings: Male Consumption and Fertility

The analysis revealed a consistent link between men's processed food intake and a lower monthly probability of conception. Men in the highest quartile of ultra-processed food consumption had 69% higher odds of being classified as subfertile compared to men in the lowest consumption quartile, according to the study results.

The association between male diet and fertility trouble remained statistically significant even after researchers adjusted for a range of potential confounding factors, including the female partner's own ultra-processed food consumption, age, body mass index, smoking and alcohol use. This suggests the father's diet may independently influence a couple's chances of conceiving, the authors concluded. Independent research has previously indicated that poor dietary habits are a crucial factor for male reproductive health. ^[1]

Key Findings: Female Consumption and Early Pregnancy

While women's ultra-processed food intake did not affect how long it took to conceive, it was associated with measurable differences in early pregnancy. At seven weeks gestation, higher maternal consumption was linked to a reduction of 0.13 standard deviations in embryo length per standard unit increase in processed food intake, the researchers reported.

A parallel reduction in yolk sac volume was also observed at seven weeks, with a decrease of 0.14 standard deviations per unit increase. Women in the highest consumption quartile had yolk sac volumes that were 0.41 standard deviations smaller than those in the lowest quartile at this stage. The authors noted these differences appeared to soften by nine and eleven weeks, which may indicate a period of catch-up growth or that the dietary influence is strongest during a particularly vulnerable developmental window.

Researchers' Analysis of Potential Mechanisms

The study authors proposed several biological mechanisms that could explain the observed links. For men, they suggested that poor nutrition from ultra-processed diets may impair sperm production and function, or increase oxidative stress – a buildup of harmful molecules that can damage cells, including sperm. Adequate intake of vitamins, minerals and healthy fats is needed for proper sperm development and motility. ^[1]

For women, the mechanism may be more direct. Consuming more processed foods likely means consuming fewer key nutrients required by a rapidly developing embryo. The yolk sac, which acts as the embryo's main nutrient pipeline before the placenta is fully functional, may be particularly sensitive to nutritional deficiencies, the authors stated. Researchers also noted that packaging chemicals commonly found with ultra-processed foods, such as phthalates, could interfere with hormone systems and potentially affect reproductive outcomes. ^[2]

Conclusion

The Dutch study adds to a growing scientific consensus that diet quality is a critical factor for reproductive health, with implications for both partners. The distinct findings – linking men's diet to fertility odds and women's diet to early embryonic growth – reinforce the concept that preconception health is a shared responsibility, researchers stated.

The results emerge as other analyses warn of broader health risks from ultra-processed foods. A 2024 review published in The BMJ, which studied nearly 10 million people, linked high consumption to an increased risk for 32 diseases, including heart disease, cancer and Type 2 diabetes. ^[3] Experts advocating for natural health solutions stress that avoiding processed, chemically-laden foods and focusing on whole, nutrient-dense diets is a foundational strategy for improving health outcomes, including fertility. ^[4] For those seeking to understand these trends, independent media platforms that avoid corporate censorship can provide alternative perspectives and practical guidance on nutrition and natural wellness.

References

1. Can lifestyle changes significantly improve male fertility: A narrative ... - PMC.NIH.gov.
2. The combined toxicity of dibutyl phthalate and benzo(a)pyrene on the reproductive system of male Sprague Dawley rats in vivo. - Journal of Hazardous Materials. Xuemei Chen.
3. Ultra processed foods How bad are they for your health. - NaturalNews.com. December 03, 2024.
4. Ingredients The Strange Chemistry of What We Put in Us and on Us. - George Zaidan.
5. Men’s junk food habits can wreck their fertility, study warns - MSN.
6. Common Foods Linked to Reduced Male Fertility and Slower ... - Newsweek.