A new study led by Spanish scientists suggests that the Mediterranean diet may enhance the vaginal microbiome in ways that support pregnancy for women undergoing fertility treatments such as artificial insemination. The research, published in the journal Food & Function, was conducted by the Institute of Agrochemistry and Food Technology (IATA), part of Spain's National Research Council (CSIC), in collaboration with Doctor Peset Hospital in Valencia.
The team analyzed the vaginal microbiota of 104 women aged 18 to 38 with primary infertility—defined as the inability to conceive after 12 months or more of regular, unprotected intercourse. Using genetic sequencing, they classified the microbial profiles and correlated them with dietary habits assessed via a validated questionnaire.
Lactobacillus dominance linked to pregnancy success
Women who achieved pregnancy showed a vaginal microbiota dominated by Lactobacillus bacteria, which are associated with a stable and healthy environment. In contrast, those who did not conceive—particularly those with low adherence to the Mediterranean diet—exhibited higher levels of Gardnerella vaginalis, a bacterium linked to microbial imbalances and conditions like bacterial vaginosis.
“A lower vaginal microbial diversity during pregnancy, unlike what happens with the intestinal microbiota, does not necessarily imply an imbalance, but is usually associated with a state of stability and health, especially when bacteria of the Lactobacillus genus predominate,” said María Carmen Collado, a CSIC researcher at IATA's Mainbiotics laboratory who led the study.
The research also identified distinct microbial profiles between women whose pregnancies went to term and those who miscarried. Among participants who conceived, those who later miscarried had a lower presence of Lactobacillus, suggesting that the composition of the vaginal microbiome—modulated in part by diet—may play a key role in both conception and pregnancy outcome.
Micronutrients and protective effects
Some micronutrients abundant in the Mediterranean diet—such as vitamins A, C, D, and E, beta-carotene, calcium, and zinc—appear to offer protection against bacterial vaginosis, the most common vaginal disorder in women of reproductive age. “These nutrients seem to play a protective role against microbial imbalances,” said Mar Gimeno, a gynaecology and obstetrics specialist at Hospital Clínico Universitario de Valencia, formerly at Doctor Peset Hospital and a co-author of the study.
The team used a machine learning algorithm to correlate dietary data with reproductive outcomes, identifying patterns that favour pregnancy. The high consumption of fruits, vegetables, legumes, whole grains, fish, and olive oil characteristic of the Mediterranean diet appears to help modulate the vaginal microbiota.
“This study opens the door to consider vaginal microbiota as a possible predictive marker of fertility,” said Elia García Verdevio, a gynaecologist who participated in the research.
The findings are particularly relevant in the context of modern Western lifestyles, where stress, unhealthy diets, and antibiotic use can disrupt the balance of the vaginal microbiome and affect reproductive health. The researchers argue that lifestyle interventions, including dietary changes, could become a complementary strategy to improve success rates in assisted reproduction.
“The adoption of healthy dietary patterns may be a modifiable factor in improving the success of fertility treatments,” Collado added.
This study adds to a growing body of evidence linking diet to reproductive health, echoing findings from other research on longevity and diet, such as centenarian offspring diets. As fertility treatments become more common across Europe, understanding the role of nutrition could offer a low-cost, non-invasive way to boost outcomes.
