A Spanish study finds that the Mediterranean diet favours a more stable and healthy environment in the micro-organisms of women with primary infertility who manage to become pregnant.
Following a Mediterranean diet may improve the vaginal microbiome in ways that support pregnancy in women undergoing fertility treatment, such as artificial insemination, according to a new study.
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The research was led by scientists at the Institute of Agrochemistry and Food Technology (IATA), part of Spain's National Research Council (CSIC), with participation from Doctor Peset Hospital in Valencia, Spain.
The research team analysed the vaginal microbiota of 104 women aged between 18 and 38 with primary infertility using genetic sequencing. The results show that women who follow the Mediterranean diet have more favourable microbial profiles for the implantation and maintenance of pregnancy.
Women who were unable to achieve pregnancy after 12 months or more of sexual intercourse adopted the Mediterranean diet using a validated questionnaire. The study, published in the scientific journal 'Food & Function', shows that women who managed to become pregnanthad a vaginal microbiota dominated by bacteria of the genus Lactobacillus, associated with a more stable and healthy environment.
However, those who did not achieve pregnancy, especially those with low adherence to the Mediterranean diet, showed a higher presence of bacteria such as Gardnerella vaginalis, linked to microbial imbalances.
Differentiated microbial profiles between miscarriages and full-term pregnancies
In addition, the study identifies distinct microbial profiles between pregnancies that went to term and those that ended in miscarriage, suggesting that the composition of the vaginal microbiome, modulated in part by diet, may play a key role in both conception and pregnancy outcome.
"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 in the Mainbiotics laboratory at IATA who led the study.
Bacteria that promote reproductive health
The team classified the vaginal microbiota of each woman into different types, according to the predominant microorganisms. They paid special attention to the genus Lactobacillus, bacteria that act as a protective shield for the vaginal environment and promote reproductive health.
This information has been correlated with data on diet and reproductive outcomes usinga machine learning algorithm capable of identifying patterns that favour pregnancy.
Eating habits could become a complementary tool to improve the success rates of assisted reproduction treatments, according to the study. This is particularly relevant in the current context, where Western lifestyles, with stress, unhealthy diets and antibiotic use, can alter the balance of the vaginal microbiota and affect women's reproductive health.
Micronutrients and vitamins in the Mediterranean diet
Some micronutrients present in abundance in foods typical of the Mediterranean diet, such as vitamins A, C, D and E, beta-carotene, calcium and zinc, "appear to play a protective role against bacterial vaginosis, the most common vaginal disorder in women of reproductive age, characterised by an imbalance in the vaginal microbiota", said Mar Gimeno, a specialist in gynaecology and obstetrics at the Hospital Clínico Universitario de Valencia, previously at the Hospital Dr. Peset and co-author of the study.
Among the participants who achieved pregnancy, those who subsequently suffered a miscarriage showed different microbial profiles, with a lower presence of Lactobacillus.
Strategies to improve fertility outcomes
The data suggest that lifestyle interventions, such as diet, could become a complementary strategy to improve fertility outcomes in assisted reproduction.
"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 study.
The high consumption of fruits, vegetables, legumes, whole grains, fish and olive oil characteristic of the Mediterranean diet contributes to modulating the vaginal microbiota. "The adoption of healthy dietary patterns may be a modifiable factor in improving the success of fertility treatments," said Collado.
The study highlights that fertility does not depend solely on hormonal or genetic factors, but also on modifiable elements such as diet and vaginal microbiota, which could become a useful biomarker for predicting the success of artificial insemination.
