An intervention based on the Mediterranean diet during pregnancy positively modifies the mother’s gut microbiota

A structured intervention based on the Mediterranean diet during pregnancy can significantly influence the maternal gut microbiota, promoting bacteria associated with better metabolic health. This is demonstrated by the study Effects of Mediterranean diet or Mindfulness-Based Stress Reduction during pregnancy on maternal gut and vaginal microbiota: a subanalysis of the Improving Mothers for a better PrenAtal Care Trial BarCeloNa (IMPACT BCN) trial, led by researchers from BCNatal (Hospital Clínic and Hospital Sant Joan de Déu) and the Sant Joan de Déu Research Institute (IRSJD), recently published in The American Journal of Clinical Nutrition.

The study analyses data from the IMPACT BCN project, a randomized clinical trial with more than 1,200 pregnant women at high risk of having a baby small for gestational age. In a subsample of 351 participants, the researchers studied the effect of two non-pharmacological interventions during pregnancy -one based on the Mediterranean diet and another on stress reduction through mindfulness- on the maternal gut and vaginal microbiota.

The results show that the Mediterranean diet intervention modifies the overall structure of the gut microbiota, increasing the presence of bacteria associated with the production of short-chain fatty acids, considered beneficial for health. In contrast, the stress-reduction intervention has a more modest impact, although it shows changes in some bacteria related to better health status. Neither intervention showed a relevant effect on the vaginal microbiota.

What the gut microbiota is and why it is key during pregnancy

The gut microbiota is the group of microorganisms -mainly bacteria- that naturally live in the intestine and have a fundamental role in health. These microorganisms participate in essential processes such as digestion, metabolism, immune system regulation and the production of substances with anti-inflammatory effects. During pregnancy, the maternal microbiota becomes particularly relevant, as it can influence both the mother's health and the fetus's development, as well as the baby's initial microbial colonization. Maintaining a balanced gut microbiota is associated with better general metabolic health.

As Francesca Crovetto, IRSJD researcher and last author of the study, explains, "pregnancy is a unique window of opportunity to intervene in the health of the mother and the baby. This study shows that relatively simple lifestyle changes, such as following a Mediterranean diet, can modify the gut microbiota, a key system with potential impact on maternal-fetal health."

Crovetto also highlights the clinical value of the findings: "Although the microbiota was not the main objective of the trial, the results suggest that it could be a mechanism involved in the previously observed benefits of these interventions on fetal growth. This opens the door to future prevention strategies based on lifestyle during pregnancy."

The researchers stress that this is one of the first studies derived from a clinical trial to demonstrate a direct relationship between lifestyle interventions during pregnancy and the composition of the maternal gut microbiota. Even so, they point out the need to continue researching to understand the long-term impact of these changes on both the mother and the child.