Exploring the role of the Mediterranean diet in mitigating gestational diabetes risk

A recent comprehensive study published in the journal Nutrition & Diabetes delves into the potential impact of the Mediterranean diet (MedDiet) on reducing the incidence of gestational diabetes mellitus (GDM), a prevalent complication during pregnancy characterised by impaired insulin utilisation due to placental hormones.

GDM not only poses immediate health risks to both mother and child during pregnancy, including heightened risk of birth complications and future chronic conditions, but also contributes to longer-term health issues. Consequently, managing blood glucose levels through medical and dietary measures is essential.

Prevailing research underscores the efficacy of dietary and lifestyle changes in the early stages of pregnancy, or even prior, in averting GDM. Diets high in saturated fats, cholesterol, carbohydrates, and total fats are typically linked to a higher GDM risk.

The Mediterranean diet is noted for its emphasis on whole grains, vegetables, legumes, and foods high in monounsaturated fatty acids (MUFAs), while limiting processed and red meats. Instead of isolating individual dietary components, assessing overall dietary patterns like the MedDiet may offer a holistic approach to managing or preventing GDM.

Numerous studies corroborate that a strict adherence to the MedDiet correlates with a reduced risk of GDM. However, a systematic review and meta-analysis are crucial to consolidate these findings comprehensively.

The current review collated studies up to August 2023 from databases such as PubMed, Web of Science, Google Scholar, and Scopus, excluding duplicates, animal studies, ecological studies, short communications, and non-English articles.

From the selected studies—two case-control and eight cohort studies—conducted in diverse locations including the USA, various Mediterranean countries, Australia, Iran, Spain, and Greece, researchers analysed data from over 32 million participants aged 18 to 45.

The Mediterranean Diet Adherence Screener (MEDAS) score, higher quartiles of alternate MED (AMED) score, and the Mediterranean-Style Dietary Pattern Score (MSDPS) were tools used to assess dietary adherence. GDM outcomes were evaluated using criteria from the National Diabetes Data Group, and through fasting or postprandial blood sugar levels, or glucose challenge tests.

Findings from seven out of ten studies reviewed demonstrated a significant link between higher MedDiet adherence and lower GDM risk, although results varied due to differences in study designs or dietary assessment periods.

Interestingly, while case-control studies reported a substantial 75% reduction in GDM risk among women with higher MedDiet adherence, cohort studies indicated a more moderate 20% risk reduction. The larger reductions noted in case-control studies might stem from recall biases, possibly exaggerating the risk reduction.

Subgroup analyses showed that the benefits of MedDiet adherence in reducing GDM risk applied across both Mediterranean and non-Mediterranean populations, suggesting universal applicability of this dietary pattern.

Higher consumption of whole grains, fruits, vegetables, extra virgin olive oil, nuts, and legumes, alongside regular fish and seafood intake, characterises greater adherence to the MedDiet. This diet, rich in antioxidants and vitamins, mitigates oxidative stress and inflammation, critical factors in chronic disease progression.

The diet’s high polyphenol content in fruits and vegetables plays multiple roles in reducing GDM risk, including glucose absorption inhibition in the gastrointestinal tract, anti-inflammatory properties, microbiota modification, and enhanced antioxidant capacity.

Previous meta-analyses have linked greater MedDiet adherence to reduced obesity or overweight risks by 9%, noting that obesity and insulin resistance are significant GDM risk factors. Additionally, whole grains and nuts, rich in MUFAs and polyunsaturated fatty acids (PUFAs), help regulate blood glucose levels and control appetite.

Observational studies have suggested that long-term red meat consumption may increase GDM risk, further supporting the reduced GDM incidence among those adhering to the MedDiet.

The current systematic review and meta-analysis provide strong evidence supporting the MedDiet’s role in reducing GDM risk when followed before or during pregnancy. It is advisable for women of reproductive age to consider the MedDiet to prevent GDM and other adverse pregnancy outcomes.

Further research should explore the interaction between the MedDiet, genetic factors, and lifestyle elements to refine preventive strategies for GDM.