Does the Mediterranean diet meet nutritional requirements during pregnancy?

By Neha MathurSep 4 2023Reviewed by Lily Ramsey, LLM

In a recent article published in the Frontiers in Public Health Journal, researchers evaluated whether adopting a healthy diet, such as the Mediterranean diet (MedDiet), during pregnancy could meet the unique macro- and micronutrient requirements of pregnancy.

Study: Diet quality and nutrient density in pregnant women according to adherence to Mediterranean diet. Image Credit: AntoninaVlasova/Shutterstock.com

Background

Diet usually is not enough to meet the nutrient requirements of pregnancy, which, in turn, impairs fetal growth and maternal health.

Studies have described that up to 30% of pregnant females remain deficient in micronutrients, such as folic acid and vitamins A, B6, C, D, and E. Dietary patterns during gestation. However, a modifiable factor might have permanent health consequences on the neonate.

The guidelines for nutritional supplementation during pregnancy vary widely across different geographical regions.

For instance, in Spain, they only recommend additionally supplementing folic acid and iodine during pregnancy and rely mainly on adhering to MedDiet to meet the requirements of most other micronutrients.

MedDiet includes fruits and vegetables, whole grains, legumes, seeds, nuts in high amounts, and fish, seafood, eggs, and fermented dairy products, e.g., yogurt, in moderate amounts. It uses extra virgin olive oil (EVOO) as the main source of fat for dressings and cooking.

In the recent Improving Mothers for a Better Prenatal Care Trial BarCeloNa (IMPACT BCN), a nutritional intervention based on MedDiet, demonstrated a decreased prevalence of perinatal complications by 26%.

Assaf-Balut et al. showed that adherence to MedDiet lowered the risk of gestational diabetes, premature birth, and urinary tract infections.

Multiple recent studies have described the health benefits of the MedDiet for mother and fetus. However, studies have not explored the extent to which pregnant women in Mediterranean areas could benefit from local food.

About the study

In the present study, researchers performed a cross-sectional study between February 2017 and August 2021 in Barcelona, Spain, to evaluate whether a high adherence to MedDiet met the micronutrient requirements of pregnant females.

The study cohort comprised 1,356 pregnant females aged ≥18 years and in their second trimester, gestation period (19–23 weeks). They were fluent in Spanish and carried a viable singleton non-malformed fetus, as assessed by an ultrasound scan.

At enrollment, a dietitian categorized all the study participants into three groups based on a 17-item MedDiet adherence score, where scores <6, 6–11, and ≥12 points indicated low, medium, and high adherence to MedDiet.

Trained personnel also assessed the cardiometabolic health parameters of participants at enrollment, including body weight, height, waist circumference, body mass index (BMI), and blood pressure (BP).

The researchers also collected maternal sociodemographic data, age, ethnicity, etc., and clinical data, e.g., physical activity levels, at enrollment.

Further, the team enquired about each participant's usual and frequent consumption of enlisted foods in the Food Frequency Questionnaire (FFQ). They computed energy and nutrient intake, i.e., total dietary fiber, vitamins, and minerals intake, using the FFQ-derived food consumption data.

They included participants with energy intake in a predefined limit between <500 kcal/day and >3,500 kcal/day.

They compared dietary intake of magnesium, iron, calcium, zinc, sodium, phosphorous, potassium, and vitamins B1, B9, B12, A, C, D, and E with pregnancy requirements per the dietary reference intakes (DRIs) for the European and American DRI for pregnant women and Spanish general population, where intake levels above DRI implied a lower probability of inadequate micro and macronutrient intake.

Finally, the team used multivariate linear regression models to assess the variations in nutritional intake below the DRIs between study groups while controlling for confounding factors.

Results

The final study sample had 1,356 pregnant women whose MedDiet adherence scores, FFQ scores, and total energy intake data were available.

In the group with low MedDiet adherence scores, the maternal age was lower, the number of Latin pregnant women was higher, and there were more smokers; in addition, these women had a higher waist circumference at enrollment and higher weight and BMI throughout gestation. 

Conversely, in the group with high MedDiet adherence scores, white females were more, and women had attained a higher education. They consumed more protein, fat, and fiber and fewer carbohydrates.

Among the low and high adherence groups, vitamin A and B12 intake were comparable, but vitamins B1, B9, C, D, and E varied.

Thus, among participants with an intake of macro and micronutrients below 2/3 DRIs, the authors noted an insufficient vitamin D, B9, iron, and calcium intake in 82.3%, 12.3%, 52.6%, and 13% of participants, respectively.

Likewise, the authors profiled these two groups for fatty acid intake and observed significant differences for all FA items.

The participants with higher adherence to the MedDiet had adequate EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), two FAs essential for fetal growth, especially of the brain and eyes.

Notably, EVOO in MedDiet supplemented mono- and polyunsaturated fatty acids (MUFAs and PUFAs) as oleic, α-linolenic, and linoleic acids. 

Conclusions

According to the authors, this is the first study directly assessing whether adherence to the healthy MedDiet was associated with sufficient micronutrient (and overall nutrient) intake per DRIs specified for pregnancy.

They noted a direct association between nutritional status and adherence to a pregnancy-adapted MedDiet. 

Even though it is an easy-to-follow diet, some nutrient requirements are challenging to meet only with the MedDiet diet, including in high-income countries. Thus, many pregnant females in the study cohort were deficient in multiple micronutrients, especially vitamin D and B9, iron, and calcium.

However, high adherence to the MedDiet lowered the proportion of participants with micronutrient intake below DRIs (without supplementation) for iron, calcium, folic acid, magnesium, and vitamin C.

These associations remained significant even after adjusting for potential confounders, such as age, educational level, and pre-conceptional BMI, to name a few.

To conclude, pregnancy-adapted MedDiet should be promoted as a cost-effective public health strategy in one-to-one nutritional counseling given to expecting women.

With minimal or no financial cost, it could help avoid multiple pregnancy-related challenges, such as maternal weight gain, nutrient deficiencies, and other complications.