Mediterranean Diet During Pregnancy Associated with Improved Maternal Health Outcomes
Tree nuts, predominately walnuts, and extra virgin olive oil featured as key foods in a new clinical trial that assessed the impact of a Mediterranean diet on maternal and fetal outcomes
A new clinical trial found women who followed a Mediterranean-style diet during pregnancy, including a daily portion of tree nuts (half being walnuts) and extra virgin olive oil, had a 35% lower risk of gestational diabetes and on average, gained 1.25kg less, compared to women who received standard prenatal care.1
A Mediterranean-style diet rich in good, unsaturated fats, found in foods like walnuts and extra virgin olive oil, has been shown to reduce the risk of heart attack, stroke, and cardiovascular death in adults, according to a 2018 landmark PREDIMED study. Walnuts, in particular, are a traditional food in the Mediterranean diet because of their omega-3 ALA content (2.7g/ 30g) – the only nut significantly high in this essential fatty acid) and bioactive compounds. While there has been extensive research on the Mediterranean diet to date, the diet’s potential to improve maternal and offspring outcomes has not been widely evaluated, making this study particularly valuable.
Conducted by researchers at Queen Mary University of London and the University of Warwick, a new study included 1,252 multi-ethnic inner-city pregnant women with metabolic risk factors, including obesity and chronic hypertension. In addition to receiving folic acid and vitamin D supplementation, the women were randomly assigned to either a Mediterranean-style diet or a control group that received dietary advice per UK national recommendations for prenatal care and weight management during pregnancy.
Those who followed the Mediterranean diet consumed a daily portion of nuts (30g/day; 15g walnuts, 7.5g almonds, 7.5g hazelnuts) and used extra virgin olive oil (0.5L/week) as their main source of cooking fat. In addition, the diet emphasised fruit, vegetables, non-refined grains and legumes; moderate to high consumption of fish; small to moderate intake of poultry and dairy products; low intake of red meat and processed meat; and avoidance of sugary drinks, fast food, and food rich in animal-based fat.
Participants received dietary advice at 18, 20, and 28 weeks’ gestation to help improve compliance and make sure the diet was made culturally sensitive. Investigators measured dietary compliance using self-reported feedback from the participants, so it’s important to note that there could have been human error in the reporting.
The investigators also assessed the effect of a Mediterranean diet on other pregnancy complications such as high blood pressure, pre-eclampsia, stillbirth, small for gestational age fetus, or admission to a neonatal care unit, but did not find any significant associations.
One in four mothers enter pregnancy with pre-existing obesity, chronic hypertension or raised lipid levels, which can lead to pregnancy complications, long-term risk of diabetes and cardiovascular complications for mothers and their children.2,3,4 These findings provide additional support for following a Mediterranean-style diet which has been linked to additional health benefits such as improved cognitive function.
The California Walnut Commission (CWC) provided walnuts for this research. The CWC has supported health-related research on walnuts for more than 25 years with the intent to provide knowledge and understanding of the unique health benefits associated with consuming walnuts. While the CWC does provide funds and/or walnuts for various projects, all studies are conducted independently by researchers who design the experiments, interpret the results and present evidence-based conclusions. The CWC is committed to scientific integrity of industry-funded research.
1 H. Al Wattar B, Dodds J, Placzek A, Beresford L, Spyreli E, Moore A, et al. (2019) Mediterranean-style diet in pregnant women with metabolic risk factors (ESTEEM): A pragmatic multicentre randomised trial. PLoS Med 16(7): e1002857. https://doi.org/10.1371/journal.pmed.1002857
2 Galtier-Dereure F, Boegner C, Bringer J. Obesity and pregnancy: complications and cost. Am J Clin Nutr. 2000;71(5):1242s–1248s.
4 Osterman MJK, Martin JA, Curtin SC, et al. Newly released data from the revised U.S. birth certificate, 2011. National Vital Statistics Report 62(4), 2013. Hyattsville, MD: National Center for Health Statistics.