Mediterranean diet may prevent gestational diabetes, weight gain
A Mediterranean-style diet may reduce the risk of gestational diabetes and weight gain in pregnant women with metabolic risk factors, but not the overall risk of maternal and offspring adverse outcomes, according to the ESTEEM* trial.
The researchers conducted a multicentre trial involving 1,252 pregnant women (<18 weeks gestation) with metabolic risk factors ie, obesity (BMI ≥30 kg/m2), chronic hypertension (≥140 mm Hg for systolic BP or ≥90 mm Hg for diastolic BP), and raised serum triglycerides (≥1.7 mmol/L). The participants were randomized to receive either the Mediterranean diet supplemented with mixed nuts 30 g/day (eg, walnuts, hazelnuts, and almonds) and extra virgin olive oil 0.5 L/week (intervention arm, n=627) or routine antenatal care (control arm, n=625). Food Frequency Questionnaire (FFQ) and modified short questionnaire (ESTEEM Q) were used to assess the dietary intake of women at 18, 20, and 28 weeks of gestation. [PLoS Med 2019;16:e1002857]
After adjusting for potential confounders, women who received the Mediterranean diet had a significantly lower risk of gestational diabetes compared with those in the control group (17.6 percent vs 24.9 percent, adjusted odds ratio [adjOR], 0.65, 95 percent confidence interval [CI], 0.47–0.91; p=0.01).
Women in the intervention arm also had significantly less gestational weight gain than those in the control arm (mean, 6.8 vs 8.3 kg, adjusted difference, -1.2 kg, 95 percent CI, -2.2 to -0.2; p=0.03).
However, there was no significant difference between the intervention and control groups in the overall incidence of a composite of maternal (22.8 percent vs 28.6 percent, adjOR, 0.76, 95 percent CI, 0.56–1.03; p=0.08) or a composite of offspring outcomes (17.3 percent vs 20.9 percent, adjOR, 0.79, 95 percent CI, 0.58–1.08; p=0.14).
The intervention also had no significant effect on the occurrence of pre-eclampsia (6.2 percent vs 4.6 percent, adjOR, 1.43, 95 percent CI, 0.84–2.43; p=0.19) or the individual components of the composite offspring outcomes, such as small-for-gestational age (9.8 percent vs 12.2 percent, adjOR, 0.78, 95 percent CI, 0.53–1.15; p=0.21), stillbirth (0.2 percent vs 0.4 percent, adjOR, 0.49, 95 percent CI, 0.04–5.57; p=0.56), and neonatal unit admission (adjOR, 0.79, 95 percent CI, 0.53–1.18; p=0.25).
“Overall, the [Mediterranean-style diet] intervention [in pregnancy] did not significantly reduce the composite maternal and offspring outcomes; still, it had an apparent protective effect to reduce the incidence of gestational diabetes and gestational weight gain,” said the researchers.
A previous study showed that the beneficial effects of a Mediterranean diet on gestational diabetes was mediated through the high intake of dietary polyphenols, such as mixed nuts and extra virgin olive oil, “by reducing insulin resistance, stimulating insulin secretion, activating insulin receptors, modulating glucose release, and increasing the uptake of glucose in the insulin-sensitive tissues,” noted the researchers. [Oxid Med Cell Longev 2017;2017:6723931]
“In [this study,] women randomized to the intervention [had] an increased intake of not only nuts and olive oil but also changes in the consumption of other key components of Mediterranean-style diet such as increased intake of fish, preferential intake of chicken and turkey over veal and sausages, and reduced consumption of red meat and butter compared with the control group,” the researchers added.
The results of the present and previous studies have shown that the intake of mixed nuts and extra virgin olive oil can help to reduce the risk of gestational diabetes and weight gain and “delivering such dietary intervention is feasible as part of routine antenatal care,” they said.
Future trials could assess the impact of an extra virgin olive oil- and nut-based diet during pregnancy on childhood obesity, allergy, and asthma, they suggested.
*ESTEEM: Effect of Simple, Targeted Diet in Pregnant Women with Metabolic Risk Factors on Pregnancy Outcomes