Mediterranean diet cuts preeclampsia risk by 22%, with greater benefit for Black mothers
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Women who self-reported higher adherence to a Mediterranean-style diet were up to 26% less likely to develop preeclampsia compared with women reporting lower adherence to the eating plan, with a stronger benefit observed for Black mothers.
In an analysis of a racially and ethnically diverse cohort, the association persisted after adjusting for factors including maternal age, race, education, parity and prepregnancy obesity.
“Maternal mortality and maternal morbidity in the United States is higher than what is expected in other nations of our economic level and it is not clear why,” Anum Minhas, MD, MHS, chief cardiology fellow at Johns Hopkins Heart and Vascular Institute, told Healio. “Preeclampsia increases long-term risk for CVD. We are appreciating more that the same women who have preeclampsia go on to develop HF and coronary disease later in life. We wanted to study what we could do that would be safe in pregnancy.”
Multiple studies have demonstrated a benefit of the Mediterranean diet, characterized primarily by high intake of vegetables, fruits and healthy fats, in reducing CVD risk in the nonpregnant population, according to Noel T. Mueller, PhD, MPH, FAHA, associate professor of epidemiology at the Welch Center for Prevention, Epidemiology and Clinical Research of the Johns Hopkins Bloomberg School of Public Health. A previous study also demonstrated that in pregnant women, greater adherence to a Mediterranean-style diet was associated with reduced risks for preterm birth and low birth weight.
“Preeclampsia is one condition that is very difficult to prevent; there are very few modifiable risk factors,” Mueller told Healio. “We wanted to understand whether there were lifestyle factors and, in particular, dietary adherence that could help prevent preeclampsia. Translation is key to a lot of the research we do.”
Boston Birth Cohort data
Minhas, Mueller and colleagues analyzed data from 8,507 women participating in the Boston Birth Cohort (1998-2016), which recruited pregnant women from Boston Medical Center, the largest safety net hospital in Boston (47% Black; 28% Hispanic). Researchers obtained maternal sociodemographic and dietary data via interview and food frequency questionnaire within 24 to 72 hours postpartum, respectively.
“The PREDIMED study from Spain previously showed there was strong evidence for the Mediterranean reducing CVD in adults,” Mueller said in an interview. “Mediterranean diet is also similar to the DASH (Dietary Approaches to Stop Hypertension) diet, which has also been shown to reduce BP consistently. However, these dietary patterns had not been previously rigorously examined in a diverse population of women to see if they could protect women from developing preeclampsia.”
For the final diet score, each food group was added on the basis of the reported intake with a score assigned from 0 to 4. The final Mediterranean-style diet score was divided into tertiles for analysis, with the third tertile (score, 27-38) representing the highest adherence to Mediterranean-style diet and the first tertile (score, 4-23) corresponding to the lowest. Additional clinical information, including physician diagnoses of preexisting conditions and preeclampsia, was extracted from medical records. The researchers derived a Mediterranean-style diet score from the food frequency questionnaire and examined the association of the Mediterranean-style diet score with any form of preeclampsia, including mild or severe preeclampsia, eclampsia or HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome.
The findings were published in the Journal of the American Heart Association.
Within the cohort, 10% of women developed preeclampsia. Women in the highest tertile of Mediterranean-style diet score were older, were more likely to be parous, had lower prepregnancy obesity and diabetes, were more likely to be married and were less likely to have a college education.
Researchers found the greatest adherence with a Mediterranean-style diet (highest tertile) was associated with 22% lower risk for developing preeclampsia compared with women in the lowest tertile (adjusted OR = 0.78; 95% CI, 0.64-0.96).
“This means the women in the top third of following a Mediterranean-style diet had a 20% to 25% lower risk for preeclampsia compared with women in the lowest tertile; that is much better than many medications,” Minhas said. “These findings are striking because there are no preventive therapies approved for preeclampsia except aspirin. If we can get this much benefit through a dietary intervention and, in particular, from a diet we already know is healthy for most people for CV benefit, that is great.”
Greater benefit for Black mothers
Additionally, in analyses stratified by race, the association was stronger for Black mothers, who had a 26% lower risk for developing preeclampsia with high adherence to a Mediterranean-style diet compared with women reporting low adherence (aOR = 0.74; 95% CI, 0.76-0.96). In the same analyses, a 1-standard deviation increment in Mediterranean-style diet score for Black women was associated with 15-fold odds for preeclampsia.
“Looking at the joint association of Mediterranean-style diet score and Black race with preeclampsia, we found that Black women in the lowest tertile had the highest adjusted odds (1.72; 95% CI, 1.16–2.55) for preeclampsia compared with non-Black women in the highest tertile,” the researchers wrote.
“In the U.S., Black women are at highest risk for developing preeclampsia,” Minhas said. “When we looked at Black vs. non-Black women, it is remarkable that in the highest risk group, there is potentially a benefit with a dietary intervention.”
‘Keeping the message simple’
The researchers noted that a Mediterranean-style diet may contribute to improved placental vascular function in the setting of pregnancy, through improved endothelial function. Adherence to a Mediterranean diet has also been shown to result in a unique metabolic signature, which has been predictive of reduced CVD risk.
Minhas said it is important clinicians get a good pregnancy history before addressing nutrition or physical activity with patients.
“This is particularly applicable for non-OB/GYN’s, internists or even cardiologists if we see a pregnant woman: Ask about her diet and physical activity,” Minhas said. “Those are very small things where we can encourage our patients to live a healthy lifestyle.”
Additionally, Minhas said societal interventions — addressing food insecurity and so-called food deserts — can help underserved women who could benefit the most from a Mediterranean-style diet gain access to healthy foods.
“Making sure this type of information gets out there to the patients and providers is key, but then the second level must be at a state and federal advocacy level,” Minhas said.
Mueller agreed.
“Sometimes people can get confused by different dietary messages, but it is clear that a Mediterranean-like diet or a DASH-like diet is beneficial across the board for adults,” Mueller said. “If there are slight modifications one needs to make, that is fine. But in general, a diet rich in fruits and vegetables, whole grains, low in processed foods, saturated fats and red meat is beneficial for CV health and pregnancy complications. If you are a clinician, keeping the message simple is helpful.”
For more information:
Anum Minhas, MD, MHS, can be reached at aminhas2@jhmi.edu.
Noel T. Mueller, PhD, MPH, FAHA, can be reached at noeltmueller@jhu.edu.
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