Could fruit and vegetables, legumes and whole grains reduce the risk of hypertension linked to gestational diabetes?
The study, published in Hypertension, was conducted by Dr. Cuilin Zhang, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Rockville, MD, and colleagues.
"Our current study shows that a healthy diet, which has been proven to reduce high blood pressure risk in the general population, appears to be equally effective in reducing the risk in this group of high-risk women."
Gestational diabetes is a common health problem for pregnant women, affecting around 5% of all pregnancies. During pregnancy, the placenta produces a number of hormones that can prevent insulin from working properly, leading to high blood sugar levels.
After birth and the delivery of the placenta, gestational diabetes usually goes away. However, gestational diabetes can have long-term effects; the condition increases the risk of type 2 diabetes later in life, as well as high blood pressure - also known as hypertension.
For the study, Dr. Zhang and her colleagues followed 3,818 women with a history of gestational diabetes who were participating in the Nurses' Health Study II. The women were followed for over 22 years and completed a questionnaire about their eating habits every 4 years.
During the study period, 1,069 of the participants developed hypertension. The researchers found that the women who followed a healthy diet were 20% less likely to develop hypertension than those who did not follow a healthy diet.
The researchers identified three healthy diets for the study: the alternative Mediterranean diet, the Alternative Healthy Eating Index and the Dietary Approaches to Stop Hypertension (DASH).
Each of these healthy diets involved eating large amounts of fruits and vegetables, legumes, whole grains and fish. They also involved only small amounts of red meat, processed meat and salt.
Hypertension risk reduction should 'serve as an early warning signal'
The higher risk of hypertension associated with less healthy diets could partly be explained by weight gain. However, the researchers found that only 20-30% of this association could be explained in this way.
- Hypertension is often caused by lifestyle factors such as physical inactivity
- If left untreated, hypertension increases the risk of aneurysm and heart failure.
Following a healthy diet appeared to reduce the risk of hypertension regardless of any changes in weight.
The researchers also adjusted their results for other factors that could have influenced the results, including smoking, ethnicity and family history of hypertension.
Participants who followed healthy diets were less likely to smoke and consume trans fats and more likely to eat a large amount of cereal fiber, exercise regularly and be moderate drinkers of alcohol.
"While the majority of these women's glucose levels will return to normal after delivery, our study should serve as an early warning signal," Dr. Zhang concludes.
Treatment plans for gestational diabetes typically include following a healthy diet alongside exercising regularly and monitoring blood sugar levels. Dr. Zhang adds that health care providers should encourage women to continue with these lifestyle alterations after pregnancy.
One limitation of the study is that the participants of the Nurses' Health Study II are predominantly white, and so the findings may not extend to the wider population.
First co-author Dr. Shanshan Li suggests that future research should examine the links between gestational diabetes, hypertension and diet in minority populations such as Hispanic and African-American women, as these groups have a higher risk of developing hypertension.
Recently, Medical News Today reported on a study that found the babies of women who are both obese and develop gestational diabetes are significantly more likely to be excessively large by 6 months of pregnancy.