DHA supplementation during pregnancy may prevent high blood pressure in early childhood

26 Feb 2019 --- Daily supplementation of 600mg of DHA omega 3 fatty acid during pregnancy can help prevent the development of high blood pressure in obese or overweight offspring in early childhood. This is according to research from the University of Kansas (KU) and the KU Medical Center, published in JAMA Network. The researchers seek to further explore the way “developmental programming” – how prenatal environment impacts a fetus’ metabolism – works in preventing disease, such as obesity, later in life.

“This research is aimed at expectant mothers and pediatricians who wonder what you can do prior to the birth of your child to optimize health and behavior outcomes,” says co-author John Colombo, KU Professor of Psychology, Director of KU’s Life Span Institute and currently KU’s Interim Vice Chancellor for Research.

The importance of fatty acids is well known, with many foods already fortified with DHA, such as eggs, and an abundance of supplements that tout high fatty acid concentration. However, the researchers note that the amount needed is much higher than what is already included in supplements.

“There are already many prenatal supplements that contain DHA. However, most contain half dose used in this study,” Susan Carlson, co-author and AJ Rice Professor of Nutrition in the KU Department of Dietetics and Nutrition tells NutritionInsight.

“There are also several food products with added DHA, however, it is important to pay attention to the label to know how much DHA some of these formulated products provide,” she notes.

The new study followed 171 women with low-risk pregnancies from the Kansas City area who signed up at the KU Medical Center's Maternal and Child Nutrition and Development Lab between March 2006 and September 2009. Half of the women were randomly assigned a prenatal supplement of 600mg of DHA to be received daily and half were given a placebo. The primary outcomes of the intervention were pregnancy outcome and child development through age six. The secondary outcome was blood pressure that was measured longitudinally at different ages in 171 children.

The main finding showed that being overweight or obese came with a high blood pressure in the 82 children whose mothers received the placebo, but not to the 89 children whose mothers received the DHA supplement. “Maternal DHA intake during pregnancy appeared to mitigate the association between childhood overweight condition or obesity and blood pressure,” the research says. 

Obese and overweight children of mothers in the placebo group had a large mean increase of 3.94mm Hg for systolic BP (blood pressure) and 4.97mm Hg for diastolic BP compared with overweight/obese children of DHA-supplemented mothers. These differences were statistically significant, according to the researchers.

Credit: KU News Service  University of KansasHow much DHA is needed?
While the researchers stress that the optimal amount of DHA needed is still unknown, they also note that the DHA supplements available in the US contain much less than 600mg of the fatty acid.

“We do not know the optimal amount [of DHA supplementation] to have this favorable effect on blood pressure, however, there is evidence that maternal DHA can also reduce birth before 34 weeks gestation; and our results show that benefit continued to accrue all the way up to 600 mg/day,” Carlson says.

“There is one study that shows that supplementation for the first four months of life resulted in lower BP at age six. We suspect there is a critical window in development but we don’t know what that window is,” she adds.

Several studies have shown that DHA levels in pregnant women can be low which may cause complications such as preterm birth. Researchers previously identified that a DHA target blood level of 5 percent or higher may reduce the risk of preterm birth significantly.

“Many American children have serious weight issues (overweight and obesity). What the study shows is that if they become overweight or obese for any of a multitude of reasons that [via DHA supplementation during pregnancy] they are protected against the increase in blood pressure that is associated with overweight and obesity,” she notes.

Despite the possible benefits of DHA supplementation, BDA dietician and spokesperson Aisling Pigott tells NutritionInsight that the role of nutrition is also significant and natural sources of fatty acids should not be overlooked. 

“The study has looked simply at a high dose supplement. We know from other research that regular consumption of oily fish has multiple health benefits. Plus, there will be additional nutrients in a food source. At the moment, we would suggest food can be enough to maximize benefit,” she stresses.

Developmental programming against high blood pressure
Overweight and obesity are large problems among US children with nearly one in five school-age children and young people aged 6 to 19 years being obese, according to the US Centers for Disease Control 2015-16 data.

“There's a phenomenon called ‘developmental programming’ and researchers have studied the effects of the prenatal environment on long-term outcomes since World War II. The prenatal environment programs a fetus’ metabolism for what to expect in the postnatal environment. Part of DHA's known effects may be in programming cardiac function that preserves normal blood pressure in the case of high postnatal weight gain,” says Colombo.

“Prenatal DHA exposure appears to program the developing fetus to be protected against the blood pressure-elevating effects of obesity in childhood,” adds Carlson

The authors believe that lower blood pressure at age six might extend beyond childhood. “It is known that blood pressure tracks over time such that people with higher BP early in life are more likely to have higher BP later in life,” Carlson says.

Next in research
The study and phase 3 clinical trial were supported by the US National Institutes of Health (NIH) and the researchers are currently conducting more research to determine the effects of DHA supplementation.

“We have just completed assessments of BP at seven, eight and nine years of age in the children in our recent report, so we will be able to determine if the finding persists out to these ages. It would be nice to know how DHA is programming the protection we observed, however, those studies cannot be done in humans,” says Carlson 

“From the work of others, we already suspect that maternal DHA intake protects the developing autonomic nervous system and reduces stress in mom and baby. These are definitely areas that could and are being explored further in human pregnancy trials funded by the US National Institute of Child Health and Human Development (NICHD),” she concludes.

By Kristiana Lalou