Breastfeeding can promote lower blood pressure among children, a new study says.

Longer-term breastfeeding appears to populate a baby’s gut with diverse bacteria that could help lower blood pressure, researchers found.

Children who were breastfed for at least six months had lower blood pressure at age 6, researchers report in the Journal of the American Heart Association.

“Our findings suggest a potential significance of early-life gut microbiota on cardiovascular health in early childhood,” concluded the research team led by senior investigator Noel Mueller, an associate professor of epidemiology with the University of Colorado Anschutz Medical Campus.

For the study, researchers reviewed data on 526 children enrolled in a Danish study of childhood asthma.

As part of the study, stool samples were collected from each child at 1 week, 1 month and 1 year of age. These samples were analyzed to determine the content of their gut bacteria.

The study also checked the children’s blood pressure at 3 and 6 years of age.

Researchers found that children with more diverse gut bacteria at 1 month had lower blood pressure at age 6.

The blood pressure-lowering effect of diverse gut bacteria was further amplified among children who were breastfed for at least six months, results show.

Children with highly diverse gut bacteria had systolic blood pressure about two points lower than average at age 6 if they had been breastfed at least six months, compared to those not breastfed, researchers said. (Systolic measures the pressure inside blood vessels during a heartbeat; it's the upper number in a blood pressure reading.)

Researchers pointed to several potential reasons why gut bacteria could improve blood pressure, particularly among breastfed children.

Certain gut bacteria have evolved to help babies more easily digest breast milk, researchers noted.

But if these bacteria don’t have breast milk to break down, they might instead feed on the lining of a baby’s gut, researchers said. This could result in “leaky gut,” a condition in which bacteria and fat enter the bloodstream.

Leaky gut has been linked to increased blood pressure and inflammation in adults, researchers noted.

“This finding holds significance for public health, given the established pattern of blood pressure tracking from childhood into adulthood and its long-term health implications,” researchers concluded.

“Our study also reinforces the importance of promoting breastfeeding through infancy, not only for optimal gut microbiota development but also for better cardiovascular health across the life course,” they added.