Breastfeeding for six months may spur beneficial gut bacteria linked to lower childhood blood pressure

Nursing for at least six months may spur beneficial gut bacteria connected to better heart health years later.

An observational study supported by the National Institutes of Health (NIH) found that infants who had more diverse bacteria in their gut had lower childhood blood pressure, and this protective association was stronger if they were breastfed for at least six months. The findings published in the Journal of the American Heart Association.

For the research, investigators reviewed data from 526 children enrolled in a prospective study in Denmark. They looked for connections between infant gut bacteria, which can be influenced by nutrition and supports a variety of health functions, and childhood blood pressure. To assess this, they collected fecal samples to analyze bacteria in the infants' intestines during their first week, month, and year of life. Three and six years later, they measured the children's blood pressure.

The researchers found children with more diverse gut bacteria at one month had lower blood pressure six years later. They then assessed the influence of breastfeeding, which was measured in this study for durations of at least six months. They discovered that among children breastfed for at least six months, the blood-pressure lowering effect of having more diverse bacteria in their gut was even stronger. Specifically, those with a greater diversity of gut bacteria throughout the first month of life had systolic blood pressure that was about 2 mm Hg lower six years later if they were breastfed for at least six months.

Researchers believe there may be several reasons for these associations. Certain gut bacteria have evolved specialized biologic machinery that allows them to convert otherwise indigestible carbohydrates in breast milk into calories and substances that can be used by the body. Specific Bifidobacterium species, including B. infantis, are superstars when it comes to breaking down these carbohydrates and turning them into short-chain fatty acids that may influence blood pressure and support cardiovascular health.

In infants who are not breastfed, bacteria that do not have breast milk carbohydrates to feed on may instead break down carbohydrates that line the intestines. This could result in a condition called a "leaky gut," where bacteria and fat could enter the bloodstream. A leaky gut has been linked to inflammation and increased blood pressure in adults.

Additionally, the researchers found that some types of bacteria, including H. pylori, were present in some infants and these bacteria were linked to increased blood pressure years later. H. pylori, which can be passed from a mother to child, can create persistent levels of low inflammation and may influence a "leaky gut."

To make participants in the study as comparable as possible, the researchers accounted for a mother's medical history, their diet during pregnancy, pregnancy complications, when and how a child was born, and how long they were breastfed.

About 4% to 7% of children worldwide have high blood pressure, which can start when the fetus develops in the womb. These rates have doubled since 2020, which is why researchers are studying factors that may offset these risks and improve cardiovascular health.

The study was supported by the National Heart, Lung, and Blood Institute (NHLBI) grant K01HL141589.