NIH grants US$1.7M for nitrogen and human milk research

02 Sep 2021 --- The National Institutes of Health (NIH) has awarded a nutritional scientist a US$1.69 million grant to investigate how beneficial microbes in the gut use nitrogen in human milk to support pediatric nutrition and development. 

The new experiments may also yield molecular targets to improve nitrogen metabolism efficiency through the microbiome in infants, and possibly adults. With sufficient evidence, this could support grounds to develop new probiotic supplements for maternal and infant nutrition. 

Lead researcher David Sela, associate professor at the department of food science at the University of Massachusetts Amherst, US, is the recipient of the five-year grant to pursue this research.

Previous research established that the nutrients and bioactives in human milk were transferred directly to the nursing infant in a linear manner. 

“Now there is considerable evidence that human milk directs early establishment of the microbiome through molecules, such as oligosaccharides, that modulate specific microbial populations to impact infant health and wellness,” Sela explains.

David Sela, assistant professor of the food science department at UMass Amherst.Understanding urea 
Sela and his research team study Bifidobacterium infantis, which colonizes babies’ guts. 

“This particular microbe has a close relationship with the infant. It utilizes mother’s milk products, including those that the babies don’t digest but would otherwise pass through their body,” Sela says.

In June, a study from Evolve revealed that a B. infantis strain can help shape babies’ immunity via human milk oligosaccharide metabolism. The probiotic’s health benefits also range from targeting intestinal disease to Type 2 diabetes and iron deficiency anemia.

Sela’s early work identified that some of the microbe’s genes are related to urea hydrolysis, which is a waste product in humans that is passed out when urinating. 

“Why do we see so much urea in breast milk?” questions Sela. “We put two and two together, and I came up with a hypothesis that this microbe actually has another connection with human milk: it’s utilizing this waste product as a nitrogen source.”

Salvaging urea nitrogen is known to be important in ruminant animals. A study from 2007 explains that urea from the bloodstream can pass into the gastrointestinal tract, where bacteria expressing urease cleave urea into ammonia and carbon dioxide. 

The bacteria utilize the ammonia as an nitrogen source, producing amino acids and peptides necessary for growth. 

Sela highlights it could therefore be a key feature of the interactions between the infant and microbiome. “It may be of critical importance to infants in general or in certain nutritional contexts,” he puts forward.

There is “considerable evidence” that human milk directs early establishment of the microbiome through molecules, says Sela. Probiotics in the bigger picture
Sela’s latest research will feature experiments to understand both the details of these research questions and the bigger picture.

“We want to have an understanding of the system by which nitrogen and metabolism is intertwined between mom’s diet, mom’s breast milk and the infant’s needs, as well as how the microbes contribute to infant nitrogen metabolism,” Sela states. 

“We want to mechanistically characterize what is going on within the microbes themselves. We’re trying to reduce the system into its components and then paint the larger picture once we understand the smaller aspects of it.”

Should the researchers show sufficient evidence that urea nitrogen salvaging is important to infant development, they will begin focusing on potential nutritional supplements for mother or infant, including probiotics. 

“These are the open questions that we’re hoping to solve in the next few years,” adds Sela.

Other research strides are already demonstrating probiotics’ potential in infant nutrition. Just this week, Swedish probiotic company Probi reported two of its probiotic strains are well tolerated in newborns’ gut microbiomes. 

Indeed, infant nutrition is expanding far beyond formula, with offerings like probiotic drops and powders coming to the fore.

Edited by Anni Schleicher