Certain fats used in some infant formulas may strain the developing liver and contribute to early signs of steatotic liver disease, according to a new study led by researchers in Virginia Tech’s College of Agriculture and Life Sciences.
In the study, published in the American Journal of Physiology-Endocrinology and Metabolism, newborn pigs fed formulas with specific medium-chain fats accumulated liver fat faster than pigs fed formulas with long-chain fats, despite receiving the same calories and protein.
The researchers also found that steatotic liver disease develops differently in early life than it does in adults. In adults, fat builds up when the liver slows down its fat burning. In the developing liver, however, they observed that fat accumulated even as fat burning increased.
Steatotic liver disease, formerly known as non-alcoholic fatty liver disease, happens when excess fat builds up in the liver. Once considered a condition affecting adults with obesity, it is increasingly being diagnosed in children and also has been identified in some infants, raising questions about how early nutrition may influence liver health.
To explore that connection, the research team, led by Associate Professor Samer El-Kadi of the School of Animal Sciences, used a neonatal pig model to study how different fats commonly used in infant formulas affect liver metabolism during early development.
Two fats with surprisingly different effects
Infant formulas are designed to provide complete nutrition and typically use blends of plant-based oils to approximate the fat composition of breast milk. Newborn pigs are widely used in nutrition research because their digestion and fat metabolism are similar to those of human infants.
To understand how individual fats affect the developing liver, the researchers tested two simplified formulas that differed only in fat type. One was rich in medium-chain fatty acids derived primarily from coconut oil, a common fat source used in some infant formulas. The other was rich in long-chain fatty acids derived from animal fat, which more closely resembles the natural fat composition of whole sow milk.
Pigs fed the medium-chain fat formula accumulated liver fat more rapidly than pigs fed the long-chain fat formula, despite receiving the same amount of calories and protein.
“Even within seven days, we could see fat starting to build up in the liver,” El-Kadi said. “By about two weeks, it had progressed from simple steatosis to a more severe inflammatory form of the disease.”
Under normal circumstances, increased fat burning would be expected to protect the liver from fat buildup. In this study, however, the opposite occurred.
“We saw the liver activate both fat-making and fat-burning pathways at the same time,” El-Kadi said. “Even with those adaptive responses, the developing liver became overwhelmed. That was surprising to us. Based on what we know from adult disease, increased fat burning should have been protective.”
