Certain fats commonly used in infant formulas may contribute to the development of steatotic liver disease – formerly known as non-alcoholic fatty liver disease – in infants, according to a new study led by researchers at Virginia Tech. The research, published in the American Journal of Physiology-Endocrinology and Metabolism, found that newborn pigs fed formulas containing specific medium-chain fats accumulated liver fat at a faster rate than those fed formulas with long-chain fats, despite receiving identical calorie and protein intake.
The study challenges conventional understanding of how liver disease develops, particularly in infants. While in adults, fatty liver typically arises from a slowing of fat burning, researchers observed that in the developing livers of the pigs, fat accumulated even as fat burning increased. “We saw the liver activate both fat-making and fat-burning pathways at the same time,” explained Associate Professor Samer El-Kadi of Virginia Tech’s School of Animal Sciences, who led the research team. “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.”
Steatotic liver disease, increasingly diagnosed in children and even infants, was once considered primarily a condition affecting obese adults. This rise in pediatric cases has prompted investigation into the role of early nutrition in liver health. To explore this connection, El-Kadi’s team utilized a neonatal pig model, chosen for its similarities to human infant digestion and fat metabolism. The researchers tested two simplified formulas, differing only in their fat composition: one enriched with medium-chain fatty acids (primarily from coconut oil), and the other with long-chain fatty acids derived from animal fats.
Within seven days of feeding, pigs consuming the medium-chain fat formula began to show signs of fat buildup in their livers. By two weeks, the condition had progressed to a more severe inflammatory stage, according to the study. The medium-chain fats are a common ingredient in many infant formulas, used to mimic the fat composition of breast milk.
El-Kadi emphasized that the study is not intended to discourage the use of infant formula, stating that breast milk remains the “gold standard” for infant nutrition and that formula is a critical alternative when breastfeeding is not possible. “When our own child needed supplemental nutrition, we used formula—no questions asked,” he said. “The immediate benefits of feeding far outweigh any potential long-term risks. Our goal is not to discourage formula use. It’s to understand how different components of formula affect the developing body, so they can be improved over time.”
The research coincides with a broader reevaluation of infant formula composition by the U.S. Department of Health and Human Services and the Food and Drug Administration through the Operation Stork Speed initiative. This initiative aims to encourage research to enhance the safety and nutritional quality of infant formulas. El-Kadi’s team is continuing to investigate the effects of specific fatty acids on liver metabolism in early life, including examining whether different types of medium-chain fatty acids have varying impacts and optimal quantities.
The study was conducted in collaboration with researchers from the University of Maryland. El-Kadi indicated that further research is planned to refine understanding of the complex interplay between early nutrition and liver development.