Certain fats commonly used in some infant formulas may put stress on the developing liver and contribute to early signs of fatty liver disease, according to new research led by scientists at Virginia Tech.
In experiments, the team found that newborn pigs fed formulas containing specific medium‑chain fats accumulated liver fat more quickly than those given formulas containing long‑chain fats—even though both groups consumed the same calories and protein.
Early-Life Liver Disease May Develop Differently From Adult Disease
The researchers also discovered that steatotic liver disease—formerly known as non‑alcoholic fatty liver disease—behaves differently in early development than in adulthood. In adults, liver fat tends to build up when fat‑burning processes slow down. In the developing liver, however, fat accumulation occurred even as fat burning increased.
Steatotic liver disease occurs when excess fat builds up in the liver. Once considered an adult condition linked to obesity, it is being diagnosed more frequently in children and has even been documented in some infants, raising questions about how early nutrition influences liver health.
To investigate that connection, the researchers used a neonatal pig model to examine how fats commonly used in infant formulas affect liver metabolism during early development.
Two fat sources, two very different outcomes
Infant formulas typically rely on blends of plant‑based oils intended to approximate the fat composition of breast milk. Newborn pigs are a well-established model for infant digestion because their gastrointestinal and metabolic systems resemble those of human newborns.
To isolate the effects of fat type, researchers formulated two simplified diets that differed only in the kind of fat used. One formula was rich in medium-chain fatty acids primarily sourced from coconut oil, a common ingredient in some infant formulas. The second formula was rich in long-chain fatty acids derived from animal fat, which more closely mimics the natural composition of whole sow milk.
Pigs fed the medium‑chain fat formula showed faster and more pronounced liver fat accumulation than pigs fed long‑chain fats.
“Even within seven days, we could see fat starting to build up in the liver,” said paper author and animal scientist professor El‑Kadi in a statementSamer . “By about two weeks, it had progressed from simple steatosis to a more severe inflammatory form of the disease.”
Unexpectedly, the researchers found that the developing liver activated both fat‑making and fat‑burning pathways at the same time.
“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.”
What this means for infant nutrition
El‑Kadi stressed that the findings do not imply that parents should avoid infant formula. Breastfeeding is recommended as the nutritional gold standard, but formula remains essential when breastfeeding is not possible or sufficient.
“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 aligns with growing federal interest in formula composition. The Department of Health and Human Services and the Food and Drug Administration are reevaluating formula standards through the Operation Stork Speed initiative, which supports research aimed at improving formula safety and nutritional quality.
El‑Kadi’s team plans to continue examining how individual fatty acids shape liver metabolism, including whether different medium‑chain fats have distinct effects and how quantities influence those outcomes.
“If we understand how early nutrition shapes liver metabolism, that knowledge can eventually help guide better nutritional strategies,” he said.
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Reference
Yadav, R., Lima, M. R. M., McMillan, R. P., Sunny, N. E., & El-Kadi, S. W. (2026). Concurrent increase in fatty acid oxidation and fatty acid synthesis: A unique metabolic state in a pig model of pediatric steatotic liver disease. American Journal of Physiology-Endocrinology and Metabolism, 330(1). https://doi.org/10.1152/ajpendo.00299.2025
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