Fever, the Liver, and Brown Adipose Tissue in Newborn Babies and Young Children
According to studies a mild cold stimulus can promote brown fat activation in newborns. If a neonate is exposed to a mild cold stimulus on the first day of their lives, this can improve their body temperature adaptation response to subsequent cold events later on.
That being said though, hypothermia is a common cause of death in newborn babies. The uterus is warmer than other areas of the body so when a fetus is still inside the womb, it is kept very warm. After birth, a neonate is exposed to a much colder environment. In order to survive, newborn babies might shiver or use brown fat to produce a non-shivering thermogenesis.
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Newborn babies have about 10 times more brown adipose tissue than adults. Their bodies are made up of about 5% brown adipose cells. In contrast, adult humans have brown fat that comprises about 0.5% of their bodies. As children grow into adolescence, brown fat cells slowly regress. In babies, brown adipose tissue is found primarily in the upper back, neck, and shoulders. In adults, brown fat is found in the neck, chest cavity, along the spine, and in the kidneys, and adrenal glands. People who are thinner have a higher brown-fat percentage in their bodies than people who are overweight.Click here to subscribe to the Living Database now.
Fever in Newborn Baby, Thermogenesis, and Brown Fat
When newborn babies are exposed to cool ambient temperatures, their sympathetic (fight-or-flight) nervous system is activated. Cool ambient temperatures can more than double a baby’s resting metabolic rate through brown fat cell thermogenesis. Some scientists believe that exposure to normal room temperature naturally causes a newborn baby’s body to slowly warm-up through brown fat cell activation. This slow warming or thermogenesis by brown fat cells occurs through sympathetic nervous system activation that eventually causes the baby to wake up in order to be fed. In other words, scientists believe that brown adipose tissue causes cycles of heating and cooling in the body that help babies regulate sleeping and feeding cycles. This highlights the importance of brown adipose tissue in infant health.Babies cry to attract their mother’s attention and the baby’s desire to be fed happens in response to a dip in blood sugar levels due to stimulation of glucose utilization in the brown adipose cells. The end of a feeding happens in response to higher body temperature produced by brown fat cells in the infant’s body.
In human babies, adaptive internal heat production can come from one of 4 sources:
- Skeletal muscle and brown fat
- Shivering
- Non-shivering thermogenesis by brown fat
- Diet-induced thermogenesis by brown fat
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Fever, on the other hand, is a different type of heat production. Fever is an abnormal type of heat production. We’ve discussed changes that happen in the body during a fever. Insulin resistance, for example, is common during a fever. Children with insulin resistance caused by infection and fever typically lose their appetite to avoid taking in too many sugars. Red wine can be offered in very low doses to a child with a fever to stop iron sequestration and fat-soluble vitamin sequestration, a mechanism that we’ve discussed elsewhere. Low-dose red wine therapy can lower a fever in part through its ability to change the cellular dynamics in terms of insulin resistance and provoke cells to become insulin-sensitive again. Brown fat cells plays a role in insulin sensitivity as well as in some types of fever production. Indeed, brown fat cells contain iron which becomes functionally deficient during infection as the body tries to protect its stores of iron and prevent pathogens from gaining access to it.Bone morphogenic protein 8 / BMP-8 is associated with the brown fat tissue response in newborn babies which highlights a relationship between bone tissues and brown adipose tissue. BMP-8 is significantly altered by exposure to glucocorticoids like dexamethasone that are sometimes used to treat childhood illnesses. Dexamethasone and other glucocorticoid treatments damage bone tissues as well as brown adipose tissue through its impact on BMP-8.
There’s an important connection between brown fat cells and liver health that warrants attention in this discussion of fever in newborn babies and young children. The liver is one of the most important detoxifying organs in the body. The liver is also the organ that carries anger and certain forms of emotional trauma. The liver plays a vital role in blood sugar regulation and it plays a role in releasing fat-soluble vitamins that are necessary in order for the body to overcome infection. When the body has plenty of brown adipose tissue, the liver is typically healthy. A healthy liver, in turn, promotes a healthy mood-state, the ability to concentrate and learn new things, and it helps promote general physical health and the ability to overcome infection. When brown fat is present in a child’s body in adequate amounts and when the liver is also healthy (high brown fat stores are correlated with a healthy liver), children are more resistant to infection. While brown fat plays a major role in heat production and sometimes also in fever production, the liver also acts as a core body temperature regulator. Immune cells in the liver known as Kupffer cells produce Interleukin-12 / IL-12 that modulate heat production during an infection. Studies have shown that IL-12 secreted by liver-infiltrating macrophages can block the production of FGF21, a hormone that’s produced by the liver to regulate body heat production in brown fat. Essentially, macrophages in the liver regulate brown fat thermogenesis. In newborn babies and young children, there are a number of mechanisms of action in the body that can produce a fever. Brown fat and liver involvement in infection is just one mechanism of action that the body might use to increase heat production.
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Resources:
• Bienboire-Frosini, C. et al. (2023). The Role of Brown Adipose Tissue and Energy Metabolism in Mammalian Thermoregulation during the Perinatal Period. Retrieved April 20, 2026 from https://pmc.ncbi.nlm.nih.gov/articles/PMC10339909/
• Urisarri, A. et al. (2021). BMP8 and activated brown adipose tissue in human newborns. Retrieved April 20, 2026 from https://www.nature.com/articles/s41467-021-25456-z
• Himms-Hagen, J. (1995). Does thermoregulatory feeding occur in newborn infants? A novel view of the role of brown adipose tissue thermogenesis in control of food intake. Retrieved April 20, 2026 from https://pubmed.ncbi.nlm.nih.gov/8521153/
• Tews, D. & Wabitsch, M. (2022). Brown Adipose Tissue in Children and Its Metabolic Function. Retrieved April 20, 2026 from https://www.ovid.com/journals/hrin/fulltext/10.1159/000518353~brown-adipose-tissue-in-children-and-its-metabolic-function
• Kosa, J. P. et al. (2011). The protective role of bone morphogenetic protein-8 in the glucocorticoid-induced apoptosis on bone cells. Retrieved April 20, 2026 from https://www.sciencedirect.com/science/article/abs/pii/S8756328211000214#:~:text=BMP%2D8%2C%20(a%20novel,countries%20is%20taking%20oral%20GCs.
• No Author (2022). Hepatology: Immune cells in the liver regulate body temperature. Retrieved April 20, 2026 from https://www.cnic.es/en/noticias/hepatology-immune-cells-liver-regulate-body-temperature
