Whether the adage goes that it is best to feed a fever and starve a cold or the other way around depends upon which grandparent you ask. However, no matter how you square it, the concept of meddling with diet during times of illness is old. More importantly, the body does this all on its own by making you lose your appetite during certain sorts of infections. However, nobody has really looked into the biochemistry of all this. Now a new study is revealing that glucose is key.
The researchers behind the work knew from past animal studies that fasting was helpful for surviving some but not all infections. They also knew that fasting was vital to surviving really terrible bacterial infections. This led them to wonder which aspect of fasting was helping to combat the bacteria.
To explore this, they infected mice with dangerous bacterial and viral infections and monitored how they responded to diets that were limited in various ways. Glucose restriction dramatically improved survival in the mice with bacterial infections but proved lethal in the mice with viral infections. The reason for this, they suspect, is because bacterial infections drive cells in the body to shift from relying heavily on glucose for energy to relying on other compounds and that when glucose is provided in large amounts it gives the cells fuel that they cannot possibly use which forces the body to expend precious resources processing the unused glucose.
You can read more in The Economist article that I wrote on this here.