Despite the advances of modern medicine, infections caused by viruses and bacteria still remain one of the leading causes of death in the world. This has increased scientists’ interest in whether certain dietary components can influence the functioning of the immune system.
A team from the University of Vienna found for the first time that monocytes, important immune cells in the blood, begin to respond more strongly to bacterial toxins after consuming fructose. And this enhanced reaction turns out to be harmful, not protective. Researchers have found an increase in the number of receptors that recognize bacterial components, making the body more prone to inflammation.
To evaluate this effect, scientists conducted two randomized studies involving healthy volunteers. They compared the immune response after consuming fructose drinks and glucose drinks. The researchers also studied isolated monocytes and conducted cell culture experiments to better understand the biology behind the observed changes.
The findings showed that fructose – unlike glucose – causes an increase in the level of Toll-like receptor 2 in monocytes. This receptor plays an important role in controlling the immune response. Its increase increased the sensitivity of cells to lipoteichoic acid, a toxin of bacterial origin. Increased release of pro-inflammatory molecules such as interleukin-6, interleukin-1β and tumor necrosis factor α was also observed.
The scientists emphasize that future studies need to examine how long-term and increased fructose consumption may affect immunity and the risk of infections, especially in people with pre-existing metabolic disorders such as type 2 diabetes or fatty liver disease.