Intermittent fasting could make immune cells more effective in fighting pathogens and cancers
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Intermittent fasting has become all the rage in recent years because it promotes weight loss by depriving the body of glucose, which forces it to break down fat to produce an alternative fuel source called ketones. Intermittent fasting could also boost immunity and help combat disease, going by a finding in mice showing that immune cells more effectively fend off infections and cancer when using ketones as an energy source.
It is widely believed that cells prefer glucose for energy. However, Russell Jones at the Van Andel Institute in Michigan and his colleagues previously found that certain immune cells that combat pathogens, called T cells, don’t produce much energy using glucose.
“We said, ‘well this is weird,’” says Jones. “These cells need lots of energy. So, what are they using to make [it]?”
He and his colleagues collected data from three other studies that genetically analysed T cells responding to infections and tumours. They found that, compared with dysfunctional T cells, effective T cells had increased activity in genes involved in breaking down ketones, indicating that they derived energy from ketones when fighting disease.
Next, the researchers genetically engineered three mice so that they couldn’t break down ketones and compared their response to an infection with an equal number of mice that could. They found that, on average, the normal mice had 50 per cent more T cells producing substances to kill off pathogens, called cytokines, than the engineered animals, and that these animals could churn out more cytokines per T cell as well. In other words, the ability to break down ketones made T cells more effective at fighting off infections in mice. Or, as Jones says, it increased the number of soldiers and ammunition on the front line.
Jones and his team also injected cancerous cells into the mice and found that after 22 days, tumours in the mice that were unable to break down ketones were twice the size of those in the mice that could.
Together, these findings suggest that immune cells are more effective at fighting disease when using ketones rather than glucose for fuel, says Jones.
They also explain why previous research has shown that fasting for 12 or more hours daily improves immune function in mice, says Satchidananda Panda at the Salk Institute for Biological Studies in California, who was not involved in the study.
Additionally, the results could help us understand how dietary interventions that boost ketone production, such as intermittent fasting, may affect our ability to fight off infections and cancer, says Jones. However, he cautions that not all ketone-producing diets have the same effects. For instance, the low-carbohydrate ketogenic diet may impair immunity as high levels of fat can suppress immune cells, he says.
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