Study Links a Diet Heavy in Fat and Food Additives to Fever After Covid-19 Vaccines

Why do some people run a fever after a vaccine while others feel fine? A new study points to the gut, and to what people eat.

TLDR

• The study, published in Science, followed 171 young adults.
• An inflammatory gut microbiome was associated with fever after mRNA Covid-19 vaccines.
• That microbiome was linked to diets higher in fat or processed food additives.
• Antibody responses were not affected. Cause and effect is not yet proven.

The Study

Researchers profiled the gut microbiomes of 171 young adults before and after mRNA SARS-CoV-2 vaccination and took their temperatures three times a day, FoodNavigator reported. People with more gut inflammation before vaccination, or more gut flagellin, were more likely to develop a fever. Flagellin is a protein made by some gut bacteria, such as Lachnospiraceae, that can switch on inflammatory immune pathways.

Where Diet Comes In

Diets higher in fat or processed food additives, or lower in whole plant foods, were correlated with the inflammatory microbiome linked to fever. Vegetarian diets were correlated with microbiome features linked to less fever. Diet and inflammation did not appear to change how well the vaccine worked, measured by antibody response. The report does not specify which additives were involved.

“Diet, microbial ecology, and the metabolic state are not immutable, and people might one day prepare for vaccination as deliberately as the vaccine itself is formulated,” wrote Stanford immunologist Bali Pulendran in a perspective on the study.

Why It Matters

The findings are a correlation, and causality still has to be established. But they add to a growing body of research connecting processed food and additives to gut inflammation, and to how the body responds to everything from infection to medicine.

Source: FoodNavigator. Read the report.