 Consuming high amounts of red meat is commonly linked to an increased risk of developing cancer, especially colorectal cancer. At the same time, antibodies against new 5Gc, a carbohydrate derived from red meat, have been observed to worsen cancer in human-like mice. While these antibodies and red meat consumption are each believed to increase cancer risk, it remains unknown how diet affects the antibodies. Now, research suggests that consuming new 5Gc from red meat and dairy can modulate the amounts and properties of anti-new 5Gc antibodies in humans, providing clues to how the carbohydrate might be linked to cancer. The team behind the study calculated daily intake of new 5Gc for more than 19,000 subjects aged 18 or older. These participants provided regular logs of food consumed over 24-hour periods as part of the Nutranet-Sante study, which was designed to investigate relationships between nutrition and health status. Antibodies against new 5Gc and their properties were evaluated using precision techniques for 120 representative individuals. Results showed that a diet high in new 5Gc, sex and age, affected various aspects of antibodies against new 5Gc, including the amount of antibodies and the specificity with which those antibodies bind their target. Men consumed more new 5Gc than women, mostly from red meat, and also showed higher overall levels of anti-new 5Gc antibodies. A detailed glycan microarray analysis revealed that high new 5Gc specificity and increased amounts of anti-new 5Gc antibodies were associated with higher consumption of new 5Gc from red meat and cow dairy. The study is the first to provide experimental evidence of an association between a dietary carbohydrate and the induction of antibodies against it, other than an allergy. The findings suggest that the positive correlation observed between dietary meat and a higher incidence of colorectal cancer could be mediated by an increase in certain antibodies against new 5Gc. That enabled researchers to formulate a GCMIC index to measure the amount of new 5Gc in foods. This index could potentially be adapted to provide dietary recommendations that help reduce cancer risk. More work is needed to explore that relationship and new 5Gc's possible role in other diseases.