Currently selected for this coming member’s digest by team member Melisa B.

The World Health Organizations classifies red meat as a carcinogen based on epidemiological studies showing positive associations between eating red meat and developing colorectal cancer as well as strong mechanistic evidence. Multiple components present in red meat likely contribute to this risk, including saturated fat and heme iron. New research suggests that Neu5Gc, a type of sugar, provides another possible mechanism to explain the cancer-promoting effects of diets high in red meat and dairy products.

Neu5Gc is a carbohydrate produced by non-human mammals and found in red meat and dairy products. Humans cannot produce Neu5Gc so the body recognizes it as foreign and produces antibodies against it called “anti-Neu5Gc IgG.” Research has demonstrated a link between high anti-Neu5Gc IgG levels and increased colon cancer risk; however, no direct correlation between diet and blood levels of anti-Neu5Gc IgG has been shown.

The authors of this report collected data from nearly 20,000 participants enrolled in NutriNet-Santé, an ongoing observational cohort study based in France. Participants self-reported their diet using a 24-hour recall method and gave blood for biomarker measurement. After reviewing the diet record data for Neu5Gc content, the authors chose a subset of 120 participants with varying levels of estimated Neu5Gc consumption and measured the anti-Neu5Gc IgG concentration of their banked blood samples.

The authors reported a distinct dose-dependent positive association between dietary content of Neu5Gc and blood concentrations of anti-Neu5Gc antibodies. Men consumed significantly more Neu5Gc in their diets, especially from red meat, and exhibited corresponding increases in anti-Neu5Gc IgG levels. In addition to the link between diet and antibody concentrations, the authors also report a link between increased meat and dairy consumption and the diversity of anti-Neu5Gc IgG. Antibodies vary slightly in structure so that one antigen may produce many different antibodies. Consuming more Neu5Gc increased the variety of anti-Neu5Gc antibody types in the blood, which may lead to a stronger immune reaction.

These findings are the first to demonstrate a link between dietary intake of Neu5Gc and anti-Neu5Gc IgG response. This novel observational research may have important implications for colon cancer risk; however, controlled trials are necessary to explore any causative role of Neu5Gc in disease.

• Link to full study.

• Learn more about Neu5Gc in our overview article.