There has been some evidence linking red meat and dairy to cancer. Some researchers have speculated that in the case of red meat, it may be due to over-cooking or “charring” the meat which produces carcinogenic substances, however research is showing it could be related to a non-human sugar found in high levels in meat and dairy called Neu5GC.
Q & A with Dr. Pearce and the Cancer Research Institute
CRI: Why have you singled out the sugar Neu5Gc as a culprit of diet-related cancer?
Pearce: For some time now red meats and to a lesser extent milk products have been linked to cancer. While many blame mutagens which arise from cooking the meat or ingestion of saturated fats, we learned that red meat and milk products contain high levels of a non-human sugar called Neu5Gc. If we look at our closest evolutionary cousins, the chimpanzees, who are omnivores like us, we noted they don’t seem to be prone to developing the types of cancer that we see in humans. We asked ourselves what was different about them. We noticed two separate but related differences. The first was that chimps, unlike humans, are still able to synthesize Neu5Gc and so naturally display it on their cell surfaces, and the second was that chimps have cell receptors called Siglecs that are responsible for regulating immune responses, while in humans the genes for these receptors have undergone a series of mutations that limit their expression and function.
CRI: What’s the connection between Neu5Gc and cancer?
Pearce: Let’s say you’re a chimp, and you eat a big meal of red meat. Neu5Gc in the meat is going to get taken up into your epithelial cells and presented on their surface. But because Neu5Gc is a natural part of epithelial cell surface anyway there is no adverse immunological response. Now, humans no longer make Neu5Gc. We used to, but approximately 2 to 3 million years ago our ancestors lost the ability to make it. However all the cellular machinery is still present to process this sugar as if it were natural. So when we eat red meat, Neu5Gc still gets picked up by our epithelial cells and presented on their surface, but our immune system recognizes it as foreign and therefore dangerous.
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For a brilliant video on understanding Neu5GC and how evolutionary biology is providing answers to health and well-being, watch this video below:
Primate Evolution and Human Disease by Ajit Varki MD