Neu5Gc, Malaria, and Adaptations
Sialic acids are found at the outermost edge of cells, and these act as a sort of cellular recognition mechanism1. Cells are able to determine what cells belong together, which should interact with each other, and which cells should be avoided by use of sialic acid signatures.
In order for infectious diseases to operate, they must gain entry into our cells, so, in essence, they must trick our cells with a signature that will let them in. These invading cells must find a key that will unlock our cells. In particular, malaria uses this mechanism to gain access to the human cells. Evolutionary biologists now believe that millions of years ago humans (or our ancestors) were being ravaged by a particular kind of malaria2. Specifically, this malaria used a particular “key” to open a sialic acid “lock” called Neu5Gc. Over time, we adapted to fight off this invader by no longer making the Neu5Gc acid. In essence, we changed the locks to keep malaria out. Eventually, malaria also adapted and now has a specific form that infects only humans as a result. The original malaria is still around today, but infects only other mammals.
The outcome of this evolutionary arms race is that humans are one of the very few mammals that do not produce Neu5Gc3. This change had both advantages and disadvantages. The advantage of course, was immunity from malaria trying to use keys for Neu5Gc. The disadvantage occurs when we ingest Neu5Gc molecules.
Neu5Gc and Inflammation
Instead of Neu5Gc, humans produce a very similar sialic acid, Neu5Ac, which differs by only one oxygen atom3. Neu5Gc and Neu5Ac are so similar that Neu5Gc molecules are allowed to enter the Neu5Ac cells as if they were Neu5Ac cells themselves. The problem, however, is that our immune system isn’t fooled, and our bodies produce an anti-Neu5Gc antibody response3. This antibody response, in turn, results in chronic low-grade inflammation, as our bodies try to wipe out what our immune system believes to be a foreign invader.
In the case of Neu5Gc induced inflammation, there seems to be two distinct effects on our health: 1) increased risk of cancer growth and 2) increased risk of heart disease
Neu5Gc and Cancer
Cancer tends to thrive in environments of low level inflammation4. There are plenty of examples of this: ulcerative colitis leading to colon cancer, chronic pancreatitis leading to pancreatic cancer, chronic hepatitis leading to liver cancer, and stomach inflammation leading to stomach cancer. Cancer seems to do so well with inflammation, that it actually seeks to create such an environment by soliciting the body to attack it5. One reason cancer thrives is that inflammation stimulates angiogenesis (the creation of new blood vessels) to feed the cancer as it grows4.
Neu5Gc and Heart Disease
Accumulation of Neu5Gc isn’t uniform across the body. It tends to favor the lining of hollow organs, like the endothelium of our blood vessels3. In autopsies, Neu5Gc has been found both in the lining of blood vessels and within atherosclerotic plaques (a key marker of heart disease). The inflammation as a result from Neu5Gc being in these structures accelerates heart disease.
The authors of a revolutionary paper on this topic state, “anti-Neu5Gc antibodies can initiate, perpetuate, and/or exacerbate an inflammatory response at the endothelium, potentially playing a role in disease states such as atherosclerosis, wherein vascular inflammation is involved”3.
6
Sources of Neu5Gc
Neu5Gc has never been reported in plants3.
Conclusion
Neu5Gc is a toxic substance that only has a dietary pathway into our body, and only can be found in animal products (primarily the products of mammals). By eliminating animal products, your risk of both heart disease and cancer (our #1 and #2 killers respectively), will decrease.
1Function of Sialic Acid, https://www.youtube.com/watch?v=zb-0PZvcpUo
2Evolution and Sialic Acid, https://www.youtube.com/watch?v=D_kzVn31o18
3Evidence for a Novel Human-Specific Xeno-Auto-Antibody Response Against Vascular Endothelium, https://watermark.silverchair.com/zh805009005225.pdf
4The Flip Side of Immune Surveillance (https://www.ncbi.nlm.nih.gov/pubmed/18364013)
5Cancer as an Autoimmune Disease (https://nutritionfacts.org/video/cancer-as-an-autoimmune-disease/)
6https://www.ncbi.nlm.nih.gov/pmc/articles/PMC218710/bin/pnas_2131556100v2_index.html