Recently, I've been reading a lot about the "natural" human diet. Some people argue we've evolved to be meat eaters, others that we're naturally vegetarians. Obviously, we're pro-vegan here, but the question still rages. Are humans natural omnivores?
A few weeks ago, I bookmarked an article I saw referenced on Vegan.com. It's taken me awhile to get around to reading it, but I'm glad I did. The article, entitled "Mystery of the meat-eaters' molecule" was published in The Telegraph, and postulates that human physiology may not be able to tolerate meat and dairy. The study is being conducted by Ajit Varki, co-director of the Glycobiology Research and Training Center at the University of California, San Diego.
Varki has built up a range of evidence that potentially links Neu5Gc, a so-called sialic acid, to chronic disease. This is because the animal version is absorbed by humans as a result of eating red meat and milk products, and there is evidence that the body views it as an invader.
Professor Varki has determined that we are the only primates who do not produce this molecule, Neu5Gc. Instead, we produce Neu5Ac, a precursor to Neu5Gc. So what does this mean?
This tiny change could potentially explain some of the more unusual differences between humans and apes. Chimpanzees do not seem to suffer from heart disease, cancers, rheumatoid arthritis or bronchial asthma - common conditions in humans.
Professor Varki believes that Neu5Gc elicits an immune reaction that might contribute to a whole spectrum of human-specific diseases.
After testing a range of foods, they found the highest levels of Neu5Gc in red meat: up to 11,600 micrograms could be absorbed from the recommended daily serving of beef, 5,100 from pork and 4,900 from lamb. The level in goat's cheese was 5,500, but fell to around 700 in milk and salmon. Cod, tuna, turkey and duck were in the twenties.
Not only did the foreign sugar show up in the body soon after eating, but tests also revealed that many people carry antibodies that react to Neu5Gc - a protective immune response, but one which could trigger damaging inflammation.
Interestingly, we've been reading more and more about how better health can be achieved by eating vegan, or at least cutting down on meat and dairy products. We've found information showing that rheumatoid arthritis can be improved with a vegan diet, and that non-fat and lo-fat milk can be linked to an increased risk of prostate cancer.
Of course, Varki's studies are still in their preliminary stages. As he stresses:
"we have not proven any link to disease, just suggested that it is something to explore."
I'm looking forward to reading more about his findings. On a lighter note, Kate posted this YouTube video and commented it's one of the funniest she's seen. I agree, so here it is, it may not be the definitive explanation, but hey, it supports my point of view ;).
For further reading:
Dept of Cellular and Molecular Medicine at UCSD
Varki Lab page