I was astounded to receive a link to a recent blog post by Stuart A. Seale, MD, this morning. Dr. Seale believes there’s a lot of misinformation about the necessity of eating animal foods to obtain Vitamin B12.
It is true that vitamin B12 is found in animal foods, and plant foods contain very little. However, animals do not have the ability to manufacture vitamin B12, so the presence of B12 in animal foods is not because of some superior characteristic of the food source. In fact, it is bacteria found in the intestinal tracts of animals that produce vitamin B12. Therefore, any B12 present in animal foods is only because of bacterial contamination. This doesn’t sound much like the makings of a superior dietary component, does it? Because of the simple fact that they don’t have intestinal tracts, and therefore intestinal bacterial contamination, plant foods contain little or no vitamin B12. Bacteria in soil also can produce B12. In earlier days people actually got their hands dirty while trying to subsist, and this was probably a source of this nutrient for them.
At first I mistakenly took the Dr. to mean that intestinal flora itself constituted “bacterial contamination,” so I’m damn glad I took a closer look because this post would have read far differently, otherwise. Thankfully, both reading it over more carefully — as well as supplemental information provided in a comment by Dr. Seale — informed me that he was not, indeed, bacteriophobic.
Regarding B12 in plant foods -there aren’t any plant sources of B12 that are reliable, only because B12 is manufactured by bacteria. These bacteria reside in the colon of animals, including people, but the B12 made isn’t absorbed into the bloodstream because the colon is too far down the intestinal pathway. B12 is absorbed in the small intestine. The presence of B12 in animal foods is only because of contamination with intestinal bacteria. As my blog attempted to point out, B12 in animal foods doesn’t make them superior to plant foods – it only means they are more bacterially contaminated. It also doesn’t mean that man has evolved in some way to be a meat-eater because meat has been the only place to obtain B12. It is the relatively modern industrialized slaughterhouse process that has led to the bacterial contamination problem with animal foods. Likewise, modern industrialized agriculture has also sterilized our soils. We also now live in a bacteriophobic culture. Undoubtedly in times past when society was agrarian, soil bacteria were an important source of B12. Dirt on the hands, under the nails, and on the food that was eaten would be enough to supply adequate B12.
OK, so now I have two distinct approaches by which to challenge the doctor’s claims. The first is simply the apparent bias since, what’s the big different between eating dirty vegetables and putting your dirty fingers in your mouth, and having a little trace fecal contamination on your meat — or, I suppose, eating the entire digestive tracts of clams and oysters, both high sources of B12?
Where does he think at least a good portion of the B12 in dirt comes from, if not the droppings of various animals and birds on and around crops? “Dirt” is composed of a lot of things including waste from dead and rotted animals & bugs, as well as their waste products.
OK, fine, go right ahead and get your B12 from dirty veggies, and feel free to clean under your fingernails with your teeth. Or, go barefoot and lick your feet. My dogs do and it seems to work for them.
The second dispute I have is his apparent conflation of the digestive systems of humans and ruminants.
Bovine Digestive Tract
While my knowledge of human and bovine physiology is deficient at best, I did seem to have picked up along the way that a human stomach and a cow’s complex 4-compartment stomach function quite differently. If I’m not mistaken, the function of ruminants is to essentially create an environment for bacteria to flourish, digesting cellulose and other plant components, multiplying to ghastly numbers and then being digested via the small and large intestines.
Now, the doctor is certainly correct, as far as I can determine, about the fact that both humans and ruminants synthesize a lot of B12 via bacteria in the colon and that it’s essentially not bioavailable. Perhaps it has some other evolutionary function, such as seeding the soil with B12, as well as the bacteria that continue to synthesize it.
But the main head scratcher for me was: if all B12 in meat is a function of bacterial contamination from fecal matter, how about the high B12 content in a piece of beef liver (the highest) or a filet that has been well cooked? What, does the surface B12 from such contamination somehow burrow into the meat itself? I dunno? Does anyone?
But I also thought: waitaminute, surely with all those trillions of bacteria digesting plant matter in the rumens of sheep, goats, cattle, venison, buffalo…that surely some level of B12 has to be produced and if so, then it’s available for absorption in the small intestine. It would be odd if that turned out not to be the case. Well, fortunately, just a few minutes of Googling provided the answers at PubMed and Journal of Animal Science.
Although cobalamin [Vitamin B12] was not the major form synthesized by ruminal microflora and, even if supplementary cyanocobalamin was extensively destroyed by ruminal microflora, based on calculations of apparent intestinal disappearance, cobalamin seems to be the major form absorbed in the small intestine.
And here, from near the end and summary.
The Excretion of Vitamin B12 by Dairy Cattle
Therefore, although the amount of vitamin B12 synthesized in the rumen is unquestionably very great, it is doubtful that the full extent of this action is often of importance to the ruminant on most rations, unless the amount metabolized and not recovered is also very great. On a ration devoid of vitamin B12, however, the rumen synthesis of this vitamin is unquestionably of great importance….
Rations containing either oats or corn do not differ significantly in their favorable effect on the rumen synthesis of vitamin B12.
So, as you all note I handled this one differently than usual. Clearly Dr. Seale is no Shiite Veg*n and distinctions ought to be made.
In other news, apparently famed activist George Monblot is no longer shilling for veganism: “I was wrong about veganism. Let them eat meat – but farm it properly.”
So there you have it. The nutritional and environmental case for veg*nism toppled, in one fell swoop.
Later: Well, I did have to drop in a comment.
Ruminants also synthesize significant B12 via bacteria in the rumen where it’s available to the small intestine, then hits the portal vein directly to the liver to be doled out to other organs and lean tissues. That’s why ruminant liver is the richest source of B12 on the planet. Clams are number 2, but there, we’re consuming the entire digestive tract.
I provide PubMed and Journal of Animal Science refs at this post:
On another note, I’m not sure I appreciate the distinction between plants contaminated with dirt (partially composed of rotted animal corpses and their waste, dirty hands & nails), and trace fecal contamination of meat or milk, both of which can be rendered safe through cooking methods and pasteurization (though when I drink it rarely, my milk is raw, whole, and un-homogenized).
Someday the veg*ns are going to see that the “paleos,” such as myself have the essentials right. It’s not about eliminating a core evolutionary food group but about eliminating the modern processed manifestations of non-food.
Whole non-processed foods from animals & plants does a body good (70 pounds lost and counting).
Dr. Seale’s response?
Richard – congrats on your weight loss! Even though I don’t agree with some of the tenets of the paleo Diet, it appears you’ve found a method that works for you, and weight loss is always a good defense against chronic disease.
Hmm, total honesty on the dietary front; i.e., that the improvement in body composition likely outweighs other factors he may not advocate — which is fine, it’s a mark of honesty with me.
But to not even address my core dispute? Either ruminants produce B12 for metabolic absorption, or they don’t. It can’t be both. I say he’s dead wrong. He should extend his honesty to a broader context.
More later: my further comment at Dr. Seale’s:
Thank you for your well wishes. Indeed, the honest approach for both the vegetarian minded, the paleo minded, or whomever, is to acknowledge that all people are different and that it’s hard to argue with n=1.
If only everyone would take responsibility for their own health as I have (and you, I’m sure), self-experiment, fine tune, and find what makes you look and feel good, none of this would need to exist.
But I do have to bring up my observation that while showing a lot of honesty in acknowledging that what’s working for me may be the best defense, you did not address my core argument in the slightest respect.
Doctor, you have stated that “any B12 present in animal foods is only because of bacterial contamination” and I have directly contradicted that assertion, with journal published references.
Should you not broaden your characteristic honesty to confront that? Moreover, I’m not just a muckraker. I have at least a dozen MDs who are fans of my blog, read it regularly, exchange emails with me and comment (there are a few in the last two posts). Some give my blog URL to patients, mostly diabetics, because paleo plain works for managing a broken metabolism (as does vegan or raw vegan..I acknowledge — I have a post about that, in fact).
It would be a shame for you to go forth under a paradigm based on a crucial error, wouldn’t it? I’m not saying that the fact that ruminants produce high B12 naturally — and they absolutely do — and not by industrial contamination invalidates veg*nism alone, but it is at the very least a very pesky fact to deal with, given that you are advocating supplementation which is certainly not anywhere in the evolutionary scheme of things.
I guess we’ll see.