The vegan myth of a B12 Eden

I am currently in the process of transitioning to a vegan life style. My reasons are ethical and environmental and those reasons have firmed themselves due to the advocacy of my wife. Nutrition-wise there’s almost no problem with being vegan: all essential amino acids can be found in plant-based foods, if one pays a bit of attention one gets enough protein, and so that’s that.

The only thing that needs supplementation is B12 vitamin because it only occurs in animal products. Interestingly though, it is produced by bacteria, not synthesized directly, which is the reason that humans need to consume it. Not a big deal, though, B12 gets produced by bacteria colonies and can be added to foods or taken as a supplemental pill.

So far so good but there is a vegan myth about B12 that bothers me. That myth goes something like this: in the past, the B12-synthesizing bacteria were plentiful in the soil, so that if one ate produce that had not been washed too thoroughly, one got the B12 one needed. Nowadays, however, produce gets cleaned too thoroughly, and anyway, the over-fertilization and/or use of pesticides has leeched the soil of the bacteria, making this unfeasible.

Note, first, how ideally this fits into vegan propaganda – there’s no reason to eat animals, in fact there never was a reason for eating animals or their products, humans can live completely on plants. This alone makes me suspicious. The fact that we can eat meat, and have so in the past, is no good reason to continue nowadays, when we can access other food sources and can supplement. But the fact that we don’t need to nowadays is not at all an argument that we never needed to. I have the vague suspicion that an Inuit vegan wouldn’t have survived very long, for instance. And if B12 only occurs in animal products then those who didn’t eat meat/eggs/dairy/sea food at all might not have survived very well or very long either.

Second, there’s actually never a study cited for this claim. Everything I find on the hypothesis comes from vegan sites and blogs. My favorite hedge takes this form:

Since there are tons of microbes in the soil, it used to be present there, but the soil has been very worn out by modern agriculture – how intense it is and all the chemicals used. So it is likely that back in the day some used to get absorbed by plants. B12 wasn’t discovered until the 1950s, and modern agriculture with heavy pesticides started right after WWII, when all the chemical warfare companies needed to find something to do with their chemicals.

Awesome, right? The reason we don’t find B12 in plants is because we started looking too late, which is support for the leeching out hypothesis. Reminds me of WMDs in Iraq.

Instead, the arguments are based on studies that claim to show a reduction in certain nutrients in plants over the past decades. But as Quick and Dirty tips argues:

These studies are widely—but very selectively—cited in books, articles, and websites that sell nutritional supplements. You never see any mention of the fact that the level of some nutrients has apparently increased in the last 50 years, for example. Instead, the 80% decline in copper levels observed in the British study is frequently translated as, “Fruits and vegetables have lost 80% of their nutritional value,” which is obviously a gross mischaracterization of the findings.
The authors of both studies are very candid that most of the differences are probably explained by factors other than nutrient depletion of the soil—and it’s not at all clear that these changes pose a problem. For example, the dramatic decline in copper levels in vegetables from 1960 to 1990 is probably because copper-based pesticides, which were widely used then, are not as commonly used now.

But even if we overlook this issue, I run up against other problems:

  • Not every place on earth has been heavily and intensely farmed – so I’d expect a study or two that looked at “wild” soil and plants, and found that there’s plenty of B12 there. But it seems there are none, or at least I haven’t found any.
  • B12 is produced in the digestive track of herbivores and absorbed either by rumination, or by reingestion of cecotropes. There’s basically no other type of animal that’s more likely to consume unwashed plant matter, and probably occasionally some of the soil along with it, than herbivores. Yet precisely those animals live in symbiosis with B12-producing bacteria. That indicates that there was an evolutionary advantage for this – probably because not enough B12 can be ingested otherwise.
  • Add to this that a study, while finding benefits of soil ingestion actually had sheep ingest 100g of soil per day, and it seems that occasional accidental soil might just not be enough.

There is a grain of truth to the “depleted soil” idea – it seems that the cobalt content of soil in agricultural areas has gone down, which inhibits the B12 synthesis by herbivores. This points toward the fact that the consumption of animal products alone might not be enough anymore to satisfy our B12 needs, but it is not support for claiming that eating only plants was ever enough.

All in all, there’s no reason to assume that there was vegan Eden in which one could live well without eating animal products, but instead quite a few indications otherwise. But nowadays, when we can produce B12 by other means, there is no good excuse for continuing to exploit animals.

This entry was posted in environmental sustainability, evolution, pseudo-science. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s