Pax and Art: B12 can be found in eggs and cheese. Ironically We humans produce B12 but too far down or digestive tract to reabsorb into our systems.
I'm not a fan of the medical/chemical industrial complex, neither am I suggesting a vegan life style. I spent most of my working life cooking beef steak as a broiler chef.
I'm looking at the proposition only as it relates to our carbon foot print as this thread suggests.
I don't think depending on manufactured dietary supplements is the end of the world. We already supplement milk with vitamin D. It certainly is more carbon neutral than factory farms. Speaking of which they depend on big pharm to load up cattle with various wonder substances. So unless you get organically grown beef, to argue against dependence on big pharm dietary supplements is a bit ironic.
Even if we do decide to forgo supplements to meat consumption or using an ovo-lacto alternative; how much meat do we have to eat to get the RDA of B12 and other aminos? I'd suggest that we could safely cut average US meat consumption by half and still get what we need.
OK so I.m adding this about RDA for B12.
http://dietary-supplements.info.nih.gov/factsheets/vitaminb12.asp
The adult RDA for B12 is 2.4 mcg the DV is 6.0 mcg.
The two highest listed sources for B12 are Beef liver and clams at 800% and 570% of the daily value per serving. They don't say how many ounces of liver, it's 3oz for the clams. So a cup of clam chowder a day is more than you need. Unfortunately canned clam chowder has a truck load of sodium so it has its has other issues.
Just as a side note clams were a very large part of the coastal colonial diet in America. The founders were loaded with B12.
Beef steak meets the RDA at 3oz.
Here's a handy chart on American meat consumption.
http://www.usda.gov/factbook/tables/ch2table21.jpg
We average about 8oz of meat a day if you do the math 195.2 x 16 / 365 = 8.55
So if we do away with those nasty carbon spewing factory farms and depend on getting our meat from Pax's neighbor's carbon friendly grass feed beef, the price of beef will go up. But because we don't "need" as much meat in our diet the resultant lowering of beef consumption will not cause a dietary disaster in America.
A side benefit is that with an increase in the cost of commercial meat, hunting becomes more cost effective. Hopefully this would lead to an increase in hunting. An increase in hunting would mean Americans would be eating more venison, which contains "good" cholesterol and helps lower "bad" cholesterol. This of course saves the world from communism and the encroaching evil of the golden arches.