According to the Framingham Offspring Study, 39 percent of people aged 26 to 83 years, primarily flesh-eaters, have low B12 levels. Since vegans form less than one percent of the population, this study indicates that B12 deficiency plagues nearly 40 percent of people who eat animal products.
B12 Deficiency May Be More Widespread Than Thought / August 2, 2000 / News from the USDA Agricultural Research Service
In this study, consumption of supplements and fortified foods (i.e. foods with the supplement added) markedly reduced the risk of low serum B12 levels:
"The researchers also expected to find some connection between dietary intake and plasma levels, even though other studies found no association. And they did find a connection. Supplement use dropped the percentage of volunteers in the danger zone--plasma B12 below 185 pmol/L--from 20 percent to 8. Eating fortified cereals five or more times a week or being among the highest third for dairy intake reduced, by nearly half, the percentage of volunteers in that zone--from 23 and 24 percent, respectively, to 12 and 13 percent."This report does not make it clear whether or how the researchers sorted the effect of supplements and fortified foods from the effects of dairy. I predict that since people commonly pour cow milk over their fortified cereals, and that people who consume more milk tend also to be more likely to use fortified cereals and supplements, because these behaviors would characterize people who have conventional health consciousness. If so, high dairy intake would strongly correlate with intake of supplements and fortified cereals, making it very difficult to separate the effects of these three potential B12 sources.
However, the research found no relationship between flesh intake and plasma B12 levels.
"Oddly, the researchers found no association between plasma B12 levels and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet. “It’s not because people aren’t eating enough meat,” Tucker said. "The vitamin isn’t getting absorbed.”"
Well, apparently the vitamin is getting absorbed from supplements, fortified foods, or dairy. Tucker seems to have presented evidence to make this statement more correct: "The vitamin isn't getting absorbed from meat, fish, or poultry."
|Got Vitamin B12? Source.|
Regarding dairy, a cup of milk supplies 0.9 mcg of B12, and an ounce of cheese supplies about 0.5 mcg. In comparison, one serving of Kellogg's All Bran cereal provides 5.8 mcg of B12 (more than twice the RDA). One-half cup of All Bran provides about 10 times the amount of B12 found in one-half cup of milk or one ounce of cheese. Most people will eat more than one-half cup of All Bran in one sitting (it only provides 80 calories), probably more like one- and one-half or two cups (17.4 to 23.2 mcg of B12). Three-quarters of a cup of General Mills Cocoa Puffs provides 1.5 mcg of B12, three times what is found in one-half cup of milk used to top it. Again, three-quarters cup of Cocoa Puffs only provides about 100 kcal; I think most kids would consume two to three of those servings, providing 3.0 to 4.5 mcg of B12. I would guess that odds favor that a person who eats milk, cheese, and fortified cereal will probably get a larger dose of B12 from the cereal than from the milk products.
Now take a look at supplements. Bayer's One-A-Day for Women contains 6 mcg of B12, and the One-A-Day for men contains a whopping 18 mcg. A woman would have to consume more than six cups of milk, or 12 ounces of cheese to get the same B12 intake as found in her One-A-Day for Women; and a man would have to consume more than 18 cups of milk and 36 ounces of cheese to get the B12 in his One-A-Day.
So these Tufts University researchers have found some evidence suggesting that animal flesh does not reliably constitute a good source of B12, and that among omnivores, the people who consume B12 supplements or fortified foods have the best B12 status.
Seems we have to say goodbye to these ideas:
Eating flesh reliably prevents B12 deficiency. -- False
Only vegans get B12 deficiency. -- False
Since only microbes produce vitamin B12, I guess modern antibiotic hygiene and agricultural practices, which have reduced the number of B12-producing bacteria in our soils, water, and general environment, have caused this epidemic of vitamin B12 insufficiency.
Vegan or flesh-eater, this research suggests you probably need to get your B12 from microbes by taking a B12 supplement or eating B12 fortified foods, which provide microbial-source B12 in adequate quantities.