January Views of the Vis from WellSpring Naturopathic

"Of the Month"

It's been an entire year since we discussed a B vitamin - it seems about time. So cobalamin, better known as Vitamin B-12, is the first Of the Month topic for 2011.
History. Effects of a lack of Vitamin B-12 were known long before it was actually identified and isolated in 1948. Pernicious anemia, caused by a deficiency in B-12, killed around 10,000 people per year until 1926 when it was discovered that most of these cases could be cured by eating large amounts of raw liver (a solid half pound!) I know some people who would rather die of pernicious anemia, but this raw liver treatment actually got 3 men a Nobel prize in medicine in 1934! Cobalamin got its name for the cobalt atom that lies in the center of its corrin ring structure.
Vitamin B12 in the Body. Vitamin B12 has a rather complicated method of absorption into the body - much more complicated than the other water soluble vitamins. First, with the help of a stomach enzyme, it is released from the food that contained it. Absorption then requires contact with two different proteins - first R proteins which move B12 from the stomach to the small intestine, then Intrinsic Factor (IF) which allows B12 to bind to the mucosal lining of the small intestine and be absorbed into the bloodstream. Absorption if B12 is slow and not completely understood. Once absorbed, however, B12 has a long half-life in the body and is the only water soluble vitamin that is stored in any significant amounts. The liver stores most of it, but small amounts are found in other organ tissues as well.
Functions of Vitamin B12. Cobalamin is a required co-factor in some important biochemical pathways. It is necessary for the production of the amino acid methionine from homocysteine. Why is this important, you ask? Because methionine is required to make S-adenosylmethionine! Of course! And that substance is required as a methyl donor for countless other reactions in the body, including vital actions of our DNA. Additionally, if we don't make enough methionine there tends to be a build-up of homocysteine - which has been implicated as a marker for increased risk in cardiovascular disease. B12 is also required for another conversion resulting in succinyl-COA which is necessary for the energy production from fats and proteins, and for the production of hemoglobin.
Deficiency of Vitamin B12. Megaloblastic anemia is caused by a deficiency in B12. In this anemia, the red blood cells are too large. Cobalamin plays some role in the myelin sheaths of nerves and there are frequently neurological symptoms associated with a B12 deficiency including numbness and tingling in the legs and arms, possible difficulty walking, memory loss and some dementia. Disturbances of the GI tract may also occur.
Most problems with B12 deficiencies are caused by poor absorption rather than poor intake. Pernicious anemia is one cause. Reduced production of Intrinsic Factor may be the result of normal aging and various gastric surgical procedures. Other gastrointestinal problems may inhibit proper absorption as well. Some liver diseases may decrease storage ability and excess alcohol intake is also associated with deficiency of B12. A strict vegetarian may also be at risk for a B12 deficiency, as sources of B12 are almost entirely animal-based. It is estimated that our livers store 3-6 years worth of Vitamin B12, so it may take several years for deficiency symptoms to be noticed. There are lab tests that can determine levels of Vitamin B12.
Sources and Recommendations for B12. As mentioned above, meat and other animal products are the primary sources of Vitamin B12. B12 is also made by bacteria and we may get some amounts from that source, provided we have a healthy flora balance in our GI tract. There is some discussion about B12 sources from sea vegetables and algaes. Some people feel that the B12 from these sources actually come from bacterial "contamination" and it is difficult to know for sure amounts of B12 in these preparations. The current recommended intake of Vitamin B12 for adults is 3 mcg/day. If you are a regular meat eater, you are likely getting at least that amount - especially if you eat liver! Remember, however, that absorption is impaired in many situations. If you have gastrointestinal problems, are over 50 or frequently drink to excess, you may not be absorbing well.
Therapeutic Uses. High doses of B12 are generally sufficient to reverse megaloblastic anemia. B12 has also been used for asthma, neuropathies, herpes zoster, psoriasis, fatigue, dementia, insomnia, depression and cardiovascular disease. Since the absorption of B12 is slow and inefficient, larger doses are often given in an intramuscular injection.
Toxicity and Interactions. There are no known cases of B12 toxicity and no set Upper Limit for dietary intake. Some pharmaceutical drugs inhibit the absorption of food-bound B12. These include the proton-pump inhibitors like omeprazole, Metformin, colchicine, neomycin and a few others. Supplemental B12 is not affected in the same way as it does not need the stomach acids and calcium to be released and bound. Likewise, injections bypass the difficulties in GI absorption.

So enjoy your liver and onions - at 93.5mcg in 3 oz, you're getting a month supply of Vitamin B12!