Vitamin B12 Deficiency: What are the consequences?

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Nutritional Sources of vitamin B12 in your diet 

Persons with a standard "omnivore" type of diet usually get enough vitamin B12, however, those who have inflammatory conditions in the intestine, such as IBD, or have atrophic gastritis, or who are on medication for gastric ulcers, or are taking metformin for diabetes, or who are vegans, or are seventh day adventists, can be deficient in vitamin B12. The recommended daily dietary intake for vitamin B12 is 6 microgram. Representative amounts found in food are given in the table below. There is almost no vitamin B12 in any vegetable.



% DV


Clams, cooked 3 oz 84.1 1402 <1
Liver, beef, cooked 3 oz 70.7 1178 <1
VB12-fortied breakfast cereals (100%/serve) 6.0 100 1.0
Trout, rainbow, wild, cooked 3 oz 5.4 90 1.1
Salmon, sock eyed, cooked 3 oz 4.8 80 1.3
Trout, rainbow, farmed, cooked 3 oz 3.5 58 1.8
Tuna fish, light, canned in water, 3 oz 2.5 42 2.2
Cheeseburger, double patty and bun 2.1 35 3.0
Haddock, cooked 3 oz 1.8 30 3.3
Beef, top sirloin, broiled 3 oz 1.4 23 4.0
Milk, low fat, 1 cup 1.2 18 5.2
Yogurt, fruit, low fat 8 oz 1.1 18 5.2
Cheese, Swiss 1 oz 0.9 15 6.0
Ham, cured, roasted, 3 0z 0.6 10 10
Egg, whole, hard-boiled, large 1 egg 0.6 10 10
Chicken, breast meat, roasted, 3 oz 0.3 5 20

From the above table it can be seen that whilst eggs and chicken can substitute for fish, liver, and beef, that you would need 10 eggs per day, with a cholesterol of 201 mg/egg (2.1 gm/10 eggs), or you would need around 60 oz of chicken, with a cholesterol value of 80mg/3 oz (4.8 gm/60 oz). Contrast that to 12 oz of beef (cholesterol (0.24gm/12 oz).

No matter what the source of dietary vitamin B12 is, in order for it to be absorbed it must be first "released" from food by the action of gastric acid, and must then be bound to gastric Intrinsic Factor. Inhibition of production of gastric acid also inhibits the "release" of vitamin B12 from food. 

Alternative sources of Vitamin B12 

During the initial phases of dietary insufficiency, it is possible to compensate for a deficient diet by daily supplementation with oral vitamin B12 tablets, or multivitamins. Unfortunately, once the levels of vitamin B12 in serum and more particularly in the brain start to decrease, and a long time before any overt signs of deficiency occur, it is almost impossible to get sufficient vitamin B12 either by changing your diet, or by the use of supplements. This problem is exacerbated in those who have gastro-intestinal disorders, or who are on drugs that interfere with vitamin B12 metabolism or absorption. At this stage sufficient vitamin B12 can only be obtained by ultra high dose oral supplement, or regular injections, or more recently through topical application of The topical form of vitamin B12 developed by Boston Transdermal. This form of vitamin B12 is a specially formulated preparation that is an easy to apply to the skin using a needle-free delivery system. Twice weekly application of a this topical form of  vitamin B12 to the forearm and can supply adequate vitamin B12 even for those on vegan or vegetarian diets. In addition, the topical formulation is particularly suited to patients who may have gastro-intestinal problems, such as Crohn’s Disease and Ulcerative Colitis, or those who are on oral medications such as metformin, cholestyramine, cymetidine, clofibrate, colchicine, methotrexate, methyldopa, neomycin, omeprazole, some oral contraceptives, phenobarbital, ranitidine, tetracyclines, valproic acid and zidovudine (AZT) that either affect vitamin B12 uptake or which cause vitamin B12 deficiency. In vegetarian and vegan diets, dietary insufficiency with vitamin B12 is further complicated by deficiencies in some essential amino acids, such as methionine.

Further Information on Dietary Requirements for vitamin B12

Further Information on the recommended daily allowance for vitamin B12 can be found at the following web-sites : (an excellent publication)

Further information on topical vitamin B12 can be obtained by contacting  directly.