Vitamin B12 deficiency is one of the most dangerous micronutrient deficiencies because it is not easily recognized and the delayed diagnosis can cause permanent damage. (1) There are various causes for this vitamin deficiency, which, depending on the reference range used, may affect up to 70% of the populations studied. (2,3,4) The deficiency itself can vary in severity, but given the serious problems it can lead to, it is worth preventing.   

What factors can lead to vitamin B12 deficiency? 

We store a fair bit of vitamin B12, so it can take years for a deficiency to develop.  

The most common causes of vitamin B12 deficiency are (1): 

• Severe anemia and various digestive diseases that impair the production of a substance called IF, so vitamin B12 from food is absorbed very poorly or not at all. In such cases, it is essential to consult a doctor and have your vitamin B12 levels measured and supplemented in the right form.  

• Frequent use of medicines that inhibit the production of stomach acid or the absorption of vitamin B12. Examples include acid reducers, cholesterol-lowering drugs, and metformin.  

• Eating a plant-based diet only, as vitamin B12 is only found in foods of animal origin. In its absence, it is essential to supplement vitamin B12. 

• In elderly people, vitamin B12 deficiency is much more common, probably due to the reduced consumption of vitamin B12-rich foods and lower gastric acid production and absorption. 

How can a vitamin B12 deficiency be diagnosed? 

Blood levels of vitamin B12 can be measured and are usually the first measure used to detect a deficiency. Although a low blood level of vitamin B12 is a likely indicator of a deficiency, it is not in itself an accurate indication of the amount of vitamin B12 stored in the body.  

Other biomarkers that are measured include: 

• Holotranscobalamin, which shows the level of vitamin B12 taken up by tissues and indicates a more accurate result. Its measurement has not been used for very long. Levels can rise due to kidney disease, so it can't be used to assess B12 supply in affected individuals. 

• So-called MMA, which in this case does not refer to cage fighting, but is the abbreviation of a molecule called methylmalonic acid. This can also be used to assess vitamin B12 supply, as its level increases significantly in case of deficiency.  

• -The same is true for homocysteine, which can be increased by deficiencies of folate and other B vitamins, or even choline, so a high value is not necessarily indicative of a vitamin B12 deficiency.

In summary, it can be said that measuring these markers together gives a more accurate picture than measuring blood levels of vitamin B12 alone (1,5). 

Eliminating vitamin B12 deficiency 

If you have not been taking care of your vitamin B12 intake and have not been eating a lot of meat or dairy products, it may provide a solution merely to start paying attention to your intake. Of course, many people do not consume animal products for ethical reasons or have the above-mentioned absorption and utilization issues. Even for such cases, there are several possible solutions, the most convenient of which may be taking dietary supplement capsules.  

While 50% vitamin B12 from supplements is absorbed at a dosage of 1-2 mcg, as the dose increases, this drops significantly, such that, for example, only 3% of 50 mcg is absorbed. (5) At doses of 500-1000 mcg, B12 is absorbed by passive diffusion, so in case of a severe deficiency, it is worth consuming higher amounts for a while until stores are replenished. There is no significant difference in the absorption of different forms of vitamin B12, nor are spray and sublingual forms more absorbable than B12 supplements taken as capsules (6,7,8). 

If certain health problems persist, only B12 injections provide an adequate solution to the deficiency. For injection therapy, hydroxycobalamin is a better choice than cyanocobalamin because it is better stored, allowing for half the amount of injections. (5) However, for people without such problems, oral forms are as effective as vitamin B12 injections in eliminating deficiency. (9)