Vitamin B12

Vitamin B12, in nature, is not produced neither by plants nor animals, but by bacteria, found in soil or water.

Erba e terra

As in nature, it is thus assimilated by animals (humans included, when he lived in the wild) with the ingestion of contaminated plant foods; in a not natural state,like today’s world, it cannot be assimilated in this way, because of the necessary sanitation operations applied today. It must thus be produced using special crops: the bacteria capable of synthesizing vitamin B12 are cultivated on a carbohydrate substrate and the vitamin they produce is taken and used in human food and feed for animals.

In fact, most of the vitamin B12 thus produced is used in the feed of farmed animals (to which, as is well know, are given too many other supplements, medications, and all the residual chemicals of the cultivations) and it is only thanks to this that the animals assimilate this vitamin that then finds itself in their meats and other products (dairy products and eggs). Instead, those who do not consume animal products obtain vitamin B12 directly, namely that produced by cultured bacteria, which is sold as supplement tablets to in fortified products (vegetable milks, juices, breakfast cereals, etc.).

This is a critical nutrient for many categories of persons:

  • for omnivores who follow a diet adhering to international guidelines and therefore consume moderate amounts of meat;
  • for lacto-ovo vegetarians, who still cannot get enough vitamin B12 from dairy and eggs, unless they eat these in great quantities, which is would thus be very damaging;
  • for vegans, who eat no animal-derived foods;
  • even in the case of immoderate consumption of meat, for all those who find it difficult to assimilate B12 from animal foods and must directly assimilate that of bacterial synthesis;
  • for all those over 50 years of age, because at this age, the above-mentioned lack of absorption is widespread;
  • for those taking certain types of medications (metformin, antacids, etc).

For all these individuals, it is necessary to consume vitamin B12 produced by bacteria, which can be found in dietary supplements on the market.

Basically, only those who consume immoderate amounts of meat, with all its relevant associated risks, have no more than 50 years and have no absorption defects, can obtain vitamin B12 from animal products, which is always that synthesized by bacteria. Instead, other people must directly take the vitamin produced by bacteria.

In the vegPlate figure, vitamin B12 has been placed at the center of the plate, along with vitamin D, signifying a particular attention towards these two vitamins.

Vitamin B12 is especially important in pregnant and breastfeeding women and children from weaning onwards (see specific indications below).

It is involved in cell replication and the metabolism of proteins and fats, hence its deficiency causes damage to the central and peripheral nervous system. In the presence of low or normal levels of folic acid (a nutrient very well represented in plant-based diets with respect to the omnivorous diet) its deficiency can lead to anemia (megaloblastic anemia).

The second aspect that makes it important to have a normal blood level of vitamin B12 is that it serves to maintain low levels of homocysteine: high levels of homocysteine have been linked to cardiovascular disease, cancer, dementia and depression.

Warning: don't be surprised if the daily dose is 50 mcg, and the twice-weekly dose is 1000 (20 times as much), because the amount of vitamin B12 in maintenance doses varies widely depending on the frequency of intake (disproportionately so). The most current adult guidelines recommend:

1. minimum 3 assumptions that provide 2 mcg each (total 2+2+2 mcg per day) onsumed throughout the day, several times (at least 3) from various food sources (fortified products)


2. no less than 50 mcg, in a single daily dose, from a supplement (sublingual or chewable tablet);


3. no less than 1,000 mcg, in two distinct weekly doses (total weekly 1.000 mcg x 2), from a supplement (preferably sublingual, taking into account the variability of absorption from very high doses).

Clearly, case 1 is very difficult and cumbersome to implement, while cases 2 and 3 are the simplest.

Please note that these instructions are only valid for cyanocobalamin form of vitamin B12, because in the literature there are no available references that can provide information on the other forms of vitamin B12 available on the market (such as methyl-cobalamin).

The dosage below refer to cases of normal levels of vitamin B12, while cases of deficiency are treated with a "loading dose" for a few months, until the levels are back to normal and supplementation can return to a maintenance dose. The deficiency is determined through laboratory blood analyses, checking the values of: CBC, vitamin B12, folate, homocysteine. These values should be examined by a competent physician o determine the state of deficiency.

The values considered optimal for vitamin B12 and homocysteine are (regardless of what is printed on the sheet of the results of the analyses, which always gives incorrect minimum and maximum values):

  • vit. B12: at least 488 pg/ml
  • homocysteine: less than 12 mcmol/L

Vitamin B12 in pregnancy and lactation

The dosage of supplements to take during pregnancy and lactation is the same as in other stages of life, but taking the supplement is even more important at this stage, because a possible deficiency affects the baby much more heavily than the mother and can affect the development of the nervous system and the blood cells.

So, if you're not supplementing vitamin B12 and you are pregnant (or are you planning to become pregnant), you must do for blood tests as indicated above, to determine the correct dosage of supplements to take.

Vitamin B12 during weaning

Breast milk, when present in high quantities in the diet, can be an excellent source of vitamin B12, provided, of course, the mother takes the supplements at the right dosage. Formula milk is always enriched with vitamin B12 and the enough for the infant if present in the diet in the amount of at least 500-600 ml per day.

With the decrease of the quantity of milk during weaning, these sources are no longer sufficient, and supplementation must be started. There is no risk related to possible excess intakes, while serious effects are well documented due to vitamin B12 deficiency at this stage of life.

The most convenient form for supplements are drops