Vitamin B12

Hello,
I am interested in the mention of vitamin B12 in the introduction to Digestion Anatomy, where it is mentioned that microorganisms in the large intestine produce certain vitamins (B12 and K). Does this occur in a location where we no longer absorb B12? Is this why supplementation is necessary in the case of veganism? Thank you.

The gut microbiota can indeed produce B12 analogues, but the problem lies with their bioavailability and the site of production. For B12 to be absorbed, it must be bound to the intrinsic factor (a glycoprotein produced in the stomach), which allows B12 to be absorbed through the mucosa of the small intestine. For these reasons, there is a need for supportive supplementation in individuals who avoid consuming animal food sources.

Hello,

I am interested in knowing the bioavailability of vitamin B12 contained in spirulina. Is it an advantageous source of vitamin B12 for vegans?

Thank you.

The issue of vitamin B12 in plant sources is not entirely straightforward. It appears that plants produce B12 analogs that are chemically so similar to true B12 that they bind to the same transport molecule (intrinsic factor). We know about them that they do not have the same impact on metabolism as true vitamin B12. It has also been found that they pose a risk in that they can occupy the transport molecules of the intrinsic factor in cases where they are present in higher amounts in the diet, thus preventing the absorption of true vitamin B12, which may be theoretically sufficient in the diet.

There is a general consensus today that not only are plant analogs ineffective, but they can be health risks in excess. The only exception is chlorella products, where some studies have shown that they may contain B12 molecules that act practically the same as animal sources of B12. However, even here it is more complicated, because it was found that these B12 molecules are not produced by the algae itself, but are a result of the production of microorganisms living on the algae. The complication lies in the fact that algae available in commercial networks, i.e., those cultivated in artificial tanks, do not contain the necessary microorganisms that produce effective B12 due to sterile conditions, so this information only applies to chlorella algae living in the wild.

Good day, Mr. Jelínek,

I would first like to request a straightforward answer, thank you. If a family follows a plant-based diet, ensuring a varied and balanced diet by maintaining a ratio of grains, legumes, vegetables, and pickles, including the regular intake of micronutrients through nuts, seeds, and quality oils... to what extent are they at "risk" of vitamin B12 deficiency? We are particularly concerned about the nutrition of our children (ages 2-6). What would you recommend to us in relation to the children?

Thank you.

If the diet is purely vegan, the risk is essentially absolute. However, if you are considering a macrobiotic approach that includes meat (fish) in the diet, there should be no problem with a B12 deficiency (in this respect, it is reasonable to consume fish at least 2-3 times a week, which will ensure an adequate intake of B12 in this concept). In a purely plant-based diet, there is an issue with vitamin B12, as plant analogs are very difficult for the human body to metabolize. This leads to a deficiency, which manifests only after a certain period (often several years). In children, this period is much shorter due to development and growth, and the health impacts of B12 deficiency manifest more extensively.