Before we have written about vitamin B12 as a little bit different water-soluble vitamin that accumulates in the body. How does vitamin B12 differ from other water-soluble vitamins – read from HERE. What are typical reasons of vitamin B12 deficiency – read from HERE.

Vitamin B12 deficiency is much more common than we think. In a 2018 study by University of Tartu Hospital it appeared that vitamin B12 deficiency is best detected through infants´ screening. It was found in the same study that during a 3 year period, 14 infants in Estonia were born with innate vitamin B12 deficiency. This increases the incidents of innate vitamin B12 deficiency in Estonia to 33,8/100 000 births, which is significantly higher than thought [1]. Innate vitamin B12 deficiency infants do not include infants, whose levels of vitamin B12 have been enough after birth, but suffer from vitamin B12 deficiency during the first year of life.

Before it was thought that omnivores get plenty of vitamin B12 from food and that vitamin B12 deficiency is linked to strict vegan or plant-based diet, short bowel syndrome, poverty and hunger, pernicious anemia and bowel surgeries. Nowadays we know that vitamin B12 deficiency can be linked to atrophic gastritis, i.e. inflammation of stomach mucosa, that increases the risk of deficiency of different vitamins and minerals due to absorption disorders and that can be caused by Helicobacter pylori infection that is also very common in developed countries. Reducing the amount of animal products in diet also decreases the amount of vitamin B12 we get from food. However, vitamin B12 is often added to different food. When we decide to change dairy products that contain a lot of unhealthy saturated fat to e.g. oat products with healthy unsaturated fat, we will get enough vitamin B12 from food. It is important to substitute – when we leave out a certain vitamin or mineral from out diet, we should find a good alternative and food with added calcium and vitamins, including vitamin B12, for instance, oat products, is one good alternative. In such a way, we guarantee that we get enough vitamin B12 and also calcium from food and that amounts of those vitamins and minerals do not decrease. When we leave out all animal products, we should already use vitamin B12 food supplement.

Why should vitamin B12 be one of pregnancy vitamins?

We know that breast milk contains all necessary nutrients including vitamin B12 (except for enough vitamin D). Nowadays infants and toddlers suffer from vitamin B!2 deficiency more than we think and the main reason is mother´s poor level of vitamin B12 stores during pregnancy and small content of vitamin B12 in breast milk. Also infants, who are fed with infant formulas, are at risk for vitamin B12 deficiency when their mother has had low levels of vitamin B12 during pregnancy. Fetus gets it vitamin B12 from his or her mother during pregnancy.

Content of vitamin B12 in breast milk depends on the mother – what has been the level of B12 vitamin during pregnancy and breastfeeding. Vitamin B12 level can be inside the normal range, but more on the downside. Here we should take into account that the content of vitamin B12 depletes in the tissues faster than in blood, therefore, the analysis of vitamin B12 does not reflect the real level of vitamin B12 in our bodies. Vitamin B12 deficiency can be diagnosed with values still in the normal reference range [1]. Levels below the minimum reference value are very clearly linked to vitamin B12 deficiency. Levels near the minimum reference value, but still in the normal range, for adults <250 pmol/l (reference values 138–652 pmol/l, Synlab Estonia), are often not clear and therefore it is necessary to test the active vitamin B12 level, i.e. holotranscobalamin [2]. Reference value for holotranscobalamin in Synlab Estonia is >35 pmol/l, but University of Helsinki Hospital´s laboratory brings out clearly that the optimal reference value despite of the official >35 pmol/l value should be >70 pmol/l. Holotranscobalamin levels below 70 pmol/l can still reflect vitamin B12 deficiency. In those cases additional tests like homocysteine or more specifical, methylmalonate, can be used but these are not so ordinary tests in clinical work. Doctors mainly make decisions based on ordinary vitamin B12 test result that contains both, active and inactive form of vitamin B12 and is not the best analysis for diagnosing vitamin B12 deficiency. When the level of active vitamin B12, holotranscobalamin, is below 20 pmol/l, this links clearly to vitamin B12 deficiency. Holotranscobalamin test is more trustworthy analysis for diagnosing vitamin B12 deficiency, but its higher price makes it less used in clinical work.

In case of vitamin B12 deficiency the treatment is often the same for infants and adults – 500 mcg daily of vitamin B12 (as methylcobalamin) for 1 month, after that tests are repeated. Consult with your doctor regarding dose. Vitamin B12 is a safe vitamin even in bigger amounts and it does not have a daily upper limit intake. Still, it is better to check your level of vitamin B12 that can be done by your doctor.


[1] Reinson K, Künnapas K, Kriisa A, Vals MA, Muru K, Õunap K. High incidence of low vitamin B12 levels in Estonian newborns. Mol Genet Metab Rep. 2018;15:1-5. Published 2018 Jan 11.
[2] HUS. Test S -B12-TC2 updated 19.10.2020 / TS.
[3] L. Aru ja K.Reimand. Vitamiin B12 (S, P – Vit B12), holotranscobalamin (S-HoloTC). University of Tartu Hospital. Clinical chemistry and laboratory hematology department.[4] Esa Soppi. Rauta on kova aine. B12-vitamiini. 2020;47-48..[5] Behere RV, Deshmukh AS, Otiv S, Gupte MD, Yajnik CS. Maternal Vitamin B12 Status During Pregnancy and Its Association With Outcomes of Pregnancy and Health of the Offspring: A Systematic Review and Implications for Policy in India. Front Endocrinol (Lausanne). 2021 Apr 12;12:619176.

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