Vitamin B12 deficiency can develop for various reasons, attributable to "insufficient food intake and / or impaired absorption. Generally this deficiency does not involve particular symptoms, even if important deficiencies are accompanied by severe forms of anemia and degeneration of the nervous system. .
Pernicious anemia is the most typical vitamin B12 deficiency syndrome.
, produced by the parietal cells of the body and the bottom of the stomach. Only a small amount is absorbed by simple diffusion.
Vitamin B12 deficiencies can be the consequence of:
, including those that normally populate the human intestine. Serious vitamin B12 deficiencies due to insufficient food intake are quite rare and can affect vegan individuals (strict vegetarian diet) or elderly people in whom absorption problems coexist. Subclinical deficiencies are very common, however, both in the categories mentioned and in developing countries.intrinsic factor deficiency due to surgical resection of the stomach (bariatric surgery), to which - for example - severely obese people are subjected;
intrinsic factor deficiency due to surgical resection of the stomach (gastrectomy) made necessary - for example - to treat complicated stomach ulcers or to remove malignant tumors;
intrinsic factor deficiency for atrophic gastritis, a disease characterized by chronic inflammation of the cells of the gastric mucosa with progressive loss of the glandular component;
inherited intrinsic factor deficiency (very rare conditions transmitted on a recessive genetic basis);
ilectomy: surgical removal of the ileum (final section of the small intestine responsible for the absorption of nutrients, including vitamin B12);
Crohn's disease, malabsorption syndromes, alterations in the intestinal flora, enteric infestation by parasites, achlorhydria (absence of hydrochloric acid in the stomach, which can also be caused by the intake of proton pump inhibitors, drugs useful in the treatment of gastroesophageal reflux and peptic ulcer - see also: drugs that cause vitamin deficiencies);
taking metformin, an oral hypoglycaemic that can interfere with the absorption of vitamin B12.
, tiredness, smooth, itchy and very red tongue, tingling extremities, reduced pain perception, irritability, headache, depression, decreased mental faculties (difficulty concentrating, memory deficit), balance disturbances, sleep disturbances .
or oral. In the latter case, the doses must be significantly higher than the daily requirement, up to the order of a milligram.
