Mental confusion and irritability may indicate a lack of vitamin B12, consensus warns; eating meat does not guarantee protection AdobeStock Frequent forgetfulness, difficulty concentrating, irritability, persistent tiredness and a feeling of "foggy mind" are often attributed to routine stress or emotional disorders. But these symptoms may also be associated with vitamin B12 deficiency, a condition considered common and which can cause important neurological changes even without causing anemia. As these are non-specific signs, the investigation must consider other possible causes and be carried out with clinical assessment. The alert is part of a consensus published by the Brazilian Association of Nutrition (ABRAN), which brings together recommendations for the diagnosis, prevention and treatment of vitamin deficiency. According to the document, early recognition of the problem is essential to avoid potentially irreversible complications, especially in the nervous system. The entity recommends that the possibility of vitamin B12 deficiency be routinely considered in clinical practice, especially in more vulnerable groups. Now on g1 What is vitamin B12 and why is it so important? Also called cobalamin, vitamin B12 participates in essential processes for the functioning of the body. Among its main functions are DNA synthesis, the production of fatty acids, the formation of myelin (the structure responsible for protecting neurons) and participation in mechanisms linked to cellular metabolism, cardiovascular function, the immune system and brain functioning. According to the consensus, vitamin deficiency can cause hematological and neurological manifestations that affect practically the entire organism. Symptoms can be confused with anxiety and depression One of the points highlighted by experts is that vitamin B12 deficiency can manifest itself through symptoms also present in psychiatric disorders, sleep disorders, other nutritional deficiencies and different clinical conditions. Irritability, mood changes, constant tiredness, palpitations, difficulty concentrating and a feeling of mental confusion are among the signs reported by patients, but they are not specific to B12 deficiency and do not allow for diagnosis alone. A case that illustrates this possibility is that of photographer Fernando Beiral, 42 years old. For more than a year, he believed he was experiencing anxiety and depression-like symptoms. The discovery occurred by chance, during tests carried out for another purpose, when it was identified that his vitamin B12 levels were very low. After replacing the vitamin, he reports that he noticed an improvement in his symptoms and highlights the importance of seeking appropriate medical evaluation. The response to treatment, however, varies depending on the severity of the deficiency, the time of evolution and the presence of other associated conditions. Who is most at risk for vitamin B12 deficiency? The ABRAN consensus identifies several groups most susceptible to the problem. Among them are: Vegetarians and vegans; People aged 60 or over; Pregnant women; Patients undergoing bariatric surgery; Users of medications that reduce gastric acidity; People who use metformin; Patients with Crohn's disease; People with ulcerative colitis; Individuals with celiac disease; People with irritable bowel syndrome; Women with a history of infertility or miscarriage; Immunosuppressed; People with myelopathy; Patients with multiple sclerosis. Eating meat does not guarantee protection against deficiency Although foods of animal origin are the main sources of vitamin B12 and reduce the risk of deficiency due to low intake, regular consumption of these foods does not always prevent the problem, because absorption of the vitamin depends on gastric and intestinal factors. According to consensus, beef liver, meat, fish, eggs, milk and dairy products are among the foods richest in the vitamin. Fresh plant foods are not considered reliable sources of cobalamin. In vegetarian or vegan diets, adequate intake usually depends on fortified foods or supplementation, according to professional guidance. According to the Abran consensus, the main food sources include: Sources of vitamin B12 However, absorption of the vitamin depends on a complex process that involves gastric acid, transport proteins and intrinsic factor produced in the stomach, with subsequent absorption in the small intestine. Therefore, gastrointestinal diseases, surgeries and some medications can interfere with this process. Therefore, according to endocrinologist Marcia Helena Costa, PhD from USP and professor of Endocrinology at the Federal University of the State of Rio de Janeiro (Unirio), even people who regularly consume foods rich in vitamin B12 can develop a deficiency if there is difficulty in absorption. "Even people who eat foods rich in vitamin B12, such as meat, fish, chicken, liver, milk and dairy products, may be deficient, because it depends on absorption. It is necessary to have adequate absorption", he explains. Disability affects children, adults and the elderly The document shows that the deficiency is present in different age groups, but the prevalence varies depending on the population studied, diet, income, age, associated diseases, use of medications and laboratory criteria adopted. In the United States, it affects approximately 3% of people between the ages of 20 and 39, 4% between the ages of 40 and 59, and 6% of individuals over the age of 60. Levels considered borderline are found in more than 20% of elderly people. In South America, Africa and Asia, the prevalence can exceed 40% in certain population groups. In Brazil, the consensus cites that 14.2% of children under five years of age have vitamin B12 deficiency, a situation more common in lower-income families and in the North and Southeast regions. What are the symptoms of deficiency? Manifestations can mainly affect the hematological and nervous systems. Among the changes described are: Macrocytic anemia; Pancytopenia; Thrombosis associated with hyperhomocysteinemia; Various neurological symptoms. In children, the deficiency can cause psychomotor regression, hypotonia, delayed myelination and even brain atrophy. The consensus highlights that early identification can allow the condition to be reversed. In adults, paresthesias, numbness, loss of proprioception and difficulties in performing delicate tasks, such as writing or buttoning clothes, may appear. In the elderly, deficiency can contribute to depression, gait changes, falls, cognitive impairment, psychosis and urinary and fecal incontinence. When to investigate vitamin B12 deficiency? Investigation is recommended especially in people who have: Macrocytic anemia; Neurological symptoms; Advanced age; Vegan diet; Vegan pregnancy or lactation; Babies of vegan mothers; Infertility; Gastrointestinal diseases. How is the diagnosis made? According to consensus, patients belonging to risk groups should initially undergo a complete blood count and serum vitamin B12 measurement. The results are interpreted as follows: Above 300 pg/mL: normal; Between 200 and 300 pg/mL: borderline; Below 200 pg/mL: established deficiency. When the results are considered borderline, the recommendation is to complement the investigation with tests such as holotranscobalamin, methylmalonic acid (MMA) and homocysteine. Endocrinologist Marcia Helena Costa emphasizes that an isolated test should not be used alone to define the diagnosis. According to her, the evaluation must consider clinical history, symptoms, laboratory tests and medical and nutritional monitoring. Treatment includes different forms of supplementation Vitamin B12 can be administered intramuscularly, subcutaneously, orally, sublingually or intranasally. Available formulations include cyanocobalamin, hydroxocobalamin, methylcobalamin and adenosylcobalamin. According to the consensus, all are converted into active cobalamin within cells. The oral route has the advantages of lower cost and practicality, but may be less effective in situations of malabsorption. Intramuscular administration remains indicated especially for patients with pernicious anemia, gastrectomy, ileum resection or malabsorption syndromes. Sublingual route gains space among recommendations One of the highlights of the document is the increase in evidence in favor of the use of sublingual supplementation. The studies analyzed showed that sublingual formulations of cyanocobalamin and methylcobalamin were as effective as intramuscular application in correcting serum levels of the vitamin and hematological changes in children with deficiency. Other studies have also demonstrated the effectiveness of the sublingual route in different populations, including patients using metformin and individuals with marginal deficiency of the vitamin. According to ABRAN, this form of administration offers advantages such as comfort, safety, practicality, rapid absorption and independence from the gastrointestinal tract. What does the ABRAN consensus recommend? Among the main recommendations are: Always consider the possibility of vitamin B12 deficiency in clinical practice; Carry out prophylactic supplementation in risk groups, regardless of laboratory tests; Investigate borderline results with complementary exams; Start treatment quickly when there is an established deficiency or prophylaxis is indicated; Reserve the oral route for patients without absorption problems and without therapeutic urgency; Consider parenteral and sublingual routes as preferred; Recognize that parenteral and sublingual routes remain effective even in patients with altered intestinal absorption. The document concludes that, considering efficacy, safety and comfort for the patient, sublingual supplementation can be the option of choice in most cases of prevention and treatment of vitamin B12 deficiency.