Vitamin B12 deficiency: the most effective dietary supplements

Vitamin B12, also known as cobalamin, is a water-soluble vitamin essential to many vital processes within the body. Like folates, this vitamin is crucial for the DNA synthesis, the production of red blood cells, and the maintenance of the nervous system. In addition, vitamin B12 plays a key role in the methylation process, facilitating the conversion of homocysteine to methionine. This process is fundamental to the regulation of gene expression, DNA synthesis, and neurotransmitter production, thereby affecting many aspects of health, including cognitive and cardiovascular function.

Physiological Role of Vitamin B12

Vitamin B12 is indispensable for several vital functions. It is necessary for the formation of healthy red blood cells and the prevention of anemia. In addition to its role in the production of DNA and red blood cells, vitamin B12 is essential for the synthesis of myelin, a substance that protects nerves and allows rapid transmission of nerve impulses. A B12 deficiency can therefore lead not only to hematological problems but also to neurological disorders.

Dietary Sources of Vitamin B12

Vitamin B12 is found exclusively in animal-derived products. Among the richest dietary sources of B12 are lamb liver, sardines, oysters, egg yolk, fish, beef, kidneys, cheese, and milk. However, the bioavailability of vitamin B12 varies depending on the food source: it is higher in meat and dairy products and relatively low in eggs. People following a vegan diet, with no animal products, are particularly at risk of vitamin B12 deficiency unless they take dietary supplements.

Symptoms and Consequences of Vitamin B12 Deficiency

A vitamin B12 deficiency can take years to appear because of the large B12 stores in the liver. However, once it develops, it can cause serious symptoms, including: • Megaloblastic Anemia: This form of anemia is characterized by abnormally large and immature red blood cells, leading to extreme fatigue, general weakness, loss of appetite, and sometimes pallor. • Neurological Disorders: Neurological symptoms include paresthesias (tingling sensations), ataxia (difficulty coordinating movements), peripheral neuropathy, and in severe cases, demyelination of the nerves, leading to cognitive problems such as memory loss, depression, and even psychotic disorders. • Gastrointestinal Problems: Loss of appetite, nausea, constipation or diarrhea, as well as abdominal pain, are also common signs. • Psychopathologies: Disorders such as depression, irritability, personality changes, dementia, and in some cases, delusions may occur. Older adults, vegans, people with gastrointestinal disorders such as Crohn's disease, and those who have undergone gastric surgery are particularly at risk of developing a vitamin B12 deficiency. In addition, certain medications, such as proton pump inhibitors (PPIs) and H2 receptor blockers, can reduce the absorption of vitamin B12.

Supplementation and Prevention of Deficiencies

Preventing vitamin B12 deficiency is primarily based on a balanced diet rich in sources of B12. However, certain populations, such as vegans, older adults, or those with absorption disorders, may require supplementation to maintain good health. It is important to detect a B12 deficiency before symptoms worsen. However, many studies have shown that serum B12 levels (in the blood) are not always a reliable indicator of B12 status. About 50% of people with subclinical deficiencies may present normal B12 levels on blood tests, which can delay diagnosis. This is particularly concerning for older adults, who may develop neurological or psychiatric symptoms before hematological signs (such as anemia) appear. To prevent a deficiency, vitamin B12 supplements can be taken daily, with recommended preventive doses generally ranging between 25 and 100 mcg for healthy adults. It is advisable to consult a healthcare professional to determine the most appropriate dosage based on individual needs.