Management of vitamin B12 deficiency in primary care

Vitamin B12 (also known as cobalamin due to its metal cobalt content) is an essential water-soluble vitamin. It is one of the nutrients in B complex vitamins, which is synthesised by bacteria primarily found in foods containing meat, fish, and dairy products. However, it is not naturally found in foods like grains, nuts, fruits, and vegetables. Therefore, vegan individuals may suffer from vitamin B12 deficiency (National Health Service 2020; British Nutrition Foundation 2021). Moreover, B12 is crucial for the production of red blood cells, nervous system function, and DNA synthesis during cell division (Arora et al. 2019; Hanna et al. 2009; Langan and Goodbred 2017).

Vitamin B12 deficiency is a condition resulted from inadequate intake or malabsorption of vitamin B12. This deficiency affects people at all ages including infants, children, men, women especially elderly people (Green et al. 2017). According to Gomollón et al. (2017), the diet of Western individuals consists of 3–30 micrograms of vitamin B12 daily, where only 1–5 micrograms are absorbed. The National Health Service (NHS, 2020) and British Nutrition Foundation (2021) recommended 1.5 micrograms daily intake of vitamin B12 for adults aged 19–64 years. Whilst the European Food Authority (2015, 2023) suggests an adequate intake of 4 micrograms daily cobalamin for adults aged over 18 years. They found that daily intake of 4 micrograms cobalamin was associated with serum cobalamin concentrations within normal range from healthy participants. In contrast, the Institute of Medicine in the United States (IOM, now National Academies Sciences Engineering Medicine) adopted the World Health Organization's recommended daily intake of 2.4 micrograms cobalamin daily (Otten et al. 2006; WHO 2004). Consequently, there is a substantial storage of vitamin B12 in a person's liver. Hence, it may take up to 10 years before symptoms of deficiency appear (Langan and Goodbred 2017).