Introduction
Vitamin B12 (Cobalamin; Cbl) is a water-soluble molecule characterized by its chemical complexity, large size, and cobalt ion which is centrally located in the corrin ring1. Vitamin B12 is essentially obtained from dietary sources such as red meat, dairy products, eggs, and fish2-4. Absorption and transportation of vitamin B12 are processes that occur by hydrophobic binding protein carriers including haptocorrin (HC), intrinsic factor (IF), and transcobalamin (TCN)5-7. Around 80% of cobalamin is carried by inactive haptocorrin (or transcobalamin I) and 20% is transported by active TCN II in the bloodstream8-10. The deficiency of vitamin B12 is attributed to many factors including insufficient dietary supply, malabsorption, and deficient absorption cases11-15. In addition, many risk factors are related to vitamin B12 deficiency including genetic predisposition, age, weight, gender, and ethnic variations16-19.
Vitamin B12 has a vital role in many processes including the synthesis of nucleic acids, regulating the metabolism of the macronutrients (proteins, fats, and carbohydrates), as well as some neurological functions 20-24. Moreover, vitamin B12 plays a necessary role in myelin biosynthesis, manufacturing, and development of erythrocytes (hematopoiesis)11,25,26. Therefore, vitamin B12 deficiency is associated with serious neurological, hematological, and metabolic disorders21,27-30. Vitamin B12 deficiency is most prevalent in the elderly, children, pregnant women, nursing mothers, and vegetarians31-34. The most significant diagnostic characteristics and symptoms related to a deficiency of B-12 are fatigue, memory impairment, skin pallor, skin hyperpigmentation, glossitis, and severe hematological, neurological, and psychiatric disorders35-41.
Vitamin B12 deficiency is a worldwide concern16,42,43. Notably, vitamin B12 deficiency is not prevalent in wealthy countries except in the elderly, compared to developing countries where the prevalence of vitamin B12 deficiency can reach more than 50% of the population16,42,44-49. For instance, the prevalence of vitamin B12 deficiency in the United States and the United Kingdom is approximately 6% in people under the age of 60 and about 20% of those over 60 years, whereas countries in Latin America have a deficiency incidence of approximately 40%50-56. In Jordan, vitamin B12 deficiency is a considerable health problem57, where the prevalence varies according to the study population in the last decades57-59. In different studies in Jordan, vitamin B12 deficiency was estimated at different prevalence (16–50%) with the highest prevalence in the elderly above 55 years old16,17,59-61.
Based on our previous findings, we proposed the geographical location as an important factor in the estimation of vitamin B12 which may be related to socioeconomic status, lifestyle, and cultural background. We reported significant differences in the frequencies of vitamin B12 deficiency in different locations in Jordan. In particular, the results showed a lower frequency of vitamin B12 deficiency in the southern parts of Jordan compared to the northern cities17. Consequently, the current study aimed to evaluate vitamin B12 levels among the Jordanian population in Aqaba city (the most southern city) and to assess the prevalence of vitamin B12 deficiency in Aqaba’s Jordanian population. This study will complete the portrait of the national situation of vitamin B12 level.
Materials and Methods