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