Vitamin B12 and folate deficiency
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Causes of Vitamin B12 and Folate Deficiency
Vitamin B12 deficiency most often results from low intake of animal-source foods, making strict vegetarians, some lacto-ovo vegetarians, and populations in less-industrialized countries particularly vulnerable. Malabsorption is another key cause, especially in the elderly due to gastric atrophy or Helicobacter pylori infection. Genetic factors, such as polymorphisms in transcobalamin genes, can also influence vitamin B12 status. Folate deficiency is primarily linked to low consumption of legumes and green leafy vegetables, with increased risk during lactation and in individuals with alcoholism. Both deficiencies can occur due to insufficient dietary intake or poor absorption, and are more common in populations with limited access to animal products or folate-rich foods 17.
Prevalence and Risk Groups for Vitamin B12 and Folate Deficiency
The prevalence of vitamin B12 and folate deficiency increases with age, particularly in people over 65, where rates can rise from 5% in those aged 65–74 to 10% or more in those over 75. Folate deficiency shows a similar age-related trend, but only a minority of those with low B12 also have low folate. In children and adolescents, especially in countries like India and Brazil, vitamin B12 and folate deficiencies are significant public health concerns, with higher rates observed in adolescents and in children from lower socioeconomic backgrounds. In India, adolescent boys are more affected than girls, and in Brazil, children under two years old and those with less educated mothers are at higher risk. However, folate deficiency is less common than B12 deficiency in these populations 2510.
Health Consequences of Vitamin B12 and Folate Deficiency
Deficiencies in vitamin B12 and folate can lead to megaloblastic anemia and, in the case of B12, additional neurocognitive impairments. Both vitamins are essential for one-carbon metabolism, which is crucial for DNA synthesis and methylation. In children, deficiencies are linked to stunting and underweight, especially when both B12 and folate are low. In older adults, these deficiencies can contribute to disability and cognitive decline. In patients with chronic heart failure, B12 and folate deficiencies are relatively rare and not associated with prognosis, but iron deficiency is much more common and impactful 4610.
Interactions Between Vitamin B12 and Folate
Vitamin B12 and folate are closely linked in metabolism. B12 deficiency can cause a functional folate deficiency by trapping folate in a form that cannot be used by the body, a phenomenon known as the "methyl trap." This interrelationship explains why symptoms of deficiency can overlap, and why B12 deficiency must be addressed to resolve certain folate-related problems. High folate intake, especially from supplements or fortified foods, can mask the hematological symptoms of B12 deficiency, potentially allowing neurological damage to progress unnoticed. Recent evidence suggests that excess folic acid may even worsen neurocognitive effects and other metabolic issues in people with B12 deficiency 349.
Public Health Strategies and Monitoring
Mandatory folic acid fortification has successfully reduced folate deficiency and birth defects in many countries, but has also increased the risk of excessive folic acid intake, particularly in populations with underlying B12 deficiency. Monitoring vitamin status using reliable indicators and consistent thresholds is essential for identifying at-risk groups and evaluating intervention effectiveness. Strategies to improve intake include dietary diversification, supplementation, and food fortification, with special attention to vulnerable groups such as the elderly, vegetarians, pregnant and lactating women, and young children 789.
Conclusion
Vitamin B12 and folate deficiencies remain significant public health issues, especially among the elderly, children, adolescents, and populations with limited access to animal-source foods or folate-rich vegetables. The close metabolic relationship between these vitamins means that deficiencies often overlap and can complicate diagnosis and treatment. While food fortification has reduced folate deficiency, it has also highlighted the need for careful monitoring to prevent the masking or worsening of B12 deficiency. Vigilance in at-risk groups and targeted public health interventions are essential to reduce the burden of these deficiencies and their associated health consequences 1234+5 MORE.
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