Dosage vitamin b12 seniors
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Optimal Dosage of Vitamin B12 for Seniors
Prevalence of Vitamin B12 Deficiency in Seniors
Vitamin B12 deficiency is notably prevalent among the elderly, with estimates ranging from 5% to over 20% of older adults experiencing marginal or frank deficiency. This is primarily due to atrophic gastritis, which reduces the production of stomach acid and digestive enzymes necessary to release vitamin B12 from food sources like meat, poultry, fish, and dairy.
Recommended Dietary Allowance and Crystalline Vitamin B12
For adults over 50, it is recommended to meet the dietary allowance of vitamin B12 through its crystalline form, which does not require gastric acid or enzymes for digestion. A clinical trial has suggested that an oral dose of 500 micrograms per day of crystalline vitamin B12 is effective in reversing biochemical signs of deficiency in older adults.
Daily Vitamin B12 Requirements
The daily intake of vitamin B12 needed to compensate for daily losses varies significantly, ranging from 3.8 to 20.7 micrograms per day, depending on various assumptions and health indicators such as body stores, cognitive function, bone health, and biomarkers of vitamin B12 status . Current recommendations for vitamin B12 intake, which range from 1.4 to 3.0 micrograms per day, are based on the amount needed to maintain hematologic status or compensate for obligatory losses.
Cognitive Function and Vitamin B12
The relationship between vitamin B12 intake and cognitive function in the elderly has been extensively studied. However, evidence from randomized controlled trials and cohort studies shows no consistent association between vitamin B12 intake and cognitive function. Although some studies have reported significant associations between sensitive markers of vitamin B12 status and the risk of dementia or global cognition, the current evidence is insufficient to include cognitive function in the development of vitamin B12 recommendations.
Bioavailability and Absorption
The bioavailability of vitamin B12 from food varies widely, with absorption rates ranging from 4.5% to 83% depending on the food source and dose. Daily vitamin B12 losses in healthy adults and the elderly range from 1.4 to 5.1 micrograms, suggesting that intake requirements to compensate for these losses range from 3.8 to 20.7 micrograms.
Supplementation and Health Outcomes
Supplementation with vitamin B12, often combined with folic acid, has been shown to lower elevated plasma homocysteine concentrations, which may have a small positive effect on health-related quality of life in older adults. However, it does not significantly reduce depressive symptoms. Additionally, vitamin B12 supplementation has been effective in normalizing elevated metabolite concentrations in the elderly, even in those with normal serum vitamin levels, indicating that metabolic evidence of vitamin deficiency is common in this population.
Conclusion
In summary, while the recommended dietary allowance for vitamin B12 in seniors is generally met through crystalline forms, higher doses, such as 500 micrograms per day, may be necessary to reverse deficiency. The daily intake required to compensate for losses varies widely, and current evidence does not support a direct link between vitamin B12 intake and cognitive function. Supplementation can improve certain health outcomes, but more research is needed to refine these recommendations.
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