Daily Vitamin B12 Dose for a 75-Year-Old Male
For a healthy 75-year-old male without deficiency, the recommended daily intake is 4 μg/day of crystalline (synthetic) vitamin B12, preferably from fortified foods or supplements rather than food-bound sources. 1
Standard Recommendations for Older Adults
The European Food Safety Authority (EFSA) recommends 4 μg/day for elderly adults, based on intakes associated with normal functional markers. 1 This is higher than the basic Dietary Reference Intake of 2.4 μg/day for younger adults, reflecting the increased needs and absorption challenges in this age group. 1
The key distinction for adults over 50 is that this vitamin B12 should come from crystalline (synthetic) sources—either supplements or fortified foods—rather than protein-bound food sources. 2, 3 This recommendation exists because 10-30% of people over age 51 have protein-bound vitamin B12 malabsorption due to atrophic gastritis, which affects up to 20% of older adults. 2, 1
Practical Supplementation Approach
For routine supplementation in healthy older adults:
- 500-1000 μg/day orally is a safe and commonly used dose that ensures adequate absorption even with age-related changes. 1
- Vitamin B12 has no established upper tolerable limit because excess amounts are readily excreted in urine without toxicity. 4, 5
- Absorption of crystalline vitamin B12 remains intact in older people, even those with atrophic gastritis. 2
High-Risk Populations Requiring Higher Doses
Certain conditions warrant screening and potentially higher supplementation:
- Age ≥75 years alone is a risk factor, with 18.1% of those >80 years having metabolic B12 deficiency. 1
- Metformin use >4 months impairs B12 absorption. 6, 1
- PPI or H2 blocker use >12 months reduces B12 absorption. 6, 1
- Gastric or intestinal resection, particularly ileal resection >20 cm, requires 1000 μg IM monthly for life. 7, 6
- Vegetarians or vegans need supplementation due to limited dietary B12. 6, 1
When to Screen for Deficiency
While routine screening of average-risk adults is not recommended, screening is warranted in this 75-year-old if he has any of the above risk factors. 6 Initial testing should include serum B12, with methylmalonic acid (MMA) testing if levels are indeterminate (180-350 pg/mL). 1, 6
If deficiency is confirmed (B12 <180 pg/mL or <150 pmol/L), treatment requires much higher doses: 1000-2000 μg daily orally or 1000 μg intramuscularly. 1, 6, 8
Critical Considerations
- Never take folic acid supplements without ensuring adequate B12 status, as folic acid can mask B12 deficiency anemia while allowing irreversible neurological damage to progress. 4, 7
- Atrophic gastritis results in bacterial overgrowth that can bind vitamin B12, but crystalline B12 absorption remains intact. 2
- The ability to absorb crystalline vitamin B12 does not decline with advancing age, making oral supplementation effective. 2
Monitoring
For those taking supplements prophylactically, no routine monitoring is needed unless symptoms develop. 1 For those with confirmed deficiency being treated, recheck B12 levels at 3 months, then 6 and 12 months, followed by annual monitoring. 4, 7