Vitamin B12 deficiency
Supplements studied for Vitamin B12 deficiency.
Overview
SupplementDEX currently indexes Vitamin B12 for vitamin b12 deficiency. See the heatmap and evidence reviews below for the full rating.
Effect graph
Relevant supplements
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| Vitamin B12 | ★★★★★ | High |
Studies
Find individual evidence reviews for supplements sorted by DEX Score.
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Vitamin B12View supplement →
Consider purchase·★★★★★
How we scored this▸
- Vitamin B12 deficiency is usually defined as blood levels below 180–200 pmol/L (around 240 pg/mL).
- It is common in older adults because the body’s ability to absorb B12 often decreases with age.
- Vitamin B12 can be taken by mouth, injection, or nose spray.
- All methods can work well.
- Taking a high enough oral dose — around 647–1032 mcg daily — increases B12 levels as effectively as injections, even for people with absorption problems or pernicious anemia.
- Injections are preferred when the deficiency is severe or when there are nerve symptoms, vomiting, diarrhea, or trouble following a daily treatment plan.
- Daily supplements of 50–100 mcg can correct low levels, and 25–37.5 mcg can maintain normal levels.
- Fortified foods such as milk and bread are also useful, providing about 55–60% absorption in older adults.
- People who have had stomach surgeries, such as gastrectomy or gastric bypass, are at higher risk.
- Ordinary multivitamins do not prevent deficiency in these cases.
- Methylcobalamin 500 mcg daily can help after total gastrectomy, and cyanocobalamin 5000 mcg daily can prevent deficiency after gastric bypass.
- Vegans, pregnant women, and people with certain health conditions — including thyroid disease, anemia, bleeding, cancer, liver, or kidney disease — may also need more B12.
- Teenagers who followed a strict vegan or macrobiotic diet early in life might need higher intake to rebuild healthy levels.
Browse 17 studies
ObservationalEnteral Vitamin B12 Supplementation Is Effective for Improving Anemia in Patients Who Underwent Total Gastrectomy2021n=133
A study of 133 found that vitamin B12 deficiency was found in 71.4% of postoperative patients who underwent total gastrectomy for gastric cancer, and enteral vitamin B12 supplements might be effective to improve anemia in these patients.
- Effect
- Benefit
- Population
- Post-gastrectomy patients
- Participants
- 133
ObservationalLong-Term Iron and Vitamin B12 Deficiency Are Present after Bariatric Surgery, Despite the Widespread Use of Supplements2021n=52
An observational study of 52 found that long-term nutritional deficiencies were greater than the general population among men for iron and among women for vitamin B12.
- Effect
- No Benefit
- Population
- Bariatric surgery patients
- Participants
- 52
- Avg age
- 38.1±10.6
ObservationalVitamin B12 supplementation orally and intramuscularly in people with obesity undergoing gastric bypass2021n=29
A study of 29 found that methylmalonic acid also remained within reference values in both groups, with no significant differences.
- Effect
- No Benefit
- Duration
- 6 months
- Population
- Bariatric surgery patients
- Participants
- 29
RCTOral versus intramuscular administration of vitamin B12 for vitamin B12 deficiency in primary care: a pragmatic, randomised, non-inferiority clinical trial (OB12)2020n=143
A randomized trial of 143 found that 1 mg/day at week 52, the percentage of patients who achieved normal B 12 levels was 73.6% in the oral arm and 80.4% in the IM arm; these differences were -6.3% (103 out of 112 vs 115 out of 117; 95% CI: -11.9 to -0.1; p=0.025) and -6.8% (103 out of 140 vs 115 out of 143; 95% CI: -16.6.
- Effect
- Benefit
- Duration
- 52 weeks
- Dose
- 1 mg/day
- Population
- Older adults
- Participants
- 143
- Ages
- 65+
Systematic reviewOral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency2018n=153
A systematic review of 153 studies found that 1000 μg/day for 6–72 years one trial used 2000 μg/day vitamin B 12 and demonstrated a mean difference of 680 pg/mL (95% confidence interval 392.7 to 967.3) in favour of oral vitamin B 12 .
- Effect
- Benefit
- Dose
- 1000 μg/day
- Participants
- 153
- Ages
- 18+
Guidelines for the diagnosis and treatment of cobalamin and folate disorders2014
A study found that the clinical picture is the most important factor in assessing the significance of test results assessing cobalamin status because there is no 'gold standard' test to define deficiency.
Open-labelHematological response to short-term oral cyanocobalamin therapy for the treatment of cobalamin deficiencies in elderly patients2006
A study in older adults found that our findings support the view that one month of oral crystalline cyanocobalamin is effective to correct serum vitamin B12 levels and to obtain hematological responses in elderly patients with cobalamin deficiency related to FCM.
- Effect
- Benefit
- Duration
- 1 month
- Population
- Older adults
- Avg age
- 78±17
RCTOral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial2005n=120
A randomized trial of 120 older adults found that 2.5–1,000 µg cyanocobalamin/day for 16 weeks daily doses of 647 to 1032 mug of cyanocobalamin were associated with 80% to 90% of the estimated maximum reduction in the plasma methylmalonic acid concentration.
- Effect
- Benefit
- Duration
- 16 weeks
- Dose
- 2.5–1,000 µg cyanocobalamin/day
- Population
- Older adults
- Participants
- 120
Open-label[Early response to oral cobalamin therapy in older patients with vitamin B12 deficiency]2003n=14
A study of 14 older adults found that 1,000 µg oral cyanocobalamin/day cyanocobalamin given orally during one week may be an effective treatment for cobalamin deficiency related to food-cobalamin malabsorption and nutritional deficiency and may avoid painful intra-muscular injections in older patients.
- Effect
- Benefit
- Duration
- 1 week
- Dose
- 1,000 µg oral cyanocobalamin/day
- Population
- Older adults
- Participants
- 14
- Ages
- 80+
RCTA randomized, double-blind, placebo-controlled study of oral vitamin B12 supplementation in older patients with subnormal or borderline serum vitamin B12 concentrations2002n=10
A randomized trial of 10 older adults found that the change in the 10-microg cyanocobalamin group was not significantly different from that in the placebo group (P=.186).
- Effect
- Benefit
- Duration
- 1 month
- Population
- Older adults
- Participants
- 10
- Avg age
- ~81
ObservationalIs low-dose oral cobalamin enough to normalize cobalamin function in older people?2002
An observational study in older adults found that oral Cbl (2-37.5 microg/day) intake by community-dwelling healthy older adults is associated with higher serum levels of Cbl and improved or normalized Cbl function, as indicated by lower concentrations of the metabolites MMA, HCYS, and MCTR.
- Effect
- Benefit
- Population
- Older adults
Clinical trialResponse of elevated methylmalonic acid to three dose levels of oral cobalamin in older adults2002n=11
A study of 11 older adults found that 25–1,000 µg oral cobalamin/day for 6 weeks a dose of 1,000 microg/day proved to be the most effective in lowering MMA levels to within normal limits.
- Effect
- Benefit
- Duration
- 6 weeks
- Dose
- 25–1,000 µg oral cobalamin/day
- Population
- Older adults
- Participants
- 11
- Avg age
- ~79
RCTOlder men and women efficiently absorb vitamin B-12 from milk and fortified bread2001
A randomized trial in adults found that mean absorptions from water, milk and fortified bread were 55, 65 and 55%, respectively, and did not differ.
- Population
- Adults
- Ages
- >60
ObservationalSigns of impaired cognitive function in adolescents with marginal cobalamin status2000n=24
An observational study of 24 children/adolescents found that a significant relation between test score and cobalamin deficiency (P: = 0.01) was observed for a test measuring fluid intelligence (correlation coefficient: -0.28; 95% CI: -0.48, -0.08).
- Population
- Children/adolescents
- Participants
- 24
- Ages
- 10–16
Oral or parenteral therapy for B12 deficiency1998
Normalization of low vitamin B12 serum levels in older people by oral treatment1997
A study in older adults found that normalization of low vitamin B12 serum levels in older people by oral treatment..
- Population
- Older adults
Vitamin B-12 deficiency in elderly individuals: diagnosis and requirements1994
A study in older adults found that vitamin B-12 deficiency in elderly individuals: diagnosis and requirements..
- Population
- Older adults
Evidence visualised
Same ratings as above, aggregated so you can see coverage and imbalance.
| Supplement | DEX | Studies | Meta-analyses | Share |
|---|---|---|---|---|
| Vitamin B12 | ★★★★★76% | 17 | 0 | 100% |