Iron vs Vitamin B12 for energy
Short answer: For energy, users rate them about the same: 88% report improvement with Iron (49 reports) and 90% with Vitamin B12 (103 reports).
Iron has 243 meta-analyses and 693 randomized trials on PubMed; Vitamin B12 has 376 and 572.
Based on 252 reports about Iron and 630 about Vitamin B12. Not medical advice.
| Iron Supplement | Vitamin B12 Supplement | |
|---|---|---|
| Users say it helped | 69%helped88 reports · medium confidence | 66%helped202 reports · high confidence |
| Verdict | Mostly positive | Mostly positive |
| Research | AResearch: Strong | AResearch: Strong |
| Meta-analyses / RCTs | 243 / 693 | 376 / 572 |
| Mainly used for | ||
| Energy % reporting improvement | 88% (49) | 90% (103) |
| Mood % reporting improvement | 100% (8) | 89% (46) |
| Focus % reporting improvement | 86% (7) | 88% (17) |
| Anxiety % reporting improvement | 100% (3) | 62% (21) |
| Sleep % reporting improvement | 100% (2) | 42% (12) |
| Common side effects | stomach issues, liver accumulation, overdose toxicity, iron overload | acne, anxiety, jitteriness, weakness |
| Typical dose reported | 65 mg | 1 ml |
High-level ID female athletes experience a negative impact on endurance performance, which can be improved by supplementing with ∼100 mg of elemental iron per day or bi-daily. The decrements in other performance parameters characterizing a range of sports coincide with the severity of iron deficiency.
J Sport Health Sci, 2025 ↗“I supplemented with sublingual b12 and iron and daily electrolytes and I'm feeling much better.”
Subgroup analyses indicated that the use of vitamin B12 supplements among vegans contributes to significant improvements in all biomarker concentrations compared to their unsupplemented counterparts. Our findings underscore the need for improved strategies to redress poor vitamin B12 status with appropriate B12 supplementation use among those adhering to vegetarian and vegan diets.
Nutr Bull, 2024 ↗“I supplemented with sublingual b12 and iron and daily electrolytes and I'm feeling much better.”
Related comparisons
Percentages come from first-hand user reports and are not clinical outcomes. Talk to a doctor before starting, stopping or combining anything. How we rate