Iron for Post-Bariatric Nutritional Support
B Good Evidence At least one randomized trial supports this, with mostly consistent results.Iron deficiency occurs in 33-55% of post-bariatric patients. ASMBS guidelines recommend 45-60 mg elemental iron/day after gastric bypass. Ferrous bisglycinate is the preferred form for tolerability. Monitoring every 3-6 months is mandatory.
The Bottom Line
Iron deficiency occurs in 33-55% of post-bariatric patients. ASMBS guidelines recommend 45-60 mg elemental iron/day after gastric bypass. Ferrous bisglycinate is the preferred form for tolerability. Monitoring every 3-6 months is mandatory.
Key Study Findings
Population: Severely obese adults undergoing bariatric surgery
Population: Metabolic and bariatric surgery candidates
Population: None
Population: None
Key Statistics
10
Studies
1000
Participants
Positive
Grade
Referenced Papers
Dosage & Usage
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units
Commonly Used Dosages
- general:
- 8-18 mg/day (RDA)
- menstruatingwomen:
- 18 mg/day
- deficiencycorrection:
- 100-200 mg elemental iron/day under medical guidance
Upper limit: 45 mg/day (elemental iron); excess iron increases oxidative stress
Dosages Studied in Research
| Dosage | Duration | Effect | N |
|---|---|---|---|
| None | 520 weeks | Positive | 240 |
| Various (oral supplements, megadoses, injections) | -- | Mixed | -- |
| None | -- | Mixed | -- |
| None | -- | Mixed | -- |
| None | -- | Positive | -- |
Best taken: On empty stomach with vitamin C for absorption; avoid with calcium, coffee, tea
Safety & Side Effects
Reported Side Effects
- ⚠ Constipation
- ⚠ Nausea
- ⚠ Stomach pain
- ⚠ Black stools
- ⚠ Oxidative stress (excess iron)
Known Interactions
- ● Levothyroxine (reduced absorption — take 4 hours apart)
- ● Tetracycline antibiotics (reduced absorption)
- ● Calcium supplements (reduced absorption)
- ● Proton pump inhibitors (reduced absorption)
Tolerable upper intake: 45 mg/day (elemental iron); excess iron increases oxidative stress
Always consult your healthcare provider before starting any supplement.
Frequently Asked Questions
Does Iron help with Post-Bariatric Nutritional Support?
How much Iron should I take for Post-Bariatric Nutritional Support?
Are there side effects of Iron?
How strong is the evidence for Iron and Post-Bariatric Nutritional Support?
Related Evidence
Other ingredients for Post-Bariatric Nutritional Support
Iron for other conditions
References
- [1] Fatemeh Chinisaz et al.. Obes Surg. 2026. Comparative Analysis of Postoperative Hair Loss and Micronutrient Deficiencies After One-Anastomosis Gastric Bypass Versus Sleeve Gastrectomy. doi:10.1007/s11695-026-08597-2 PubMed
- [2] Ilmari Saarinen et al.. Br J Surg. 2025. Nutritional deficiencies after sleeve gastrectomy and Roux-en-Y gastric bypass at 10 years: secondary analysis of the SLEEVEPASS randomized clinical trial. doi:10.1093/bjs/znaf132 PubMed
- [3] Xueying Tang et al.. J Acad Nutr Diet. 2025. Preoperative Micronutrient Repletion Strategies in Metabolic and Bariatric Surgery: A Systematic Review. doi:10.1016/j.jand.2024.09.007 PubMed
- [4] R Gambioli et al.. Eur Rev Med Pharmacol Sci. 2023. Risks and limits of bariatric surgery: old solutions and a new potential option. doi:10.26355/eurrev_202306_32822 PubMed
- [5] Benjamin Elstrott et al.. Eur J Haematol. 2020. The role of iron repletion in adult iron deficiency anemia and other diseases. doi:10.1111/ejh.13345 PubMed
- [6] Zin W Myint et al.. Ann Hematol. 2018. Copper deficiency anemia: review article. doi:10.1007/s00277-018-3407-5 PubMed
- [7] Emmy Parkes. Am J Med Sci. 2006. Nutritional management of patients after bariatric surgery. doi:10.1097/00000441-200604000-00007 PubMed
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