Taking iron with vitamin c
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The Impact of Taking Iron with Vitamin C: A Comprehensive Review
Introduction to Iron and Vitamin C Co-Supplementation
Iron deficiency anemia (IDA) is a prevalent condition worldwide, often managed through oral iron supplementation. However, iron absorption can be suboptimal, leading to the common practice of co-supplementing with vitamin C. Vitamin C is believed to enhance iron absorption by converting non-absorbable ferric iron (Fe³⁺) to its absorbable ferrous form (Fe²⁺) 1. This article synthesizes current research on the efficacy and safety of combining iron with vitamin C in treating IDA.
Efficacy of Iron and Vitamin C Co-Supplementation
Hemoglobin and Ferritin Levels
Several studies have investigated the impact of vitamin C on iron absorption and its subsequent effect on hemoglobin and ferritin levels. A systematic review and meta-analysis found a small but statistically significant increase in serum hemoglobin (0.14 g/dL) and ferritin levels (3.23 µg/L) when iron was supplemented with vitamin C compared to iron alone 1. Another meta-analysis reported no significant difference in hemoglobin and ferritin levels between groups receiving iron with vitamin C and those receiving iron alone, suggesting that the clinical relevance of these findings might be limited 2.
Short-Term and Long-Term Effects
Short-term studies have consistently shown that vitamin C enhances non-heme iron absorption from meals, significantly increasing iron absorption percentages 6. Long-term supplementation studies also indicate a significant increase in hemoglobin levels, although the effect on ferritin levels remains inconsistent 6.
Specific Populations
In young women, a dietary intervention with iron and vitamin C administered separately showed improvements in hematocrit levels, suggesting that baseline iron status and vitamin C intake might influence the effectiveness of the intervention 7. In female martial artists, combining iron tablets with 1000 mg of vitamin C significantly increased hemoglobin levels and cardiovascular capacity compared to iron or vitamin C alone 10.
Safety and Adverse Effects
Gastrointestinal and Oxidative Stress
The safety profile of iron and vitamin C co-supplementation has been a point of concern. A study found no significant differences in the incidence of adverse effects such as constipation, nausea, or vomiting between the iron-only and iron plus vitamin C groups, although gastrointestinal upset was lower in the latter 1. However, another study highlighted potential oxidative stress risks, particularly in pregnant women, where combined supplementation increased lipid peroxidation, suggesting a need for caution in populations with high oxidative stress 9.
Liver Protection
Interestingly, vitamin C may offer protective benefits against liver damage induced by iron overload. In a study on mice, vitamin C supplementation prevented liver damage by reducing oxidative stress and mitochondrial dysfunction, indicating a dual role in both enhancing iron absorption and protecting against iron-induced toxicity 4.
Conclusion
The addition of vitamin C to iron supplementation appears to offer modest benefits in increasing hemoglobin and ferritin levels, although the clinical significance of these increases is debatable. The safety profile is generally acceptable, but caution is advised in populations at risk of oxidative stress. Further research is needed to fully understand the long-term implications and to identify specific populations that may benefit the most from this co-supplementation strategy.
Sources and full results
Most relevant research papers on this topic
Efficacy of Vitamin C with Iron Supplementation in Iron Deficiency Anemia Patients: A Systematic Review and Meta-Analysis
Oral iron supplementation with vitamin C may slightly improve hemoglobin levels and ferritin levels in patients with iron deficiency anemia, but does not significantly differ in adverse effects.
Meta-AnalysisTreatment efficacy of vitamin C or ascorbate given as co-intervention with iron for anemia - A systematic review and meta-analysis of experimental studies.
Oral vitamin C or ascorbate given with iron does not significantly improve hemoglobin or serum ferritin levels in anemia patients, and future clinical trials are needed to confirm this treatment.
Meta-AnalysisThe Efficacy and Safety of Vitamin C for Iron Supplementation in Adult Patients With Iron Deficiency Anemia
Oral iron supplements alone are comparable to a regimen of vitamin C supplemented with oral iron for patients with iron deficiency anemia.
RCT
Large Human Trial
Rigorous JournalDual action of vitamin C in iron supplement therapeutics for iron deficiency anemia: prevention of liver damage induced by iron overload.
Vitamin C boosts iron absorption in iron deficiency anemia treatment and prevents liver damage caused by excessive iron intake, acting as a "double agent" in iron supplementation therapy.
RCT
Animal StudyDo iron and vitamin C co-supplementation influence platelet function or LDL oxidizability in healthy volunteers?
Co-supplementation with iron and vitamin C improves antioxidant status, platelet function, and LDL oxidizability in healthy volunteers.
RCTThe Regulation of Dietary Iron Bioavailability by Vitamin C: A Systematic Review and Meta-Analysis
Vitamin C significantly increases iron absorption and has a positive long-term effect on haemoglobin levels in healthy adults.
Meta-AnalysisEffectiveness of Dietary Intervention with Iron and Vitamin C Administered Separately in Improving Iron Status in Young Women
Dietary intervention with iron and vitamin C administered separately may effectively improve iron status in young women, especially with higher baseline iron levels and lower vitamin C intake.
Non-RCTRigorous JournalEffects of Iron and Vitamin C on Growth Performance, Iron Utilization, Antioxidant Capacity, Nonspecific Immunity, and Disease Resistance to Aeromonas hydrophila in Chinese Mitten Crab (Eriocheir sinensis)
Dietary 700.90 mg/kg of vitamin C improves growth performance, iron utilization, and disease resistance in Chinese mitten crabs, with the highest survival rate after Aeromonas hydrophila challenge.
Increased lipid peroxidation in pregnant women after iron and vitamin C supplementation
Combined iron and vitamin C supplementation during pregnancy can increase lipid peroxidation, potentially causing adverse effects for both mother and fetus.
RCT
Highly CitedIron tablets and vitamin C (1000 mg): Can they enhance haemoglobin levels and cardiovascular capacity in female martial athletes?
Combining iron tablets and 1000 mg of vitamin C significantly increases hemoglobin levels and maximum oxygen volume in female martial arts athletes, contributing to overcoming anemia and improving cardiovascular capacity.
RCT