Introduction:
Iron deficiency anemia (IDA) is one of the leading causes of anemia, globally. Although there is no evidence, Vitamin C is regarded to enhance iron absorption and is commonly prescribed along with iron for persons with anemia. We conducted this systematic review and meta-analysis to determine the treatment efficacy of experimental studies where vitamin C or ascorbate was given as co-intervention with iron compared to giving only iron among participants with anemia of all ages.

Methodology:
A comprehensive strategy was used to search literature from PubMed, Cochrane and Google Scholar. Experimental studies conducted among participants with lab-confirmed anemia at baseline, with “ascorbic acid or vitamin C given as co-intervention with iron” as intervention and “only iron” as comparator, and reported the outcomes hemoglobin or ferritin, were selected. Random-effects model was used to estimate standardized mean differences or odds ratio of outcomes and sensitivity analyses were done. Sub-group and meta-regression analyses were conducted to evaluate the reasons for heterogeneity. (PROSPERO number: CRD42022306612)

Results:
Of the total nine studies included in the review, seven studies with 905 participants were included for meta-analysis. The pooled estimate for Standardized mean difference (SMD) of hemoglobin (g/dL) and Serum Ferritin (mcg/L) for intervention type ferrous ascorbate were 0.44 (95% C.I.: -0.30, 1.26) and 0.03 (95% C.I.: -0.68, 0.73) respectively, and were not statistically significant. The pooled estimate for SMD of hemoglobin (g/dL) and Serum Ferritin (mcg/L) for intervention type ‘iron and vitamin C’ were 0.11 (95% C.I.: -0.05, 0.28) and -0.90 (95% C.I.: -1.09, -0.72) respectively, and were not statistically significant.

Conclusion:
The SMD of hemoglobin or serum ferritin between the intervention group were not significantly favouring the intervention, when the intervention group was ferrous ascorbate or iron and vitamin C, and the quality of evidence of these effect measures were low.