Response of urinary biomarkers of systemic oxidation to oral iron supplementation in healthy men.

BACKGROUND: Urinary biomarkers are used in assessment of severe, clinical oxidative stress. Little is known, however, about their diagnostic value within the normative range. OBJECTIVE: To evaluate the response of urinary thiobarbituric acid reactive substances (TBARS) and 8-hydroxy-2-deoxyguanosine (8-OHdG) as indicators of systemic oxidation in response to short-term oral iron and antioxidant supplementation. METHODS: Five healthy adult men participated in the pilot study phase and 12 in the definitive intervention trial. For 7 days each, separated by 12-day washouts, the subjects received different treatment regimens, consisting of 120 mg of iron, 120 mg of iron in refined palm oil, and 120 mg of iron in palm oil combined with one of the two doses of Carotino Tocotrienol Carotene Mixed Concentrate (CTCMC). Creatinine-normalized urinary TBARS and 8-OHdG concentrations were quantified in samples taken from subjects with and without active supplementation. Temporal and correlative associations between TBARS and 8-OHdG were explored. RESULTS: Daily intake of supplemental iron failed to produce any increment in urinary excretion of TBARS or 8-OHdG. However, a significant within-individual correlation between the urinary biomarkers was observed (Spearman r = 0.697, p < .0001, n = 466). Both doses of CTCMC significantly lowered urinary excretion of both oxidation indicators. CONCLUSIONS: Despite the lack of effect of oral iron on the biomarkers of systemic oxidation, they show a strong and significant mutual association within the nonpathological range of oxidative stress in healthy male adults.

Antioxidant-rich oral supplements attenuate the effects of oral iron on in situ oxidation susceptibility of human feces.

Prophylactic doses of 120 mg of iron (Fe) are commonly used to prevent Fe-deficiency anemia in vulnerable populations, especially in developing countries. Evidence shows that residual Fe in the large bowel may alter the normal antioxidant capacity of the fecal stream. Our objective was to evaluate the effect of dietary antioxidants from the Carotino Tocotrienol-Carotene Mixed Concentrate (CTCMC) on the depletion of fecal antioxidant capacity by oral Fe supplementation. In total, 17 healthy male adults participated in the 2 phases of the study, 5 in the pilot study and 12 in the definitive intervention trial. Participants received different treatments, separated by washout periods. These included: 120 mg Fe; 120 mg Fe and refined palm oil (FeOil); and 120 mg Fe in refined palm oil combined with 1 of 2 dosages (0.4 g and 0.8 g) of CTCMC/5 mL of refined palm oil (CTCB and CTCA treatments, respectively). Fecal samples were collected and analyzed to quantify the products of hydroxyl radical attack on salicylic acid (2,5 dihydroxybenzoic acid, 2,3-dihydrobenzoic acid, and catechol) at baseline and after active supplementation. Fe supplementation in either form (Fe or FeOil treatments) increased the concentrations of hydroxylated compounds in fecal samples. The production of hydroxylated compounds was significantly lower in treatments CTCB and CTCA than in the FeOil reference. Baseline antioxidant capacity state was virtually restored with dietary carotenoids and tocotrienols from the CTCMC. In conclusion, dietary antioxidants can reverse the depletion of fecal antioxidant capacity induced by oral Fe supplements.

A double-masked, randomized control trial of iron supplementation in early infancy in healthy term breast-fed infants.

OBJECTIVES: To test whether iron supplementation affects hematologic, biochemical, and developmental status in term breast-fed infants. STUDY DESIGN: Term breast-fed infants (n=77) were randomly selected to receive either 7.5 mg per day of elemental iron as ferrous sulfate or placebo from 1 to 6 months of age. Investigators and families were unaware of group assignment. Complete blood count and ferritin, red cell superoxide dismutase, catalase, plasma ferric reducing antioxidant power, and zinc and copper levels were analyzed at 1, 3.5, 6, and 12 months of age. Bayley mental and psychomotor developmental indexes (MDI and PDI) and visual acuity (with the use of Teller acuity cards) were assessed from 12 to 18 months of age. Analysis performed by analysis of variance and t tests was by intention to treat. RESULTS: Iron supplementation resulted in higher hemoglobin and mean corpuscular volume at 6 months of age and significantly higher visual acuity and PDI at 13 months of age (100+/-12 vs 93+/-9 [+/-SD]). Treatment and placebo groups did not differ in anthropometric indexes, compliance, biochemical status, or demographic characteristics. CONCLUSIONS: Iron supplementation of breast-fed infants appears safe and might have beneficial hematologic and developmental effects for some infants.