EFFECTS OF CO-SUPPLEMENTATION OF IRON WITH ASCORBIC-ACID ON ANTIOXIDANT - PROOXIDANT BALANCE IN THE GUINEA-PIG

The relationship between intake of iron with ascorbic acid and their u ptake into the plasma and liver of guinea pigs was studied. The influe nce on the antioxidant/pro-oxidant balance of liver microsomes was als o determined. Animals were fed a standard pelleted diet low in iron an d ascorbic acid for 35 days. The pellet diet was supplemented by oral dosing with a solution containing either maintenance dietary levels of ascorbic acid and iron, or one of three regimens that increased the d osage of these substances ten fold. There were no significant differen ces in animal growth rate or food intake between these regimens. Liver and plasma total ascorbate levels were significantly increased (p < 0 .05) in animals receiving either ascorbic acid alone (liver 126 +/- 36 mu g/g tissue wet wt. and plasma 51.7 +/- 17.0 mu M; n = 9) or ascorb ic acid and iron (105 +/- 18 mu g/g and 40.3 +/- 15.3.0 mu M; n = 8) c ompared to controls (84 +/- 36 mu g/g and 15.3 +/- 8.5 mu M; n = 11). Total iron levels in the liver (76.7 +/- 7.3 mu g/g; control; n = 6) a nd plasma (2.4 +/- 0.03 mg/l; control) were not significantly raised i n animals under these conditions of iron or ascorbate intake. Liver mi crosomes isolated from animals receiving iron had a greater susceptibi lity to oxidative stress in terms of malondialdehyde production during auto-oxidation compared to those from control animals under the same conditions. This effect was eliminated on combining ascorbic acid with the iron supplementation, suggesting that oral administration of vita min C has a protective rather than a pro-oxidant effect under these ci rcumstances.