Effect of aging and chronic vitamin a (VA) status on hematological and iron status indices in rat

We determined hematological and iron status parameters in a 3X3 factorial study designed to evaluate the interaction of VA status and age on immune function. Male Lewis rats (n=144) were fed a nutritionally adequate purified diet containing either 0.3 (marginal), 4.0 (control) or 50 (supplemented) μg retinol equivalents (as retinyl palmitate) / g of diet from the time of weaning until sacrifice at 2.5 (young), 8-10 (middle-aged) or 1820 (old) months of age. Age had a more pronounced effect on all indices examined. Hemoglobin, hematocrit and liver iron (μg/g) increased significantly (p<0.05) from young to middle-age and then decreased significantly (p<0.05) in old rats. Preliminary analyses of serum iron, total-iron binding capacity and transferrin saturation showed a declining trend with age. VA status had no effect on all indices examined except hemoglobin. Marginal VA rats had significantly (p<0.05) lower hemoglobin than control VA rats. There was no interaction effect between VA status and age on any of the indices examined. Although it is widely accepted that there is an improvement or no change in iron stores and status with aging, our data show a consistent decline in hematological and iron status parameters in old rats irrespective of VA status; the mechanism(s) and cause(s) of which need to be further evaluated.