Nutrient-gene interactions in mitochondrial function: vitamin A needs are increased in BHE/Cdb rats

The BHE/Cdb rat has a maternally inherited mutation in the ATPase 6 mitochondrial gene that associates with impaired oxidative phosphorylation (OXPHOS) and glucose intolerance. A longevity study revealed that feeding an egg-rich (vitamin A-rich) diet delayed the onset of impaired glucose tolerance. Two experiments were conducted to test the hypothesis that BHE/Cdb rats require more dietary vitamin A than normal rats. Experiment 1 was a dose-response study examining OXPHOS in BHE/Cdb rats fed one of six levels of vitamin A. In experiment 2 BHE/Cdb and Sprague-Dawley rats were used. The rats were depleted of retinol stores, then repleted with 4 or 12 IU vitamin A/g diet. Vitamin A status was assessed in depleted, never depleted, and depleted/repleted rats. OXPHOS was optimized at 4 IU/g diet for the Sprague-Dawley rats and 12 IU/g diet for the BHE/Cdb rats. These results suggested that the criteria for vitamin intake adequacy in the BHE/Cdb rats is the optimization of mitochondrial OXPHOS. Using this criteria, we conclude that diabetes-prone BHE/Cdb rats require more dietary vitamin A than normal rats.