Giving rats 40 IU of vitamin E per kg of food stopped almost all fat damage — giving them even more (100 IU) didn’t help any further.

When rats didn't get any vitamin E in their food, their bodies showed more signs of fat damage, no matter what kind of fats they ate.

When rats ate diets with different types of fats, giving them a specific amount of vitamin E (40 or 100 IU per kg of food) greatly lowered signs of fat damage in their bodies, and that amount was enough to stop most of the damage.

Even when rats ate a lot more of the kind of fat that's more likely to go bad (polyunsaturated), their fat damage didn't go up as long as they got enough vitamin E.

Even with different fat diets and different amounts of vitamin E, the rats' testicles and sperm storage areas looked normal — vitamin E didn’t change their appearance.