As part of a healthy diet or in supplement form, vitamin E can bolster your immune system. It's an antioxidant, so it can inhibit damage caused by free radicals, certain molecules created when your body processes food, or from toxins, such as cigarette smoke. Although vitamin E can promote health in recommended doses, researchers at Johns Hopkins University indicated in 2004 that excessive doses of vitamin E can be dangerous.
Recommended Daily Allowance
People 14 years old or older need 22.4 International Units, or IU, of vitamin E per day. This translates to 15 milligrams. Children and younger teenagers need less, between 6 and 11 milligrams, depending on their age. Women who are nursing need more, up to 19 milligrams.
How Much is Too Much
The Office of Dietary Supplements sets tolerable upper intake levels for all vitamins, including vitamin E. ULs are the safest amount you can consume -- from food and supplements -- without facing a significant risk of side effects. The UL for teenagers between 14 and 18 years old is 1,200 IU per day, or 800 milligrams. If you're 19 or older, you can consume up to 1,500 IU per day, or 1,000 milligrams. More than this amount, especially if you take it regularly, might present health risks. Significantly more than this in one dose might present complications from overdose.
Overdoses of vitamin E are rare. It's virtually impossible to overdose through diet alone. But, if you take supplements, and if you take more than the tolerable upper intake level for your age, you might risk blurred vision, weakness, dizziness, nausea and diarrhea. If you're also taking an anticoagulant medication, such as warfarin, bleeding can result. Repeated daily doses of vitamin E of 400 IU or more, or above 267 milligrams per day, are associated with an increased risk of death, according to the researchers at Johns Hopkins University. This is well below the ULs issued by the Office of Dietary Supplements.
According to Aetna InteliHealth, if you eat one egg, 1 ounce of toasted almonds and 1 ounce of wheat germ per day, you'll meet the recommended daily allowance for vitamin E without needing supplements. Even if you also take a single vitamin E supplement, it's unlikely that you would reach or surpass the UL levels. Other natural sources of vitamin E include leafy green vegetables, fruits, whole grains, nuts and nut oils, as well as poultry, meat and eggs.