Antioxidants: Vitamin C, Vitamin E, Selenium, and Carotenoids

Jennifer Hillan, MSH, RD, LD/N

Family, Youth, and Community Sciences

University of Florida/IFAS

Free Radicals

• Oxygen and nitrogen molecules with unpaired electrons– highly reactive, unstable

– attack and damage cells

• Free radical damage may lead to development of variety of diseases (including cancer, heart disease) and even the aging process itself.

Rock, 1998

Sources of Free Radicals

• Normal activities occurring in the body’s cells, such as energy production

• Environmental sources– UV sunlight– Alcohol– Ozone– Cigarette smoke– Smog and other pollutants

Functions of Antioxidants

• Attack free radicals in various ways, such as:– Removing free radicals from bloodstream

– Donating electrons to stabilize free radicals

• Repair damage caused by free radicals

Different antioxidants work in different ways and in different places in the body, so it’s important to eat a variety of foods to get a variety of antioxidants!

Definitions

• Recommended Dietary Allowances (RDA): amount of nutrient that will meet the needs of 97-98% of a population group

• Tolerable Upper Intake Level (UL): maximum amount of a nutrient that does not pose a health risk to individuals

Intakes above UL increase risk of harmful effects. No established benefit for healthy people to get higher amounts than the RDA.

Vitamin C• Stabilizes free radicals by donating electrons• RDA:

– women: 75 mg/day

– men: 90 mg/day

– smokers: additional

35 mg/day

• UL: 2,000 mg/day

Food and Nutrition Board, 2000

Vitamin C Sources

• Citrus fruits• Dark green vegetables• Guava• Papaya• Cantaloupe• Strawberries• Peppers• Tomatoes• Mangoes• Potatoes

Vitamin E

• Converts free radicals to harmless waste products

• RDA: 15 mg/day or 22 IU• UL: 1,000 mg/day or

1,500 IUHigher intakes increase risk of bleeding.

Food and Nutrition Board, 2000

Vitamin E Sources

• Nuts & seeds• Vegetable oils & foods made from vegetable

oils like margarine and salad dressing• Fortified cereal• Wheat germ• Leafy green vegetables• Avocadoes

Selenium

• Part of enzymes that attack free radicals• Works closely with vitamin E• RDA: 55 mcg/day

Most people get this amount from the diet. Supplements are not recommended.

• UL: 400 mcg/day

Food and Nutrition Board, 2000

Selenium Sources

• Seafood, especially halibut, salmon, snapper, scallops, and clams

• Brazil nuts

• Liver

• Kidney

• Meat

• Grains

Carotenoids• Many in plants, including beta carotene, lycopene, lutein• Body uses carotenoids to make vitamin A• Conflicting evidence of antioxidant benefits• No RDA or UL set• Can get too much from supplements, but not food

Carotenoid-rich fruits & vegetables recommended, NOT supplements!

Food and Nutrition Board, 2000

Carotenoid Sources

• Dark green leafy vegetables– Broccoli, spinach,

romaine lettuce

• Deep yellow and orange fruits and vegetables– Sweet potatoes,

carrots, mangoes, cantaloupe

Resources for Consumers and Educators…

UF/IFAS Publications

• FCS8639 - Facts About Vitamin A

• FCS8702 - Facts About Vitamin C

• FCS8641 - Facts About Vitamin E

Miscellaneous Factsheets

• National Institutes of Health– Vitamin A– Vitamin E– Selenium

• The American Dietetic Association– Antioxidant Vitamins for Optimal Health

Summary

• Antioxidants attack free radicals and help repair cell damage caused by free radicals.

• Aim for RDA; avoid intakes higher than UL.

• Eat a variety of food, including five or more fruits and vegetables every day!