Vitamin A and Beta-Carotene
May help: Cancer of the lung, stomach, esophagus, mouth, cervix, and colon; angina; genital herpes; colds and flu; osteoarthritis; and low immunity in people with HIV.
Daily Value: Beta-carotene—no DV; vitamin A—5,000 international units (IU), or 1,500 retinol equivalents (RE).
Special instructions: For maximum absorption, take supplements with meals that contain some fat. Do not take with meals or supplements that contain large amounts of pectin, a type of soluble fiber found in citrus fruits.
Who’s at risk for deficiency: Cigarette smokers, alcoholics, and people who eat fewer than three servings a day of fruits or vegetables.
Good food sources: Beta-carotene—dark green, leafy vegetables, orange and yellow vegetables, and yellow fruits. (One large carrot—one of the best food sources—has about 10,600 IU.) Vitamin A—fortified milk and milk products, such as cheese, cream, and butter, and fortified margarine.
Cautions and possible side effects: Avoid taking more than 25,000 IU of beta-carotene as supplements. There is evidence that it causes lung cancer in smokers taking 50,000 IU in supplement form.
Do not take preformed vitamin A supplements unless you are under a doctor’s supervision. Taking more than 50,000 IU (15,000 RE) of preformed, animal-source vitamin A a day over a long period of time can lead to headaches, blurred vision, hair loss, joint pain, dry skin, drowsiness, diarrhea, and enlargement of the liver and spleen. Symptoms slowly disappear once the dosage is reduced. Do not take more than 5,000 IU if you are pregnant or trying to conceive.