The only problem that may arise from high amounts of beta-carotene, as can occur with a high intake of yellow and orange fruits and vegetables and the leafy greens, is an orange-yellow discoloring of the skin. This occurs occasionally when people drink large amounts of carrot juice daily over time. It is of no real consequence and will clear when there is a reduction in carotene intake. Carotenosis can be differentiated from jaundice somewhat by the color and also by the fact that the white parts of the eyes do not turn color as they do with jaundice.

Too much vitamin A intake, however, can lead to slight swelling of the brain and resulting pressure headaches, which may be described as the feeling of a tight band around the forehead. Nausea and vomiting may also occur, as can irritability, dizziness, abdominal pain, and hair loss. Itchy, flaky, or dry skin can also result from too much vitamin A. Anorexia (loss of appetite) and resulting weight loss, liver enlargement, menstrual problems, bone abnormalities or stunted growth, and dry or bleeding lips may also occur. There may be an increased risk of birth defects in pregnant women taking high amounts of vitamin A, say over 400 IUs per pound of body weight. (To be safe, I suggest that pregnant women limit their preformed vitamin A to 15,000 IUs, with additional amounts taken only as beta-carotene.) Children have lower requirements, and toxicity has been seen in babies given adult doses of vitamin A, 20,000–30,000 IUs per day.

Requirements: The Recommended Daily Allowance (RDA)—that is, the minimum dietary or supplemental amount to prevent vitamin A deficiency—is approximately 5,000 IUs per day for the adult. About 10,000–15,000 IUs of beta-carotene will probably convert to about 5,000 IUs of vitamin A in the body. Approximately two medium-sized carrots will give us that daily amount. Since this vitamin is fat soluble and stored in the body, daily sources are not absolutely necessary. Requirements, however, depend on body weight, so larger people need more A. Vitamin A needs are also increased with illness, infection, trauma, anxiety or stress, pregnancy, lactation, and alcohol use or smoking.