Your body will convert beta carotene to the active retinol- vitamin A at the rate your body requires, and that requirement is proportional to your body weight. An adut males needs about 1000 RE per day, a women 800, unless she's pregnant or nursing, in which case she needs more. If you get your vitamin A in its preformed state, either from food or a supplement, what you take in beyond your needs will be stored. Stored vitamin A can reach toxic levels. Its hard to reach toxic levels if you get all your vitamin A from food, but toxicity is a real danger for people who take vitamin A in capsule form.
Excesses stored in the liver can cause jaundice and liver damage.
Toxic doses begin at 5 to 10 times the recommended intake. Unlike vitamin A, even in large doses beta carotene is not toxic. If you eat lots of foods rich in carotene the biggest danger is that your skin may turn harmlessly orange. Many an infant whose favorite food is pureed carrots has caused him mom to worry when his skin turned a jaundiced looking yellow. Beta carotene receives lots of good press these days, not because of its ability to be converted into vitamin A, but because of its recently discovered anti-oxidant properties.