But you wouldn't want to rely on the provitamin beta-carotene to meet your Vitamin A requirements.

但是你不能指望β-胡萝卜素来满足人体对维生素 A 的需求。

This is because carrots don't contain Vitamin A but a carotenoid called beta carotene which is a “provitamin” — a substance that can be converted into a vitamin.

因为胡萝卜所含的并不是维生素 A，而是一种叫做β-胡萝卜素的类胡萝卜素，它是一种“维生素原”，一种可以转化成维生素的物质。