How many known Carotenoids are there?

Info Source:

http://www.nlm.nih.gov/medlineplus/ency/article/002400.htm

Carotenoids are dark-colored dyes (pigments) found in plant foods that can turn into a form of vitamin A. There are more than 500 known carotenoids. One such carotenoid is beta-carotene.

• Beta-carotene is an antioxidant. Antioxidants protect cells from damage caused by substances called free radicals. Free radicals are believed to contribute to certain chronic diseases and play a role in the aging processes.
• Food sources of carotenoids such as beta-carotene may reduce the risk for cancer.
• Beta-carotene supplements do not seem to reduce cancer risk.