The addition of alcohol groups and the positions of the carbon double bonds account for a great number of the different carotenoids. Probably the most familiar carotenoid is beta-carotene, which causes the orange color in carrots. It is one of the most widely distributed compounds in nature, and occurs, together with other carotenoids, in green leaves, flowers, and fruits of almost all plants. It is also a food coloring and is used to color margarine yellow. Beta-carotene is considered a drug or dietary supplement and can be purchased in local stores.
Many common plants contain other carotenoids.
The red pigment in tomatoes is lycopene, while Zeaxanthin produces the yellow in corn. The dominant carotenoid in leaves is lutein and violaxanthin is found in yellow flowers. These pigments differ only slightly in chemical structure from beta-carotene. Just as the artist uses a brush and paints to produce a work of art, nature is skilled at synthesizing the appropriate amounts and types of carotenoids to create spectacular arrangements of colors. Virtually all of the colored leaves, flowers, and berries in Alaska contain carotenoids, even the blue and purple ones.