Carotenoids

Sources of carotenoids

Carotenoid-containing foods are often red, yellow or orange, but not always. Louis Premkumar, a professor of pharmacology at Southern Illinois University School of Medicine and author of “Fascinating Facts about Phytonutrients in Spices and Healthy Food” (Xlibris, 2014), told Live Science that carrots, yams, sweet potatoes, papaya, watermelon, cantaloupe, mangos, spinach, kale, tomatoes, bell peppers and oranges are among the fruits and vegetables in which carotenoids can be found.

Animals cannot manufacture carotenoids themselves; they have to get it in their diets. Carotenoids need to be consumed with a fat in order for the body to absorb them. According to the Linus Pauling Institute at Oregon State University, carotenoids need to leave the food they came in and become part of mixed micelles, which are combinations of bile salts and lipids. The presence of a fat makes this process possible.

The carotenoid family

There are more than 600 types of carotenoids. The most common ones in the Western diet, and the most studied, are alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, zeaxanthin and lycopene, according to the Linus Pauling Institute.

There are two broad classifications of carotenoids: carotenes and xanthophylls, said Premkumar. The difference between the two groups is chemical: xanthophylls contain oxygen, while carotenes are hydrocarbons and do not contain oxygen. Also, the two absorb different wavelengths of light during a plant’s photosynthesis process, so xanthophylls are more yellow while carotenes are orange.

Nutritionally, there is another, potentially more useful, grouping of carotenoids: provitamin A and non-provitamin A. Provitamin A carotenoids can be turned into vitamin A (retinol) in the intestine or liver. Vitamin A is an important component to human health. It helps maintain eye health, healthy mucus membranes and immunity. Alpha-carotene, beta-carotene and beta-cryptoxanthin are provitamin A carotenoids; lutein, zeaxanthin and lycopene are not.