Carotenoids

Carotenoids are naturally occurring fat-soluble pigments that are synthesized by plants, algae and photosynthetic bacteria. Carotenoids are the sources of the yellow, orange, and red colors in many plants, e.g., the orange-red colors of oranges, tomatoes and carrots and the yellow colors of many flowers.

Carotenoids can be broadly classified into two classes:

  • carotenes e.g., beta-carotene and lycopene
  • xanthophylls e.g., lutein and zeaxanthin.

Some carotenoids such as beta-carotene can be converted to vitamin A and are referred to as provitamin A carotenoids. As carotenoids cannot be synthesized by humans they must be obtained from vegetables in the diet.

Additional sources for carotenoids are dietary supplements. They are also used to fortify or color many manufactured foods and drinks either in the form of natural extracts or as pure compounds manufactured by chemical synthesis.

Carotenoids are important factors in human health and essential for vision. The role of some carotenoids (e.g. beta-carotene) as the main dietary source of vitamin A is well studied. In addition, potential protective effects of carotenoids against degenerative eye diseases and other deficiency-related disorders have been recognized. Thus, a sufficient intake of carotenoids is crucial for preventing the development of deficiency-related diseases. Moreover, some carotenoids have considerable potential for health promotion and disease treatment.

The contradictory results of some studies show the complexity of the relationship between health and nutrition. The methods for measuring effects are fairly limited and in some cases are considered insufficient (see also Principles – The contradictory science of micronutrients).

Health Functions

Sufficient intake of carotenoids is important, because by working as antioxidants they help the body to protect cells, tissues and organs against the damaging effects of free radicals, which may contribute to the development of disorders such as cancer, heart disease and eye diseases.

Disease Risk Reduction

Results of population studies suggest that carotenoid-rich diets are associated with reduced risk of cardiovascular disease, while other studies did not show such effects *.

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Carotenoids are essential to life and healthy living.

  • Other Applications

    A clinical trial found that people with age-related macular degeneration were able to slow its progression by supplementing with beta-carotene, vitamin C, vitamin E, zinc, and copper. Further studies need to confirm this beneficial effect.

  • Intake Recommendations

    European and U.S. health authorities have decided that the existing evidence is insufficient to establish intake recommendations for carotenoids. Until now, dietary intake of carotenoids that can be converted to vitamin A has been expressed as part of the intake recommendations for vitamin A. Apart from their function as provitamin A, data continues to be accumulated supporting the role of carotenoids as important micronutrients in their own right.

  • Supply Situation

    Scientific and government organizations in Europe and the U.S recommend consumption of foods rich in beta-carotene. The average amount that people currently consume in the U.S. and several European countries is lower than these intake recommendations. To date, there is only very limited data on the consumption of lycopene, lutein, and zeaxanthin.

  • Deficiency

    A low dietary intake of carotenoids has not been directly associated with disease. However, above average intake can improve health (see Disease Risk Reduction and Other Applications).

  • Sources

    Carotenoids are best absorbed with fat as part of a meal. The best sources of carotenoids are yellow/orange vegetables such as carrots, sweet potatoes, pumpkins, and winter squash as well as fruits such as apricots, cantaloupes, papayas, mangoes, carambolas, nectarines, and peaches. Dark green leafy vegetables such as spinach, broccoli, endive, kale, chicory, escarole, watercress and beet leaves are also rich in carotenoids.

  • Safety

    To date, no toxic effects of carotenoids have been reported. An excessive intake of provitamin A carotenoids i.e., beta-carotene, does not produce vitamin A intoxication, making them a safe sources of vitamin A.