Carotenoids, also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria and fungi. Carotenoids give the characteristic color to pumpkins, carrots, corn, tomatoes, canaries, flamingos, and daffodils.
Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms. The only animals known to produce carotenoids are aphids and spider mites, which acquired the ability and genes from fungi, and it is produced by endosymbiotic bacteria in whiteflies.
Carotenoids from the diet are stored in the fatty tissues of animals, and exclusively carnivorous animals obtain the compounds from animal fat. In the human diet, absorption of carotenoids is improved when consumed with fat in a meal. Cooking carotenoid-containing vegetables in oil increases carotenoid bioavailability.
Many common foods contain rich sources of polyphenols which have antioxidant properties only in test tube studies. As interpreted by the Linus Pauling Institute, dietary polyphenols have little or no direct antioxidant food value following digestion. Not like controlled test tube conditions, the fate of flavones or polyphenols in vivo shows they are poorly absorbed and poorly conserved (less than 5%), so that most of what is absorbed exists as metabolites modified during digestion, destined for rapid excretion. Spices, herbs, and essential oils are rich in polyphenols in the plant itself and shown with antioxidant potential in vitro.
Typical spices high in polyphenols (confirmed in vitro) are:
Typical herbs are:
Dried fruits are a good source of polyphenols by weight/serving size as the water has been removed making the ratio of polyphenols higher.
Typical dried fruits are:
Dried raisins are high in polyphenol count. Red wine is high in total polyphenol count which supplies antioxidant quality which is unlikely to be conserved following digestion.
Deeply pigmented fruits also have significant polyphenol content.
Typical deeply pigmented fruits:
Typical cooked vegetables rich in antioxidants are:
Nuts are a moderate source of polyphenol antioxidants.
Typical nuts are:
Procyanidins are large molecular weight compounds found in many fruits and some vegetables. Partly due to the large molecular weight (size) of these compounds, their amount actually absorbed in the body is low, an effect also resulting from the action of stomach acids, enzymes and bacteria in the gastrointestinal tract where smaller derivatives are metabolized and prepared for rapid excretion.
Sources of procyanidins are: