University of Hawai‘i at Mānoa Food Science and Human Nutrition Program and Human Nutrition Program
Phytochemicals are chemicals in plants that may provide some health benefit. Carotenoids are one type of phytochemical. Phytochemicals also include indoles, lignans, phytoestrogens, stanols, saponins, terpenes, flavonoids, carotenoids, anthocyanidins, phenolic acids, and many more. They are found not only in fruits and vegetables, but also in grains, seeds, nuts, and legumes.
Many phytochemicals act as antioxidants, but they have several other functions, such as mimicking hormones, altering absorption of cholesterol, inhibiting inflammatory responses, and blocking the actions of certain enzymes.
Phytochemicals are present in small amounts in the food supply, and although thousands have been and are currently being scientifically studied, their health benefits remain largely unknown. Also largely unknown is their potential for toxicity, which could be substantial if taken in large amounts in the form of supplements. Moreover, phytochemicals often act in conjunction with each other and with micronutrients. Thus, supplementing with only a few may impair the functions of other phytochemicals or micronutrients. As with the antioxidant vitamins, it is the mixture and variety of phytochemicals in foods that are linked to health benefits.
Table 9.33 Some Phytochemical’s Obtained from Diet and Their Related Functions
| Phytochemical | Phytochemical Source | Phytochemical Function: |
| Carotenoid | Yellow-orange fruits, dark green leafy vegetables | May possess strong cancer-fighting properties |
| Indoles | Cruciferous vegetables (i.e. bok choy, broccoli, choy sum) | May inhibit the development of cancer-causing hormones and prevent tumor growth |
| Phytoestrogen | Grapes, berries, plums, soybeans, tofu, garlic | May lower the risk for osteoporosis, heart disease, breast cancer, and menopausal symptoms |
| Stanols | Grains, nuts, legumes | May lower blood cholesterol levels and reduce the risk of heart disease and stroke |
| Saponins | Broad beans, kidney beans, lentils | May decrease blood lipids, lower cancer risks, and lower blood glucose response |
| Terpenes | Citrus fruits | May slow cancer cell growth, aid in immune system support, and prevent virus related illness |
| Flavonoids | Fruits, vegetables, chocolates, wines, teas, nuts, seeds | May benefit the immune system and prevent cancer cell growth. |
| Anthocyanidins | Fruits and vegetables with vibrant colors of orange, red, purple, and blue | May prevent cardiovascular disease, reduce cancer cell proliferation (growth/multiplication) and inhibit tumor formation. |
| Phenolic acids | Coffee, fruits, vegetables, nuts, cereals, legumes, oilseeds, beverages and herbs | May prevent cellular damage due to free-radical oxidation reaction and promote anti-inflammatory conditions in the body. |
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Learning Activities
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A substance found in plants that is not an essential nutrient but may have health-promoting properties.
A class of retinoids that can serve as precursors of vitamin A.
Essential nutrients that are needed by the body in small amounts. These include vitamins and minerals.
Compounds that inhibit the oxidation of other substances.
