Phytochemicals
Phytochemicals are natural compounds found in plants that are not classified as traditional nutrients or vitamins but play a significant role in promoting health. They are produced by plants to protect themselves from environmental stresses, such as pests, and to attract pollinators. Phytochemicals are abundant in a diet rich in fresh fruits, vegetables, and whole grains, and they are thought to contribute to lower incidences of various diseases, including cancer, diabetes, and heart conditions, largely due to their antioxidant properties.
There are thousands of types of phytochemicals, two well-known groups being carotenoids and flavonoids. Carotenoids are found in colorful vegetables like carrots and bell peppers, while flavonoids, abundant in fruits like blueberries and beverages such as tea, are recognized for their antioxidant benefits. Despite ongoing research into their protective effects, scientists have yet to identify specific phytochemicals responsible for health benefits, suggesting that the synergistic effects of multiple compounds may be essential.
It is recommended to obtain phytochemicals through a varied diet rather than supplements, as concentrated forms may pose health risks over time. As research continues into the role of phytochemicals in supporting the immune system and reducing inflammation, they remain a focus of interest for their potential health implications and contributions to overall well-being.
Phytochemicals
Biology
Anatomy or system affected: All
Definition: Nonnutritive chemicals produced by plants that provide health benefits to humans who eat plant-derived foods
Protective Role and Abundance
People who eat a diet rich in fresh fruits, vegetables, and whole grains obtain some protection from various diseases because of the phytochemicals that the plants contain. Phytochemicals are not traditional nutrients, such as proteins, carbohydrates, or fats, nor are they vitamins or minerals. Instead, they are substances that plants produce to protect against environmental stresses, such as attack by fungi and other organisms, or to attract animal pollinators or seed dispersers. Many phytochemicals are plant pigments, giving fruits and vegetables their animal-luring colors. There are thousands of phytochemicals, and plant species vary widely in the kinds and amounts that they contain.
Many phytochemicals have antioxidant properties, meaning that they help protect cells from oxidative damage, which has been implicated in cancer, diabetes, heart disease, strokes, and other disorders. Some phytochemicals function in humans in ways similar to the female hormone estrogen.
Although diets rich in plant-based foods have been shown to result in lower incidences of a number of diseases, scientists have had difficulty pinpointing which of the many different phytochemicals are protective. It may be that the interaction of a variety of naturally occurring phytochemicals, rather than any particular ones, is a significant factor in promoting health.
Well-Known Types
One important group of phytochemicals, carotenoids, includes many antioxidants. Carotenoids may be found in pumpkins, carrots, and bell peppers. Of the numerous health claims that have been made for these plant pigments, one of the few to be substantiated is that increased consumption of lutein, a carotenoid found in green leafy vegetables such as collards, kale, spinach, and broccoli, is associated with a lowered risk for macular degeneration, an eye disease associated with advanced age.
Flavonoids, pigments that belong to a major class of phytochemicals called polyphenols, are abundant in vegetables, fruits such as blueberries and raspberries, and beverages such as tea, red wine, and fruit juices. Some flavonoids, including the widely occurring group anthocyanins, have antioxidant properties. Flavonoids, called isoflavones, are plant estrogens plentiful in soy products.
Other phytonutrients include anthocyanidins, found in red and purple berries; beta-carotene, found in orange and dark green vegetables; catechins, found in apricots and strawberries; isoflavones, found in soybeans; and polyphenols, found in cherries and dark cherries.
Perspective and Prospects
The discovery that phytochemicals are important to human health was not made until late in the twentieth century, and research continues. Scientists do not advise taking dietary supplements of particular phytochemicals but recommend a diet high in a variety of fruits, vegetables, and whole grains. Taking concentrated forms of phytochemicals might be harmful over the long term. Research as of the early 2020s indicated phytochemicals ensure proper functioning of the immune system when infection does occur, and they may reduce inflammation in individuals with inflammatory diseases.
Bibliography
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Meskin, Mark S., Wayne R. Bidlack, Audra J. Davies, and Stanley T. Omaye, eds. Phytochemicals in Nutrition and Health. CRC Press, 2002.
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"What are phytochemicals? (And Why Should You Eat More of Them?)." UCLA Health, 10 May 2023, www.uclahealth.org/news/what-are-phytochemicals-and-why-should-you-eat-more-them. Accessed 15 July 2023.