What are Phytochemicals? Definition, Sources and Health Benefits

Anne Kamiya, John Koshuta
  • Author
    Anne Kamiya

    Anne has experience in science research and writing. She has a graduate degree in nutrition (focus on nutritional microbiology) and undergraduate degrees in microbiology (immunology and medical microbiology) and English (myth and folklore). She has also worked as an ocean & Earth science educator.

  • Instructor
    John Koshuta
Explore phytochemicals. Learn the definition of phytochemicals and discover the foods that contain them. See the benefits of phytochemicals with examples. Updated: 02/19/2022

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What Are Phytochemicals?

The prefix phyto means plant, and phytochemicals are plant-derived chemicals with bioactive properties (that is to say, they are natural chemicals with specific effects on health). Phytochemicals are found in all plant foods, including fruits, vegetables, legumes, nuts, grains, tea, wine, spices, and more. Phytochemicals are protective for plants against ultraviolet light, predators, insects, and disease. Many phytochemicals also act as pigments and give fruits and vegetables their varied and bright hues. Examples of phytochemical pigments are the orange in carrots and the blue in blueberries. Phytochemicals are the desired area of study in medical and nutritional science because many of them have antioxidant, anticarcinogenic, neuroprotective, or anti-inflammatory properties. The phytochemicals definition will be discussed in detail in the following sections.

Plant-based foods, like fruits and vegetables, contain phytochemicals. Phytochemicals are also what imparts colorful pigments to these foods.

A variety of colorful plant foods high in phytochemicals.

Phytonutrients: Definition and Other Terminology

Phytonutrients are phytochemicals that have known or suspected beneficial properties to health. So, think of phytochemicals as a general category encompassing all bioactive plant-based chemicals (whether beneficial to health or not) and phytonutrients as a specific category encompassing bioactive plant-based chemicals with benefits to health.

It is important to clarify that phytonutrients are not essential nutrients like vitamins and minerals. Vitamins and minerals are called essential because they are required for basic biological function and are critical for survival. Lack of essential nutrients causes deficiency-based diseases that can be severe or fatal. If vitamin C is removed from the diet, for instance, deficiency causes scurvy. If thiamine is removed, deficiency causes beriberi. No phytochemicals are essential, but they certainly can be protective against some diseases and enhance health and wellness.

When phytonutrients are extracted in a lab and put into supplement form, they are called nutraceuticals. All phytonutrients can potentially become nutraceuticals, but not all nutraceuticals are phytochemicals. For example, probiotics, those good bacteria that help the gut stay healthy, can also be classified as nutraceuticals.

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Types of Phytochemicals

At least 10,000 different kinds of phytochemicals are known to exist, but only a handful of them have been studied in detail. Phytochemicals are separated into different categories based on their chemical structure. The twelve major classifications of phytochemicals are polyphenols, carotenoids, glucosinolates, polysaccharides, lectins, terpenes, alkaloids, polyacetylenes, allium compounds, chlorophyll, capsaicinoids, and betalains. Most of those categories include phytochemicals with chemical or pharmaceutical but not phytonutrient qualities.

Phytochemicals with phytonutrient qualities are generally classified as polyphenols or carotenoids. Fruits and vegetables tend to be the best place to get these phytochemicals from. Some well-studied polyphenols include anthocyanins, isoflavones, cinnamic acid, and tannins. Some well-studied carotenoids include beta carotene, lutein, lycopene, and zeaxanthin. These are just a few phytochemicals. Examples will be discussed in the following sections.

Anthocyanins

Anthocyanins are polyphenols. They are also pigments and water-soluble, so they do not require fat in the diet to be absorbed. Flavonoids are of great research interest because of their anti-inflammatory and neuroprotective properties. Anthocyanins may possibly have health benefits for cardiovascular health, metabolic disease, cancer, and inflammation.

What makes anthocyanins particularly stand out is the intense red, purple, and blue hues they impart. Flowers of these colors, whether edible or inedible, also contain anthocyanin pigments. Some food sources of anthocyanins include berries, red spinach, red kale, purple corn, purple sweet potatoes, red cabbage, acai berries, grapes, and purple carrots.

The image shows two bunches of spinach, side by side. Although both vegetable leaves contain phytochemicals, only the red spinach will have anthocyanins because of its purple pigment.

Red and green spinach with and without anthocyanin pigment.

Carotenoids

Carotenoids include over 700 different phytochemical pigments. Some of these carotenoids are responsible for the yellow, orange, and red hues found in many plant foods. Because they are fat-soluble, carotenoids require fat in the diet to be absorbed. Beta carotene, found in carrots, is a vitamin A precursor, but it is also a carotenoid. Some food sources of carotenoids include carrots, orange and yellow sweet potatoes, bananas, pumpkin, winter squash, plantains, oranges, and tomatoes. Carotenoids may have potential health benefits for cancer, eye diseases, and cardiovascular disease, and are antioxidants.

Lutein

Lutein is an antioxidant and carotenoid that is absorbed into the eye. It is best known for its benefits to retinal and visual health. Lutein may also have neuroprotective qualities because it crosses the blood-brain barrier and enters the brain. Green vegetables such as spinach, kale, collards, dandelion greens, mustard greens, avocado, broccoli, and brussel sprouts have lutein.

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Frequently Asked Questions

Which foods are high in phytochemicals?

Plant-based foods are high in phytochemicals, especially fruits and vegetables. Papaya, tomatoes, berries, leafy greens, and broccoli are some foods all high in phytochemicals.

What are phytochemicals and what is their function?

The natural function of phytochemicals is to protect plants from predators or the environment. However, many of them also happen to have bioactive health properties. Many phytochemicals have anti-carcinogenic, antioxidant and anti-inflammatory health benefits.

What are examples of phytochemicals?

Phytochemicals are natural chemicals in plant-based foods, particularly colorful ones. The major phytochemicals are polyphenols and carotenoids. Specific phytochemicals include lutein, quercetin, anthocyanins, lycopene, curcumin, resveratrol, cinnamic acid, and capsaicin.

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