Phytonutrients, also known as phytochemicals, are natural chemical substances that can be found in plant foods. In fact, “phyto” comes from the Greek word for “plant”. These substances are produced by plants in response to environmental changes as attractants for pollination or to protect themselves against insect and pest attacks, pathogens, ultraviolet sunlight, predators, germs, fungi, bugs, and other threats.
Phytonutrients contribute to the flavor, aroma, and to the beautiful colors of whole plant foods. They are typically found in fruits, vegetables, whole grains, nuts, beans, herbs, tea, coffee, and even in dark chocolate.
Phytonutrients comprise many different chemicals, including carotenoids, indoles, glucosinolates, organosulfur compounds, phytosterols, polyphenols, and saponins.
More than 25.000 phytonutrients can be found in plant foods. On this Wikipedia list of phytochemicals in food you can find an extensive list of phytonutrients and information about where these can be found in foods.
Extensive research has found that when we eat plant foods, phytonutrients protect us from chronic diseases, such as cardiovascular disease, and have potent anti-cancer and anti-heart disease effects. For more details about these health benefits, this recent scientific review of more than 23.000 studies provides Clinical Evidence of the Benefits of Phytonutrients in Human Healthcare.
In any case, you don’t need to read dozens of scientific data to understand how to benefit from the properties of phytonutrients in your eating routine. The best way to benefit from these powerful health effects of phytonutrients is simply to include as many plant-based colorful foods in your meals as possible. In fact, each color provides specific health benefits, and if you maximize the amount of colors you eat, you also maximize your insurance for good health, whilst enriching the range of aromas and flavors you can enjoy with your meals.
Of course, these colors must come from natural whole plant foods, like vegetables and fruits with their skin whenever it’s edible. In fact, plants use phytonutrients to protect themselves against the threats from the external environment, that’s why typically the skin of vegetables are normally brightly colored and offer an high concentration of healthy phytonutrients. This is one of the reasons why it’s important to eat vegetables and fruits with their skin whenever this is possible, such as apples, peaches, eggplants, etc.
In additional to bringing important micronutrients such as vitamins and minerals, plant foods play a crucial role in helping us build and maintain our health by giving us precious phytonutrients. Let’s discover what phytonutrients are and where to find them in foods.
The Connection Between Colorful Foods and Good Health: Why You Should Eat the Rainbow
What follows is just a very small selection of some of the most important phytonutrients and where they can be found in common foods. It’s impossible to make an exhaustive list of phytonutrients, given that there are more than 25.000 of them and in most cases it’s hard to make 1:1 connections between specific phytonutrients and their benefits on health. In fact, a fair assumption is that it is not a certain isolated substance that have beneficial effects on our body, but rather than eating the “whole package”, i.e. eating whole plant foods such as fruits and vegetables, that contain hundreds, of not thousands, phytochemicals that, in combination one with the other, are beneficial for our health.
Having said that, the following list provides some great examples about what types of health benefits are brought by whole foods of various colors.
Red Foods That Contain Phytonutrients
| EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|
| Red foods contains the carotenoid lycopene, which has a powerful effect in protecting us from the gene-damaging free radicals, against prostate cancer, and heart and lung disease. | Strawberries, cranberries, raspberries, tomatoes, cherries, apples, beets, watermelon, red grapes, red peppers, red onions. |
Yellow and Orange Foods That Contain Phytonutrients
| EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|
| Yellow and orange foods contain cryptothanxin, which may help prevent heart disease. | Carrots, sweet potatoes, yellow peppers, oranges, bananas, pineapple, tangerines, mango, pumpkin, apricots, winter squash (butternut, acorn), peaches, cantaloupe, corn. |
Green Foods That Contain Phytonutrients
| EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|
| Green foods are rich in cancer-blocking chemicals like sulforaphane, isothiocyanates, and indoles, which inhibit the action of carcinogens (cancer-causing compounds). | Spinach, avocados, asparagus, artichokes, broccoli, alfalfa sprouts, kale, cabbage, Brussels sprouts, kiwi fruit, collard greens, green tea, green herbs (mint, rosemary, sage, thyme, and basil) |
Purple And Blue Foods That Contain Phytonutrients
| EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|
| Purple and blue foods contain anthocyanins, which are powerful antioxidants that are believed to delay cellular aging and help the heart by blocking the formation of blood clots. | Blueberries, blackberries, elderberries, Concord grapes, raisins, eggplant, plums, figs, prunes, lavender, purple cabbage. |
White And Brown Foods That Contain Phytonutrients
| EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|
| The onion family contains allicin, which has anti-tumor properties. Other foods in this group contain antioxidant flavonoids like quercetin and kaempferol. | Onions, cauliflower, garlic, leeks, parsnips, daikon radish, mushrooms. |
An Overview of Phytonutrients
The 2022 scientific article Clinical Evidence of the Benefits of Phytonutrients in Human Healthcare, published on the journal Nutrients, provides a representation of the main families and chemical structures of phytonutrients found in dietary plants (see the schema below). According to this article: “The properties of phytonutrients allow them to play a role in aspects of metabolic syndrome and associated mechanisms, notably inflammation and oxidation. Experimental studies in cells or in animals have deciphered their mechanistic actions as being antioxidant, anti-inflammatory, antimicrobial, and anticancer in nature.”.
The following schema represents the main families of phytonutrients. For a complete list of phytonutrients and where they can be found in foods, this Wikipedia list of phytochemicals in food is a great source of information.
The Powerful Antioxidant Benefits of Flavonoids
Flavonoids are one specific family of phytonutrients that have very beneficial effects on our health because of their powerful antioxidative properties.
Our body is under constant attack from chemicals called free radicals. When they are in very high levels, they are capable of damaging cells and genetic material. Free radicals are generated by the body as byproducts of transforming the food we eat into energy. Free radicals are also formed after exercising or exposure to cigarette smoke, air pollution, and sunlight.
Free radicals steal electrons from any nearby substances by radically altering their structure or function. Free radical damage can alter our DNA, and it can make circulating low-density lipoproteins (LDL, sometimes called bad cholesterol) molecule more likely to get trapped in artery walls. Free radicals can also alter cells membrane. A chronic and excessive amount of free radicals is called oxidative stress, which can lead to chronic diseases.
Flavonoids are phytonutrients that have powerful antioxidative properties. In a the recent study Long-term dietary flavonoid intake and subjective cognitive decline in US men and women, the authors report: “Scientists found that people with the highest daily flavonoid intakes were 19% less likely to report trouble with memory and thinking, compared to people with the lowest daily flavonoid intakes.”.
In addition to fighting cognitive decline, eating plant foods that contain flavonoids bring several additional health benefits, including the following: hepatoprotective (reduce toxin accumulation and fibrosis), geroprotective (reduce the progression of degenerative diseases), antidiabetes (increase insulin action and glucose utilization), anticancer (decrease cancer cell creation and increase programmed cell death, a process called apoptosis), cardioprotective (decrease bad cholesterol and hypertension), antimicrobial (increase probiotic bacteria and decrease pathogenic microbes), anti-inflammatory (decrease proinflammatory cytokines and leukocyte immobilization), neuroprotective: reduce amyloid deposition (associated with Alzheimer’s disease, Huntington’s disease, etc.) and monoamine oxidase, which removes neurotransmitters from the brain.
There are several types of flavonoids, here is a list with some of the main ones:
| TYPE OF FLAVONOID | PRESENCE IN FOOD |
|---|---|
| Flavones (e.g. luteolin) | Green Chile peppers, celery |
| Flavonols (e.g. quercetin) | Onions, kale |
| Flavanones (e.g. naringenin) | Grapefruit, oranges |
| Flavan-3-ol monomers (e.g. catechins) | Red wine, strawberries |
| Anthocyanins (e.g. cyanidin) | Blackberries, red cabbage |
| Polymers (e.g. theaflavins) | Black tea |
More Beneficial Health Effects of Additional Phytonutrients
Here is a selection of additional phytonutrients and their beneficial effects on our health, according to this WebMD article.
| PHYTONUTRIENT | EFFECT ON HEALTH | PRESENCE IN FOOD |
|---|---|---|
| Alpha-carotene, beta-carotene, and beta-cryptoxanthin | The body converts these phytonutrients to vitamin A | Yellow and orange foods like pumpkins and carrots |
| Lycopene | Lowers the risk of prostate cancer | Red or pink foods, like tomatoes, watermelon, pink grapefruit |
| Lutein and zeaxanthin | May help protect from cataracts and age-related macular degeneration | Green foods like spinach, kale, collards |
| Ellagic Acid | May help protect against cancer by slowing the growth of cancer cells and by helping the liver neutralize cancer-causing chemicals (studies have mainly been done in the laboratory, so its benefits for human health is uncertain) | Red berries and other plant foods like strawberries, raspberries, pomegranates |
| Resveratrol | Antioxidant and anti-inflammatory. Might play a role in reducing the risk of heart disease and certain cancers. May help extend life (based on animal studies, more human studies are needed to confirm this effect). | Grapes, purple grape juice, red wine |
| Glucosinolates | The glucosinolates are trasformed into other chemicals during the cooking process and by digestion of the foods that contain them. These chemicals may help against the development and growth of cancer. | Cruciferous vegetables like brussels sprouts, cabbage, kale, broccoli (glucosinolates are responsible for the odor and flavor of these vegetables) |
| Phytoestrogens (isoflavones and lignans) | Phytoestrogens can have estrogen-like effects and block the effects of the body’s natural supply of estrogen. Isoflavones may lower risk of endometrial cancer and of bone loss in women. Lignans, another type of phytonutrient, are converted by the body into chemicals with some estrogen-like effects. However, there is limited research supporting a role for lignans in preventing endometrial cancer or osteoporosis. | Soy foods (phytoestrogens). e.g. tofu Flaxseeds and sesame seeds (lignans) |
