Phytonutrients, also called phytochemicals, are chemicals produced by plants. Plants use phytonutrients to stay healthy. For example, some phytonutrients protect plants from insect attacks, while others protect against radiation from UV rays.

Phytonutrients can also provide significant benefits for humans who eat plant foods. Phytonutrient-rich foods include colorful fruits and vegetables, legumes, nuts, tea, whole grains and many spices. They affect human health but are not considered nutrients that are essential for life, like carbohydrates, protein, fats, vitamins and minerals.

Among the benefits of phytonutrients are antioxidant and anti-inflammatory activities. Phytonutrients may also enhance immunity and intercellular communication, repair DNA damage from exposure to toxins, detoxify carcinogens and alter estrogen metabolism. The U.S. Department of Agriculture (USDA) notes that consuming a phytonutrient-rich diet seems to be an “effective strategy” for reducing cancer and heart disease risks.

Many phytonutrients give plants their pigments, so a good way to tell if a fruit or vegetable is rich in phytonutrients can be by its color, according to Louis Premkumar, a professor of pharmacology at Southern Illinois University School of Medicine and author of “Fascinating Facts about Phytonutrients in Spices and Healthy Food” (Xlibris, 2014). Look for deep-hued foods like berries, dark greens, melons and spices. These foods also are rich in flavor and aroma, which makes them more palatable. But some phytonutrient-rich foods have little color, like onions and garlic, and you don’t want to discount them.

Understanding the effectiveness of phytonutrients

There is ample evidence that a diet high in phytonutrient-rich plant foods is good for humans. “For centuries, there have been implications that healthy food garnished with exotic spices and condiments provides vital ingredients that help ward off diseases and promote longevity,” Premukar said. “Obviously, it appears to be true based on the evidence that people who consume healthy, wholesome food as individuals or as a group in certain parts of the world, have enjoyed health benefits, using longevity as a metric.

“For example, Seventh-day Adventists, with their pure vegetarian diet, have a lower incidence of heart disease, diabetes, and certain types of cancers; Kuna Indians in Panama, who consume large quantities of unprocessed cocoa-containing beverages, show lower incidence of heart disease,” he continued. “More recently, the Mediterranean diet, which consists of olive oil, fresh produce, fish, and wine, has been shown to reduce the incidence of grave diseases.”

Though population studies demonstrate the effectiveness of a diet full of phytonutrient-rich foods, scientists are still working to understand the specific mechanisms of how phytonutrients work. Premkumar said that not enough randomized, large-scale clinical trials have been undertaken, and even when they are it can sometimes be difficult to quantify the results. Furthermore, many trials have been done on phytonutrient or antioxidant supplements, which have returned fairly poor results when it comes to disease prevention, according to the National Institutes of Health(NIH). But this is likely because supplements interact with the body differently than whole foods.

It can sometimes be hard for scientists to link health benefits to specific phytonutrients. All plants contain complicated mixtures of bioactive compounds and effects like antioxidant activity can be difficult to quantify. Furthermore, each individual plant possesses a unique biochemical makeup. “The levels of active ingredients can vary, depending upon where the plant is grown, the amount of fertilizers used, whether they are cooked on uncooked, and so on,” Premkumar said.

Additionally, it can be difficult to infer the levels at which the phytonutrients act in each individual body, said Premkumar. Phytonutrients are diverse in nature and affect multiple areas of the body, which sometimes makes it challenging to know precisely which phytonutrient is acting on which part of the body, and if the phytonutrients are helping temporary symptoms or systemic problems.

Despite these challenges, Premkumar said that the health benefits from phytonutrients, even if they cannot be demonstrated readily, “have to be taken seriously.” Government agencies like the USDA, NIH and several health organizations seem to agree, and encourage people to eat more fruits and vegetables and take advantage of the potential benefits from these foods.

According to Premkumar, one thing we do know is that the beneficial effects of phytonutrients will not be seen immediately, but over months or years. He pointed out that phytonutrients and other healthy compounds like vitamins and minerals can only prevent or delay developing diseases. “Once a disease has manifested, the only option to combat is to consult with a physician and take appropriate medications that have been unequivocally proven to be effective in large clinical trials,” he said.

Types of phytonutrients

There are classes of phytonutrients, determined by chemical structure. Phytonutrient classes include:

  • Betalains
  • Chlorophyll
  • Indoles
  • Organosulfides
  • Phenols
  • Terpenes
  • Triterpenes

Within these classes are dozens of phytonutrient groups, which in turn contain hundreds of phytonutrients.

Phytonutrient groups include:

  • Carotenoids
  • Curcuminoids
  • Flavonoids
  • Glucosinolates
  • Hydroxycinnamic acids
  • Lignans
  • Lipids
  • Stilbenes
  • Sulfides
  • Tocopherol

There are more than 25,000 types of phytonutrients. Scientists consider these six phytonutrients or phytonutrient groups to be of particular note.


Lignans can mimic the effects of estrogen, so lignans are considered phytoestrogens, though they can also affect the body through non-estrogenic means, according to the Linus Pauling Institute at Oregon State University.

Like all phytonutrients, lignans are found in fruits and vegetables, especially kale, broccoli, apricots and strawberries, according to Premkumar. They are particularly abundant in seeds and whole grains, including sesame seeds, poppy seeds, rye and oat bran. Flaxseeds are the richest source of lignans.

Lignans are associated with preventing hormone-related cancers because of their estrogen-like activity, according to the Linus Pauling Institute. Research is mixed about their effectiveness in preventing breast cancer, but studies have shown positive results in terms of endometrial and ovarian cancers. A Journal of the National Cancer Institute study looking at lignans and endometrial cancer showed a reduced risk in postmenopausal women with high lignin intake, while another study, published in the Journal of Nutrition, saw women with the highest lignin intake had the lowest ovarian cancer rates, regardless of age or menopausal status.

Scientists are beginning to study the relationship between lignans and prostate cancer and osteoporosis. So far, results are inconclusive.


Resveratrol has gotten a good deal of buzz in recent years because large concentrations of it are found in red wine. It is a member of the stilbenoid phytonutrient group.

The best-known source of resveratrol is grapes. Resveratrol has particularly high concentration in grape skin and red wine. It is also found in peanuts, grape juice, cocoa, blueberries and cranberries. The presence of resveratrol in red wine may explain what Premkumar called the “French paradox,” in which French people who drink a good deal of red wine enjoy long and healthy lives despite eating saturated fats and smoking. Premkumar said this is likely because of resveratrol’s ability to reduce the risk of heart disease through antioxidant and anti-inflammatory activities.

According to the Linus Pauling Institute, resveratrol may help slow cognitive decline. In animal studies, resveratrol has shown neuroprotective activities and promotion of healthy peptides. A 2010 human study published in the American Journal of Clinical Nutrition found that resveratrol increased cerebral blood flow but did not lead to improved performance in cognitively difficult tasks. Scientists will continue to study resveratrol’s effects in this area.

Resveratrol is also being studied as a possible treatment for type 2 diabetes because in animal studies, it has been shown to improve insulin sensitivity and glucose tolerance, according to a 2015 article in Biochimica Biophysica Acta.


There are more than 600 carotenoids. They are yellow, orange and red pigments in plants. The most common carotenoids in a Western diet are alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, zeaxanthin and lycopene. Each of these carotenoids carries a distinct set of actions, benefits and originating fruits and vegetables.

Premkumar listed carrots, yams, sweet potatoes, papaya, watermelon, cantaloupe, mangos, spinach, kale, tomatoes, bell peppers and oranges among the fruits and vegetables in which carotenoids can be found. In order to be properly absorbed, carotenoids should be consumed with a fat.

Carotenoids are associated with antioxidant activity, eye health, immune system activity, intercellular communication and reduced risk of cancer and cardiovascular disease, according to the Linus Pauling Institute.

The body can covert alpha-carotene, beta-carotene and beta-cryptoxanthin into vitamin A (retinol), which is associated with anti-aging and immune system function. Lutein and zeaxanthin are the only carotenoids found in the retina and are associated with lower risks of macular degeneration, according to the Linus Pauling Institute.


Curcumin is found primarily in turmeric, a member of the ginger family. It gives turmeric its distinctive yellow color. Because of its curcumin, turmeric has been used as a medicinal remedy in India for centuries, said Premkumar.

“The claimed effects of curcumin range from relieving flatulence to curing Alzheimer’s disease and cancer,” said Premkumar. Animal studies have shown good results when looking at oral administration of curcumin and to inhibit the spread of mouth, stomach, liver and colon cancer. Studies are under way to investigate this effect in humans.

Curcumin is an effective anti-inflammatory agent and antioxidant. It may also affect carcinogen metabolism, helping the body get rid of toxic compounds, and aid in combating cancer cell growth and tumors, according to the Linus Pauling Institute. All of these factors contribute to its being a potentially effective cancer-prevention agent.

Based on successful animal trials, it has been suggested that curcumin could aid in inflammatory diseases like rheumatoid arthritis as well as cystic fibrosis and Alzheimer’s disease, but studies are either not yet under way or are inconclusive, according to the Linus Pauling Institute.

According to Premkumar, curcumin can also be helpful in cardiovascular protection by lowering LDL cholesterol levels and increasing HDL (good) cholesterol levels. “Treatment with curcumin selectively increases the expression of low-density lipoprotein (LDL) receptor levels and is able to clear LDL, which is bad or lousy cholesterol,” he said.

Ellagic acid

Ellagic acid is also called a tannin. It is found in raspberries, strawberries, blackberries, cranberries, grapes, pomegranates and walnuts, according to Premkumar. It can also be produced during the body’s process of breaking down larger phytonutrients called ellagitannins. It is absorbed rapidly.

Ellagic acid is associated with antioxidant, anti-inflammatory and anti-cancer activity, as well as reducing blood pressure and arterial plaque, said Premkumar.

According to the Memorial Sloan Kettering Cancer Center, scientists hypothesize that ellagic acid enhances detoxing enzymes in the liver while also inhibiting liver enzymes that encourage metabolism. Combined, these actions cause carcinogens to be removed before they can be metabolized. Another hypothesis is that ellagic acid changes the cellular structure of tumor cells. Both of these hypotheses have been supported by animal studies but have not been proven in humans.

Another potential benefit from ellagic acid is improved glucose metabolism. According to a 2010 article in the Journal of Medicinal Food, ellagic acid may block the intestinal enzyme alpha-glucosidase, which triggers glucose absorption. This means that less glucose enters the bloodstream, which could be beneficial for type 2 diabetics and hyperglycemics.


Flavonoids are a very large group of phytonutrients. Well-known flavonoids include quercetin and kaempferol. There are several significant subgroups of flavonoids, including flavones, anthocyanins, flavonones, isoflavones, flavonols and flavanols.

Because they are so diverse, flavonoids are found across a large range of foods. Premkumar listed apples, onions, coffee, grapefruit, tea, berries, chocolate, legumes, red wine, broccoli, cabbage, kale, leeks, tomatoes, ginger, lemons, parsley, carrots and buckwheat as a sampling.

Flavonoids are associated with longevity and reduced risk of cardiovascular disease and cancer. One large-scale, 25-year study, published in Archives of Internal Medicine, looked at men across seven countries and found that flavonoid consumption was significantly associated with longevity.

Phytonutrients … polyphenols … antioxidants … what do all of these terms mean?

The term phytonutrients is a broad name for a wide variety of compounds produced by plants. They’re found in fruits, vegetables, beans, grains, and other plants. Each phytonutrient comes from a variety of different plant sources and has different proposed effects on, and benefits for, the body. Some researchers estimate there are up to 4,000 phytonutrients! Scientists have identified thousands of them, although only a small fraction of phytonutrients have been studied closely.

Common Names for phytonutrients: antioxidants, flavonoids, phytochemicals, flavones, isoflavones, catechins, anthocyanidins, isothiocyanates, carotenoids, allyl sulfides, polyphenols

How Do You Get Phytonutrients?
Phytonutrients are found in plant foods (fruits, vegetables, beans, grains). By maintaining a balanced eating pattern that includes different forms and colors of fruits and vegetables, you’ll provide your body with a wide variety of all beneficial compounds, including phytonutrients! So, enjoy your fruits and veggies during every eating occasion … just fill half your plate with them and leave the rest for grains and protein.

The Health Benefits of Phytonutrients
New experimental studies are emerging that demonstrate multiple effects of fruits and vegetables (and their phytonutrients), suggesting that they may have an even greater role to play in human health than the already positive results seen to date.

Top 6 Phytonutrients You May Know About

Phytonutrient Proposed Benefits Food Sources Fun Facts
Beta-Carotene Immune System
Skin Health
Bone Health
Sweet Potato
Winter Squash
Collard Greens
Think orange and dark, leafy green veggies
Lycopene Cancer (Prostate)
Heart Health
Pink Grapefruit
Red Peppers
Tomato Products
The heating process makes lycopene easier for the body to absorb
Lutein Eye Health
Heart Health
Collard Greens
Brussels Sprouts
This phytonutrient is found in the macula of the eye
Resveratrol Heart Health
Lung Health
Red Wine
1 cup of red grapes can have up to 1.25 mg of resveratrol¹
Anthocyanidins Blood Vessel Health Blueberries
Red Onions
Red Potatoes
Red Radishes
Think red and purple berries
Isoflavones Menopause
Cancer (Breast)
Bone Health
Joint Inflammation
Lower Cholesterol
Soybeans ½ cup of boiled soybeans offers 47 mg of isoflavones²

Caution about Supplements: Phytonutrients, in the amounts consumed in a healthy diet, are likely to be helpful and are unlikely to cause any major problems. Some people assume that because phytonutrient supplements come from “natural” sources, they must be safe and free from side effects, but this is not always true. Check with your doctor and pharmacists before consuming any phytonutrient. ¹ Linus Pauling Institute. “Macronutrient Information Center,” Oregon State University, Accessed March 19, 2012 from

² 2Linus Pauling Institute. “Macronutrient Information Center,” Oregon State University, Accessed March 19, 2012 from

What Are These Phytonutrients Everyone Keeps Talking About?

Photo: Enrique Díaz / 7cero / Getty Images

When it comes to healthy eating, superfoods tend to steal the show-and for good reason. Inside those superfoods are vitamins and minerals that keep your body functioning at an optimal level. This includes phytonutrients-or phytochemicals-which are the chemical compounds found in many colorful fruits and vegetables. The good news? This is one health food trend you’re probably already following. Still, here’s what you need to know about why phytonutrients matter and what eating them is doing to protect the only *one* body you’ve got.

What Is a Phytonutrient?

Phytonutrients are natural compounds produced by plants. Think of them as superfoods for plants-including your favorite fruit and veggies-that help maintain the health of the plant by protecting it from environmental elements such as the sun and insects. Phytonutrients have antioxidant and anti-inflammatory properties within their compounds that have a slew of health benefits, says Maya Feller, M.S., R.D., C.D.N., a Brooklyn, NY-based dietitian nutritionist. Phytonutrients are found in many fruits, vegetables, grains, and legumes (think: strawberries, kale, brown rice, and chickpeas) so there’s a good chance you’re already eating them.

Health Benefits of Phytonutrients

Phytonutrients are major disease-fighters. Eating them on the regular is associated with a “decreased risk of heart disease, type 2 diabetes, many cancers, as well as other chronic and preventable diseases,” says Jessica Levinson, M.S., R.D.N., C.D.N., culinary nutrition expert and author of 52-Week Meal Planner. And women, in particular, can really benefit from phytonutrients because research has linked phytonutrients to a reduced risk of breast and ovarian cancers, says Feller. But it’s really the antioxidant effect that has everyone’s attention, says Levinson. “It’s this antioxidant function of combating cell-damaging free-radicals that protects the body from certain cancers and other inflammatory diseases.”

Not to mention, antioxidants have long been heralded for their skin-care benefits. Just look at the incredible benefits of vitamin C skin care and the booming vitamin C beauty products business. Brighter, younger-looking skin by way of blueberries and almonds? Can’t get much easier. (Related: Skin-Care Products That Protect Against Pollution)

How You Can Eat More Phytonutrients

Out of the many different phytonutrients (there are as many as 10,000 different kinds!) consider prioritizing these four in your diet:

  • Flavonoids: Flavonoids contain the common antioxidants catechins and anthocyanins, which are known to fight against cancer and heart disease. You can find flavonoids in green tea, coffee, chocolate (opt for dark chocolate with at least 70 percent cocoa) and citrus fruits like grapefruit and oranges. (Related: Flavonoids are found in many of these anti-inflammatory foods you should be eating regularly.)
  • Phenolic acids: Similar to flavonoids, phenolic acid works as an antioxidant to reduce inflammation in the body. You can find them in cruciferous vegetables such as broccoli, cauliflower, and Brussels sprouts. Fruits that have phenolic acids are apples (leave the skin on because it has a higher concentration), blueberries, and cherries.
  • Lignans: An estrogen-like chemical that can regulate hormones in the body, lignans also contain both soluble and insoluble fiber on top of supporting your immune system. You can find lignans in seeds, whole grains, and legumes. Levinson says that flaxseed is a rich dietary source of lignans, so make sure to sprinkle some of it on top of all those smoothie bowls you eat. (Inspiration: The Ultimate Peanut Butter and Banana Smoothie Bowl Recipe)
  • Carotenoids: These plant pigments have been shown to protect against certain cancers and eye-related diseases. Carotenoids are responsible for the red, yellow, and orange hues in many fruits and vegetables. (Check out these different colored veggies that pack a big nutrition punch for more evidence.) Under the carotenoid umbrella are phytochemicals such as beta-carotene (the orange in carrots) and lycopene (the red in tomatoes). Other food sources include sweet potatoes, winter squash, watermelon, and grapefruit.
  • By By Colleen Travers


Just when you thought you’d learned everything there is to know about anti-oxidants, you may have started reading reports about phytochemicals. Don’t panic — phytochemicals may sound futuristic, but the name is just the most recent label emphasizing the plant source of most of these protective compounds. What is “new” about phytochemicals is recent research about the disease preventing possibilities they hold.

Phytochemicals are certain organic components of plants which scientists have isolated as being beneficial to human health in a different way from traditional anti-oxidants. They are sometimes referred to as phytonutrients, but unlike the traditional nutrients (protein, fat, vitamins, minerals), they are not “essential” for life so the term phytochemical is more accurate. Still, a true nutritional role for phytochemicals is becoming more probable every day as researchers uncover more and more benefits. It is possible that phytochemicals may indeed someday be classified as essential nutrients.

Phytochemicals have proven to be beneficial in many ways. They may serve as anti-oxidants in a bodily system when required; for example, the phytochemical beta-carotene can metabolize to create vitamin A, a powerful anti-oxidant. Additionally, phytochemicals may enhance immune response and cell-to-cell communication, allowing for the body’s built-in defenses to work more efficiently. Phytochemicals may even alter estrogen metabolism, cause cancer cells to die (apoptosis), repair DNA damage caused by smoking and other toxic exposure, and detoxify carcinogens by working with bodily enzymes.

Some of the common classes of phytochemicals include carotenoids, flavonoids, phenols and terpenes. Of all the phytochemicals, we probably know the most about carotenoids, the red, orange and yellow pigments found in fruits and vegetables. Carotenoids are actually a subclass of a phytochemical called terpenes, probably the most common of all the phytochemicals. Terpenes can be found in almost all plant life and have a beneficial function within plants themselves; in humans, they also seem to battle against certain cancers and even heart disease. The subclass carotenoids include alpha- and beta- carotene, beta-cryptoxanthin, and lutein, found in carrots, leafy green and yellow vegetables, and citrus or pulpy fruits. Another cartenoid, lycopene, is found heavily in tomatoes. There have been several studies suggesting that these compounds are among the most beneficial components of fruits and vegetables.

Polyphenols are another common phytochemical and generally come in two classifications: flavonoids and non-flavonoids. Found in strawberries, blueberries, raspberries, teas, and soybeans, polyphenols appear to fight allergies, inflammation, free radicals, hepatotoxins, platelet aggregation, microbes, ulcers, viruses and tumors. Some sub-classes of polyphenols also inhibit specific enzymes; for example, flavonoids block the angiotensin-converting enzyme (ACE) that is responsible for raising blood pressure. Flavonoids also protect the vascular system and strengthen the tiny capillaries that carry oxygen and essential nutrients to all cells.

Our understanding of phytochemicals is still in its infancy, but research in this area is expanding rapidly because it appears that phytochemicals offer a measurable amount of protection against oral cancer and other diseases. Will phytochemicals be the preferred “prescription” of tomorrow? Possibly, but in any case they are helping teach us more about natural defenses against cancer, and that is a good thing by any name.








Parental concerns



Phytonutrients are a class of nutrients that are thought to have health-protecting properties. The prefix phyto is from the Greek and means plant, and it is used because phytonutrients are obtained only from plants.


Unlike the macronutrients (proteins, carbohydrates, fats ) and micronutrients (vitamins, trace minerals ) that are needed for growth, metabolism, and other body functions, phytonutrients are not considered essential. This is because they can be lacking in the diet without harmful health consequences. However, throughout history, plants have been cultivated and used to prevent and treat various human diseases. More recently, understanding the chemical role played by these phytonutrients in plants has provided new clues as to how they may help humans. When eating plant-based foods, some of these phytonutrients identified as protectors in plants are transferred to our

Ways phytonutrients may protect human health

Serve as antioxidants

Enhance immune response

Enhance cell-to-cell communication

Alter estrogen metabolism

Convert to Vitamin A (beta-carotene is metabolized to vitamin A)

Cause cancer cells to die (apoptosis)

Repair DNA damage caused by smoking and other toxic exposures

Detoxify carcinogens through the activation of the cytocrome P450 and Phase II enzyme systems

More research is needed to firmly establish the mechanisms of action of the various phytochemicals

SOURCE:Agricultural Research Service, U.S. Department of Agriculture

(Illustration by GGS Information Services/Thomson Gale.)

bodies. The herbs and spices used for adding flavors and tastes to foods are now known to be associated with a long list of potential beneficial effects on human health. Phytochemicals derived from the plants to this day remain the basis of several medications used for the treatment of a wide range of diseases. Throughout the world, botanists and chemists actively search the plant kingdom for new phytochemicals. Over 40% of medicines now prescribed in the Unites States contain chemicals derived from plants. For example, ephe-drine, a phytochemical, is used in the commercial preparation of pharmaceutical drugs prescribed for the relief of asthma symptoms and other respiratory problems. Phytochemicals isolated from plants have also been a great help for discovering a large proportion of the drugs now available for the treatment of a wide range of human diseases such as pulmonary diseases, cardiovascular diseases, diabetes, obesity, and cancers.


There are three broad classes of phytonutrients: phytochemicals, medicinal plants and herbs and spices.


Thousands of phytochemicals have been isolated and characterized from plants, including fruits and vegetables. The most well-known include include ter-penes, carotenoids, flavonoids, limonoids, and phy-tosterols. In nature the bright green and red pigments present in cabbages and lettuce, tomatoes and strawberries have evolved to help absorb otherwise harmful ultraviolet radiation from the sun. They include the yellow, orange, and red carotenoids. Green and leafy vegetables are also rich in a carotenoid called beta-carotene. Flavonoids are other reddish pigments, found in red grape skins and citrus fruits. Other phy-topigments include lutein that makes corn yellow, and lycopene that makes tomatoes red. Aroma compounds in garlic and onions help protect plants from bacterial and viral infections. Others are enzyme blockers that forme to fight toxic pollutants. Plants have developed literally hundreds of thousands of naturally phyto-protective chemicals. It is therefore believed that if people consume them, they may gain some of these protective benefits. When extracted from plants, isolated phytochemicals are grouped into distinctive classes depending on the number and kind of atoms that they contain and according to the chemical structure of their main functional groups. The main classes of phytochemicals are:

  • Alkaloids. This class contains molecules with cyclic carbon groups containing at least one nitrogen atom in the carbon ring. They are obtained chiefly from many vascular plants and some fungi and include steroids and some saponins extracted from beans, cereals, herbs.
  • Aromatics. This class includes substances that contain a benzene ring that consists of six carbon atoms in a flat, hexagonal pattern and are found in aromatic plants such as garlic and onions.
  • Flavonoids. Many are extracted from fruits, and vegetables. They include flavones (found in chamomile), flavonols (found in grapefruit and rutin-buck-wheat), flavanones (from citrus fruits, milk thistle) and the isoflavones (found in soy, peanuts, lentils).
  • Indoles. Indoles, extracted from cabbage, are carbon compounds with two rings, a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring.
  • Phytosterols. Sterols can be extracted from most plant species. Although green and yellow vegetables contain significant amounts, their seeds concentrate the sterols. Most of the research on phytosterols has been done on the seeds of pumpkins, yams, soy, rice and herbs.
  • Terpenes. These are extracted from green vegetables, soy products and grains, and represent one of the largest classes of phytochemicals. The most intensely studied terpenes are carotenoids (from fruits, carrots). A subclass of terpenes are the limonoids found in citrus fruit peels.

It is well-known that plants produce phytochemicals to protect themselves and recent research increasingly shows that they may protect humans as well. Some examples of their health benefits include:

  • Antioxidative properties. Most phytochemicals show antioxidant activity and are thus liable to protect lipids, blood and other body fluids from damage (oxidative stress) from reactive oxygen species while reducing the risk of developing certain types of cancer. Phytochemicals with antioxidant activity include allyl sulfides (onions, leeks, garlic), carotenoids, flavonoids, and polyphenols (tea, grapes).
  • Hormonal properties. Isoflavones, also called phytoestrogens may function as human estrogens and help to reduce menopausal symptoms and osteoporosis.
  • Enzyme stimulation. Indoles stimulate enzymes that lower the activity of estrogen and could reduce the risk for breast cancer. Other phytochemicals, which interfere with enzymes, are protease inhibitors (soy and beans) and terpenes.
  • Interference with DNA replication. Saponins interfere with the replication of cell DNA, thereby preventing the multiplication of cancer cells. Capsaicin, found in hot peppers, is believed to protect DNA from carcinogens.
  • Antibacterial properties. The phytochemical allicin from garlic has antibacterial properties. The intake of proanthocyanidins (from cranberries) will reduce the risk of urinary tract infections and will improve dental health.
  • Cholesterol control. Phytosterols are believed to compete with dietary cholesterol for uptake in the intestines.
  • Adhesion properties. Some phytochemicals bind to cell walls and it has been suggested that they prevent the adhesion of pathogens to human cell walls. Proanthocyanidins are responsible for the anti-adhesion properties of cranberry.

Medicinal plants

Medicinal plants have been used since the dawn of history to prevent and treat various diseases and disorders. They were first discovered by trial and error, for instance by noticing that pain went away when drinking tea made from the bark of a willow tree. It is only much later as science developed in the 20th century that chemists isolated salicylic acid from willow bark, the active ingredient in aspirin. Of the estimated 250,000 plant species, only 2% have been thoroughly investigated for phytochemicals with potential medicinal use. Some of the most well-known include:


Analgesic— A substance capable of producing analgesia, meaning one that relieves pain.

Antianemic— Preventing or curing anemia, a condition characterized by a lower than normal count of red blood cells.

Antiemetic— Agents that prevent nausea and vomiting. Antifungal—Substance that prevents the growth of fungi.

Antihyperlipidemic— Substance used in the treatment of very high serum triglyceride levels. Antimicrobial—Substance that prevents the growth of microorganisms including bacteria, viruses and fungi.

Antimutagenic— Substance that protects against genetic mutation.

Antinociceptive— Substance that reduces sensitivity to painful stimuli.

Antioxidative— A substance that inhibits oxidation.

Antipyretic— An agent that reduces or prevents fever.

Antitussive— Preventing or relieving cough.

Astringent— Tending to draw together or constrict tissues.

Atherosclerosis— Clogging, narrowing, and hardening of the body’s large arteries and medium-sized blood vessels.

Carminative— A substance that stops the formation of intestinal gas and helps expel gas that has already formed.

Demulcent— A substance that soothes irritated tissue, especially mucous membranes.

Diaphoretic— An agent that promotes sweating.

Emetic— A medicine that induces nausea and vomiting.

Emollient— An agent that softens and soothes the skin when applied locally.

Enzyme— A protein that accelerates the rate of chemical reactions.

Estrogen— A hormone produced by the ovaries and testes. It stimulates the development of secondary sexual characteristics and induces menstruation in women.

Expectorant— A substance that stimulates removal of mucus from the lungs.

Hematemesis— The medical term for bloody vomitus.

Intermittent claudication— Symptoms that occur when the leg muscles do not receive the oxygen rich blood required during exercise, thus causing cramping in the hips, thighs or calves.

Hypolipidemic— Promoting the reduction of lipid concentrations in the serum.

Hypotensive— Agent that lowers blood pressure.

Laxative— A medicine that helps relieve constipation.

Narcotic— An agent that causes insensibility or stupor; usually refers to opioids given to relieve pain.

Nervine— An agent that calms nervousness, tension or excitement.

Neurogenic bladder— An unstable bladder associated with a neurological condition, such as diabetes, stroke or spinal cord injury.

Osteoarthritis— A form of arthritis, occurring mainly in older persons, that is characterized by chronic degeneration of the cartilage of the joints.

Psoriasis— A chronic disease of the skin marked by red patches covered with white scales.

Sedative— A substance that reduces nervous tension.

Sialagogue— Promotes the flow of saliva.

Tonic— An agent that restores or increases body tone.

Trace minerals— Minerals needed by the body in small amounts. They include: selenium, iron, zinc, copper, manganese, molybdenum, chromium, arsenic, germanium, lithium, rubidium, tin.

  • Arnica (Arnica montana). Anti-inflammatory, antimicrobial, muscular soreness, pain relief.
  • Arrowroot (Maranta arundinacea). Anti-inflammatory, digestive, antiseptic.
  • Belladonna (Atropa belladonna). Antispasmodic, narcotic, reduces sweating, sedative.
  • Bergamot (Citrus bergamia). Disinfectant, muscle relaxant.
  • Calendula, marigold (Calendula officinallis). Anti-inflammatory, astringent, heals wounds, antiseptic, detoxifying.
  • Camphor (Cinnamomum camphora). Antiseptic, antispasmodic, analgesic, expectorant.
  • Cardus, milk thistle (Carduus marianus). Digestive, liver tonic, stimulates secretion of bile, increases breast–milk production, antidepressant.
  • Chamomile (Chamomilla recutita). Antiinflammatory, antiseptic, antispasmodic, relaxant, carminative.
  • Clove (Eugenia caryophyllata). Antiseptic, mind and body stimulant, analgesic, antibacterial, carminative.
  • Comfrey (Symphytum officinale). Antiinflammatory, wound healing, astringent.
  • Dandelion (Taraxacum officinale). Diuretic, digestive, antibiotic.
  • Eucalyptus (Eucalyptus globulus). Antiseptic, expectorant, stimulates local blood flow, antifungal.
  • Gentian (Gentiana luted). Digestive stimulant, eases stomach pain.
  • Ginkgo (Ginkgo biloba). Circulation stimulant and tonic, anti-asthmatic, antispasmodic, anti-inflammatory.
  • Ginseng (Panax ginseng). Tonic, stimulant, physical and mental revitalizer.
  • Hawthorn (Crataegus oxyacantha). Heart tonic, diuretic, astringent, dilates blood vessels, relaxant, antioxidant.
  • Jasmine (Jasminum grandiflorum). Antispasmodic, expectorant.
  • Juniper (Juniperus communis). Diuretic, antimicrobial, carminative, anti-rheumatic.
  • Lavender (Lavandula officinalis). Carminative, relieves muscle spasms, antidepressant, antiseptic and antibacterial, stimulates blood flow.
  • Malva, common mallow (Malva silvestris). Antiinflammatory, emollient, astringent, laxative.
  • Melissa (Melissa officinalis). Relaxant, antispasmodic, increases sweating, carminative, antiviral, nerve tonic.
  • Mistletoe (Viscum album).Tranquilizer, reduces pain, controls blood pressure.
  • Motherwort (Leonurus cardiaca).Antispasmodic, hepatic, nervine, hypotensive, cardiac tonic.
  • Nettle (Urtica dioica).Diuretic, tonic, astringent, prevents hemorrhaging, anti-allergenic, reduces prostate enlargement.
  • Palmetto (Sabal serrulata).Tonic, diuretic, sedative.
  • Passion flower (Passiflora incamata). Anti-inflammatory, antispasmodic, hypotensive, sedative.
  • Peppermint (Mentha piperita). Carminative, relieves muscle spasms, increases sweating, stimulates secretion of bile, antiseptic.
  • Rose (Rosa gallica). Antidepressant, sedative, antiinflammatory.
  • Rue (Ruta graveolens). Antispasmodic, increases peripheral blood circulation, relieves eye tension.
  • Sarsaparilla (Smilax sarsaparilla). Diuretic, antiinflammatory, anti-rheumatic.
  • Scots pine (Pinus sylvestris). Antiseptic, diuretic and anti-rheumatic.
  • St.-John’s wort (Hypericum perforatum). Antidepressant, antispasmodic, astringent, sedative, relieves pain, antiviral.
  • Valerian (Valeriana officinalis). Sedative, relaxant, relieves muscle spasm, relieves anxiety, lowers blood pressure.
  • Verbena (Verbena officinalis). Nervine, tonic, mild sedative, stimulates bile secretion.
  • Witch hazel (Hamamamelis virginiana). Astringent, anti-inflammatory, stops external and internal bleeding.
  • Wormwood (Artemisia absinthium). Stimulates secretion of bile, anti-inflammatory, eliminates worms, eases stomach pains, mild antidepressant.
  • Yarrow (Achillea millefolium). Antispasmodic, astringent, bitter tonic, increases sweating, lowers blood pressure, reduces fever, mild diuretic and urinary antiseptic.

Herbs and spices

Spices have always been important in history. Spices belonged to the most valuable items of trade in the ancient and medieval world, providing the incentive for exploration and most great sea voyages of discovery. When Christopher Columbus discovered America, he described to his sponsors the many new spices available there. Herbs are leafy, green plant parts used for flavoring foods. They are usually used fresh. Unlike herbs, spices are almost always dried. Herbs and spices that are considered phytonutrients that are beneficial to health and have therapeutic properties include the following:

  • Anise (Pimpinella anisum). Has carminative, sedative, antidepressant, antispasmodic, antifungal, and diuretic properties, used as a tonic.
  • Bay leaves (Laurus nobilis). Has carminative, antifla-tulent, antimicrobial, antirheumatic, anticonvulsive and insect repellent properties.
  • Black cumin (Nigella sativa). Has anti-inflammatory, analgesic, antioxidant, sedative, carminative, stimulant and anti-asthma properties.
  • Black pepper (Piper nigrum). Used as a central nervous system stimulant, has analgesic and antipyretic properties.
  • Caraway (Carum carvi). Used for flatulence, indigestion, and irritable bowel syndrome.
  • Cardamom (Elettaria cardamomum). Has stimulant and carminative, digestive, anti-obesity, aphrodisiac properties.
  • Cinnamon (Cinnamomum zeylanicum).Used against heartburn, heavy menstruation, peptic ulcer, poor appetite, yeast infections.
  • •Cayenne Pepper (Capiscum frutescens). Topical use for diabetes, neurogenic bladder, osteoarthritis, pain and psoriasis.
  • Celery (Apium graveolens L.). Used as antimicrobial, antifungal, and antihyperlipidemic agent.
  • Coriander (Coriandrum sativum L). Used for treating bacterial infections, worm infections, indigestion, and inflammation.
  • Dill (Anethum graveolens).Used against digestive problems
  • Fennel (Foeniculum vulgare). Used against indigestion and irritable bowel syndrome.
  • Garlic (Allium sativum).Used against atherosclerosis, high triglycerides, athlete’s foot, bronchitis, heart attack, high blood pressure, high cholesterol, intermittent claudication
  • Ginger (Zingiber officinale). Used against motion sickness, nausea and vomiting following surgery, morning sickness, and chemotherapy.
  • Lemon Grass (Cymbopogon citratus). Has antimicrobial, antifungal, antibacterial, and mosquito repellent properties.
  • Marjoram (Origanum majorana). Has carminative, antispasmodic, diaphoretic, and diuretic properties.
  • Mustard (Brassica alba). Used as an emetic and a muscle relaxant.
  • Nutmeg (Myristica fragrans). Has carminative, hallucinogenic, stimulant, expectorant, and sialagogue properties.
  • Onion (Allium cepa L). Used against pain, diarrhea, hematemesis, diabetes, asthma, cough and tumors.
  • Oregano (Origanum vulgare). Has antifungal and antimicrobial properties and protects against colds.
  • Paprika (Capiscum annuum). Has anti-inflammatory and antinociceptive properties, and is used as a circulatory stimulant
  • Parsley (Petroselinum crispum). Has antihyperlipidemic, anticoagulant, antimicrobial, antioxidative, antianemic, and laxative properties, used as a tonic.
  • Red beet root (Beta vulgaris). Has antioxidant and liver-protecting properties
  • •Saffron (CrocussativusL).Has antispasmodic, diaphoretic, carminative, heart-protective, hypolipidemic, antitussive, antioxidant, sedative, and memory-enhancing properties.
  • •Sage (Salvia officinalis). Used against night sweats and to relieve oral cavity and throat inflammations.
  • Savory (Satureja hortensis L). Has antibacterial, antifungal, antioxidative, antispasmodic, antidiar-rheal, sedative, and anti-inflammatory properties.
  • Sesame (Sesamum indicum). Used as a tonic and a laxative, emollient, demulcent, has antidiabetic and antioxidant properties.
  • Spearmint (Mentha spicata).Has antibacterial, antiinflammatory, carminative, analgesic and antimuta-genic properties.
  • Sweet basil (Ocimum basilicum L). Has antioxidant, heart-protective, anti-fertility, anti-diabetic, liver-protective, anti-inflammatory, antifungal, antimicrobial, antiemetic, antispasmodic, and analgesic properties.
  • Thyme (Thymus vulgaris). Has carminative, and antitussive properties.


There are no recorded harmful effects associated with medicinal plants, nor with herbs, and spices, except for unpalatable food when used in exaggerated quantities. Phytochemicals in isolated forms, however, can have adverse effects on some people and may not provide all of the health benefits of the whole plant foods they were extracted from. Phytonutrients are relatively new in nutritional public awareness. While there is ample evidence to support the health benefits of diets rich in plant foods such as fruits, vegetables, whole grains and nuts, hard evidence concerning the benefits of specific phytonutrients is limited. This is because plant-based foods are complex mixtures of numerous bioactive compounds, and information on potential health effects is linked to information on the health effects of foods that contain a group of phytochemicals rather than on the effect of a specific phy-tochemical. A wealth of information exist about vitamins and minerals, but researchers are still trying to determine scientifically the types of phytochemicals that are present in foods, how they interact with each other and the body and what their health benefits are. There is also a trend to package and promote phyto-nutrient supplements as the new magic cure for all diseases and disorders, which makes it difficult to assess the claims that are made concerning their benefits. Taken in the form of supplements, caution should accordingly be exercised to avoid excessive intake. For example, carotenoids are not toxic to the human body. An excessive intake of carrots and other vegetables containing carotene can lead to a yellowing of the skin, in itself harmless. However, beta-carotene in the form of a phytonutrient supplement be dangerous for smokers and people exposed to secondhand smoke or asbestos. The American Cancer Society has requested that warning labels for these people be placed on phytonutrient supplements containing any isolated form of vitamin A or beta-carotene.


Though beneficial for certain conditions, phytonutrient supplements can not always capture the many different interactions of the phytonutrients found in food. For example, flavonoids and carotenoids are believed to have more health-promoting properties when they are taken together rather than separately in a supplement. The hundreds of phytonutrients present in plant foods help each other biochemically—and presumably also in the body. The food science and pharmaceutical developments of the past decades have consistently demonstrated the need to consume a broad range of whole foods on a regular basis. Eating a whole tomato is better than taking a supplement that contains a phytochemical isolated from a tomato. Eating a carrot does not only provide the beta carotene that could be obtained in a pill, but also the health benefits of hundreds or thousands of other phytonutrients that have not yet been identified or characterized. Some interactions are possible between phytonutrients. Citrus bioflavonoid preparations, such as grapefruit juice, may interact with drugs containing naringin. Naringin increases the oral bioavailability of calcium channel blocker medications such as: nifedipine, verapramil and felodipine. Naringin may enhance the effect of these drugs and result in a serious drop in blood pressure. Naringin also inhibits the breakdown of various drugs such as caffeine, coumarin, and estrogens. It is recommended to avoid flavonoid preparations containing naringin when taking any of these drugs. Studying the health benefits of individual phytonutrients is just one aspect of understanding how fruits and vegetables contribute to health, buy much research remains to be done on how the phytonutrients interact with each other and how they may protect against disease.


In case of adverse or allergic reaction, the use of phytonutrient supplements should be discontinued.


One risk associated with phytonutrients is if they are taken as supplements because they are then in a concentrated and more potent form. Hence, some may cause allergic reactions in hypersensitive people. They should also be kept out of reach of children. As with any nutritional supplement, a healthcare professional should be consulted if taken by pregnant or lactating women or by people with health conditions. For example, cauliflower contains goitrogens that can interfere with the functioning of the thyroid gland. Individuals with already existing medical problems may have to avoid specific phytonutrients.

Parental concerns

There is a danger that phytonutrient classifications over-simplify the process of building a healthy diet. Most foods are packed with protective phytonutrients. They are present in all plant foods, and eating a wide variety of fruits and vegetables should be preferred to taking specific supplements, unless recommended by a health practitioner. Information on the disease-fighting functions of phytonutrients is becoming widely available and should be used to understanding their many properties. It is not possible to cover all of the cautions for people considering the purchase of phytonutrient supplements. However, one simple sentence covers whole foods and whole food supplements: they can be a safe and important method by which people improve their health and well-being because they are made from the whole fruit or vegetable and do not just contain isolated components.



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Balch, P. A. Prescription for Herbal Healing: An Easy-to-Use A-Z Reference to Hundreds of Common Disorders and Their Herbal Remedies. Torquay, UK: Avery, 2002.

Balch, P. A. Prescription for Nutritional Healing, 4th Edition: A Practical A to Z Reference to Drug–Free Remedies Using Vitamins, Minerals, Herbs & Food Supplements. Torquay, UK: Avery, 2006.

Bratman, S., Kroll, D. The Natural Pharmacist: Natural Health Bible from the Most Trusted Alternative Health Site in the World: You’re A-Z Guide to Over 300 Conditions, Herbs, Vitamins, and Supplements. New York, NY: Three Rivers Press, 2000.

Deutsch-Mozian, L. Foods That Fight Disease: A Simple Guide to Using and Understanding Phytonutrients to Protect and Enhance Your Health. London, UK: Avery (Penguin Group), 2003.

Grieve, M. A Modern Herbal. The Medical, Culinary, Cosmetic and Economic Properties, Cultivation, and Folklore of Herbs, Grasses, Fungi, Shrubs and Trees with All Their Modern Scientific Uses. New York, NY: Dorset, 1992.

Larson Duyff, R. ADA Complete Food and Nutrition Guide, 3rd ed. Chicago, IL: American Dietetic Association, 2006.

Tucker, G., Salter, A. Phytonutrients. London, UK: Black-well Publishing, 2008.


American Society for Nutrition (ASN). 9650 Rockville Pike, Bethesda, MD 20814. (301) 634-7050. <>.

Monique Laberge, Ph.D.

Polynesian diet seePacific Islander diet

Because plant-based foods contain more than 100,000 different disease-preventing nutrients—more specifically, more than 100,000 phyto-nutrients, phyto for the Greek word for plant. Blueberries have anthocyanins that may help with memory. Tomatoes are rich in the red pigment lycopene, which may help target heart disease and cancer, and ginger has gingerols that may help with hypertension. Intake of citrus has been associated with reduced stroke risk perhaps thanks to its phytonutrient hesperidin, which appears to increase blood flow throughout the body, including the brain. The list goes on. And we can’t just take these phytonutrients in a pill. When it comes to food, the whole is often greater than the sum of its parts. Beta carotene pills, for example, may actually increase cancer risk, as opposed to the whole carrot, which may lower our risk. (Who could swallow 100,000 pills a day anyway?)

Hundreds of phytonutrients have been found to have anti-inflammatory and antioxidant activity. Six months of consuming the phytonutrients curcumin, the bright-yellow pigment in turmeric, and quercetin, which is found naturally in such fruits and vegetables as red onions and grapes, appeared to decrease the number and size of polyps by more than half in patients with a hereditary form of colorectal cancer. And many phytonutrients may help block the formation of new blood vessels that feed tumors, and others appear to defend against toxic invaders. Researchers found that phytonutrients in such plant foods as fruits, vegetables, tea leaves, and beans can block the effects of dioxins in vitro, for example. Having phytonutrient levels in the bloodstream achieved by eating three apples a day or a tablespoon of red onion appeared to cut dioxin toxicity in half. As these phytonutrient effects lasted only a few hours, we should make sure to eat healthy foods at every meal.

Image Credit: Joshua Resnick © This image has been modified.

Did you know that adding color to your meals will help you live a longer, healthier life? Colorful fruits and vegetables can paint a beautiful picture of health because they contain phytonutrients, compounds that give plants their rich colors as well as their distinctive tastes and aromas. Phytonutrients also strengthen a plant’s immune system. They protect the plant from threats in their natural environment such as disease and excessive sun.

When humans eat plant foods, phytonutrients protect us from chronic diseases. Phytonutrients have potent anti-cancer and anti-heart disease effects. And epidemiological research suggests that food patterns that include fruits and vegetables are associated with a reduced risk of many chronic diseases, including cardiovascular disease, and may be protective against certain types of cancers.

The American Cancer Society recommends 2 1/2 cups per day of fruits and vegetables. The most recent US Dietary Guidelines recommend consuming even more: 2 1/2 cups of vegetables and 2 cups of fruit, based on a 2,000-calorie diet.

Getting started

To get started, try to include as many plant-based colors in your meals and snacks as possible. Each color provides various health benefits and no one color is superior to another, which is why a balance of all colors is most important. Getting the most phytonutrients also means eating the colorful skins, the richest sources of the phytonutrients, along with the paler flesh. Try to avoid peeling foods like apples, peaches and eggplant, lest you lose their most concentrated source of beneficial chemicals.

Phytonutrients in every color

Following is a rundown of fruits and vegetables sorted by color, along with the phytonutrients they contain, and which foods you’ll find them in.

Red: Rich in the carotenoid lycopene, a potent scavenger of gene-damaging free radicals that seems to protect against prostate cancer as well as heart and lung disease.
Found in: strawberries, cranberries, raspberries, tomatoes, cherries, apples, beets, watermelon, red grapes, red peppers, red onions

Orange and yellow: Provide beta cryptothanxin, which supports intracellular communication and may help prevent heart disease.
Found in: carrots, sweet potatoes, yellow peppers, oranges, bananas, pineapple, tangerines, mango, pumpkin, apricots, winter squash (butternut, acorn), peaches, cantaloupe, corn

Green: These foods are rich in cancer-blocking chemicals like sulforaphane, isocyanate, and indoles, which inhibit the action of carcinogens (cancer-causing compounds).
Found in: 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)

Blue and purple: Have powerful antioxidants called anthocyanins believed to delay cellular aging and help the heart by blocking the formation of blood clots.
Found in: blueberries, blackberries, elderberries, Concord grapes, raisins, eggplant, plums, figs, prunes, lavender, purple cabbage

White and brown: The onion family contains allicin, which has anti-tumor properties. Other foods in this group contain antioxidant flavonoids like quercetin and kaempferol.
Found in: onions, cauliflower, garlic, leeks, parsnips, daikon radish, mushrooms

Reach for the rainbow

Reaching a total of 4 1/2 cups of colorful fruits and vegetable a day is the goal for a powerful plate. Here are some ways to make it happen:

  • Servings are not that big. 1/2 cup of chopped raw vegetables or fruit makes one serving. Leafy greens take up more space, so 1 cup chopped counts as a serving. 1/2 cup of dried fruit equals one serving.
  • Think in twos. Try to eat two servings in the morning, two in the afternoon, and two at night.
  • Snacks count, too. Feeling hungry between meals? Munch on a piece of fruit or grab some sliced raw vegetables to go.
  • When shopping, look at your cart. If you find most of your choices are the same one or two colors, swap out a few to increase the colors — and phytonutrients — in your cart.
  • Dine out colorfully. Start out with a cup of vegetable soup. Choose an arugula or spinach salad and see if they can add extra vegetables. Top off your meal with fresh fruit for dessert and a soothing cup of green tea.
  • Look local. Farmers markets, co-ops, buying clubs, and community supported farms are usually great sources of fresh produce. Ask a farmer for fresh ideas on how to prepare fruits and vegetables that are new to you.
  • Frozen produce is okay too! It is best to eat in season, but since seasonal produce may be limited, frozen fruits and vegetables count and are just as nutritious as fresh.

Remember, color in fruits and veggies is king, and the greater variety the better.

What do phytonutrients do

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