What Are Phytonutrients?

All about phytochemicals

Who would’ve thought that the same things that give plants their vivid colors could also help improve our immune systems? (Spoiler alert: we did.) Phytonutrients are what give fruits and vegetables their bright hues and provide yet another reason we should eat plant foods.

Phytonutrients—also called phytochemicals—are defined as bioactive plant-derived compounds linked to positive health effects.1 Interestingly enough, the first part of the word “phytonutrients,” phyto-, means plant.2

Phytonutrients infographic

J.S. Bland, PhD, FACN, CNS, and functional medicine pioneer, says that “all families of plant food are known to contain phytonutrients, that is, unique substances produced during the natural course of plant growth and development that are specific to each plants’ genes and environment.”3

Phytonutrients play various roles within a plant. Not only do they give plant foods their colorful pigments, but they also protect plants. And, by consuming them, we can receive the benefits of phytonutrients too.

Researchers have discovered that although they are not essential nutrients, phytonutrients have “important properties such as antioxidant activity, antimicrobial effects, modulation of detoxification enzymes, stimulation of the immune system, decrease of platelet aggregation and modulation of hormone metabolism, and anticancer property.”4

That’s quite a bit to digest, so let’s look at the fascinating world of phytochemistry in more depth.


Some common phytonutrient families include saponins, stilbenes, lignins, isoflavones, flavonols, limonoids, oregano (allylic sulfides), carotenoids, phytosterols, anthocyanins, and catechins. Within these groups are many more types. In fact, there are hundreds of thousands of phytonutrients found within plant foods!

Isoflavonoids are a type of phytonutrient found in legumes and soy products; they are antioxidants, anti-inflammatory, and anticarcinogenic.5 And this is just isoflavonoids; other phytonutrients offer additional benefits.

Take carotenoids for instance. They are contained in plant foods with red, yellow, and orange pigments like carrots, tomatoes, and sweet potatoes. They contribute to cardiovascular protection and have antioxidant and anti-inflammatory properties. They might also inhibit cancer growth and boost immunity.6

Anthocyanins are found in plant foods with blue, red, and violet pigments such as blueberries, raspberries, and cherries. They defend cells, prevent blood clotting, and can lower blood pressure. Berries and red wine contain anthocyanins.

What do blueberries, onions, parsley, tea, apples, citrus, and coffee have in common? They all contain flavonoids, which act as chemical messengers, physiological regulators, and cell cycle inhibitors. Flavonoids may fight inflammation and tumor growth, according to Harvard Health Publishing.

You can consume limonoids through eating citrus fruits. Limonoids aid in preventing cancer and can act as antioxidants.

Phytosterols are plant-like sterols like vegetable oil, wheat germ, whole grains, and bran. They compete with cholesterol absorption.

As you can see, phytonutrients can benefit our health in many ways and can be received by eating various plant foods like fruit and vegetables, nuts, seeds, grains, and legumes. Here are some foods rich in phytonutrients:7

  • Chickpeas
  • Broccoli
  • Brussel sprouts
  • Cabbage
  • Cauliflower
  • Tomatoes
  • Carrots
  • Mangoes
  • Oranges
  • Peppers
  • Cantaloupe
  • Berries
  • Garlic
  • Onion
  • And more!

Starting to see a pattern yet? Maybe we’ll follow this up with a much, much shorter piece about what phytochemicals can’t do.


We briefly touched on some of the roles phytonutrients or phytochemicals play, but let’s dig a little deeper.

As mentioned, many phytochemicals have antioxidant properties. “Antioxidants are substances that prevent damage to cells from highly reactive, unstable molecules called ‘free radicals’,” says Karen Collins. Free radicals can be very damaging to our health if kept unchecked. They can lead to cell damage associated with certain chronic diseases.8 Phytonutrients provide support to that much needed checking.

Phytonutrients play a role in metabolism as well. According to Gary Beecher, a research chemist at the Beltsville Human Nutrition Research Center in Maryland, phytochemicals elicit biological responses consistent with reduced risk of one or more diseases. For example, carotenoids can reduce the risk of adult macular degeneration. Glucosinolates, isothiocyanates, indoles, and phytoestrogens alter estrogen metabolism.9

In addition, phytonutrients are involved in your skin’s health. The skin is the largest organ in the body and the most exposed to the environment. Phytonutrients can protect skin against damage from sunlight exposure, inflammation, oxidative stress, the breakdown of cells, and the development of cancer on the skin. In particular, foods that contain vitamin E, flavonoids, carotenoids, b-carotene, lycopene, and lutein are most beneficial.10

According to Nutrients journal, vitamin E may act as a protectant with the aid of other antioxidants. One phytonutrient family, flavonoids, can too. Flavonoids have been “radical scavengers, UVA absorbent, cytoprotective, anti-inflammatory anti-apoptotic, and inhibit DNA damage, and affect cellular signaling pathways.”11 Now what does all that mumbo jumbo mean? Basically that flavonoids help out in a lot of areas within your body.

Eating flavonoid-rich foods has been linked to reduction in types of skin cancer. One study found a correlation between a decreased risk of cutaneous melanoma and daily tea drinking, high consumption of vegetables (like carrots and cruciferous and leafy vegetables), and fruits such as citrus. More particularly, drinking flavanol-rich cocoa can decrease erythema, skin roughness, and scaling and can improve blood flow of tissues, skin density, and skin hydration. Green tea is one that also improves elastic tissue content.

Lycopene is another phytonutrient that is involved in skin health. It is part of the carotenoid family and is found in tomatoes and other red produce. Nutrients explains that there is significant correlation with skin roughness and lycopene concentrations in the skin. Lycopene can be used to increase antioxidant activity in skin and inhibit growth of certain cancer cells.

Lutein decreases the risk of skin cancer, as well, and contributes to skin color. Lutein is found in leafy green vegetables, broccoli, corn, and peas.

Some phytonutrients, like lutein, affect eye health. Nutrients shares that lutein intake is associated with reduced risk of cataracts and age-related macular degeneration. It also acts as an antioxidant and absorbs blue light, which is emitted from electronic devices and sunlight.

“Bluelight is of concern because it has more energy per photon of light than other colors in the visible spectrum,” says Dr. David Ramsey, a contributing writer at Harvard Health Publishing. “Blue light, at high enough doses, is therefore more likely to cause damage when absorbed by various cells in our body.”12

Intense blue light can affect eye health; electronic devices emit a less intense kind. Their blue light is actually more likely to affect your sleep, circadian rhythm, and other aspects of your health before harming your eyes. Still, reducing any amount of a bad thing can be a good idea, so be sure to snack on some broccoli to increase your intake of lutein and receive its benefits.

Phytonutrients also play a role in detoxification. Several compounds found in plant foods (phytochemicals) have been found to help support detoxification of harmful substances as well as reduce cancer risk. The liver operates to rid the body of toxins, and nutrients provide help in carrying out this task. Inability to detoxify the body can lead to a number of health issues like inflammatory and neurological disease and unpleasant symptoms such as headaches, pain, fatigue, and allergy or flu-like symptoms.13

Dr. Mark Percival, writer for Clinical Nutrition Insights, claims that “adequate intake of antioxidants, such as vitamin C and vitamin E, and certain naturally occurring phytochemical compounds help protect the liver against free radical damage.”

Glutathione is one of these compounds. Free radicals can cause cell damage and mutation. To increase your intake of glutathione you can eat avocado, asparagus, broccoli, grapefruit, potatoes, strawberries, oranges, tomatoes, peaches, and spinach.14

He also discusses how phytochemicals present in plant foods block or prevent carcinogens from “reaching or reacting with critical target sites in tissue” while others suppress changes in cells exposed to carcinogens that would cause cancer.

Isoflavones could also help reduce the risk of getting certain cancers. Soy isoflavones are consumed traditionally in the Japanese diet.15 And consuming 30 to 50 mg a day was shown to help lower breast cancer among Japanese women.

Therefore, adequate nutrition will help maintain proper liver function, lower cancer risk, and allow you to have better health as a result.

Bone health is also influenced by phytonutrients. An article in the British Journal of Clinical Pharmacology explains how a high consumption of fruits and vegetables positively affects bone health, particularly in how it might protect against the deterioration of bone tissue during aging.16

It states that “dietary patterns consisting of a high consumption of fruits and vegetables, legumes, seafood, nuts, seeds, rice and/or rice dishes have been shown to be directly associated with bone mineral density.” As you now know, many of these foods contain phytonutrients. Lycopene is one of these phytonutrients. It protects against various diseases including osteoporosis.

Osteoporosis is a skeletal disease in which bone strength is weak, increasing the risk of fractures and breaks. Data shows a link between lycopene intake and bone mass, bone turnover, and fracture risk. Higher levels of lycopene were proven to positively affect bone mineral density in the lumbar vertebrae and lower the risk of hip and nonvertebral fractures in elderly men and women.

Another compound involved in bone health are polyphenols. Polyphenols are also found in fruits, vegetables, beans, grains, juices, coffees, and teas. Types of polyphenols include phenolic acids, flavonoids, stilbenes, tannins, coumarins, and lignans. Flavonoids is the type most associated in supplementing bone health. Within that subgroup, flavonols are believed to reduce risk of fracture and increase bone mineral density; however, more research is needed.

Phytochemicals sure do a lot, huh.

The Last Bite

Phytonutrition is becoming more widely studied and understood, and there’s real science to back it up. We’ve always known that eating fruits and vegetables is good for us. Turns out your mom knew what she was talking about when she told you to “eat your veggies.”

The role of nutrition in our overall health is great-- greater than you might have ever thought before. We have just scratched the surface when it comes to knowing and understanding phytonutrients’ effects on health. By adopting more plant foods into your daily diet, you can help prevent all kinds of diseases and set yourself up for a healthier, and ultimately more satisfying, life.

So… if you want to lower your risk of getting cancer, diabetes, inflammation, colds, viruses, and a bunch of other bad stuff, eat a diet full of colorful plants.

[1] “Phytonutrient.” Accessed June 15, 2020. https://www.merriam-webster.com/dictionary/phytonutrient. Merriam-Webster.

[2] “Phyto-,” Merriam-Webster (Merriam-Webster), accessed July 6, 2020, https://www.merriam-webster.com/dictionary/phyto-.

[3] Bland, J S. “Phytonutrition, Phytotherapy, and Phytopharmacology.” Alternative therapies in health and medicine. U.S. National Library of Medicine, November 1996. https://pubmed.ncbi.nlm.nih.gov/8942046/.

[4] Ditu, Lia-Mara, Madalina E. Grigore, Petronela Camen-Comanescu, and Alina Maria Holban. “Introduction in Nutraceutical and Medicinal Foods.” Therapeutic, Probiotic, and Unconventional Foods. Academic Press, April 20, 2018. https://www.sciencedirect.com/science/article/pii/B9780128146255000017.

[5] Marcus, Jacqueline B. “Nutritional and Physical Concerns in Aging.” Aging, Nutrition and Taste. Academic Press, April 12, 2019. https://www.sciencedirect.com/science/article/pii/B9780128135273000028.

[6] “Fill up on phytochemicals.” Harvard Health Publishing. February 2019. https://www.health.harvard.edu/staying-healthy/fill-up-on-phytochemicals.

[7] “Foods Containing Phytochemicals.” Breastcancer.org. https://www.breastcancer.org/tips/nutrition/reduce_risk/foods/phytochem. Published February 5, 2015.

[8] Collins, Karen. “Antioxidants and Phytochemicals.” HealthTalk: What's the difference between an antioxidant and a phytochemical. American Institute for Cancer Research, March 4, 2020. https://www.aicr.org/resources/blog/healthtalk-whats-the-difference-between-an-antioxidant-and-a-phytochemical/.

[9] Beecher, Gary R. “Phytonutrients' Role in Metabolism: Effects on Resistance to Degenerative Processes.” Nutrition Reviews. Oxford University Press, September 1, 1999. https://academic.oup.com/nutritionreviews/article/57/9/3/1860707.

[10] Evans, Julie A., and Elizabeth J. Johnson. “The Role of Phytonutrients in Skin Health.” MDPI. Molecular Diversity Preservation International, August 24, 2010. https://www.mdpi.com/2072-6643/2/8/903/htm.

[11] Ibid.

[12] Ramsey, David. “Will Blue Light from Electronic Devices Increase My Risk of Macular Degeneration and Blindness?” Harvard Health Blog. Harvard Health Publishing, May 1, 2019. https://www.health.harvard.edu/blog/will-blue-light-from-electronic-devices-increase-my-risk-of-macular-degeneration-and-blindness-2019040816365.

[13] Percival, Dr. Mark. “Phytonutrients & Detoxification.” The Foundation for the Advancement of Nutritional Education. Clinical Nutrition Insights. Vol. 5, No. 2. 1997.

[14] Phytochemicals. phytochemicals.info. Accessed June 11, 2020. https://www.phytochemicals.info/phytochemicals/glutathione.php.

[15] Bland, J S. “Phytonutrition, Phytotherapy, and Phytopharmacology.” Alternative therapies in health and medicine. U.S. National Library of Medicine, November 1996. https://pubmed.ncbi.nlm.nih.gov/8942046/.

[16] Sacco, Sandra Maria, Marie‐Noëlle Horcajada, and Elizabeth Offord. “Phytonutrients for Bone Health during Ageing.” British Pharmacological Society | Journals. John Wiley & Sons, Ltd, February 5, 2013. https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/bcp.12033.