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Phytochemicals: Complex Compounds in Plant-Based Foods

Jennifer Hanes MS, RDN, LD

Hey there, ever wondered what makes fruits and veggies so good for you? Well, besides the obvious vitamins and minerals, there’s something else that gives these natural powerhouses their superfood status – phytochemicals!

These little wonders are the secret weapons found in plants that provide an array of health benefits. So read on to learn about phytochemicals, how they can boost your well-being, and why it’s time to give them a little more love.

Phytochemicals: Definition

The word phytochemical literally means plant chemical.  These are little bioactive compounds in plant foods that perform various functions for the plant and then perform various functions for us!

For the plant, this could be a spicy taste to discourage animals from eating them, repair small injuries, encourage growth, prevent bruising, or more. For us, this can repair oxidative damage, support our immune system, and encourage normal cell division and death.

In simpler terms, including phytochemicals in your diet can reduce sick days and decrease your risk of chronic disease (diabetes, heart disease) and cancer. 

Phytochemicals: Where to get them?

 All plants contain phytochemicals. Think of this post as another way for me to tell you to eat your fruits and vegetables, haha.

Phytochemicals are abundant in fruits, vegetables, whole grains, nuts, seeds, tea, wine, and coffee.

It is estimated that there are over 5,000 different phytochemicals. However, only approximately 150 have been extensively studied. 

Think about the last time a friend recommended that you take a supplement. These products are taking advantage of some phytochemicals that are dominant in that plant.

Whether or not these products work or if they even include what’s on the label is a different story.

The best way to get phytochemicals is to eat your fruits and vegetables. And beans. And whole grains. And nuts and seeds. Drink your tea and coffee.

With over 5000 different phytochemicals, it would be impossible to discuss all of them. Instead, we will discuss them in terms of their categories and possibly subcategories.


Polyphenols are a group of phytochemicals that largely act as antioxidants.  This makes them great for counteracting inflammation and slowing down the aging process.

They appear to moderate gene expression, which, along with their anti-inflammatory and antioxidant processes, reduces the risk of most chronic diseases encountered in the second half of our lives.

There are about a million different ways the different polyphenols are categorized.  For our purposes, we are going to go with a 2 category system, the flavonoids and the non-flavonoids.


Flavonoids are highly regarded in the field of nutraceuticals and pharmaceutical medications.  

This is because they are well-documented to reduce the risk of heart disease and cancer.

Flavonoids can be further subdivided into flavones, flavanols, flavonols, flavanones, isoflavones, and anthocyanins. This division is largely due to the chemical structure of the compound rather than any health benefit or pharmaceutical use.

Frequently talked about flavonoids include quercetin, kaempferol, and epigallocatechin gallate (EGCG), but this is a very large group of compounds.

Where are the Flavonoids Found?

Because this is such a large group of compounds, there are many food sources of flavonoids.  We’ll list them out by subcategory:

Flavones – parsley, celery, oregano, rosemary, green olives, pumpkin, watermelon, bell peppers, honey, fava beans, and chickpeas.

Flavonols – onions, leeks, broccoli, kale, lettuce, apples, grapes, berries, and tea

Flavanols – chocolate, tea, grapes, red wine

Flavanones – citrus fruits, tomatoes

Isoflavones – soy and, to a lesser extent, other beans. Many of these compounds have shown anti-depressant and anti-anxiety properties.

Anthocyanins – red grapes/wine, berries, pomegranate, red cabbage

How do Flavinoids affect our health?

Again, due to the size of the group, there are a lot of different benefits. I’ll generalize them according to their subcategories again.

Flavones – anti-oxidants; protects against age-related diseases such as heart disease and cancer.

Flavonols – examples include quercetin and kaempferol. Quercetin, in particular, is a major factor in heart health, reducing inflammatory markers and blood pressure in double-blind studies.

Flavanols – prevent inflammation and allergies. EGCG in green tea is the most commonly discussed flavanol.

Flavanones – prevent cardiac disease, inflammation, and allergies.

Isoflavones – reduce triglycerides, inflammatory markers, and blood pressure.

Anthocyanins – protects against cardiovascular disease and reduces inflammation and allergies.

CategoryExamplesHealth BenefitFood Sources
Flavonesapigeninanti-oxidants; protects against age-related diseases such as heart disease and cancerparsley, celery, oregano, rosemary, green olives, pumpkin, watermelon, bell peppers, honey, fava beans, and chickpeas
Flavonolsquercetin, kaempferolmajor factor in heart health, reducing inflammatory markers and blood pressureonions, leeks, broccoli, kale, lettuce, apples, grapes, berries, and tea
FlavanolsEGCGa major factor in heart health, reducing inflammatory markers and blood pressurechocolate, tea, grapes, red wine
Flavanonesnaringenindaidprevent cardiac disease, inflammation, and allergiescitrus fruits, tomatoes
Isoflavonesdaidzeinreduce triglycerides, inflammatory markers, and blood pressure. Potentially improves symptoms of depression and anxiety.soy, other beans (in smaller amounts)
Anthocyaninscyanidinprotects against cardiovascular disease and reduces inflammation and allergiesred grapes/wine, berries, pomegranate, red cabbage
Table consolidated largely from: Flavanoids: an Overview, Major Phytochemicals: Recent Advances in Health Benefits and Extraction Method, Natural Phytochemicals in the Treatment and Prevention of Dementia, An Overview. Additional resources are linked in the above passages.


These include phenolic acids, lignans, resveratrol, ellagic acid, curcumin, rosmarinic acid, gingerol, and more.

They are found in grapes, berries, spices, and whole grains.

They play roles in wound healing, infection prevention, and reducing inflammation. Lignans are also phytoestrogens.


Carotenoids are yellow, orange, or red fat-soluble pigments and are found in many plants, algae, and bacteria. 

Fruits are the most potent source of carotenoids, but some vegetables have them as well, such as sweet potatoes, carrots, and tomatoes.

Many times you can pick out foods high in carotenoids by their color. However, sometimes high-carotenoid content is masked by the green color of chlorophyll, such as in spinach.

Because these pigments are fat-soluble, it is a good idea to pair these fruits and vegetables with a source of fat for the best absorption.

What are the Carotenoids, and Where Can I Find Them?

The carotenoids are molecules that you have likely heard of before. In addition to α-carotene and ß-carotene (a precursor to vitamin A), lutein, lycopene, xanthophylls, cryptoxanthin, and fucoxanthin are all carotenoids.  There are at least 40 different carotenoids identified, but we will focus on a specific few here.

The best sources are brightly colored fruits and vegetables. More specifically, the best sources of each carotenoid are listed below:

α-carotene – mango, pear, pumpkin, butternut squash, green beans, okra, avocado, chard, collard greens, tangerine, banana.

ß-carotene – red pepper, carrot, spinach, peach, Brussels sprout, grapefruit, sour cherries, papaya, mango, and romaine lettuce

Lutein – asparagus, spinach, kale, green beans, orange pepper, lettuce, broccoli, parsley, pistachios

Lycopene – tomato, sweet potato, grapefruit, guava, watermelon, apricot, papaya, rosehip

Xanthophylls – pumpkin, papaya, peppers, mushrooms

Cryptoxanthin – apricot, papaya, peach, cashews, apple, citrus

Fucoxanthin – brown seaweeds, algae

How Do the Carotenoids Affect Our Health?

 The main functions of the carotenoids are to function as a vitamin A precursor and an antioxidant. Specific carotenoids have additional “jobs” in our bodies as well.

α-carotene – regulates RNA production, protects against lung and prostate cancer, and promotes eye health.

ß-carotene – improves the transport of compounds between cells and improves the immune system.

Lutein – improves the immune system and eye health.

Lycopene – improves eyesight, reduces pain, and strengthens bones.

Xanthophylls – antioxidant, improves eye health and blood flow.

Cryptoxanthins – maintain lung health, prevent arthritis and inflammation, and improve the immune system.

Fucoxanthin – antioxidant and anti-inflammatory; reduces blood pressure and the risk of diabetes and cancer.

NameHealth BenefitsFood SourcesNotes
α-caroteneLycopene in tomatoes is enhanced by the cooking or canning processmango, pear, pumpkin, butternut squash, green beans, okra, avocado, chard, collard greens, tangerine, banana
ß-caroteneimproves the transport of compounds between cells and improves the immune systemred pepper, carrot, spinach, peach, Brussels sprout, grapefruit, sour cherries, papaya, mango, and romaine lettuce
Luteinimproves the immune system and eye healthasparagus, spinach, kale, green beans, orange pepper, lettuce, broccoli, parsley, pistachios
Lycopeneimproves eyesight, reduces pain, and strengthens bones.tomato, sweet potato, grapefruit, guava, watermelon, apricot, papaya, rosehipLycopene in tomatoes in enhanced by the cooking or canning process
XanthophyllsLycopene in tomatoes is enhanced by the cooking or canning processpumpkin, papaya, peppers, mushrooms
Cryptoxanthinsmaintains lung health, prevents arthritis and inflammation, and improves the immune systemapricot, papaya, peach, cashews, apple, citrus
Fucoxanthinantioxidant and anti-inflammatory; reduces blood pressure and the risk of diabetes and cancerbrown seaweed, algaefood examples include wakame and kombu seaweeds. Diatomic algae can be grown in controlled environments to make fucoxanthin supplements and functional foods.
Source: Major Phytochemicals: Recent Advances in Health Benefits and Extraction Method and Carotenoid: An Overview


Commonly called phytic acid, inositol is found in the bran of corn, oats, nuts, rye, wheat, and soy. Another reason to choose whole-grain.

Myo-inositol is a form that is more readily absorbable and can be found in many fruits, particularly oranges and cantaloupe.

This appears to work as an antioxidant and can also slow tumor growth. It can also lower triglycerides and manage symptoms of PCOS.

Indoles – Glucosinolates and Isothiocyanates

There are a few molecules that derive from indoles, such as glucobrassican, ascorbigen, tryptophan.  

These are found in cruciferous vegetables; broccoli, kale, cabbage, Brussels sprouts, and cauliflower. The indoles are often the source of that distinct smell associated with cruciferous vegetables.

They may counteract cancer-causing agents in your body, limit cancer-related hormones, prevent tumor growth, and promote normal cell death (apoptosis). Many medications used in chemotherapy are derived from naturally occurring indoles.

Terpenes aka Isoprenoids

The terpenes are limonene, myrcene, and pinene.

Limonene is found in citrus oils and reduces inflammation, improves our response to stress, and is neuroprotective. This means it may help prevent Alzheimer’s Disease.

Myrcene is found in mangos, guavas, thyme, parsley, bay leaves, lemongrass, cardamom, basil, and juniper. It appears to have anti-anxiety, anti-aging, and anti-inflammatory roles.

Pinene is found in cannabis, ironwort, and sage. It is antibacterial, antitumor, anti-inflammatory, and sedative.


These are a group of plant sterols and stanols (similar to animal cholesterol).

Examples are campesterol, sitosterol, and campestanol.  

These compounds are found in a variety of plants but mostly in plant-based foods that generally contain unsaturated fats, such as nuts and seeds, olives, and avocados.

They are prolific antioxidants, help reduce our LDL cholesterol, promote healthy hair growth, and support prostate health. Certain forms are used in the treatment of allergies, rheumatoid arthritis, chronic fatigue syndrome, migraines, and menstrual disorders.


Saponins are primarily found in beans, legumes, nuts, and seeds.

They have important roles in glucose and cholesterol management and help fight viruses and bacteria.

Chlorophyll and Its Derivatives

Chlorophyll is a green compound that plays a major role in producing food for plants.

It is found in any plant that uses photosynthesis to produce food.  This is what makes green food green. This pigment often covers other pigments in the plant, but not always.

Chlorophyll tightly binds to many compounds that are known to cause cancer, including those found in tobacco. This makes it very good at reducing the risk of some cancers. It also appears to promote wound healing and is an “internal deodorant.” 

Chlorophyll supplementation has been used to reduce the fecal odor in patients with ileostomy or colostomy bags.

Fiber and Other Polysaccharides

This is a big group of complex molecules. Polysaccharides are found in every plant-based food option you can think of!  

In the plant, these compounds are largely structural, allowing the plant to stand up and protecting them from outside elements.

Pectin, lignin, cellulose, hemicellulose, amylose, amylopectin, and resistant starches are some examples of fibers. 

Polysaccharides can reduce LDL cholesterol, improve insulin sensitivity, promote diversity of the gut microbiota, reduce the risk of colon cancer, resolve diarrhea and constipation, improve immune function, and more.

Infographic that summarizes the phytochemicals discussed throughout this post: their category, sources, and benefits.

Phytochemicals: An in-depth look at what they do for us

Improve Immune Function

“A balanced immune function — neither underactive nor overactive — can protect you against infection and diseases without overreactions and chronic inflammation.” Phytochemicals can help achieve and maintain a balanced immune system.

There are several phytochemicals that act as antimicrobial agents and lower the risk of viral and bacterial growth within the body. According to early research, phytochemicals also aid in providing an adequate immune response during an infection.

Additionally, they can help in reducing the inflammation associated with inflammatory diseases.

Cancer Prevention

Phytochemicals inhibit cancer in multiple ways.

Basically, the hallmark of cancer is the delay or elimination of programmed cell death (called apoptosis) and the development of new blood vessels to feed the increase in cell density or mass (called angiogenesis). 

Some phytochemicals inhibit both angiogenesis and the avoidance of apoptosis.  Basically, they encourage cells to die when they are supposed to.

Some phytochemicals can also prevent other compounds from causing cancer. They literally block cancer-causing agents from causing cancer. Super exciting stuff.

Regulate Hormones

Flavonoids, lignans and lignins, coumestans, and saponins can all act like hormones and induce various functions in our bodies. There is even a theory that some evolutionary changes occurred in response to these phytochemicals!

Fertility, behavior, metabolism, and thyroid function have all been shown to be influenced by various phytochemicals across different animal models, including humans.

Some plant chemicals can even bind to our own estrogen receptors, inhibiting the influence of hormone-responsive breast cancer and the progression of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease.

Although interfering with our own hormones sounds scary, these effects are generally believed to be beneficial.

Protection from chronic diseases

Various phytochemicals have properties that combat inflammation and the narrowing of arteries, enhance sugar and fat metabolism, protect the cells that produce insulin, improve the structure of our cell walls, and potentially influence the expression of certain genes.

Our diet’s ability to alter gene expression is why we discuss the environmental impact of genetic diseases! A family history means that we are prone to certain diseases, such as heart disease. However, if our diet is healthful, we can actually eat to counteract the genetic tendency to elevated cholesterol, glucose, and blood pressure.

In human studies, phytochemicals have a positive effect on heart disease, obesity, diabetes, cancer, early aging, Alzheimer’s disease, Inflammatory Bowel Disease, and more.

There is still so much more room for learning in this area of nutrition. I believe more and more information will continue to trickle out.

Support Brain Health

Many foods that are known to support brain function, such as sleep and mental health, contain phytochemicals. Phytochemicals in foods such as berries, tea, onions, and purple cabbage benefit your brain by supporting:

  • Brain plasticity – the brain’s ability to modify and adapt in response to new information, sensory stimulation, damage and other impactful experiences
  • Cognition including memory, attention and learning ability
  • Neurodegenerative disorders, by helping prevent or delay the progression of Alzheimer’s disease and Parkinson’s disease
  • Sleep – by reducing insomnia

Improve Heart Health

Phytochemicals prevent cardiovascular diseases by helping:

  • Decrease inflammation
  • Improve cholesterol absorption
  • Preventing oxidative stress
  • Reduce blood pressure

How many phytochemicals do I need?

There are no set recommendations for the intake of any of the phytochemicals. These compounds are not currently considered necessary to live, like carbohydrates, fats, proteins, vitamins, and minerals are.

However, they may be required to live healthfully. To have the energy to be productive and have fun.

Consider meeting the recommendation of 7-9 servings of fruits and vegetables per day. Add in whole grains, beans, nuts, and seeds, and you will get plenty of good for you phytochemicals. Then make sure to include a lot of spices when you cook.

Also, avoid falling into a rut of eating the same handful of fruits and vegetables. Introduce variety to your diet, and your health outcomes will improve.

Can you get too many?

Probably not.

These chemicals are found in very small amounts and are unlikely to build up to unsafe levels in your body, even if you do exceed the 7-9 servings of produce per day.

There are a handful of phytochemicals that are believed to be toxic or even carcinogenic, but these are few and far between.

Piquant Post Get Global Flavor

Cooking and Storage Tips for Preserving Phytochemicals

Cooking and other food processing can reduce the amounts of some phytochemicals. This is the argument that people use to promote a raw vegan diet.

However, some phytochemicals are actually improved with the cooking process.  Fibers are easier to digest, and many phytochemicals, particuarly carotenoids, become “released” form the binding properties of fibers when they are cooked. 

Basically, we can better absorb some phytochemicals when the food they are in are cooked.

In some cases, cooking is even necessary to remove harmful compounds, such as in beans and cassava.

Challenges and Considerations for a Phytochemical-Rich Diet

The main takeaway from this article should be that you should be aiming to eat a lot of plants, not just by volume, but also by variety.  

This is true for everyone, even your friends and family that choose to eat meat.

The main challenge to having this variety in our society in general, and in a multivore household in particular, our hectic schedule.   Convenience foods are usually low on phytochemical-rich options. 

When you are feeding a household with varying philosophies on diet, you have to also consider preferences. It’s much easier to eat the same 3-4 vegetables over and over again because everyone likes them, than it is to learn how to cook more foods, how to season them, and then listen to complaints about the food.

I often solve this by trying to stick to vegetables that everyone likes for shared meals, usually dinner.  Then I include other options available for meals eaten independently, usually lunch and snacks.

Additionally, many fruits and vegetables can be “hidden” in other foods.  Unless they are particularly pungent, you can shred many vegetables and add them to sauces or breads. Spinach makes smoothies a pretty green color, and you can’t really taste it (unlike kale).

Because we are always so busy, make grabbing fruits, veggies, nuts, and seeds as easy as it is to grab crackers. Wash and cut fruits and vegetables when you get home from grocery shopping.  Store them in a prominent location in the fridge, instead of hiding them in the crisper drawer.

Should I take a phytochemical or antioxidant supplement?

There’s no reason to do this.  Consuming them from your food will also give you the benefit of increased fiber and healthy fat intake. You will feel full and satisfied from food. You will not get that from a pill.

What’s more, various phytochemicals work together. There seems to be a synergy between phytochemicals, vitamins, minerals, carbohydrates, protein, and fats that lead to better health. 

Studies do not indicate any benefit from taking a phytochemical supplement.

Incorporating More Phytochemical-Rich Foods into Your Diet

When you have the time when meal planning, take a trip through Pinterest or various food blogs and look for foods you’ve never tried before.  

Experiment with recipes from cultures other than your own. 

Stock the heck out of your spice cabinet, and use them liberally. 

Serve a side salad or vegetable soup before all of your meals.

When snacking, think “a protein and a produce.”  Include both a source of protein and vegetable or fruit.

In Conclusion

I essentially found another way to tell you to eat your fruits and vegetables. 

I want to be clear that I am not stating by any means that eating enough fruits and vegetables will 100% prevent you from ever getting cancer, heart disease, diabetes, or other chronic diseases.

However, your risk will be much lower, and if it does occur, the severity will most likely be less than if you did not eat enough plants.

For help getting in your phytochemicals:

Roasted Vegetable Guinness Shepherd’s Pie

Mediterranean Quesadilla

Garlic Parmesan Zucchini

Mediterranean Grilled Eggplant Stacks

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