Phytochemicals (phytonutrients) are plant chemicals. They have been identified in plant foods such as fruit, vegetables, nuts, seeds, beans, and whole grains.

Unlike vitamins and minerals, most phytochemicals aren’t essential to our health (although some are also vitamins and, therefore, essential). However, they have antioxidant properties that help protect cells against damage, reducing the risk of some health conditions.

1. They’re Powerful Antioxidants

Free radicals are highly active, unstable molecules that lead to cell damage and are linked to various health conditions. Antioxidants are substances that neutralize free radicals, preventing them from causing damage.

Antioxidants help prevent damage to DNA (the molecule containing genetic information) and help remove damaged cells more quickly. An imbalance between free radicals and antioxidants is called oxidative stress.

Many phytochemicals support the body’s ability to balance free radicals and antioxidants. Eating a wide variety of plant foods helps ensure you get a full spectrum of phytochemicals rather than a large amount of a few types.

2. Can Help Prevent Chronic Disease

Cancer

No food can treat or entirely prevent cancer, but some foods may reduce the risk of developing certain types. Phytochemicals have chemopreventive properties (they can hinder cancer development). They do this by:

• Preventing DNA damage
• Helping repair mutated genes
• Helping abnormal cells die more quickly
• Slowing cancer growth

Much of the evidence supporting the role of phytochemicals in chemoprotection comes from studying people who eat mainly plant-based diets. These people have significantly lower rates of certain types of cancers than the general public. More research is needed.

Cancers that research has found phytochemicals may help protect against include:

• Breast
• Cervical
• Colorectal
• Leukemia
• Prostate

Some research found a relationship between dietary consumption of the phytochemical compounds flavonoids and reduced risk of colorectal cancer.

Indoles and glucosinolates, phytochemicals found in broccoli, cabbage, kale, cauliflower, and Brussels sprouts, may help prevent tumor growth and decrease the production of cancer-related hormones.

Heart Disease and Stroke

Phytochemicals may help:

These effects support heart health and may help prevent cardiovascular disease. Eating a variety of plant-based foods not only provides phytochemicals but also increases your fiber intake. Fiber helps reduce cholesterol and prevent cardiovascular disease.

Neurological and Cognitive Functioning

Phytochemicals may help promote brain health by supporting:

• Brain plasticity: The brain’s response to stimulation that leads to structural and functional changes
• Cognition: Processes such as thinking, learning, memory, and attention
• Neurodegenerative disorders: Prevention or delayed progression of Alzheimer’s disease and Parkinson’s disease
• Sleep: May help reduce insomnia and function as a circadian modulator (coordinating the body’s daily cycle variations)

Other Conditions

Phytochemicals may also play a role in helping to protect against conditions such as:

3. Can Help Promote Immune System Health

Research suggests antioxidants, such as those found in phytochemicals, can enhance the natural (antigen-independent) and acquired (antigen-specific) immune response. An adequate intake of various phytochemicals may help support the immune system’s resistance to infection. Antigens are substances that can trigger an immune response.

Phytochemicals can help support balanced immune function (neither underactive nor overactive). They also work as antimicrobial agents, reducing the chance that viruses and bacteria can grow in the body.

4. Can Help Reduce Inflammation

Chronic inflammation can result from underlying health conditions and lead to a variety of symptoms, such as gastrointestinal problems and joint pain.

Bioactive compounds, including those in certain vitamins, minerals, and phytochemicals, can exhibit anti-inflammatory properties.

5. Can Help Regulate Hormones

Some phytochemicals, such as isothiocyanates, may help regulate hormone production.

Phytoestrogens (one group of phytochemicals) mimic estrogen, and the body may recognize them as estrogen when eaten and absorbed during digestion.

Phytoestrogens include:

• Coumestan
• Isoflavones
• Lignans
• Stilbene

Foods that are good sources of phytoestrogens include:

• Beer
• Coffee
• Fruit
• Grains
• Nuts and seeds
• Olive oil
• Red wine
• Soy and soy products
• Tea
• Vegetables

Foods That Have Phytochemicals

Phytochemicals are only in plant-based foods, mainly fruits and vegetables, whole grains, nuts, and legumes.

The many different types of phytochemicals have varying effects and functions. Eating various phytochemical-rich foods is important to ensure you get a wide range of phytochemicals and benefit from their health-promoting properties.

Foods that are high in phytochemicals include:

Fruits such as:

• Apricots
• Apples
• Berries
• Cantaloupe
• Cherries
• Citrus fruits
• Grapes
• Pears
• Watermelon

Vegetables such as:

• Alliums (garlic, onions)
• Celery
• Cruciferous vegetables (broccoli, bok choy, Brussels sprouts, cabbage, cauliflower, turnips)
• Leafy green vegetables (collard greens, kale, parsley, spinach)
• Nightshade vegetables with colored flesh (bell peppers, tomatoes)
• Olives
• Orange-fleshed vegetables (carrots, pumpkin, sweet potatoes, winter squash)

Legumes such as:

• Beans
• Lentils
• Peanuts
• Soybeans

Other foods such as:

• Bran from corn, oats, rice, rye, wheat, whole grain products
• Cloves
• Coffee and tea, including green tea
• Dark chocolate
• Nuts
• Red wine
• Rosemary
• Seeds (flaxseed and oilseeds like canola)

Ways to Eat More 

There’s no specific recommendation for the amount of phytochemicals to consume. However, eating a diet rich in plant-based foods, especially fruits and vegetables, is a good way to ensure you get enough.

It’s important to eat a variety of plant-based foods. Some health professionals recommend “eating a rainbow,” meaning ensuring your diet includes many different colored fruits and vegetables. Try to eat the skins and peels, too (of the edible ones), as these often contain larger concentrations of phytochemicals.

Getting phytochemicals from foods rather than supplements is important because the benefits are believed to come from individual bioactive components in the foods working together. Research suggests that phytochemicals separated from food sources and taken alone as supplements do not appear to provide consistent preventive health effects.

Tips to help you eat more phytochemicals include:

• Add herbs and spices to your cooking.
• Look for brightly colored and strongly flavored fruits and vegetables.
• Bulk up your salads with colorful vegetables.
• Make soups with extra vegetables and legumes.
• Experiment with cooking methods and seasonings.

How you cook your foods also matters, as factors such as heat can degrade nutrient and phytochemical levels. Ways to help reduce the amount of phytochemicals lost during cooking include:

• Use shorter cooking times when boiling.
• Save water from boiling foods to make soups, cook rice, and prepare other foods.
• Consider steaming when you can.
• Use lower temperatures and shorter cooking times when sautéing.
• Roasting or grilling may result in higher nutrient losses because of the higher heat used.

Symptoms of Phytochemical Deficiency

While phytochemicals have important health effects, they are not considered essential nutrients (those needed for your body to function), such as proteins, carbohydrates, fats, vitamins, and minerals. Eating a diet low in phytochemicals won’t cause a deficiency, but it will deprive you of their health benefits.

Phytochemical supplements are not recommended as they are less effective than getting them in food form and may be harmful if you take too much. If you think you may have a nutritional deficiency, talk to a healthcare provider before starting any supplement.

Summary

Phytochemicals are biologically active substances found in plant-based foods. They have antioxidant properties and may help reduce the risk of developing certain health problems, such as cardiovascular disease and some kinds of cancer.

Fruits, vegetables, whole grains, nuts, seeds, and legumes are high in phytochemicals. Eating foods rich in phytochemicals is important to ensure you get different types and the benefits they offer.