Phytochemicals: Why You Should Eat the Rainbow

By Perrin Braun, December 13, 2023


Now there’s another reason to eat your fruits, vegetables and whole grains – to get phytochemicals —plant chemicals that have been shown to have a wide range of health benefits. Because they are common in plant based foods, you’re probably getting plenty of phytochemicals without even knowing it! An InsideTracker plan can tell you if you need to consume more of certain nutrients, and recommend plant-based foods that will help to improve your diet. Here is a breakdown of what phytochemicals can do for your body.

What are some common phytochemicals?

Because phytochemicals aren’t believed to be essential to maintain life, they’re not in the same category as vitamins, minerals, and other macronutrients. Even so, research suggests that phytochemicals are responsible for a wide range of health and disease-prevention benefits. Phytochemicals are commonly found in fruits, vegetables, beans, grains, and plant-based beverages like tea.

There are over 25,000 types of phytochemicals, and each provides many different benefits to your body. Here are a few:


Though polyphenols aren't the only phytochemicals with antioxidant properties, they are particularly well-known for their potency. Antioxidant molecules like polyphenols protect our cells against harmful molecules called Reactive Oxygen Species (aka ROS or free radicals), which damage cells, proteins, and DNA. For example, ROS are responsible for the browning of peeled apples when exposed to the air. True to their name, antioxidants help to prevent the oxidation caused by free radicals. On a more practical level, polyphenols have been connected to the prevention of Alzheimer's disease, cancer, dementia, and atherosclerosis.[1]

Polyphenols can be further broken down into categories:

  • Flavonoids include flavonolflavonoids with antioxidant capacity include allyl sulfides (found in onions, leeks, and garlic), carotenoids (in red and orange fruits and vegetables), flavonoids (fruits and vegetables), and polyphenols (in tea and grapes).


Found in soy, these phytochemicals imitate human estrogen and can help to strengthen bones and improve well-being in older women.


These compounds in cabbage have been shown to stimulate certain enzymes that could reduce the risk of uncontrolled cell growth, a hallmark of cancer.


A class of phytochemicals found in beans, saponins appear to strengthen the immune system and reduce the risk of poor cell health by interfering with the replication of abnormal cell DNA. 


The phytochemical allicin, found in garlic (particularly when raw), has proven anti-bacterial properties. It's also what gives garlic its unique odor.


Some types of phytochemicals bind to cell walls and prevent pathogens from adhering to them. The proanthocyanidins found in cranberries are great examples, as they can reduce the risk of urinary tract infections.


How to incorporate more phytochemicals into your diet

Eat a rainbow of fruits and vegetables! Orange-colored foods like carrots, yams, cantaloupe, squash, and apricots provide carotenoid phytochemicals. Red-, blue-, and purple-colored foods like eggplant, red cabbage, and dark grapes contain a type of phytochemical called anthocyanidin. The glucosinolate and lignin phyotchemicals occur in cruciferous vegetables like broccoli, cabbage, and cauliflower. Citrus fruits, onions, broccoli, kale, celery, garlic, and hot peppers contain a variety of phytochemicals. Most foods, except for some alcohols and refined sugars, contain some phytochemicals. When in doubt, choose brightly colored or strongly flavored fruits and vegetables, which are the best sources of phytochemicals.

What is the recommended intake of phytochemicals?

Since we don’t know exactly how the body absorbs and metabolizes phytochemical compounds, the Institute of Medicine chose not to create a Dietary Reference Intake (DRI) for these compounds. However, organizations like the American Heart Association and the American Cancer Society recommend consuming a diet that is high in fruits, vegetables, and other plant-based foods that are rich in phytochemicals. The current recommendation from the Dietary Guidelines for Americans is to consume 5 or more cups of fruits and vegetables per day. In other words, about half of the food you eat each day should be fruits and vegetables.

As with vitamins and minerals, phytochemicals are probably most beneficial when consumed as whole foods, instead of supplements. Phytochemicals in supplement form many not be as easily absorbed by the body as those from food. Additionally, by replacing actual food with supplements, you may be missing out on other important components of the food, such as the fiber that is found naturally in fruit skins or whole grains. Current evidence suggests that eating a balanced and diverse diet that is high in fruits, vegetables, and whole grains will support your overall health, so you should increase your intake of these foods if you want to consume more phyotchemicals! And have an InsideTracker blood analysis to be sure that you know which nutrients you actually need.



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