No matter what type of diet you’re following, you’ve probably heard that it should contain plenty of vegetables and at least some fruits. Of course, these are foods known to be high in nutrient density yet low in calorie density, as they’re loaded with vitamins, minerals, fiber, water, and other essential nutrient while being relatively low in calories. Yet, there’s another reason to incorporate an ample quantity of these nutrient powerhouses into your diet: They’re packed with polyphenols. What are polyphenols? Why should you eat them? What are the most polyphenol-rich foods? These are all great questions we’ll be sharing the answers to in this article.
What Are Polyphenols and Why Should You Eat Them?
The dictionary defines polyphenol as “a compound containing more than one phenolic hydroxyl group.” Say what?!? Exactly… More simply, “polyphenols are plant-based chemicals that may provide health benefits.” This group of compounds includes over 500 naturally-occurring phytochemicals (literally, “plant chemicals”) that give the plants their color and help protect them from the types of dangers plants encounter (such as UV radiation, pests, and pathogens.) And once you consume the plants, their polyphenols may provide health benefits for you too.
Yet, like relationship status, it can be complicated. There is research on the health benefits of specific polyphenols like resveratrol (found in the skin of grapes and in wine), epigallocatechin gallate (EGCG, found in green tea), and curcumin (found in turmeric root),1 but when it comes to the health benefits from certain fruits and vegetables, it’s likely that we also benefit from the entire package. That is, the plant foods provide vitamins, minerals, fiber, as well as polyphenols and other phytochemicals.
You may already be familiar with certain polyphenols, just by a different name, as they are divided up into several categories. Flavonoids, which can be subcategorized as flavanols, flavones, isoflavones, flavanones, and anthocyanidins, for example, may sound familiar. But whether or not you’ve heard of them doesn’t really matter.
What does matter is that, for the past two decades, research has been conducted to see how polyphenol-rich foods may improve human health. And a wide variety of studies indicate that folks who enjoy diets high in polyphenol-rich foods also appear to be “less susceptible to cardiovascular disease, their complications, and related mortality.”2 For example, the Mediterranean diet,3 the South Asian diet, Far Eastern diets, and the French diet4 all traditionally contain high levels of polyphenols and, likely not by coincidence, lower incidences of disease and longer health and lifespan.
Why? One way is that polyphenols have powerful antioxidant properties. Our bodies continuously battle free radicals and the chaos and destruction they can cause. Free radicals are part of normal metabolism yet also occur at much greater levels when we’re exposed to pollution, smoking, alcohol, aging, and a less-than-stellar diet (e.g., filled with fried foods, processed foods, rancid oils, and the like). Through their antioxidant powers, polyphenols can help the body in its struggle to balance out free radicals and oxidative stress. They may also support the body’s healthy response to inflammation, and some research indicates they may help slow the clogging of arteries.5
Other potential health benefits of polyphenol-rich foods include:
- Lower cholesterol
- Lower blood pressure 6
- Improved artery function and flexibility 7
- Improved insulin sensitivity 8
- Improved lifespan 9
- Improved inflammatory response after exercise 10
- Improved body-weight regulation 11
Where Can You Find Polyphenol-Rich Foods?
Polyphenols can be grouped into different categories based on their structure (such as the number of rings and the molecules attached to them). The categories include phenolic acids, flavonoids, stilbenes, and lignans.
Flavonoids are a class that appears to have both antioxidant and anti-inflammatory properties in the body, and they are divided into subclasses, including flavones, isoflavones, anthocyanidins, and catechins. A wide variety of plant foods contain the colorful flavonoids, and these foods are believed to help prevent heart disease and stroke.
- Anthocyanidins are found in the red, blue, and purple berries and grapes (and red wine).
- Flavanols can be found in tea, cocoa, grapes, berries, apples, onions, and kale.
- Flavones are found in herbs and spices like parsley, thyme, celery, and hot peppers.
- Citrus fruits like oranges, grapefruits, and lemons are rich in flavanones.
- And isoflavones are found in legumes and soy products. 12, 13
Phenolic acids are easy to find, eat, and absorb, and they appear to also have both antioxidant and anti-inflammatory actions within the body. They can be found in common beverages like coffee, tea, and red wine, as well as in various fruits, including berries, apples, cherries, plums, and kiwi. And they’re also in potatoes (especially the skin), lettuce, spinach, broccoli, Chinese cabbage, red cabbage, broccoli, carrots, radish, red beet, and eggplant.14
Stilbenes are less common than some of the other polyphenols, but you’ve likely heard of the most well-known stilbene: Resveratrol. It’s found in the skin of grapes, and along those lines, it’s most well-known for being found in red wine. It’s also in blueberries, cranberries, rhubarb, and believe it or not, peanuts. While animal research demonstrates resveratrol’s antioxidant and anti-inflammatory properties, the evidence in humans is limited. The other lesser known stilbene (pterostilbene) is also found in blueberries and grapes.15
The best sources for lignans include flaxseeds and sesame seeds, and they’re also found in curly kale, broccoli, apricots, cabbage, Brussels sprouts, strawberries, tofu, and dark rye bread.16 A diet rich in lignans has been associated with improved cardiovascular health.
While the polyphenol counts can vary depending on where a food is grown and farmed, how ripe it is, and how it’s prepared, the top ten most polyphenol-rich foods appear to be:17
- Dried peppermint
- Star anise
- Cocoa powder
- Dried Mexican oregano
- Celery seed
- Black chokeberry
- Dark chocolate
- Flaxseed meal
- Black elderberry
Polyphenol-Rich Foods: A Recap
To quote Michael Pollan from his brilliant book In Defense of Food, “Eat food, not too much, mostly plants,” as plants provide an abundance of nutrients — including polyphenols — to help our bodies perform better, fight off illness, and even improve our health span. In other words, eat your veggies every day, enjoy your coffee, tea, and red wine (in moderation, of course), use plenty of seasonings (like oregano, rosemary, ginger, cinnamon, and cumin), and indulge your sweet tooth with fresh fruit and a bit of dark chocolate. Filling your diet with plenty of polyphenol-rich foods will help you get an abundance of these powerful phytochemicals so you can enjoy the health benefits they may impart.