Health Benefits of Plant Polyphenols
They’re not the most glamorous ingredients in the world of dietary supplements, but polyphenols offer a wealth of health benefits.
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There are a lot of different ingredients in supplements, and not all of them are as familiar as the basic vitamins and minerals. So, when you see “polyphenols,” you might wonder, “Polly who?”
While the name might not be familiar, your diet is likely full of polyphenols, especially if you eat lots of fruits and vegetables, season your food with herbs and spices, and drink tea, coffee, and/or red wine. Pronounced “polly FEEnols,” they’re nutrients that plants make to protect themselves from ultraviolet radiation and pathogens. And they can protect us too. Studies show that polyphenols are antioxidants that reduce the risk of diabetes, heart disease, cancer, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
There are about 8,000 different polyphenols, and the greatest benefit comes from eating a combination of them.
Types of Polyphenols
Scientists are continually learning more about the various natural substances found in food. So far, it’s known that there are about 8,000 different polyphenols, and the greatest benefits come from a combination, rather than any single one. That fact alone is a great reason to eat a variety of plant foods. However, knowing a bit more about what different polyphenols can do just might inspire you to expand your plant menu and spice cupboard even more.
While listing every known polyphenol would take a textbook heavy enough to be a doorstop, these are the four main classes and some of their major food sources:
1. Flavonoids or Bioflavonoids
Used interchangeably, these terms describe a class of polyphenols that’s divided further into categories. Supplement labels may include any of these:
- Flavonols protect plants against damage from ultraviolet rays, and people against poor circulation and elevated cholesterol. Top sources are the skins of fruits and vegetables.
- Flavones help to relax blood vessels. Yellow and green fruits and vegetables are top sources.
- Flavanones are found in citrus fruits, such as oranges and lemons. They work with vitamin C and are anti-inflammatory and good for the heart.
- Flavanols, aka catechins, may help to protect against dementia. Top sources include plums, prunes, berries, and black tea. Quercetin, found in asparagus, is a type of flavonol available in supplements for hay fever, hives, asthma, and eczema.
- Isoflavones help to balance hormones, especially in the time leading up to menopause. Soy foods are major sources, and they are also found in supplements made from soy or red clover.
- Anthocyanins may help to lower risk of heart disease, stroke, and cancer. They’re found in red, blue, and purple plant foods.
Found in small quantities in food, the two best-known stilbenes are resveratrol, found in grape skins, red wine, peanuts, blueberries, and cranberries, and ptero-stilbene, found in blueberries and grapes. Both are available in supplements. Studies have found that both are good for the heart and help protect against cancer. Although their benefits are similar, each one works in a unique way in the human body.
Flaxseed is the richest source of lignans, followed by sesame seeds. But they’re also found in other seeds, grains, and fruits and vegetables. Lignans help balance hormones and lower chronic inflammation, blood pressure, and elevated cholesterol.
4. Phenolic acids
Found in onions, radishes, olives and olive oil, berries, cocoa, flaxseed, chestnut, sage, and rosemary, phenolic acids protect against coronary artery disease, stroke, and cancers.
Top Polyphenol Foods
In any given plant food, nature combines polyphenols in a unique way. When total amounts of polyphenols of any type are measured, herbs and spices rank highest, namely cloves, dried peppermint, and star anise. Cocoa powder is another top source.
Pomegranate juice is a popular source of antioxidants. While its total polyphenol content is comparable to other juices, it contains a unique polyphenol not found in other foods, called punicalagin, as well as more than a dozen others.
Polyphenol content alone shouldn’t be the criterion for choosing plant foods—variety is the name of the game. While polyphenols are a beneficial part of a healthy diet, an overload may interfere with thyroid function or iron absorption.
Polyphenols—or polyphenol-rich fruit and vegetable concentrates or extracts—are included in some multivitamins, fruit and vegetable powders, and standalone supplements. In others, such as the following, the main ingredient is a rich source of polyphenols:
- Grape Seed Extract
- Green Tea Extract