Polyphenols are naturally occurring chemical compounds that are beneficial to health.
What are polyphenols?
Polyphenols are naturally occurring chemical compounds that are beneficial to health. They contain antioxidant properties and are usually found in vegetables, fruits, legumes, cereals, chocolate, spices, and some beverages. The health effects of polyphenols also depend on their bioavailability and amount consumed (1). The best way of getting your daily dose of polyphenols is by including foods that contain polyphenols into your diet.
There are four main types of polyphenols in different food sources:
1. Phenolic Acids
Phenolic acids are found in a variety of vegetables, fruits, and whole grains. They are beneficial to health since they have antioxidant properties that help prevent damage to the cells caused by free radical oxidation. The walls of the intestinal tract also readily absorb this type of polyphenol.
Foods that are rich in phenolic acids help reduce inflammation in the body when they are regularly consumed. These foods include:
- Citrus fruits
- Red wine
Flavonoids are phytochemicals that have anti-inflammatory and antioxidant properties. You can get flavonoids from most fruits and vegetables. Sometimes, flavonoids are called bioflavonoids, which are often sold as dietary or herbal supplements.
Flavonoids are also divided into the following groups:
Excellent sources of lignans are flax and sesame seeds. They are also found in fruits, some vegetables, cereals, legumes, grains, and algae.
Regular consumption of foods rich in lignans may promote heart health. However, more research studies on humans are still needed in this area. Moreover, people may not always consume a lot of lignans in their diet, unless they take them as dietary or herbal supplements.
Stilbenes are a group of plant chemicals that promote a healthy cardiovascular system. The most studied and probably the most popular stilbene is resveratrol, which can be found in cranberries, blueberries, wine, and peanuts.
Studies have shown that stilbenes work as an anti-inflammatory and antioxidant agent in laboratory animals. However, significant effects on humans are still limited and require more studies.
Foods Rich in Polyphenols
Fresh fruits and vegetables are considered to be rich sources of polyphenols. However, the number of polyphenols in food can also vary on the following factors:
- The place where food is grown, farmed, and transported
- The ripeness of food upon consumption
- How the food was prepared or cooked
- Green olives
- Black currants
3. Nuts, Legumes, and Seeds
- Roasted soybeans
- White beans
4. Whole Grains
- Oat flour
- Whole grain wheat
5. Seasoning and Spices
- Dried thyme
- Cocoa powder
- Star anise
- Dried peppermint
- Curry powder
- Soy sauce
- Dried oregano
- Dried basil
- Celery seed
- Dried rosemary
Health Benefits of Polyphenols
Most health benefits that are associated with polyphenols are somewhat related to their role as being antioxidants (2). Antioxidants have the ability to protect the cells in the body from the damaging effects of oxidation.
1. Help maintain normal blood sugar levels
When blood sugar levels are elevated, certain symptoms, such as unintentional weight loss, fatigue, and frequent urination, are experienced. When chronic high blood sugar is left uncontrolled, a number of negative health effects occur, particularly symptoms of diabetes, such as slow wound healing, nerve damage, and loss of vision.
Studies have suggested that consuming polyphenols through the diet can help prevent a spike in blood sugar levels and stimulate the secretion of insulin, making polyphenols beneficial when it comes to maintaining blood sugar levels and reducing the risk of developing type 2 diabetes (3, 4).
2. Help relieve inflammation
Chronic inflammation can cause a number of negative effects on the body, which include triggering the immune system to attack healthy cells and certain conditions, such as diabetes, heart disease, and cancer. When polyphenols are consumed, they help reduce oxidative stress, which contributes to inflammation (5). The symptoms of inflammatory conditions such as lupus, rheumatoid arthritis, and inflammatory bowel disease (IBD) may also be reduced by polyphenols.
3. Rich in antioxidants
One of the best health benefits of polyphenols is that they contain power-packed antioxidants, which help fight disease and neutralize free radicals.
Oxidation is a necessary process that happens in the body. However, when oxidative stress occurs, there is a disruption in the balance between antioxidant and free radical activities. When free radicals are properly functioning, they help ward off infections, but when there is an imbalance between antioxidants and free radicals, damage to proteins, DNA, and fatty tissues of the body occurs (6). This damage can then lead to a variety of diseases over a period of time. Because of the antioxidant properties of polyphenols, consuming foods rich in polyphenols may help reduce the risk of oxidative stress and prevent the development of chronic diseases.
4. Promote heart health
According to the American Heart Association (AHA), heart disease was the most common underlying cause of death all throughout the world in the year 2013 (7). There are many other factors that can contribute to the development of cardiovascular disease, but consuming more foods that are rich in polyphenols can help keep the heart strong and healthy.
Research suggests that the risk of heart disease may be reduced due to the ability of the polyphenols to relieve chronic inflammation and hunt free radicals (8).
5. May help lower the risk of cancer
According to a clinical review published in 2010, natural polyphenols tend to possess anti-tumor properties through kinase activity inhibition (9). This means that aside from polyphenols promoting a healthy cardiovascular system, they may also help reduce the growth of tumors or cancer cells.
Many foods that have anticancer properties also happen to be high in antioxidant and polyphenol content. These nutrient-dense foods include green leafy vegetables, citrus fruits, berries, and fresh herbs or spices.
6. Reduce the risk of blood clots
The process in which blood platelets clump together is called platelet aggregation, which also promotes blood clot formation. The formation of blood clots helps prevent excessive bleeding, but can also cause life-threatening medical conditions, such as pulmonary embolism, stroke, and deep vein thrombosis (DVT).
Resveratrol is a type of polyphenolic compound found in red wine and skins of berries. According to studies, resveratrol can help reduce the risk of blood clot formation by inhibiting platelet aggregation (10, 11).