Polyphenols are found exclusively in plants and, according to experts, are said to be extremely healthy. Yes, there is always talk of the particularly health-promoting potency of these substances. But what exactly are polyphenols, why are they so good for us, and which foods are particularly rich in polyphenols?
What are polyphenols?
Polyphenols are among the secondary plant substances. They only occur in plants – for example in the outer layers of fruit and vegetables. Even if these substances do not provide the human body with any energy, they are still considered to be very health-promoting and have a similar effect on the body as antioxidants.
Polyphenols protect many plants from natural predators, environmental toxins, viruses, bacteria, UV radiation, and ozone. Various studies have shown, among other things, indications of a digestive, immune-boosting, anti-inflammatory, cell- and vascular-protecting effect.
There are two main groups of polyphenols: phenolic acids and flavonoids.
Phenolic acids and flavonoids – what’s the difference?
Phenolic acids have antioxidant and sometimes also anticarcinogenic effects. They are mostly contained in plants as tannic acids and are responsible for a rather bitter taste (e.g. black tea). For example, they can protect against heart disease and cancer. The phenolic acids include ferulic acid from grain and rice, caffeic acid (in coffee), or ellagic acid (in green tea).
Why do these polyphenols protect the heart? This may be due to its ability to prevent fat oxidation and reduce thrombocyte (platelet) aggregation.
Flavonoids (also: bioflavonoids) are the most common polyphenols in food. They are in the form of water-soluble plant pigments in fruit, vegetables, and herbs. Flavonoids give cherries or grapes their intense colors. Flavonoids can be divided into the following subgroups, the respective groups differ in their functions:
- Flavonols (e.g. in onions, endives)
- Flavanols (e.g. in apples, red wine)
- Flavanones (e.g. in oranges)
- Flavones (e.g. in peppers, celery)
- Anthocyanins (e.g. in cherries, dark or blue grapes)
- Isoflavonoids (e.g. in soybeans)
How do polyphenols affect health?
Although the intake of polyphenols in the human body is not necessary, they have been shown to offer us some health and positive effects. For example, you can inhibit inflammation and allergies, strengthen the immune system, and prevent cardiovascular disease – and some polyphenols also have anti-carcinogenic effects. The spectrum of action is broad: Polyphenols can be about …
- have an anticarcinogenic effect.
Several scientific studies show that the regular intake of fruit and vegetables has a positive effect on the risk of cancer, heart attack, or stroke.
Which foods contain polyphenols?
You can recognize plants with a particularly high polyphenol content by their strong color or their bitter taste. Polyphenols such as resveratrol (dark leaves and grapes of the vine), vanillic acid, flavonoids and anthocyanins (dark wild berries), cinnamic acid derivatives, and caffeic acid are particularly well known. The content of polyphenols can vary depending on the type of fruit and vegetable. It depends, for example, on the plant species, the climate, and the harvest month.
Polyphenols are found in the following foods, among others:
- Cocoa (raw cocoa powder or dark chocolate)
- orange juice
- Red wine
- Black tea
- Star anise
- Grapes (dark)
Note: Outdoor plants contain more polyphenols than greenhouse plants.