Polyphenols in sour cherries: Why they are so healthy

Sour cherries contain a variety of polyphenols , secondary plant compounds known for their antioxidant properties. Montmorency tart cherries, in particular, impress with their high polyphenol content and unique nutrient profile. But how do these substances work, and which forms of administration offer the greatest benefits? In this article, you'll learn why the polyphenols in sour cherries are so special and how they differ from other foods.

Here you can find out...

What are polyphenols? What function do polyphenols fulfill in plants? Which polyphenols are contained in sour cherries? Do sour cherry products differ in terms of polyphenol content? What is the polyphenol content in different dosage forms? What other foods are rich in polyphenols? Conclusion

The most important things in brief

Polyphenols are secondary plant substances that protect plants from UV rays and pests and influence their taste and aroma

Sour cherries contain numerous polyphenols , which make them a particularly healthy fruit: The sour cherry variety Montmorency has the highest content among the different cherry varieties

Because sour cherries taste sour, they are often processed, which can lead to the loss of valuable ingredients : Sour cherry products with the most polyphenols are sour cherry juices and concentrates

What are polyphenols?

Polyphenols are natural compounds belonging to the group of secondary plant substances. They are divided into various complex groups depending on the number of their ring structures and hydroxyl groups. Today, over 10,000 types of polyphenols are known (1).

Polyphenols can be divided into four main groups: flavonoids, stilbenes, phenolic acids, and lignans. These groups form the basis for the further subdivision of polyphenols. The largest and most intensively researched group is the flavonoids. Their subgroups include flavan-3-ols, flavonols, isoflavones, flavanones, and anthocyanins (2).

A few years ago, polyphenols were considered to have no health benefits. However, with increasing research, interest in phenolic compounds has increased, primarily due to the discovery of their antioxidant properties (1).

Fig. 1: Classification of polyphenols ( 2 )

What function do polyphenols fulfill in plants?

Plants produce polyphenols to protect themselves from various harmful factors. Bacteria, viruses, insects, larger animals, and even UV rays can harm plants. Therefore, over the course of evolution, plants have developed polyphenols to protect themselves from pathogens and predators and to ward off environmental stress (3).

The example of flavonoids clearly shows that polyphenols perform very different functions in plants: In addition to their defensive function, they are also responsible for the pigmentation of fruits . Anthocyanins are responsible for the red-blue coloring of many fruits and vegetables , including sour cherries (4). Flavones and flavonols protect the cells of flowers, leaves, and stems, particularly from harmful UV radiation (3). Polyphenols also play an important role in the formation of fruit flavor, aroma, and texture (5).

Which polyphenols are contained in sour cherries?

The polyphenols in sour cherries are mostly found in the skin of the fruit . They not only make them a healthy fruit but also give them a distinctive flavor (6).

Some of the polyphenols found in sour cherries are:

Anthocyanins	Hydroxycinnamic acids	Flavan-3-ols	Flavonols
Cyanidin-3-glucoside Cyanidin-3-rutinoside Cyanidin-3-sophoroside Pelargonidin-3-glucoside Pelargonidin-3-rutinoside Peonidin-3-rutinoside	Neochlorogenic acid p-coumaroylquinic acid	Catechin Epicatechin	Quercetin-3-glucoside Quercetin-3-rutinoside Kaempferol-3-rutinoside (2, 5)

Tab.1: Polyphenol types

Do sour cherry products differ in terms of polyphenol content?

Because sour cherries have a rather sour taste, they are rarely eaten fresh and are instead processed into various products. Sour cherries are often found in the form of juices, juice concentrates, jams, alcoholic beverages, and confectionery. This allows them to be consumed not only seasonally but also year-round (7).

Among the most nutrient-dense products are tart cherry juices and concentrates . They are closest to the original form of the fruit and contain a large portion of the original spectrum of phytochemicals . This was demonstrated in a study comparing various tart cherry products. The highest amount of polyphenols was found in tart cherry concentrate compared to frozen, canned, and dried tart cherries (8).

Scientists concluded in a 2021 study that tart cherry juices or concentrates are more effective than powdered tart cherry products. They point out that different manufacturing processes of tart cherry products can alter the nutrient composition , which in turn affects their effectiveness (9).