Have you ever wondered why they say it's best to eat an apple whole? If so, then you've come to the right place. Because the polyphenols, which are mainly found in the skin and in the kernels, are said to have a healthy effect on the human body. We want to show you how true this claim is.
In the following article you will find out what polyphenols are and what positive effects they can have on your body. We will also show you how much research has been done on the effects of polyphenols and which foods contain many polyphenols. So that you are fully informed, we will show you the advantages and disadvantages of polyphenols.
the essentials in brief
- The positive effect of polyphenols in the human body has not yet been researched enough to be able to definitively say that major effects are recognizable.
- Although red wine contains polyphenols, other foods have significantly more polyphenols. It is therefore questionable in this context to claim that red wine has a positive effect on health in this respect.
- In order to absorb the full content of polyphenols, it is important that you also eat the skin or peel of fruits and vegetables, as this is where most of the polyphenols in these foods are found.
Glossary entry: The term polyphenols explained in detail
If the term polyphenols is unfamiliar to you, then light is shed at this point. The following explains what polyphenols are and what effect polyphenols have.
What are polyphenols?
Polyphenols are naturally occurring substances that can only be found in plants. They belong to the secondary plant substances. This means that they play no role in either the cell structure or the energy metabolism of a plant.
Polyphenols protect the plant from "predators" or also attract insects for pollination. That is why they are mainly found in the peel or skin, i.e. the peripheral areas, of leaves, fruit and vegetables.
In addition, polyphenols also contribute to the taste, smell and color of fruits and vegetables.
Polyphenols are also referred to as aromatic compounds. Poly- stands for "a lot". This means that at least two or more hydroxy groups (oxygen + hydrogen), i.e. phenols, are attached to the aromatic ring.
At present, many thousands of compounds are referred to as polyphenols. The polyphenols can be roughly divided into two subgroups. On the one hand, there are the phenolic acids and the flavonoids. (1)
phenolic acids
Phenolic acid mostly has the properties of the tannic acid in the plant. This means that they appear more as flavor carriers. They usually give a rather bitter taste, such as that found in green or black tea. (1)
flavonoids
Flavonoids, on the other hand, are more responsible for the color of fruit or vegetables. Flavo- means yellow in Latin. This means that flavonoids are usually responsible for the yellowish color of fruit or vegetables, but they can also be red or blue. (1)
What effect do polyphenols have?
Now that you know what polyphenols are, you probably want to know what effect polyphenols have on you. In this section we bring you closer to what polyphenols have an influence on.
You should know that the state of the art in polyphenols is just beginning. Because polyphenols are generally not vital nutrients for humans, since they are not needed to sustain the human body.
In addition, the studies listed below were mostly tested outside of the human body. There are generally very few test series that have been tested on animals.
In addition, there are many studies that have been carried out with human cells, in very concentrated doses, but in the test tube and therefore the accuracy of such studies is not guaranteed. This is also due to the fact that polyphenols change again in the human body after ingestion.
Despite this, the current state of research is that polyphenols act as antioxidants in the human body. This means that the cells of the body are protected from harmful substances by the polyphenols.
In addition, they are said to have anti-inflammatory and blood pressure-lowering effects. Thus, polyphenols support the killing of pathogens and help strengthen the immune system. (1)
Are Polyphenols Healthy and Can They Help Cure Disease?
As you have already learned, polyphenols have various effects on the body. Now you will learn how these affect the body and whether polyphenols help to cure diseases.
It has been found in several studies that polyphenols make a positive contribution to the healing of cancer. It has been found that polyphenols in pomegranates help inhibit the growth of cancer cells in different parts of the body. These include the lungs, mammary glands, skin, prostate and intestines. (2)
The antioxidant effect of polyphenols should also reduce the deposit of fats in the human blood vessels. It has thus been established that polyphenols prevent arteriosclerosis, i.e. the pathological change in the arteries in the human body, also known as hardening of the arteries.
This also has a positive effect on the blood lipids and insulin sensitivity of the human body.
In general, therefore, it can be assumed that there is a connection between the intake of polyphenols and the health of the cardiovascular system in humans. (3)
In general, it should be mentioned again that the state of research in these aspects must be expanded in order to be able to confirm an exact connection. After all, other components of fruit or vegetables could theoretically also produce these positive effects.
How should the intake of polyphenols be dosed?
Now that you have found out what effects polyphenols can have on the human body and how they can affect your health, you should now learn what to consider when taking polyphenols.
In general, you can say that you can consume as many polyphenols as you want. This is because no side effects can be attributed to polyphenols. Thus, there is no prescribed dosage for the ingestion of polyphenols.
If you want to increase your intake of polyphenols, there are also dietary supplements that you can take alongside plants. You can buy these in pharmacies or in online shops.
Which foods are rich in polyphenols?
Of course, you can not only consume polyphenols through dietary supplements, but also simply by taking products with plant content or plant products themselves. In this section you will find out which foods are rich in polyphenols.
Apples also have a relatively large proportion of polyphenols. With apples, however, the ripeness of the apple also affects the content. The riper the apple, the more polyphenols it contains. Apple juice also contains polyphenols. (Image source: Aaron Blanco Tejedor / Unsplash)
| food type | Content of polyphenols at 100 grams |
|---|---|
| dark chocolate (85% cocoa content) | 1.6 grams |
| cocoa | 3.5 grams |
| nuts | between 0.03 grams and 0.5 grams |
| Berry | between 0.2 and 1.7 grams |
(5)
Cocoa and dark chocolate
Cocoa is one of the foods richest in polyphenols. With 3.5 grams in 100 grams of cocoa, it is the food with the fourth richest content. Dark chocolate with a minimum cocoa content of 85% has a polyphenol content of 1.6 grams per 100 grams.
However, you should note that taking cocoa in combination with milk can hinder the effects of polyphenols. This is because the casein found in milk can combine with the polyphenols.(4)
nuts
Nuts also contain the secondary plant substance polyphenol. The following table shows you which nuts have what content of polyphenols:
| nut type | Content of polyphenols at 100 grams |
|---|---|
| hazelnut | 0.495 grams |
| walnut | 0.028 grams |
| almond | 0.187 grams |
| pecan | 0.493 |
(4)
Berry
Berries in particular have a high content of polyphenols. The color of the berries contains a particularly large amount of polyphenols.
| berry type | Content of polyphenols at 100 grams |
|---|---|
| blackcurrant | 0.758 grams |
| blueberry | 0.56 grams |
| blackberry | 0.26 grams |
| strawberry | 0.235 grams |
| raspberry | 0.215 grams |
(4)
Fruit
Not only berries contain polyphenols. Other types of fruit also have a relatively high content of polyphenols. The following table shows what these are:
| fruit type | Content of polyphenols at 100 grams |
|---|---|
| plums | 0.377 grams |
| cherries | 0.274 grams |
| apples | 0.136 grams |
In fruit, the proportion of polyphenols also depends on the degree of ripeness of the fruit. It is usually the case that the polyphenol content is higher when the fruit is very ripe.(4)
Vegetables
You can also get polyphenols from vegetables. The following table shows you which vegetables contain the most polyphenols:
| vegetable type | Content of polyphenols at 100 grams |
|---|---|
| artichokes | 0.260 grams |
| Chicory | between 0.166 grams and 0.235 grams |
| Red onions | 0.168 grams |
| spinach | 0.119 grams |
(4)
Spices
Spices also contain relatively large amounts of polyphenols. You can see which spices are among the front runners in the following table:
| spice type | Content of polyphenols at 100 grams |
|---|---|
| clove | 15.188 grams |
| peppermint | between 11.96 grams and 0.235 grams |
| star anise | 5.46 grams |
(4)
beverages
Coffee, green tea, black tea and red wine also contain polyphenols.
| beverage type | Content of polyphenols at 100 grams |
|---|---|
| red wine | 0.101 grams |
| Black tea | 0.102 grams |
| Green tea | 0.089 grams |
When it comes to red wine, keep in mind that while polyphenols are most likely healthy, that doesn't mean you should drink red wine, which is still alcohol after all. (4.5)
Conclusion
The secondary plant substance polyphenol can therefore be divided into the two subgroups of phenolic acids and flavonoids. In general, polyphenols have not yet been adequately researched. However, it is strongly believed that they are the reason why some diseases have a curative effect. Polyphenols are said to have anti-inflammatory, antioxidant and antihypertensive effects.
It is definitely positive that taking polyphenols cannot harm you. So far no side effects have been found. The substance found in plants can be found primarily in berries, but also in other fruits, vegetables, nuts and increasingly in spices.
References
- DelRio, Daniele et al. "Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases." Antioxidants & redox signaling vol. 18:14 (2013): 1818-92. doi:10.1089/ars.2012.4581
- Aviram M, Rosenblat M, Gaitini D, et al. Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation [published correction appears in Clin Nutr. 2008 Aug;27(4):671]. Clin Nutr. 2004;23(3):423-433. doi:10.1016/j.clnu.2003.10.002
- Lansky EP, Newman RA. Punica granatum (pomegranate) and its potential for prevention and treatment of inflammation and cancer. J Ethnopharmacol. 2007;109(2):177-206. doi:10.1016/j.jep.2006.09.006
- Pérez-Jiménez J, Neveu V, Vos F, Scalbert A. Identification of the 100 richest dietary sources of polyphenols: an application of the Phenol-Explorer database. Eur J Clin Nutr. 2010;64 Suppl 3:S112-S120. doi:10.1038/ejcn.2010.221
- Thimothe J, Bonsi IA, Padilla-Zakour OI, Koo H. Chemical characterization of red wine grape (Vitis vinifera and Vitis interspecific hybrids) and pomace phenolic extracts and their biological activity against Streptococcus mutans. J Agric Food Chem. 2007;55(25):10200-10207. doi:10.1021/jf0722405
