Tannins

What are tannins? Tannins are a Group of natural or synthetic chemical compounds, which are primarily known for Modifying and ‘tanning’ proteins. The term ‘tanning’ comes from leather production, where tanning agents are used to treat animal hides durable and resistant Chemically speaking, tannins are polyphenols, i.e. plant substances with several phenol groups that can bind with proteins and cause them to cross-link or precipitate.

Where are tannins found?

They are mainly found in plants and are part of their natural defence system against predators and pathogens. They are found in many parts of plants:

• Leaves (e.g. tea leaves)
• Fruits (e.g. berries such as blueberries, strawberries)
• Seeds (e.g. coffee beans)
• Bark (e.g. oak bark, walnut leaves)
• Wood and roots

Well-known beverages such as black and green tea, red wine and pomegranate juice also contain tannins.

Chemical classification

There are two main groups of plant tannins:

• Hydrolysable tannins: These include gallotannins and ellagitannins, which can be broken down in the body through hydrolysis (splitting with water).
• Condensed tannins (proanthocyanidins): They are more stable and are not broken down as easily in the body.

How do tannins work?

They have several important effects that are beneficial in both Natur as well as in medicine:

• Protein binding and tanning: They bind to proteins and alter their structure (denaturation), making them more resistant and less susceptible to degradation. This is the basis for leather production.
• Astringent effect: Tannins contract and compact tissue. A protective film forms on the skin or mucous membrane, reducing wound secretions and bleeding.
• Antimicrobial effect: By removing nutrients and forming a protective layer, tannins hinder the growth of bacteria and fungi.
• Anti-inflammatory and pain-relieving: They can reduce inflammation and relieve pain by soothing the nerve endings in the skin.
• Plugging effect: In the gastrointestinal tract, they thicken the mucous membrane and help with diarrhoea by reducing fluid release into the intestines.
• Protects the mucous membranes: They protect the mucous membranes in the mouth, throat and intestines from irritation and infection.
• Haemostatic: Tannins can stop capillary bleeding.

Medical applications

Due to these effects, tannins are used in many ways in medicine and natural healing:

• Treatment of inflammation of the skin and mucous membranes, e.g. eczema, gum inflammation, haemorrhoids
• Supports wound healing and wound care
• Treatment of stomach and intestinal inflammation and mild diarrhoea
• Treatment of minor burns and frostbite
• Used as an antidote for heavy metal or alkaloid poisoning, as it can bind toxic metal ions.

Tannins in nutrition

Tannins are found in many plant-based foods and beverages and influence their taste, often giving them a bitter, astringent flavour (e.g. in unripe berries or black tea). They were previously considered undesirable ingredients as they can reduce the absorption of minerals such as iron and thus contribute to iron deficiency.

Today, we know that they also have health-promoting properties:

• Antioxidativ: They protect cells from harmful free radicals.
• Anti-inflammatory: They can reduce chronic inflammation.
• Antimicrobial: They help to combat harmful microorganisms.
• Cancer-inhibiting: Initial studies suggest that tannins may reduce the risk of certain types of cancer.
• Immune system booster: They support the body’s defences.
• Blood pressure regulating: Some tannins can have a positive effect on blood pressure.

Side effects and precautions

Tannins are harmless when consumed in normal quantities, but may cause side effects if consumed in excessive amounts or over a long period of time:

• Liver strain: Prolonged use may cause liver damage (hepatotoxic).
• Stomach irritation: High doses can cause inflammation of the stomach lining or nausea.
• Reduced nutrient uptake: They can impair the absorption of iron and certain medicines.
• Allergic reactions: Skin irritation or allergies may occur in rare cases.

Conclusion:

Plant tannins are found in leaves, fruits, bark and roots. They are also known as vegetable tannins or tannins. Tannins play an important role among the therapeutically active ingredients of medicinal plants. Tannins can act on tissues, such as mucous membranes, where they condense on the surface and form a protective membrane. They have an astringent and drying effect, making it more difficult for bacteria and fungi to penetrate the tissue. This also reduces wound secretion, inhibits inflammation and stops capillary bleeding.