Tannins and their role in health

Published: 08/19/2006 - Updated: 08/13/2019

They are responsible for the harshness and bitterness of the tea, red wine or Granada and are increasingly receiving more attention for their antioxidant action, which helps prevent degenerative diseases. The tannins are in fashion for their powerful antioxidant that may help prevent the appearance of aging and degenerative diseases like cancer.

These substances are water-soluble polyphenols present in many plant foods such as fruits (pomegranates, blackberries, blueberries, gooseberries, quinces) and vegetables, also found in beverages like tea, coffee and chocolate. These are substances with health benefits, but may also decrease the absorption of some nutrients.

What makes a food with tannin different? 

One of the most genuine facts of the tannins is that has a rough, dry constrictor taste. This is due to clotting or clumping of glycoproteins from saliva, which is why we are also used in tanning hides. In addition, the tannins tend to give a brownish color to food.

In what doses are they harmful? 

Tannins have shown some toxicity in very high doses (when food containing approximately 5% of tannin). In people, the problems are very rare, but can cause some gastrointestinal disturbance, in part because the tannins affect the growth of normal intestinal flora.

Are there different types of tannin?

And it can be classified into hydrolysable and condensate (Proanthocyanidins), much less soluble in water. Proanthocyanidins are purple pigments that stimulate the venous circulation.

Why are they healthy for heart? 

Proanthocyanidins or condensed tannins protect the venous and arterial walls. Hydrolysable tannins in this action are minor. Some cianidines have been used as medicine in prevention of diabetic retinopathy. People with diabetes are predisposed to suffer from vascular problems.

What have they to do with red wine? 

The virtues of the heart health of moderate wine consumption is partly due to the tannins. This applies especially in red wine because it was soaked with the skin, which is the richest tannin in the grape. The tannins are responsible for color and taste of red wine come from grapes and barrels.

How do you make a tea rich in tannins? 

Tea leaves are rich in tannins, especially green tea, which contains Gallic acid. To make a tea rich in tannins, leave tea until it becomes rough.

When are they discouraged?

The tannins may interfere with the absorption of certain elements, especially metals such as copper, calcium and iron. It is not appropriate, then, that people with anemia, for lack of iron, abuse of beverages and foods rich in tannins, such as coffee, tea and chocolate.

What are their pros and cons?

For one thing, exert antioxidant action, help the treatment of diarrhea, improve cardiovascular health and immunity, and are harmless in small doses. But its taste is rough, have nutritious little power, can cause constipation and hinder the digestibility of protein, fiber, carbohydrates and minerals.

About the author
  • Dra. Loredana Lunadei

    Dr. Loredana Lunadei is a specialist in food, dietetics and nutrition. She studied at the University of Milan where she obtained a Master in Food Science and Technology. Subsequently, she continued her studies, completing her PhD also at the University of Milan. Linkedin.