Tannins: Natural Compounds in Herbs and Their Benefits

Tannins are naturally occurring polyphenolic compounds found in many plants and herbs. They are responsible for the dry, puckering sensation often experienced when drinking strong tea or tasting certain herbs. Common sources include witch hazel, sage, yarrow, green tea, and black tea. In plants, tannins serve as a defense mechanism against insects and grazing animals. In humans, they have long been valued in traditional medicine for their astringent, anti-inflammatory, antimicrobial, and antioxidant properties.

Herbs high in tannins have a wide range of practical uses. Witch hazel is perhaps the best-known example and is widely used in modern skincare products to tighten pores, reduce inflammation, and soothe minor skin irritations. Culinary and medicinal herbs such as sage, rosemary, and yarrow contain notable amounts of tannins and are used to support digestion and oral health. Teas, especially black and green tea, are rich in tannins, which contribute to their characteristic bitter taste as well as their health-promoting effects. Other medicinal plants with high tannin content include uva ursi, black walnut, red raspberry leaf, and oak bark. European herbal traditions also highlight plants such as plantain herb, cinquefoil, and marjoram for their tannin-related benefits.

One of the key functions of tannins is their astringency. By binding to proteins in tissues, tannins create a tightening and drying effect. This makes them useful for reducing excessive secretions, such as in diarrhea, and for toning tissues, including weakened veins. Their antimicrobial and antiparasitic actions help inhibit the growth of bacteria, viruses, and intestinal parasites. Tannins also act as anti-inflammatory and antioxidant agents, reducing inflammation and protecting cells from oxidative damage linked to chronic diseases. Additionally, they help protect tissues, promote wound healing, and can assist in stopping minor bleeding.

Tannins work by binding to proteins, enzymes, and other molecules, which explains their ability to precipitate alkaloids and inhibit enzymes involved in inflammation, such as 5-lipoxygenase. According to the National Institutes of Health, tannins are only partially absorbed into the bloodstream and primarily exert their effects in the digestive tract, where they interact with gut proteins and microbes. While tannins offer many benefits, excessive intake can interfere with nutrient absorption, particularly iron. For this reason, moderation remains important when consuming tannin-rich herbs and beverages.
Tannins: Natural Compounds in Herbs and Their Benefits