Gallnut is a medicinal material from oak tree galls: a full analysis of its properties and application value

Gallnut, also known as gallnut or ink stone, is a gall formed when certain gall wasp insects lay eggs and parasitize the young branches of Quercus plants, stimulating the local tissue of the tree to proliferate. It is both a traditional Chinese medicinal material and an important natural raw material for extracting gallic acid and tannins.

Complete gallnuts are mostly irregularly spherical, with a surface ranging from grayish-yellow to grayish-brown, often bearing small wart-like protrusions. Its texture is hard, the fracture surface is uneven, and concentric ring-like patterns can sometimes be seen. The odor is faint, and it tastes astringent with a slight bitterness, possessing obvious astringency due to its rich tannin content.

In traditional Chinese medicine, gallnut is bitter in taste and astringent in nature, excelling at astringing and securing. Traditionally it is mostly seen in formulas for chronic diarrhea and chronic dysentery, spermatorrhea and night sweats, bleeding, and mouth sores, and it usually needs to be processed or used in combination with other medicinal materials. In industry, it was once an important raw material for making ink, dyes, and tanning leather in history, while in modern times it is widely used as a source for extracting gallic acid, applied in many fields such as chemicals, food, and medicine.

It should be noted that although gallnut is a natural product, oral use must be guided by a traditional Chinese medicine practitioner based on syndrome differentiation, and external use should also pay attention to concentration and compatibility, and it should not be used blindly on one's own. When purchasing, quality can be judged by aspects such as complete shape, clean surface, and clear fracture patterns, and it can simply be stored in a dry, ventilated place.