【Image Source】Professor Chang Hsien-che’s “Authentic Medicinal Materials Illustrated Guide”

【Author】Chen Ta-chen

The Huangdi Neijing (Yellow Emperor’s Inner Canon), in the ‘Suwen: Treatise on the Six-Section Viscera Manifestations,’ states: “The Kidneys govern dormancy, are the foundation of storage, the dwelling place of essence; their splendor is reflected in the hair, their abundance in the bones, they are the lesser Yin within Yin, and they communicate with the qi of winter.” Since the Kidneys communicate with the qi of winter, nourishing Kidney qi is paramount during this season. Commonly, there are two types of Kidney deficiency: Kidney Yin deficiency and Kidney Yang deficiency. The symptoms manifested by each are different, and thus, the methods of nourishment also vary.

Generally, Kidney Yin deficiency manifests with several clinical symptoms, most commonly including irritability and a sensation of heat in the palms of both hands, soles of both feet, and the center of the chest. The reason for this heat sensation could be the dense network of blood vessels in these areas, as well as the abundant distribution of brown adipose tissue. Brown adipose tissue is a heat-generating tissue commonly found in areas of the body with numerous blood vessels, leading to what is commonly known as the ‘five-palm heat’ symptom. Additionally, sympathetic nervous system excitation, which in turn relatively inhibits the parasympathetic nervous system, can lead to decreased saliva secretion and symptoms of dry mouth and throat. Furthermore, due to the influence of norepinephrine, symptoms of insomnia and excessive dreaming may occur during sleep. Sympathetic nervous system excitation can also cause excessive sweat gland secretion, leading to night sweats. From the above, it can be seen that Kidney Yin deficiency is closely linked to problems with the autonomic nervous system; when its coordination of bodily functions is compromised, various symptoms arise. Kidney Yang deficiency, also known as ‘Mingmen Fire Decline (衰),’ primarily presents with symptoms such as aversion to cold, feeling cold, and cold limbs. Research suggests it may be related to hypofunction of the hypothalamus, which is controlled by the central nervous system.

Many Chinese medicinal herbs can alleviate Kidney Yin deficiency, and among them, Goji berries (Gouqizi) are an excellent choice. According to the third edition of the Taiwan Herbal Pharmacopoeia, Gouqizi are the dried mature fruits of the solanaceous plants Lycium chinense Mill. or Lycium barbarum L. (Ningxia Goji). They are mainly produced in Ningxia, Gansu, Qinghai, and other regions. Currently, Gouqizi are also produced in Taiwan; their fruits are smaller and tend to be sweet. They are usually harvested in summer and autumn when the fruits turn orange-red, then sun-dried until the skin wrinkles, eventually becoming dry and hard on the outside with soft flesh, after which the stems are removed. Generally, large berries with thick flesh, red color, few seeds, and soft texture are considered superior. When purchasing, in addition to appearance, one can also taste them for identification. Basically, those that taste salty or excessively bitter are of poorer quality. Because the fruit surface has a waxy layer, it does not dry easily during the sun-drying process. Therefore, during processing, harvested fruits are soaked in hot alkaline water containing edible alkali (Na₂CO₃) to break down the waxy layer and accelerate drying. This explains why some commercially available Goji berries may develop a white ‘frost.’ However, some unscrupulous vendors dye black or unappealing Goji berries to improve their appearance; these are points to note when purchasing. Generally, Gouqizi from Qinghai are larger and sweeter, but Ningxia-produced ones are currently more common. If stored improperly, they can sugar out and turn blackish-red, leading to spoilage, so attention should be paid to storage conditions.

Additionally, there is a product on the market called ‘Black Goji Berry’ (黑枸杞), which turns bluish-purple when soaked in water due to anthocyanins. However, the Taiwan Ministry of Health and Welfare, in its official letter Wei Bu Zhong Zi No. 1050124948 dated August 24, 2016, stated that “Black wolfberry (Lycium ruthenicum Murr.) dried fruit, a solanaceous plant, is not listed in the Taiwan Herbal Pharmacopoeia, Chinese Pharmaceutical Dictionary, Bencao Beiyao, Bencao Gangmu, or other classics, and therefore is not managed as a Chinese medicinal material… it may not be labeled or promoted as a Chinese medicinal material.” Furthermore, the Taiwan Food and Drug Administration (TFDA) of the Ministry of Health and Welfare, in its official letter FDA Shi Zi No. 1079010490 dated May 1, 2018, stated that “‘Black Goji (Lycium ruthenicum Murr.)’ has been determined by this administration to be a ‘non-traditional food ingredient’ as defined in Guideline 1 of the ‘Application Guidelines for Non-Traditional Food Ingredients,’ and therefore, it may not be used as a food ingredient before its safety for consumption is confirmed….” Therefore, the public should exercise caution when purchasing it.