In daily life, when it comes to a certain ingredient, most people first think about whether it tastes good.

Ancients were different. They cared more about the "nature and taste" of ingredients and medicines.

Only by understanding the nature and taste of ingredients and medicines, and through proper deployment, can the whole achieve an optimized combination and produce a greater effect than when they act alone.

Studying the nature and taste of food (such as four natures and five tastes) is the foundation of TCM diet therapy for health preservation. According to TCM theory, food should be selected based on different diseases and syndromes. Therefore, it is extremely important to grasp the nature and taste of food, so that one can skillfully use diet therapy for health preservation and achieve targeted results.

1. The "Four Natures" of Food

TCM theory holds that both food and medicines have "four natures"—cold, hot, warm, and cool. Also known as "four properties", they are determined by the reactions caused after being taken by the human body.

They are usually divided into two categories: cold-cool and warm-hot, as well as neutral nature which lies between the four natures without obvious bias.

Cold-cool foods mostly have the effects of clearing heat, purging fire, detoxifying, nourishing yin, and promoting fluid production. They can alleviate or eliminate heat syndromes, nourish the body's yin fluid, and are suitable for people with a hot constitution or consumption in summer. Examples include sugarcane, water chestnut, pear, watermelon, bitter melon, cucumber, loofah, radish, pork, duck meat, mung bean, tremella, and tomato.

Warm-hot foods mostly have the effects of warming the middle energizer, dispelling cold, tonifying yang, activating blood circulation, and dredging collaterals. They can alleviate or eliminate cold syndromes or blood stasis, assist the body's yang qi, and are suitable for people with a deficient-cold constitution or consumption in winter. Examples include lamb, chicken, lychee, longan, brown sugar, wine, green onion, ginger, chives, garlic, chili, and pepper.

Neutral foods have a mild effect, no obvious side effects, and a wide range of applications. Examples include soybeans, potatoes, pumpkins, lotus seeds, Euryale ferox, coix seeds, white hyacinth beans, Chinese yam, cowpeas, black beans, fungus, carrots, shiitake mushrooms, white sugar, eggs, and carp.

2. The "Five Tastes" of Food

TCM believes that both traditional Chinese medicines and food have "five tastes": sour (astringent), bitter, sweet (light), pungent, and salty.

The "five tastes" are mainly divided according to their original flavors, and foods with different tastes have different effects.

2.1 The Impact of Five Tastes on Zang-Fu Organs

01. Pungent Taste

• Pungent taste tonifies the liver and gallbladder: It nourishes the liver and gallbladder, transforming suppressed anger into overt anger to vent it, allowing the liver and gallbladder to relax and flourish.

• Pungent taste impairs and purges the spleen and stomach: Another effect of pungent taste tonifying the liver is purging the spleen and stomach. Therefore, people who always eat spicy food tend not to gain weight.

• Unrestrained consumption of spicy food and alcohol can easily damage the gastric mucosa and impair the spleen and stomach to a certain extent. However, if the spleen and stomach have excessive yin-cold, eating pungent food is just right.

• Pungent taste disperses lung qi: If there is a lot of sticky phlegm and mucus in the lungs, how to expel it? Some people cannot spit up phlegm, while others struggle to expel it. At this time, they need to eat some pungent food to disperse the lung qi.

02. Salty Taste

• Salty medicines tonify the heart, including the pericardium meridian. Both excessive and insufficient saltiness can damage the heart.

• Human blood and sweat are salty. When the saltiness of blood and sweat is low, the person's heart qi becomes deficient, and they will have no mood or desire to do anything. If too much salt is consumed, it will lead to hyperactive heart fire, high blood pressure, hyperthyroidism, and fire in the triple burner.

• Sweat is the fluid of the heart, and blood and sweat share the same origin. Excessive sweating or blood loss will damage the heart.

• Excessive saltiness impairs the lungs and large intestine: The result of tonifying the heart is purging the lungs and large intestine, so people who eat too much salt will keep coughing.

• Saltiness moistens the kidney and softens hard masses: The kidney governs water, and water (kidney) restricts fire (heart). After the kidney's power is strengthened, to prevent damage to the heart, add some salty medicines to tonify the heart qi.

• Salty foods do not tonify the kidney but moisten it. For example, nuts are solid and tonify the kidney and brain. When eating walnut kernels, never add sugar; instead, add a little salt.

03. Sweet Taste

• Sweet taste tonifies the spleen and stomach: Sweet taste includes sweet, light, and sweet flavors, and it first tonifies the spleen and stomach. People with weak spleen and stomach (usually those who are emaciated, have thin lips and stomach walls, and cannot digest or absorb food) need to tonify the spleen and stomach.

• Nowadays, the situation is different. People's living standards have improved, and the quality of diet has become better. At this time, one should not over-tonify the spleen and stomach or eat too many sweet foods.

• Excessive sweetness impairs the functions of the kidney and bladder (purging the kidney): Tonification is accompanied by purging. The consequence of over-tonifying the spleen and stomach is purging the kidney and bladder, weakening their functions.

• We often hear people advising us to drink more water, and many doctors also give such advice. However, drinking too much water can damage the kidney.

• Sweet taste relieves liver urgency: What does relieving liver urgency mean? The liver restricts the spleen (wood restricts earth). Some people have diarrhea when eating spicy food or getting angry. This is because the "earth" (spleen) is not strong enough to relieve liver urgency, so they should eat some sweet food.

• Eating sweet food is not to purge the liver or weaken it, but to find a relative support and balance, so that liver fire does not cause too much disturbance in the body.

• Therefore, when we have severe diarrhea after eating spicy food, we should eat some sweet food to soothe the liver irritation caused by spiciness.

• For people with excessive liver fire and an irritable temper, eating an appropriate amount of sweet food can also relieve their condition.

04. Sour Taste

• Sour taste tonifies the lungs and large intestine: Examples include pears, dark plums, raw Chinese yam, cornus officinalis, and schisandra chinensis (schisandra chinensis actually has five tastes, but its main taste is sour).

• Sour taste purges the liver and gallbladder and reduces liver fire: Sour taste is warm, purges the liver and gallbladder, and helps to restrain and reduce liver fire.

• Sour taste astringes heart qi and spirit: The third effect of sour taste is astringing heart qi and spirit. Therefore, people who sweat a lot or are distracted should eat some sour food.

• The best ingredient for astringing the spirit is lotus seeds without cores. Lotus seed cores are bitter and purge heart fire, while lotus seeds without cores are astringent. They are suitable for people with insufficient yin and blood and scattered spirit, as they can astringe the spirit.

05. Bitter Taste

• Bitter taste first tonifies the kidney and bladder: We add tea leaves to water to avoid frequent urination. Because drinking too much plain water is diuretic and purges the kidney, adding something bitter can tonify the kidney and bladder and purge heart fire.

• Bitter taste purges heart fire and expels phlegm: If a person has excessive heart fire, bitter-cold medicines should be used; if a person has excessive phlegm and yin-cold, bitter-warm medicines should be used.

• Bitter taste dries dampness and enters the spleen: The third effect of bitter taste is drying dampness and entering the spleen, providing a recoil force for the kidney to prevent excessive tonification of the spleen from damaging kidney water.

• Therefore, for patients with excessive dampness such as eczema exudation and recurrent eczema, bitter medicines should be used to dry dampness.

2.2 Examples of Common Foods with Five Tastes

• Sour foods: Such as dark plums, lemons, apples, and grapes. Rich in organic acids, they have the effects of astringency, promoting fluid production to quench thirst, and astringing essence to prevent emission. They are mostly used for syndromes such as excessive liver qi elevation, spontaneous sweating, chronic diarrhea, and spermatorrhea, but excessive consumption may cause spasm.

• Sweet foods: Such as white sugar, jujubes, and sugarcane. Rich in carbohydrates, they have the effects of tonifying deficiency and harmonizing the middle energizer, invigorating the spleen and stomach, nourishing yin and moistening dryness, and relieving spasm and pain. They are mostly used for preventing and treating syndromes such as spleen-stomach weakness, insufficient qi and blood, and yin fluid consumption, but excessive consumption may block qi movement.

• Bitter foods: Such as bitter melon, almonds, and lotus seed cores. Rich in alkaloids, glycosides, and bitter substances, they have the effects of clearing heat and drying dampness, purging downward and relieving adverse qi. They are mostly used for hot constitutions, heat syndromes, tumors, and constipation, but excessive consumption may damage yang.

• Pungent foods: Such as ginger, chili, prickly ash, cinnamon, garlic, onions, chives, and coriander. Most contain volatile oils, with the effects of dispelling cold, promoting qi movement, and activating blood circulation. They are mostly used for colds, qi stagnation, blood stasis, damp stagnation, and phlegm obstruction, but excessive consumption may cause qi dispersion and internal heat.

• Salty foods: Such as table salt, laver, kelp, and shrimp. High in sodium, they have the effects of softening hard masses, resolving stagnation, and moistening the intestines. They are mostly used for treating tumors and constipation, but excessive consumption may cause blood coagulation.

2.3 Beyond the Five Tastes: Light Taste and Astringent Taste

Beyond the five tastes, there are light taste and astringent taste.

Generally, light taste is juxtaposed with sweet taste, i.e., "light taste is attached to sweet taste", and astringent taste is juxtaposed with sour taste, i.e., "astringent taste is attached to sour taste". Light-tasting foods have the effects of promoting diuresis and excreting dampness, while astringent foods have the effects of astringency and consolidation.