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What is yin-yang theory in yakuzen?

2026 6/11
Columns Vegetable yakuzen
30 July 202511 June 2026
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Yakuzen, grounded in the theory of Chinese medicine, is a way of thinking you might call kampo you eat, using the power of ingredients to keep the body in balance. At its root lies yin-yang theory. This article covers the basics of yin and yang and how to bring them into ingredients, constitution and the seasons, as yakuzen wisdom you can use day to day.

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What is yin-yang theory? The central concept of Chinese medicine

Yin-yang theory is the basic concept of Eastern philosophy, seeing everything through the two qualities of yin and yang. Within Chinese medicine and yakuzen it is an important axis, sorting constitutions, the qualities of ingredients and the turn of the seasons into yin and yang.

YinYang
Cold, quiet, inward, dark, moving downwardsHot, active, outward, bright, moving upwards

The division is not absolute but relative, and it shifts. Water is yin, for instance, but takes on the quality of yang when it boils.

What the taiji diagram means

The taiji diagram, the black and white symbol like two commas, makes the relationship between yin and yang visible.

  • Yin and yang oppose one another and complete one another
  • There is yang within yin and yin within yang (they depend on one another)
  • Yin and yang are always changing, always turning into one another

Like the diagram, the body too holds its balance while constantly changing it.

Do ingredients have yin and yang? How yakuzen sorts them

Yakuzen sorts the qualities of ingredients into yin and yang too, and uses them according to constitution and season.

What marks out yin ingredients (they cool the body)

  • Cold or cool in nature, high in water
  • They grow underground or in water
  • Pale or deep in colour

Typical ingredients:

  • Vegetables: cucumber, tomato, lettuce, Chinese cabbage, spinach
  • Fruit: banana, watermelon, pear, kiwi
  • Seaweed: wakame, kombu
  • Drinks: green tea, mineral water

What marks out yang ingredients (they warm the body)

  • Warm or hot in nature, high in fat
  • They grow above ground
  • Vivid in colour, red or yellow

Typical ingredients:

  • Meat: beef, lamb, chicken
  • Spices: ginger, chilli, pepper, cinnamon
  • Nuts: walnut, almond
  • Grains: brown rice, buckwheat
  • Drinks: black tea, coffee, alcohol

Note that yin and yang shift with how you cook as well: a raw tomato is yin, but simmered it leans towards yang.

Balancing yin and yang by constitution

The yin deficiency constitution (yin short, yang in excess)

Symptoms:

  • Flushing, heat in the hands and feet
  • A dry mouth and throat
  • A red face, irritability
  • Constipation, dark urine

Ingredients to try (yin):

  • Cucumber, tomato, Chinese cabbage
  • Watermelon, pear, banana
  • Mung beans, black soybeans, tofu, white wood ear, soy milk

Ingredients to go easy on (yang):

  • Chilli, ginger, fried food, alcohol

The yang deficiency constitution (yang short, yin in excess)

Symptoms:

  • Feeling the cold, particularly in the hands and feet
  • A pale complexion, low energy
  • A tendency to diarrhoea; fluids upset you

Ingredients to try (yang):

  • Ginger, spring onion, garlic, cinnamon
  • Lamb, chicken, walnut, black sesame
  • Unrefined brown sugar, honey

Ingredients to go easy on (yin):

  • Raw vegetables, cold fruit, cold water

The seasons and yin and yang: adjusting through yakuzen

Chinese medicine sees the turn of the seasons as a change in yin and yang too, and chooses ingredients and cooking methods to match.

Spring and summer (when yang rises)

  • Spring: yang buds. Wind has a strong effect and the autonomic nervous system is easily unsettled
    → nanohana, spring cabbage, pea shoots and lemon, quickly stir-fried or steamed
  • Summer: yang at its height, heat builds up easily
    → cucumber, tomato, watermelon and mint, eaten cold or at room temperature

Autumn and winter (when yin rises)

  • Autumn: the dry season, when the Lung takes damage easily
    → pear, sweet potato and white wood ear, steamed or in soup, to replenish moisture
  • Winter: yin at its strongest, and keeping the cold off is the key
    → root vegetables, black soybeans, walnut and ginger, simmered or in a hotpot

Yakuzen wisdom for busy days

Adjusting yin and yang by time of day

  • Morning: the time to raise yang. Warm porridge, miso soup and ginger support waking up
  • Midday: digestion at its peak. Balance staple, main and side
  • Evening: heading towards rest. A light soup or warm vegetables, so as not to load the stomach

Easy yakuzen teas and soups

  • Warming teas: ginger black tea, cinnamon apple tea (for feeling the cold and for tiredness)
  • Cooling teas: chrysanthemum tea, Job's tears tea (for flushing, swelling and rough skin)
  • Seasonal soups:
    Spring: new-season onion and pea shoot soup
    Summer: winter melon and okra soup
    Autumn: sweet potato and pear soup
    Winter: root vegetable and chicken soup

Every one of them can be made with everyday ingredients from the supermarket.

In summary: a yakuzen life that settles how you feel through the balance of yin and yang

Yin-yang theory is the foundation of Chinese medicine and of yakuzen, and health means that balance being held. Yakuzen is not special cooking; you can bring it in through how you choose everyday ingredients and small adjustments. Making a point of eating for your constitution and the season is how to aim for days that are settled and well from the inside.

I got my own health back when I met yakuzen, and I keep working to pass on what makes it worth having. Do bring its wisdom into your own days, a little at a time.

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Author of this article

Asako Yamakawa

Representative of YAKUZEN TOKYO Inc. Born 1982. After working on a D2C apparel business across both digital and physical marketing, poor health led her to Chinese-medicine yakuzen. Struck by how much the properties of ingredients changed how she felt, she now runs corporate courses, supervises staff canteens and offers yakuzen services that fit everyday life, under the idea of yakuzen made for how people live now.

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