What is Bukuryo?

Bukuryo is a dried fungus used in Kampo, the herbal medicine of Japan. Its Latin name is Wolfiporia cocos. It is also known as Poria sclerotium.

The part used is the sclerotium, a hard pale lump that grows on pine roots under the soil. Kampo uses it to help the body pass extra water, to settle the stomach, and to support weak digestion. Kampo calls that last job a spleen tonic.

Here is the honest verdict. Bukuryo has been used for hundreds of years, but human trials of it on its own are very thin. Long use in a tradition is not proof that a herb works.

How does Bukuryo work?

No one knows for sure how Bukuryo works. Most of what we know comes from lab dishes and animal tests, not from people.

Lab work points to two groups of parts. Triterpenes (fat-like natural chemicals) may make the kidneys pass more water and salt. Long sugar chains called polysaccharides may act on immune cells in the gut.

These findings are early. They do not prove that taking Bukuryo does the same thing in your body.

What forms does Bukuryo come in?

You will most often meet Bukuryo as dried white cubes or slices. These are simmered in water to make a decoction, which is a strong herbal tea.

Other forms are common in Japan. Granules (ekisu) are dried extract powders made by drug firms. Capsules, tablets and loose powder are sold too.

Bukuryo is also one part of many well-known Kampo formulas, such as Goreisan, Saireito and Ryokeijutsukanto. In China, ground Poria is baked into a sweet pastry called fuling cake.

Where it comes from:

Poria appears in the Shennong Bencao Jing, an old Chinese drug book written around 200 CE. It has been used across East Asia for about two thousand years.

Japanese doctors took it into Kampo and made it a staple. By the Edo period (1603-1868) it sat in a large share of everyday formulas. It is still one of the most used single drugs in Japan today.

What does Bukuryo help with?

• Mild puffiness from fluid (oedema): This is the classic Kampo use. Animal studies show more urine flow, and Bukuryo sits in most Kampo water-balance formulas. No good human trial has tested Bukuryo alone for swelling.
• Upset stomach and nausea: Kampo texts describe it as calming a churning stomach. It is used this way inside mixed formulas far more often than on its own. Human evidence for the single herb is lacking.
• Poor appetite and loose stools: Kampo calls this the spleen tonic role, meaning support for weak digestion. Practitioners pair it with other herbs rather than use it alone. No trial has tested this in people taking Bukuryo by itself.
• Dizziness linked to fluid balance: Traditional theory ties some dizziness to fluid sitting in the wrong place, and Bukuryo is chosen for that pattern. The formula Ryokeijutsukanto is the usual vehicle. Evidence here is traditional, not trial-based.
• Restlessness and poor sleep: Older texts describe a calming quality, and a related grade cut from around the root (Bukuryoshin) is used for this. Lab work has looked at brain receptors in animals. There is no human sleep trial for Bukuryo alone.

Which foods are rich in Bukuryo?

1. Fuling cake (fu ling jia bing) - a Chinese pastry made with ground Poria
2. Kampo and Chinese herbal soups - Bukuryo is often simmered with other herbs

Practical Tips:

Bukuryo is a medicinal fungus, not an everyday food, so you will not get it from a normal diet.

What are the side effects of Bukuryo?

• Passing urine more often
• Mild stomach upset or nausea
• Loose stools
• Dry mouth or thirst
• Skin rash or itching, from an allergy to the fungus
• Light-headedness, mostly if you are already low on fluid

Good to know:

Most people who take Bukuryo notice nothing at all. The most common effect is simply passing more urine. Serious harm has not been reported in the medical literature, but that partly reflects how little the single herb has been studied.

How much Bukuryo should you take?

• Recommended daily: No dose has been set by human trials. The amounts below come from Kampo practice, not from research. In Japan, 3 to 6 grams of the dried herb a day is the usual range in a decoction (a strong herbal tea). Some formulas go up to about 10 grams a day. For granules, powders or capsules, follow the label or your practitioner. Strengths differ a lot between brands, so do not swap one product for another gram for gram.
• Best time of day: Kampo doses are usually split into two or three, spread across the day. Because Bukuryo can make you pass more urine, many people take the last dose well before bed.
• With or without food: Kampo tradition is to take it between meals or about 30 minutes before eating, with warm water. If it upsets your stomach, take it with food instead.
• Time to effect: Any change in water balance or stomach comfort is usually noticed within a few days to two weeks. This timing comes from practice, not from measured trials.
• How long to take it: Kampo practitioners usually check how you are doing after about two weeks. If nothing has changed by four weeks, the herb or the formula is normally changed. There is no safety data for taking it for years. If you want to keep going past three months, ask a doctor or a trained Kampo practitioner to review it.