What is Jaseok?

Jaseok is the Korean name for magnetite, a heavy black iron ore. Its Latin drug name is Magnetitum. Its formula is Fe3O4, and it is also known as lodestone (magnetite).

In Korean medicine it is a mineral drug, not a plant. Healers ground the rock to powder and cooked it in water. It was given to calm a restless mind, to help sleep, and to ease ringing in the ears.

Here is the short verdict. No human trials back any of these uses. A long record of use is not proof that a remedy works.

How does Jaseok work?

No one has shown how Jaseok acts in the body. Old texts call it heavy, and say it weighs down a restless mind. That is a traditional idea, not a tested one.

Magnetite barely dissolves in water. Most of the powder passes through the gut and leaves in the stool. A small amount of iron may dissolve in stomach acid.

The pull of a magnet is not thought to do anything inside you. Any real effect would come from the iron, not from magnetism. That has not been tested in people.

What forms does Jaseok come in?

Jaseok is sold as a crushed or powdered mineral. Two forms are used: raw Jaseok, and calcined Jaseok, which is burned and then quenched in vinegar. The calcined form is softer and easier to grind.

You will most often meet it inside a mixed formula. In a water decoction (a drink made by boiling), it is boiled first for 20 to 30 minutes before the herbs go in. Pills and powders use the fine calcined powder.

Where it comes from:

Lodestone has been used as a drug for about 2,000 years. It appears in the old Chinese classic Shennong Bencao Jing. From there it passed into Korean practice.

In Korea it is listed in the Donguibogam, written by Heo Jun in 1613. It sits in the group of mineral drugs used to settle the mind. Japanese Kampo and Indian tradition used lodestone too.

What does Jaseok help with?

• Trouble sleeping (insomnia): This is the best known use. Korean and Chinese texts pair Jaseok with other calming drugs for a restless night. No published human trial has tested Jaseok for sleep.
• Ringing in the ears (tinnitus): Old books link the ears to the kidney system, and Jaseok to that system. It was mixed into pills for ear noise. There is no trial evidence that it helps.
• Poor hearing: Classic formulas such as Ercong Wan ("ear-clearing pill") include it for fading hearing. This is tradition only. Hearing loss needs a proper check by a doctor.
• A pounding or racing heartbeat (palpitations): Texts describe it as anchoring a mind that feels stirred up. It was used for fright and a thumping chest. No human study supports this, and a new pounding heart needs medical care.
• Dizziness and blurred vision: It was given when dizziness came with headache or red eyes. Modern research has not tested it for this. Sudden dizziness or vision change is a reason to see a doctor, not to self-treat.
• Wheezing and short breath: Some formulas add it to help the breath settle downward. This use is much less common. There is no trial evidence, and asthma needs proven treatment.

Which foods are rich in Jaseok?

Jaseok is a mined rock, not a food. No food contains it.

What are the side effects of Jaseok?

• Stomach ache or a heavy, full feeling
• Nausea (feeling sick)
• Poor appetite
• Constipation (hard, infrequent stools)
• Black or very dark stools
• Iron build-up in the body with long use
• Exposure to lead, arsenic or cadmium if the rock is impure

Good to know:

Gut upset is the common problem, and it usually fades when you stop. The serious worries come from long use: too much iron, and heavy metals from an untested source. Black stools from iron can look like bleeding in the gut, so never assume it is just the mineral.

How much Jaseok should you take?

• Recommended daily: No dose has been shown safe and useful in modern studies. Old texts list 9 g to 30 g of the crushed mineral a day, boiled in water. In pills or powder the amount is far smaller, about 1 g to 3 g a day. Do not act on these numbers alone. A mineral drug should come from a trained Korean medicine doctor who knows the source and purity of the rock.
• Best time of day: For sleep, it was given in the evening, an hour or two before bed. In a mixed formula, follow the schedule you were given. Keep it well away from the time you take any pill from a pharmacy.
• With or without food: Take it with food or just after food. That lowers the chance of a sore stomach or nausea (feeling sick). Leave at least 2 hours between Jaseok and any medicine you swallow, because the iron can stick to drugs and block them.
• Time to effect: Unknown. No trial has measured how fast it works, or whether it works at all. Traditional books do not promise a set time either.
• How long to take it: Use it for a short time only. Old texts warn that the mineral is hard on the stomach with long use. Think weeks, not months. Stop after 2 to 4 weeks and talk to your doctor if nothing has changed. Long or repeated courses raise the risk of iron build-up and heavy metal exposure.