Educational information, not medical advice — ask your doctor or midwife.
Dodu is the Korean name for the sword bean, the large flat seed of a climbing legume called Canavalia gladiata. In Korea it is best known as a roasted bean tea, and the young pods are also cooked as a vegetable or pickled. Folk use centres on stuffy sinuses, sore gums, piles and everyday digestive comfort.
Here is the honest verdict on the evidence. Dodu has a long and genuine place in Korean, Chinese and Japanese folk practice, but we could not find human trials that test it for any health claim. A long tradition of use tells you what people have done for centuries; it is not proof that the plant does anything to a disease.
One safety point matters more than any claimed benefit. Raw or undercooked sword beans are not safe to eat, because they contain lectins (natural bean proteins that irritate the gut) that cooking and roasting break down. Treat dodu as a food and a pleasant tea rather than as a treatment.
No one has shown how dodu works in people, because the human studies have not been done.
Laboratory work points to a few plausible ideas. The beans contain urease and lectins that are active in test tubes, plus fibre and polyphenols (plant compounds with antioxidant activity in the lab) that may act on gut bacteria and inflammation. Whether any of this survives roasting, brewing and digestion at tea-strength amounts is unknown.
Traditional Korean and Chinese practice describes dodu as a warming food that settles the stomach and helps hiccups and vomiting. That is a description of how practitioners used it, not a tested mechanism.
Common forms include:
Roasted sword bean tea, sold as whole roasted beans, sliced bean, or teabags. This is by far the most common Korean form.
Young whole pods, cooked as a side dish or salted and pickled as jangajji.
Dried mature beans for cooking, which must be soaked and boiled thoroughly.
Powders and capsules sold as supplements, which are far more concentrated than tea and have no tested dose.
Sword bean is native to tropical Asia and has been grown in Korea for centuries as a food crop and a home remedy. Korean households roast the beans for tea and pickle the young pods. Chinese materia medica lists the same bean as dao dou for hiccups and vomiting, and it appears in Japanese folk use as natamame tea, so the traditional record spans several East Asian traditions.
See a doctor if you have repeated vomiting, severe stomach cramps or watery diarrhoea after eating sword bean, especially if it may have been undercooked. Get urgent help for swelling of the lips, face or throat, a widespread rash, or trouble breathing, which can mean a serious allergic reaction. Also see a doctor if congestion lasts more than ten days, gums keep bleeding, hiccups last more than two days, or you notice blood from the back passage.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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