How to Use Kudzu Root and Kudzu Flower

Start with the Latin name, because "kudzu" and "Pueraria" cover several plants. The kudzu of Chinese medicine and of the American South is Pueraria lobata (Willd.) Ohwi, which botanists now file as Pueraria montana var. lobata (1, 2). It's a semi-woody perennial vine in the legume family, a cousin of soybeans and peas, native to East and Southeast Asia (1).

• Kudzu root (ge gen, Radix puerariae): the large, starchy tuber. This is what most supplements, teas and the alcohol studies used. A close relative, Pueraria thomsonii (fen ge), is often used interchangeably (1).
• Kudzu flower (ge hua, Puerariae flos): the purple, grape-scented blossom. A different herb with different compounds and different traditional uses.
• Pueraria mirifica: a Thai species sold in menopause products. Not the same plant.

In the U.S., kudzu is a federally listed invasive plant. It arrived in the late 1800s as an ornamental and for erosion control, and it now crowds out native species across the Southeast (2). Hence the nickname, the vine that ate the South.

Kudzu root has been part of Chinese herbal practice for more than 2,000 years, traditionally used for fever, thirst, diarrhea and dysentery, and later for what we'd now call diabetes and cardiovascular complaints (1). A review of the English and Chinese literature counted more than 70 compounds in the root, led by the isoflavones puerarin, daidzin and daidzein, and concluded that clinical efficacy still needs to be defined (1).

Korea and Japan took the root into the kitchen as much as the apothecary. Korean galgeun-cha is a tea simmered from dried root slices, and chik (kudzu) root juice is still sold at spring markets. In Japan, the starch washed out of the root becomes kuzuko, the thickener behind kuzumochi, kuzukiri noodles and kuzuyu, a warm, glossy winter drink.

The flower is the part with the alcohol reputation in tradition. Pueraria flos, not the root, is the classic Chinese and Japanese folk remedy taken after drinking (3), often paired with the fruit of the Oriental raisin tree, Hovenia dulcis. Those are old uses, not modern claims.

Here's the honest version of the studies that made kudzu famous. Nearly all come from one lab at McLean Hospital, a Harvard teaching hospital, and they measured how much beer people drank in a controlled setting, not whether anyone got better:

• 2005: Heavy drinkers took kudzu extract or placebo for 7 days, then drank their preferred beer in a lab apartment. On kudzu they drank fewer beers, in smaller sips, with no change in their urge to drink (4).
• 2013: Seventeen men aged 21 to 33, averaging about 28 drinks a week and not looking for help, took a standardized extract (250 mg isoflavones three times a day) or placebo for 4 weeks. Kudzu cut weekly drinks by 34 to 57 percent, had no effect on craving, and left liver and kidney tests unchanged. Two authors hold a patent on the extract (5).
• 2012: Ten healthy adults took 1,200 mg a day of the isoflavone puerarin for a week before a 90-minute drinking session. They averaged 2.4 beers on puerarin versus 3.5 on placebo (6).
• 2015: Twenty men took a single 2 g dose of extract (520 mg isoflavones) or placebo 2.5 hours before drinking. The kudzu group went from 3.0 to 1.9 beers; the placebo group went up (7).
• 2000, the one that didn't work: 38 veterans in an alcohol program took 1.2 g of kudzu root extract twice a day or placebo for a month. Kudzu was no better than placebo for craving or sobriety (8).

Add it up and you get roughly a hundred people across five small studies, a consistent "drank a bit less, craved the same" pattern, and nothing in people who were already dependent. Memorial Sloan Kettering puts it plainly: the studies were small, and a systematic review did not find benefit (9).

The root and the flower aren't interchangeable, and that difference is the most useful thing on this page. The leading explanation for the drinking studies is that the root slows ALDH2, the enzyme that clears acetaldehyde, alcohol's harsh byproduct (3). Lingering acetaldehyde may make the next drink less appealing, which fits the "smaller sips, slower beers" pattern. The flower sits on the other side of the evening as the traditional after-drinking herb (3). The blossom side of our own label gets its tour in our post on the flowers in The Plug.

Why it matters: a 2007 review argued that a root extract is a questionable ingredient for a product sold as a morning-after fix, precisely because of that ALDH2 effect (3). We take that seriously. The Plug Drink lists both root and flower in its 10.83 g Plug Blend, and we make no claim that either changes how much you drink, how you feel the next day or what alcohol does to you. If a kudzu product promises any of that, ask where the human data is.

Kudzu reaches the kitchen and the supplement shelf in four main forms, and they're not the same strength or purpose:

• Dried root slices (ge gen pian): the traditional form, simmered into tea or soup.
• Root powder: ground whole root for tea or as a food thickener. Mild and starchy.
• Standardized extract: capsules or tinctures concentrated for isoflavones. This is what the studies used, at roughly 1.2 to 2 g of extract, and there's no agreed dose outside those study conditions (7, 8).
• Kuzu starch (kuzuko): the washed-out starch, almost pure carbohydrate with very little of the isoflavones. A cooking ingredient, not a supplement.

Please buy it rather than dig it. Kudzu is invasive, so free harvesting is tempting, but the biggest stands grow along roadsides that are routinely sprayed with herbicide, and the roots pull up whatever is in that soil. Digging a mature taproot also means a shovel, a lot of sweat and a plant that grows right back (2). A supplier that names the species and tests its product is the better deal.

Kudzu root is dense and starchy, so it wants a simmer, not a quick steep. This is the galgeun-cha method, and it makes two mild, earthy cups.

1. Rinse 1 tablespoon (about 10 g) of dried root slices under cold water.
2. Add them to a small saucepan with 3 cups of water and bring to a boil.
3. Lower the heat and simmer, uncovered, for 20 to 30 minutes, until the liquid has reduced by about a third and turned pale gold.
4. Strain into mugs. Add honey or a slice of fresh ginger if you like.

Using root powder instead? Whisk 1 teaspoon into a cup of hot water and drink it while it's cloudy. Either way, expect a flavor somewhere between barley tea and a baked potato. Not a showstopper, but cozy!

If you just want to enjoy kudzu as food, kuzu starch is the way in. It thickens like cornstarch but sets clearer, glossier and bouncier, which is why Japanese cooks love it in sauces and desserts. Kuzumochi fans already know the wobble! Two easy uses:

1. Kuzuyu (warm kudzu drink): dissolve 1 tablespoon of kuzu in 2 tablespoons of cold water. Pour in 1 cup of just-boiled water while stirring, return it to the pot over low heat and stir until it turns from cloudy to translucent and thick, about 1 to 2 minutes. Sweeten with honey or grated ginger.
2. Sauce thickener: per cup of simmering broth, stir 1 teaspoon of kuzu into 1 tablespoon of cold water, whisk it in and cook a minute until clear.

Always dissolve kuzu in cold liquid first; dropped straight into hot broth it clumps instantly. And the starch carries almost none of the whole root's isoflavones, so it's a pleasant food, not a herbal dose.

Short-term studies found kudzu root extract well tolerated, and the 4-week McLean trial saw no changes in blood chemistry or liver and kidney function (5). Longer use is less studied, and Memorial Sloan Kettering lists two case reports: a previously healthy 55-year-old man hospitalized with liver injury after taking mistletoe and kudzu extracts, where it's unclear which product was responsible, and a woman who developed acute kidney inflammation after 10 days of kudzu root juice (9).

Kudzu's isoflavones also have weak estrogen-like activity, which is the root of most of its interactions (9). And if you drink regularly, the habits in our weekly plan for helping your liver recover from alcohol matter far more than any single herb.