May 15, 2024/Nutrition

5 Ways Konjac Can Help Boost Your Health

The glucomannan fiber in konjac can be good for your digestion, heart, weight loss and more

Bowl of white konjac noodles in wooden bowl

If you’re watching your carbs for health reasons, you may already know about konjac (pronounced “KAHN-jak”). People in Asian countries have been enjoying the benefits of this plant for centuries. And now word about konjac is spreading across the U.S.


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“Konjac plants grow from edible, starchy bulb roots called corms,” says registered dietitian Gillian Culbertson, RD, LD. “Corms are high in fiber but low in carbohydrates, calories and fat. That’s why products made with konjac fiber are growing in popularity.”

Culbertson explains how konjac can help boost your health.

What’s the difference between konjac and glucomannan?

Konjac is the name of the plant that grows in Asian countries. Glucomannan is the fiber found in the plant’s root bulb.

“Foods made from konjac corms naturally have glucomannan,” says Culbertson. “So, people often use the terms interchangeably.”

Konjac is also called elephant yam, devil’s tongue and voodoo lily. The plant that grows above ground has a single dark-purple leaf that can get as wide as 4 feet (about the width of a double bed). A flowering, purple spike inside the leaf can grow close to 2 feet tall. Corms can measure 10 inches in diameter.

How do you use konjac?

Food manufacturers and others use corms from konjac plants to make:

  • Konjac flour: Dried, ground konjac corms make flour used in gluten-free baked goods, shirataki noodles, shirataki rice and other products.
  • Konjac jelly: Highly processed konjac flour makes a gelatin substance that thickens soups and sauces (similar to cornstarch).
  • Konjac (glucomannan) supplements: Konjac or glucomannan supplements are a high-fiber supplement.

What are the health benefits of konjac?

Research suggests that konjac may help people with certain health conditions. “We’re starting to understand how konjac and glucomannan affect body systems and diseases,” shares Culbertson.

Any health-related konjac benefits are thanks to glucomannan. This water-soluble fiber forms a gel-like substance when it dissolves in liquids like water or stomach fluids.

“It takes longer for this fibrous gel to move through your digestive system,” she continues. “This slow digestive process may help prevent or improve certain diseases.”

1. Aids weight loss

A systematic review of studies found that people who have obesity or excess weight who took glucomannan supplements experienced small but significant drops in weight.

Glucomannan-based foods like shirataki noodles may also aid weight loss efforts. Konjac has almost no calories and zero fat. Its high-fiber content means you feel full faster and are satisfied for longer.

“You may be less likely to overeat as a result,” says Culbertson.

2. Improves gut health

Studies suggest that konjac may benefit gut health by improving your gut microbiome.


“Konjac glucomannan doesn’t break down in the stomach,” explains Culbertson. “It’s a prebiotic, which means it’s a food source for the healthy bacteria that live in your gut.”

3. Lowers blood sugar

Konjac food products are so low in carbohydrates and so high in fiber that your intestines don’t absorb much as the food passes through. As a result, your blood sugar levels are less likely to rise after eating. In fact, one study suggests that glucomannan may help prevent and treat diabetes.

4. Lowers cholesterol

When the U.S. Food and Drug Administration (FDA) added glucomannan to the list of naturally occurring plant fibers in 2020, it cited research findings that showed konjac glucomannan helps lower cholesterol. One lab study found that konjac glucomannan supplements reduced total cholesterol and low-density lipoproteins (LDL or “bad cholesterol”).

“The fibrous glucomannan gel coats the lining of your intestines, so food particles move through without a lot of absorption into the bloodstream,” says Culbertson.

5. Keeps you regular

Konjac glucomannan fiber helps firm up poop. Because soft, bulky stools are easier to pass, you’re less likely to become constipated and develop hemorrhoids.

What are konjac side effects?

Despite its many potential health benefits, including konjac glucomannan in your meals or taking glucomannan supplements isn’t entirely risk-free. Talk to a healthcare provider before taking any supplement.

The potential drawbacks of konjac include:

Stomach upset

Konjac’s high-fiber properties may lead to diarrhea, gas, bloating and other upset stomach symptoms, according to study findings. These issues may be worse if you have a digestive condition like irritable bowel syndrome (IBS) or take anti-obesity drugs that slow digestion.


Severely low blood sugar

If you take insulin or medications to manage diabetes, adding glucomannan may cause your blood sugar to drop too low. Severely low blood sugar (hypoglycemia) can cause seizures and become life-threatening.


Konjac glucomannan fiber swells when mixed with liquids, making konjac food products and supplements a choking hazard for children and adults, especially those with swallowing disorders. The FDA issued warnings in the early 2000s after undissolved fruit jelly candies made with konjac got stuck and swelled in some people’s throats.

Glucomannan supplements pose a similar risk, says Culbertson. “If you take a supplement, choose a pill or capsule that you can easily swallow and drink 8 ounces of water with it.”

Is konjac a healthy carb?

Given the health benefits associated with the plant, you may be wondering: Does konjac count as a healthy carb?

Sort of.

“Konjac is a good source of fiber. But it doesn’t have the vitamins, minerals, phytochemicals and energy that we associate the healthy carbs,” says Culbertson. Still, konjac foods can be part of a healthy diet.

If you want to include konjac in your meals, Culbertson recommends trying small amounts of konjac foods to see how your digestive system responds. When you do that experiment, make sure you drink plenty of water. You may discover that konjac is a new favorite fibrous food!


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