Health Benefits of Glucomannan

glucomannan header

You may have seen glucomannan listed in the ingredient list of some products and thought gluco … what? Another preservative? Friend or foe? You’ll probably be seeing a lot more if it. I first saw it as the main ingredient in Shirataki noodles a few years ago and had no clue what it actually was. It’s being added to foods and made into supplements claiming to aid in weight loss, lower blood sugar and cholesterol! Read on to get the lowdown on the health benefits of glucomannan.

Fiber has been in the news a lot lately – and for good reason. It helps with weight control, decreases risk of certain cancers, lowers blood sugar and cholesterol, promotes “regularity” and aids in gut health. There’s a new soluble fiber that is gaining attention with researchers and marketers called glucomannan.

What is glucomannan?

It’s a fiber-rich extract from the root of the Asian konjac plant. While it may be new to some of you, it’s been consumed in China, Japan and South East Asia for centuries as both a food and a traditional medicine to treat everything from asthma to tumors. Western researchers have only been interested in glucomannan’s health benefits since about the 1980s.


Rich in soluble fiber

Glucomannan (or konjac) contains mainly soluble fiber – also called viscous and fermentable fiber. Soluble fibers are soluble in water, unlike insoluble fiber. In liquid, soluble fibers form viscous gels. When consumed, these gels help to prevent cholesterol from being absorbed and slow the rise of blood sugar. They also help make you feel full which can aid in weight loss. Pic credit

tudies on health benefits of glucomannan

Soluble fiber can improve bowel health, blood sugar and lipids, and other health conditions. It can also help you lose fat and stay lean by improving satiety and appetite hormones. But what do the studies show about glucommannan specifically?

  1. Weight loss
    Some preliminary studies are suggesting glucomannan may play a role in weight loss, however more research is needed. At this time, the FDA is has not given approval to any weight loss claims despite Dr. Oz saying it’s “one of the best ways to control your hunger,” “the best appetite suppressant,” and “nature’s skinny sponge.”   Pic credit:
    How might soluble fiber help with weight loss?
    -Very low in calories
    -Promotes satiety via several mechanisms to help keep you feeling full longer
    -Slows down digestion which induces satiety
    -Inhibits carbohydrate absorption and helps to lower blood glucose levels and inhibiting insulin spikes
  2. Lowering cholesterol
    A new analysis in the American Journal of Clinical Nutrition looked at 12 small studies (totaling 370 people) and concluded that konjac glucomannan can lower LDL (“bad”) cholesterol by about 10 percent. What’s more, it found that this can be accomplished by a much lower dose of glucomannan than other soluble fibers because of its greater viscosity (which is key to the cholesterol-lowering effect). Reference
  3. Promoting regularity
    In Japan, it’s called “the broom of the intestines”—which gives you a pretty good idea of what it does. It works by absorbing water and expanding to form a bulky fiber in your gastro-instestinal tract. Since glucomannan contains minimal calories and carbs, it may be a good option for those people on a low carb diet, as these diets tend to limit high fiber foods such as fruit, whole grains and legumes. Constipation is a known side effects of low carb diets.
  4. Gut health
    Glucomannan is a potent prebiotic which is improves the types of gut bacteria we have as well as the diversity. Soluble fibers are also great food for the bacteria living in our guts (called probiotics)  See my previous post on prebiotic fibers.


Where to find it:

Glucomannan powder: This practically tasteless powder is great for mixing into smoothies and other foods. It adds a thicker consistency.

Glucomannan in food products: Japanese shirataki noodles (also marketed as “miracle noodles”) are the most famous glucomannan food product. Stay tuned for a blob post on this including recipes! Here in the U.S., you may have seen konjac (or glucomannan) added to foods as a gelling or thickening additive.

Glucomannan supplements: If you do get glucomannan pills, open the capsules open and dissolve them in some water first, or mix them into some liquids (or yogurt, etc)

Side effects and warnings

While glucomannan has many potential health benefits, there are also few words of caution:

-It may cause minor gastrointestinal complaints, such as bloating, gas, and mild diarrhea. If it does, reduce the serving size.
-It may reduce the bioavailability of oral medications. Take medications 1 hour before or 4 hours after your meal containing glucomannan.
– Glucomannan absorbs large amounts of water. There have been some incidents of esophagus, throat or intestine blockage by using glucomannan tablets due to this large water absorption. Drink 8 ounces of water with 1 gram of glucomannan before each meal. If you don’t drink enough, the fiber can literally gum up your digestive system, causing intestinal blockages and, in rare cases, choking by blocking your throat. Note that the tablets are not the same as shirataki noodles which already contain water and don’t pose this risk.

Disclaimer: please check with your doctor before increasing the fiber content of your diet or taking glucomannan powder or supplements.


Bottom line:

Glucomannan can be a  good option to add to your diet if you are trying to increase your fiber intake.  Of course, I always recommend food first … but glucomannan can be a good addition!  Studies on the potential health benefits of glucomannan, though relatively small and short so far, have been promising for lowering blood cholesterol, and possibly for weight control. It’s a excellent source of prebiotics which are important for gut health. This is especially important if you are on a low carb diet – which many of my patients are.  You could try adding glucomannan powder to smoothies, yogurt or oatmeal. Or try Japanese style shirataki noodles (one popular brand is called Miracle Noodles). So now if you see it on food labels, you’ll know it’s a “friend” not a “foe”!


Precision Nutrition 
Berkeley Wellness




I especially love problem-solving, whether it’s helping women defeat issues plaguing them for years, helping a busy executive find practical ways to get heart healthy, or providing tips to help you reverse diabetes. That’s why I’m on a constant quest to expand my knowledge by staying on top of the latest research.

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