Why do shirataki noodles not digest?

Shirataki noodles, also known as konjac noodles or miracle noodles, have become an increasingly popular low-carb, low-calorie food option. However, many people find that they are unable to properly digest these noodles, leading to gastrointestinal issues like bloating, gas, and diarrhea. In this article, we will explore the reasons why shirataki noodles may not digest well and cause discomfort for some people.

What are Shirataki Noodles?

Shirataki noodles are made from the konjac plant, which is native to parts of Asia. The main ingredient in these noodles is a water-soluble fiber called glucomannan. Glucomannan is a viscous, gel-like fiber that absorbs water and expands in the stomach. This expansion effect makes shirataki noodles very filling despite being low in calories.

In addition to glucomannan, shirataki noodles contain water and a small amount of tofu or konjac flour to help the noodles hold their shape. They are virtually zero calories and low in carbohydrates. Shirataki noodles gained popularity as a replacement for traditional noodles in low-carb diets like keto.

Why Don’t Shirataki Noodles Digest Properly?

There are a few reasons why shirataki noodles may not be easily digested:

High Fiber Content

The main factor impacting digestion is the incredibly high fiber content in these noodles. A serving of shirataki noodles can contain 5-10 grams of dietary fiber, primarily as glucomannan.

This level of viscous fiber is very difficult to break down in the gastrointestinal tract. The fiber absorbs water and takes on a jelly-like consistency. It can essentially “stick” to the intestinal walls and be resistant to digestion.

Low Starch Content

Most traditional noodles are made from starchy ingredients like wheat or rice. Starch is a complex carbohydrate that can be broken down by enzymes and absorbed in the small intestine.

Shirataki noodles lack starch and are mainly comprised of the fiber glucomannan. The body does not produce enzymes capable of breaking down this soluble fiber. This makes the noodles hard to fully digest.

Abrupt Change in Diet

Many people who try shirataki noodles make a sudden, dramatic shift in their diet by switching from high-carb, starchy noodles to this very low-carb, high-fiber alternative.

This abrupt change can shock the digestive system. The body may have difficulty adjusting to digesting such a large quantity of a new soluble fiber. Gradually introducing shirataki noodles may help.

Individual Sensitivity

Some individuals may have a personal sensitivity to shirataki noodles that makes digestion difficult. People who are prone to gas, bloating, and diarrhea from other high-FODMAP foods may react similarly to shirataki noodles.

Those with digestive conditions like IBS seem to be more prone to experiencing adverse effects like diarrhea after eating these noodles.

Common Digestive Symptoms from Eating Shirataki Noodles

The poor digestibility of shirataki noodles can cause some unpleasant gastrointestinal symptoms for many people. Here are some of the most commonly reported side effects:

Bloating and Flatulence

The soluble fiber in shirataki noodles is fermented by gut bacteria. This fermentation leads to excessive gas production, causing abdominal bloating and flatulence after eating these noodles. The viscous fiber may also slow down digestion, leading to a prolonged feeling of fullness and bloating.


For some individuals, the high fiber content of shirataki noodles causes osmotic diarrhea. The soluble fiber pulls water into the intestines, creating loose, watery stools.

Diarrhea can also occur when the noodles pass through the GI tract mostly intact due to poor digestibility. Undigested noodles can act as an irritant while moving through the colon.

Abdominal Cramping

The diarrhea and bloating caused by shirataki noodles may be accompanied by intense cramping or pains in the abdomen. The abdominal discomfort is the result of irritation to the GI tract caused by the noodles.


In some cases, people may experience feelings of nausea after consuming shirataki noodles. Nausea may be related to the prolonged bloating, gas, diarrhea, and abdominal cramps.

Tips for Easing Digestion of Shirataki Noodles

Here are some suggestions for improving the digestibility of shirataki noodles:

Cook Thoroughly

Proper cooking is important to help soften the texture and make shirataki noodles easier to digest. Cook for 3-5 minutes longer than package instructions to ensure noodles are fully heated through.

Rinse Well

Rinsing the noodles under running water can help remove excess fiber gel and lower the glycemic index slightly. This may support better digestion.

Pair with Starchy Foods

Consuming starchy foods like rice or potatoes alongside shirataki noodles may aid the digestion process. The additional starch helps balance out the high fiber content.

Stay Hydrated

Drink plenty of water when eating shirataki noodles to support digestion and ease stool passage. Proper hydration is key when consuming high-fiber foods.

Introduce Slowly

Limit portion sizes when first introducing shirataki noodles. Gradually increase intake over time to allow the body to adjust to digesting the glucomannan fiber.

Avoid Overcooking

Overcooking shirataki noodles can make them mushy and more difficult to digest. Cook just long enough to reach package instructions. Letting them sit in hot liquid after cooking can also overly soften the noodles.

Take Digestive Enzymes

Consider taking a digestive enzyme supplement when eating shirataki noodles to help properly break down the fibers. Products with glucomannanase may be particularly helpful.

Eat Probiotic Foods

Consuming probiotic-rich foods like yogurt, kefir, and fermented vegetables may support healthy gut flora needed to digest soluble fibers. Healthy gut flora can aid digestion.

When to Avoid Eating Shirataki Noodles

Despite efforts to improve digestion, some people may do best to avoid shirataki noodles if they experience consistent, severe gastrointestinal distress after eating them. You may want to avoid these noodles if you have:


Individuals with irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or other chronic digestive conditions may be more prone to experiencing adverse reactions to the high fiber content in shirataki noodles. Their symptoms may be exacerbated by these noodles.

Food Intolerances

People with known intolerances to high-FODMAP foods or soluble fibers may wish to avoid shirataki noodles due to the likelihood of diarrhea, bloating, and cramping after eating them. The noodles may trigger reactions.

Food Allergies to Konjac

Rare cases of allergic reactions to konjac have been reported. People with known allergies to konjac flour should avoid shirataki noodles due to risks of triggering anaphylaxis or other hypersensitivity responses.

Digestive Conditions Causing Malabsorption

Individuals with diseases impacting nutrient absorption like celiac disease, Crohn’s disease or gastric bypass surgery may already struggle with malabsorption of some fibers. Shirataki noodles could exacerbate diarrhea and deficiencies.

Slow Digestion of Fiber

Some people simply lack the gut bacteria needed to ferment and digest soluble fibers efficiently. If shirataki noodles consistently result in diarrhea, they may need to be avoided.

The Bottom Line

Shirataki noodles contain a glucomannan fiber that is difficult for many people to properly digest. This can lead to unpleasant symptoms like bloating, flatulence, abdominal cramps, and diarrhea in some who consume them. Cooking and preparing shirataki noodles carefully can maximize digestibility. However, people prone to fiber sensitivity or digestive problems may be better off avoiding them altogether. As with any new food, pay attention to how your body reacts and adjust your intake accordingly.

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