What is Konjac and why should I care?

What is Konjac and why should I care?

Konjac, also known as glucomannan, is a herb that grows in parts of Asia. It’s known for its starchy corm, a tuber-like part of the stem that grows underground. The corm is used to make a rich source of soluble dietary fibre.

It is used as a gelatin substitute and to thicken or add texture to foods. It’s also used in traditional Chinese medicine. In the Western world, they are best known as a dietary supplement for weight loss and cholesterol management.

Konjac side effects

Glucomannan is generally well-tolerated. Like most high-fibre products, however, it may cause digestive problems such as:

  • bloating
  • diarrhea or loose stools
  • abdominal pain
  • gas
  • nausea

Benefits of Konjac

The high fibre content of Konjac has many health benefits. Soluble fibre helps lower cholesterol and blood glucose levels. A diet high in fibre may also help regulate bowel movements, prevent hemorrhoids, and help prevent diverticular disease. Here’s what the research says:


2008 study found that glucomannan may help prevent constipation. The study showed that adding glucomannan to a low-fibre diet increased the amounts of probiotic bacteria in feces. It also increased bowel movement function by 30 per cent.

Weight Loss

Fibre is filling. Eating it regularly helps keep you fuller longer, so you’re less likely to overeat or snack between meals. Konjac also expands in the stomach to help keep you full.

According to a 2005 study trusted Source, adding a glucomannan fibre supplement to a balanced, 1,200-calorie diet caused more weight loss than a 1,200-calorie diet plus a placebo. Adding fibre supplement (guar gum or alginate) didn’t have an impact.


2008 systematic review found that Konjac may help lower total cholesterol, LDL (bad) cholesterol, and triglycerides. It also reduces body weight and fasting blood sugar. Researchers concluded that glucomannan could be an adjuvant therapy for people with diabetes and high cholesterol. A later study found that it lowered LDL and recommended its use to reduce the risk of cardiovascular disease.

Skin Health

According to a 2013 study, Konjac can reduce acne and improve the health of the skin. It’s thought to reduce allergic response and improve wound healing.

How to use Konjac

Konjac supplements are available online or in most natural health stores. There’s no approved, standardised dose of Konjac but it is recommended to take it with plenty of water, preferably before a meal. Recommended dosages vary by manufacturer and what you’re using it for. They typically range from 2 to 6 grams. Follow the manufacturer’s dosage instructions, or contact your doctor or a qualified natural health practitioner for advice.

More recently, Food company’s are incorporating Konjac into their products to create weight loss and healthy food options. One of the leaders in this group is Slendier. Slendier has developed a health range of Konjac weight loss pasta, noodles and rice have proven so popular that they’ve extended the range to include pasta sauces, bean pasta, ready to eat meals and smoothies. 

Risks and Precautions

According to the FDA, some Konjac candies have caused choking deaths in the elderly and in children. This prompted the FDA to issue an import alert in 2011 for these candies. These candies have a gelatinous structure that doesn’t dissolve in the mouth like other gelatin products.

Konjac supplements may also expand in your esophagus or bowel and cause an obstruction. The risk is higher if you:

  • take Konjac tablets
  • take Konjac in any form without water
  • are elderly
  • have problems swallowing

Several countries have banned the use of Konjac because of the high incidence of bowel or throat obstruction. Children and pregnant or breastfeeding women should not take Konjac supplements.

Stop taking Konjac and get medical help if you have symptoms of an allergic reaction such as:

  • difficulty breathing
  • hives or a rash
  • itchy skin
  • rapid heart rate
  • swelling

Glucomannan has been shown to lower blood sugar levels. It may slow the absorption of sugar, so people with diabetes should carefully monitor their blood sugar. Consult your doctor before using it if you take insulin or other diabetes medications.

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