Introduction

If you’ve been exploring low-calorie meal options, you’ve probably come across Shirataki noodles. Known for their low-calorie count and unique texture, these “miracle noodles” have sparked the curiosity of health enthusiasts. However, you might know little about the source of these noodles, the konjac plant.

Here, we will help you answer the question: Is Konjac really good for you? By the end, you will have insights about its nutritional profile, health benefits, and potential risks and side effects to help you make an informed decision about incorporating konjac into your diet. 

Origin and botanical background of konjac

The konjac plant (scientifically known as Amorphophallus konjac) is a perennial plant native to tropical and subtropical countries in eastern Asia, such as Japan and Indonesia. Also found in southern China, the plant is renowned for its therapeutic uses and has widespread uses in traditional Chinese medicine.¹ Beyond its medicinal usage in China, konjac flour, prepared from the corm of konjac, has been used for other purposes.¹ 

• Medicinal uses: Konjac flour is used for the treatment of burns, coughs, breast pain, asthma, and more 
• Culinary uses: Konjac flour is used to produce noodles, tofu, and snacks 
• Dietary uses: Konjac glucomannan (KGM) is a dietary fibre isolated from konjac and can aid in lowering blood pressure and has anti-diabetic and anti-obesity uses
• Other uses: Konjac flour made from leaves and corms of konjac is used as an insect repellent and animal fodder²

Nutritional profile of konjac

Konjac’s primary advantage lies in its high dietary fibre content, which supports digestive health and contributes to a sense of fullness. Despite konjac’s high fibre content, it’s worth noting that konjac is relatively low in protein and vitamins.³ Hence, for a well-rounded diet, it’s important to pair konjac with various nutrient-rich foods to ensure your body is supplied with the essential vitamins and minerals it requires. 

Konjac glucomannan (KGM)

Glucomannan is a water-soluble dietary fibre, and it is extracted from konjac. Its molecular structure makes it pass into the colon relatively unchanged, as it cannot be broken down significantly by enzymes in the saliva and pancreas. In addition to this, its high molecular weight means it can absorb up to 50 times its weight in water. As such, it promotes satiety and has been associated with weight loss.⁴ 

Health benefits of konjac

Weight management

Konjac products have widely been praised for their supposed weight loss benefits–these apparent benefits are due to KGM. However, the efficacy of KGM for weight loss has been investigated in multiple clinical studies with varying results and conclusions being drawn. 

Findings from clinical studies

• Well-tolerated daily doses (2-4 g) of glucomannan can lead to significant weight loss in individuals with obesity or overweight⁵
• Short-term KGM consumption by healthy individuals with obesity or overweight may help reduce body weight, but not body mass index (BMI)⁶

Digestive health 

Konjac’s role, particularly konjac glucomannan (KGM), in gut health has been investigated.³ 

Laxative activity

Laxative activity is the effect of konjac on bowel movement and its ability to relieve congestion. KGM promotes defecation frequency in healthy adults, benefits in treating constipation, and eases the symptoms of inflammatory bowel disease. 

Prebiotic activity

Prebiotic activity refers to organic substances (in your food) capable of facilitating the growth of intestinal microbial flora by acting as its nutritional substrate. Studies using bacterial cultures highlight konjac as a universal prebiotic that stimulates beneficial gut microbiota.⁷ 

Therefore, adding 1.5 g of KGM powders with every meal could be an optimum supplementation dosage to promote defecation frequency and increase stool bulk. Furthermore, the prebiotic impact of konjac is said to be on par with the widely recognised prebiotic inulin.⁸ 

Blood sugar and cholesterol levels

Impact on glycemic control

Multiple studies have found konjac glucomannan to control blood sugar levels by alleviating elevated glucose levels in individuals with diabetes. Hence, KGM is suggested to be a safe option for treatment in individuals with type 2 diabetes, especially with cardiovascular disease-associated factors.³ 

The reason why konjac reduces blood glucose levels is due to its ability to delay stomach emptying and slow down the absorption of glucose into the small intestine, which results in more gradual increases of glucose in the blood after meals have been consumed.⁸

Reduction in LDL cholesterol

KGM can potentially reduce LDL cholesterol levels, which in turn reduces the risk of cardiovascular diseases and strokes. A glucomannan-supplemented diet alongside a total body exercise program can reduce total cholesterol levels, as well as LDL cholesterol levels, significantly.⁹

Potential anti-inflammatory effects

Studies in non-human models show hydrolysed KGM to produce an anti-inflammatory response to atopic dermatitis and post-immunisations. Additionally, research on people who have active acne vulgaris lesions shows that KGM could be used to treat this condition because it has positive effects on the skin.³

Potential risks and side effects

Digestive discomfort

While konjac can offer the benefits outlined before, it can also cause digestive discomfort, with symptoms like flatulence, bloating, loose stools, and diarrhoea.³ Due to KGM’s water-absorbing nature, insufficient water intake alongside konjac consumption can lead to GI tract obstructions.¹⁰ As such, it is important to only consume konjac in very small amounts and in conjunction with other nutrient-rich foods and water. 

Choking hazard

As mentioned before, insufficient water intake can cause blockages when consuming konjac. The problem extends beyond GI tract obstructions to esophageal obstructions, too. Konjac jelly, especially, can be a choking hazard if the fibre clogs the oesophagus before reaching the stomach.³ Therefore, it’s recommended that anyone with pre-existing esophageal issues not consume konjac. 

Konjac in various forms

Konjac can be consumed in various forms the most notable form of konjac is shirataki noodles, which are made from flour derived from the konjac corm. Additionally, konjac also exists in a jelly form, which is sourced from the konjac plant bulb; this can be consumed with soups and stews. Similar to shirataki noodles, konjac rice (also called shirataki rice) can be added to a balanced diet.  

Konjac’s benefits can also be reaped via glucomannan pills and powders. However, given the risk of choking, it is recommended to opt for powders over pills. Even in that case, it's important to drink plenty of water. Additionally, if you are already on other medication, please consult your physician before consuming glucomannan pills or powders. 

Summary 

Konjac can be a good addition to a balanced diet, providing benefits for your digestive health and aiding the control of blood sugar and cholesterol, alongside other benefits. However, it’s important to note its risks and act accordingly This means to drink lots of water when consuming konjac to prevent blockages and to consume konjac alongside other nutritious foods to supplement its lack of necessary minerals and vitamins. Additionally, children and pregnant women should avoid konjac, given that studies have not been done specifically investigating the risks of these groups.