What is Glucomannan?
Glucomannan is a food additive, and commonly used as a thickener. It has been used in asia in traditional foods such as tofu, noodles, and heat stable gelled foods. There are a wide variety of foods containing Glucomannan that's marketed under different brands, and there are also a variety of dietary supplements that contain Glucomannan sold to combat obesity. Lipozene is one such diet pill making Glucomannan its only ingredient. There are also other diet pills that use Glucomannan as an ingredient in its blend of thermogenic ingredients such as Trimspa.
Glucomannan does not dissolve in water. Instead, it forms a gel when mixed with a liquid. It does not get digested by the body, so it is passed through the digestive system. There are various health benefits of Glucomannan that have been studied. It has been found to be helpful in treating obesity, helps lower cholesterol, helps treat constipation, and may also be beneficial in treating diabetes.
Glucomannan is high in fiber, which makes it very beneficial for the digestive system. As we'll see in a bit, Glucomannan provides a host of benefits for the digestive system, and has been found to help alleviate constipation in adults and children. It comes from the Konnyaku root (Konjac), which is grown in China, Japan, and Korea. It is often used in different foods in Chinese, Japanese, and Korean cuisine.
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Benefits of Glucomannan
The health benefits of Konjac (Glucomannan) is widely known for centuries in Asia, and it is a common food item in Chinese and Japanese Cuisines. It has little taste, and is valued for its texture more than flavor. It is common to find Konnyaku noodles in Japan. In parts of China, such as Sichuan Province, it is very commonly used in konnyaku duck stews - a local specialty.
Glucomannan helps reduce cholesterol, is beneficial for diabetics, absorbs toxic substances, helps normalize blood sugar, and is also an effective weight loss aid. Some health benefits of Glucomannan include:
Glucomannan and Constipation - because Glucomannan is a soluble fiber, it has been studied for the treatment of constipation. There are various studies that confirm the benefit of Glucomannan in treating constipation. In one study involving 7 constipated subjects, the participants consumed Glucomannan over 21 days. They found that bowel movement frequency increased by 30% and also helped improve colonic ecology in the constipated adults . Other similar studies have found that consuming Glucomannan significantly increased defecation frequency, and also increased the stool weight. 
Studies have also found Glucomannan to be beneficial in the treatment of childhood constipation. In a study involving children with chronic constipation, the subjects were given either a placebo or a Glucomannan fiber supplement at 100mg/kg of body weight, up to 5g/day max. Treatment lasted 4 weeks. They found that of the 31 children who completed the study (16 boys, 15 girls) 45% were successfully treated for constipation (measured by having 3 or more bowel movements in one week). 68% of the parents had assessed that their child had better bowel movements while taking the Glucomannan. No significant side effects were reported during the 4 week treatment period. 
Glucomannan and Cholesterol - Glucomannan has also been studied for its cholesterol lowering effects. One study involving 63 healthy men in a double blind, crossover, placebo controlled study, had the participants consume 3.9g of Glucomannan or a placebo for 4 weeks, while maintaining normal diets. The study found that Glucomannan reduced total cholesterol by 10%, and reduced blood pressure by 2.5% . Other studies have also found Glucomannan beneficial in lower cholesterol in people with diabetes.
Glucomannan and Diabetes - Glucomannan has also been found to be beneficial for individuals with type 2 diabetes. One study found that "In type 2 diabetes, pre-prandial glucomannan ingestion attenuated a rise of blood glucose without significantly affecting insulin levels... Supplement of glucomannan may be beneficial to the glycemic and lipid controls in type 2 diabetes mellitus." 
In a study involving 22 diabetic subjects with high blood cholesterol levels, the participants consumed 3.6g of Glucomannan per day for 28 days. They found that compared to the placebo group, the Glucomannan group had reduced blood plasma cholesterol by 11.1%, and LDL cholesterol by 20.7%.
Glucomannan and Obesity - Obesity is one of the most prevalent health problems around the world. There are numerous studies showing the benefit of Glucomannan in treating obesity. When glucomannan comes in contact with liquid, it can absorb up to 50 times its weight. Many of these Glucomannan based diet pills help with weight loss by helping the individual feel fuller and reduce their appetite.
In one study involving 200 obese subjects, Glucomannan or a placebo were given for 16 weeks. They found that Glucomannan & fiber group lost 4.52kg on average compared to 0.79 of control group. The Glucomannan group also had increased satiety compared to control group. LDL cholesterol was significantly reduced as well during the 16 week period. The study also reported that the treatments were well tolerated, and did not report any side effects. 
A 8 week double blind trial involved 20 obese patients. A placebo or a glucomannan fiber supplement (1gram) was given to the subjects one hour before each meal. No changes were made to the diet or exercise habits of the patients. The study found that over the 8 week period, cholesterol levels were significantly reduced, and the Glucomannan group had an average weight loss of 5.5lbs. 
Glucomannan Side Effects
While most studies found glucomannan to be well tolerated, there are some possible side effects. Because of its ability to absorb liquid and expand, there are rare cases where the Glucomannan tablets may get stuck in the throat. Some more common side effects of Glucomannan include:
- Increased bowel movement
- Gas and bloating
- Feeling full
- Upset stomach
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