In the 1980s the obesity epidemic was in full swing in both the United States and other Western countries including the United Kingdom. In response the medical community, driven by its paymasters in big pharma, was desperate to find a solution (money making idea) that would solve this issue. The nearest thing to a miracle pill in existence was ephedrine, and this had been available in herbal form in Chinese medicine for thousands of years. Because ephedrine could not be patented as it is naturally available, the solution to this problem was to ban ephedrine from sale, and instead try to produce an effective alternative. In the preceding three decades the number of effective weight loss drugs that have been produced amounts to a big fat zero. However, this should not be a surprise to those who understand nutrition. The belief that the hundreds of metabolic changes that occur through consumption of the low quality foods present in the Western diet can be reversed by a single pill is fantasy thinking to the extreme.
Two of the most disastrous solutions the drug companies found were fat blockers called chitosan and cholestyramine. Chitin is an acylated mucopolysaccharides that can broadly be called a polyglucosamines as it is structurally composed of randomly repeating glucosamine and acetylated glucosamine units. Chitin can be sourced from the exoskeleton of crustaceans including crabs and shrimps where it can be differentiated based on their degree of acetylation. While chitin has roughly 20 % acetylation and is highly insoluble, it can be processed into a soluble form through reduction of the number of acetyl groups in its structure and in this way a compound called chitosan can be formed. Chitosan has properties similar to some dietary fibres because of its viscous properties. Cholestyramine is a bile acid sequestrant that binds bile acids and prevents their absorption. Both chitosan and cholestyramine are anion exchange resins that act as hypolipidemic agents and as such can prevent the absorption of fat.
Both chitosan and cholestyramine are similarly effective in their ability to prevent the absorption of fats, and have been shown in animal to reduce the absorption of a number of different lipids. For example, in one study1, researchers tested the effects of 50 mg of chitosan and cholestyramine on the absorption of oleic acid and cholesterol in rats. The lipid levels of the blood of the rats was then assessed using a cannula in the thoracic duct lymphatic channel. Over a 24 hour period, cholestyramine caused a 47 % decrease in cholesterol absorption and a 32 % decrease in oleic acid absorption. Over the same time period, chitosan caused a 51 % decrease in cholesterol absorption and a 41 % decrease in oleic acid absorption. While these results were obtained from intragastric administration of the fats and fat blockers, similar results were also seen when rats were fed the fat and fat blockers as part of a normal diet. The authors concluded that although the fat blockers might work by different mechanisms, their effects are comparable in rats.
Therefore both chitosan and cholestyramine are able to block the absorption of lipids in rats. Human studies using these compounds also showed similar fat blocking effects. However, the chitosan and cholestyramine form insoluble complexes with the fat in the intestine and this can cause problems with digestion. In particular both compounds are associated with the production of a loose stool that results in severe side effects such as intestinal cramps and loose faecal discharge. In addition, both compounds prevent the absorption of a wide range of lipid substances including fat soluble vitamins. Therefore continued use of the compounds can result in vitamin deficiencies. These problems had been present since the early testing of these compounds, but were effectively brushed under the carpet. The fact that they did not cause successful long term weight loss was the final nail in the coffin for the fat blockers. They have now fallen out of favour because they are simply ineffective and produce too many side effects.
Dr Barrington’s Comments: Anyone who understands the causes of weight gain will understand that both chitosan and cholestyramine are pointless gimmicks. If limiting fat absorption really caused weight loss, then limiting fat intake would also have the same effect. However, calorie counting through limiting fat intake is not effective at causing long term weight loss, because overconsumption of fat is not the cause of weight gain. Weight gain is caused by eating the low quality foods found in the typical Western diet and the solution to weight gain is therefore to avoid such foods and consume a high quality diet based on traditional whole food practises.
RdB
