High fructose corn syrup (HFCS) is another type of sugar that can cause insulin resistance. High fructose corn syrup is artificially created for food manufacturing purposes, partly because of its sweet taste and partly for cost reasons. High fructose corn syrup was developed from corn starch, which can be thought of as long chains of glucose molecules forming what is technically a polysaccharide. These glucose units are connected with glycosidic bonds, which can be hydrolysed enzymatically through the addition of enzymes and water in a hydrolysis reaction, or through a purely chemical process. Once glucose units are formed, another enzyme can be added and this turns some of the glucose into fructose. However, only around half of the glucose turns to fructose and this produces a mixture of both fructose and glucose in varying concentrations depending on the exact manufacturing process. Two common products are high fructose corn syrup 55 and high fructose corn syrup 42, which are 55 and 42 % fructose respectively.
High fructose corn syrup is therefore a refined sugar that contains roughly equal portions of fructose and glucose. Compositionally, high fructose corn syrup is similar to normal table sugar (sucrose), which is a disaccharide composed of an equal mixture of fructose and glucose. High fructose corn syrup is sweet like sugar, which is why it is produced and added to many foods, particularly soft drinks in the United States of America. However, because high fructose corn syrup contains fructose, it has the same detrimental effects as sugar (sucrose) and is therefore similarly a metabolic poison. Consumption of high fructose corn syrup is associated with obesity and weight gain, and animal experiments show that high fructose corn syrup causes insulin resistance. As with sucrose, the detrimental moiety of high fructose corn syrup is likely the fructose, which when in its refined states overloads the liver with energy, and this stimulates the de novo lipogenesis pathway.
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