Obesity rates are increasing in Western countries with a resulting burden on health care systems and budgets. One of the consequences of the rise in obesity is a rise in associated diseases, most particularly type 2 diabetes. Research has shown that diabetes cases increased 765% from between 1935 to 1996, that over 16 million Americans have diabetes and that 47 million Americans have metabolic syndrome (syndrome X). Metabolic syndrome is characterised by insulin resistance, blood lipid changes and abdominal weight gain, and is a risk factor for diabetes and cardiovascular disease. The exact cause of metabolic syndrome is unknown, but evidence suggests that high intakes of fructose and other refined sugars (like high fructose corn syrup) are at least partly responsible for decreases in the sensitivity of skeletal muscle to insulin as well as increases in levels of VLDL-triglyceride levels.
Research published in the American Journal of Clinical Nutrition in 20041 investigated the association between refined carbohydrates and type 2 diabetes in the United States using an ecological correlation study. The researchers measured the per capita nutrient consumption in the United States between 1909 and 1997 which was obtained from the US department of agriculture. This was then compared to figures for the prevalence of type 2 diabetes obtained from the Centres for Disease Control and Prevention. The results showed that when total energy content was controlled for, corn syrup was positively associated with the prevalence of type 2 diabetes. In addition, dietary fibre showed a negative correlation with type 2 diabetes. Protein and fat consumption were not associated with the development of type 2 diabetes. Between 1909 and 1997 the use of corn syrup as a caloric sweetener increased by 2100%.
Commercial production of high fructose corn syrup (HFCS) began in 1967. High fructose corn syrup is produced by isomerising a large proportion of the glucose molecules in corn syrup into fructose and in 1967 at its inception, the fructose content was around 15%. Advances in technology increase the fructose content and now it is possible to commercially prepare HFCS to around 90% fructose. The increase in fructose in HFCS over the last four decades mirrors the rise in both obesity and diabetes. From 1980 to 1997 total energy increased by >500 kcals per day with 80% accounted for by carbohydrates. At the same time type 2 diabetes increased by 47% and obesity increased by 80 %. During this period fat intakes decreased, suggesting that fat is not associated with the prevalence of diabetes or obesity.
These results suggest that there is a strong association between refined carbohydrate and the prevalence of type 2 diabetes. In particular the increases in the use of corn syrup as a sweetener appears to show strong association with the increases in diabetes and obesity. From 1909 to 1963, dietary carbohydrate decreased from around 500 g per day to around 374 gram per day. This was accompanied by a 40 % decrease in fibre because most of the carbohydrates were whole grains. After 1963, carbohydrate intake increased back to around 500 grams per day, but this was not accompanied by an increase in dietary fibre due to the refined nature of the carbohydrates sources. Dietary fibre is known to be protective of a number of diseases and intakes shows a negative correlation with risk for obesity and diabetes.
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