Clinical experts have challenged current dietary guidelines concerning added sugar consumption in order to tackle “a worsening epidemic of type 2 diabetes.” In particular, they identify fructose as a principal driver of type 2 diabetes.
A new report published in Mayo Clinic Proceedings advises people to replace processed foods containing high levels of added sugars and fructose with whole foods such as fruit and vegetables.
Present guidelines from the Institute of Medicine allow for up to 25% of total daily calories to come from added sugars. However, added sugars such as sucrose and high-fructose corn syrup have been associated with the development of diabetes and other metabolic disorders that can increase the risk of cardiovascular disease.
In the US, 1 in 11 people has type 2 diabetes – a total of around 29 million adults. Worldwide, the number of individuals diagnosed with the condition has more than doubled in recent times, from 153 million people in 1980 to 347 million in 2008.
Another 86 million Americans have prediabetes – also referred to as “borderline” diabetes – whereby their blood sugar levels are higher than they should be.
“Approximately 40% of US adults already have some degree of insulin resistance with projections that nearly the same percentage will eventually develop frank diabetes,” says lead author James DiNicolantonio of Saint Luke’s Mid America Heart Institute, Kansas City, MO.
After assessing several observational studies and clinical trials, the authors of the report conclude that excessive fructose consumption causes insulin resistance and disturbs the metabolism.
In comparison with glucose or starch, the authors found that consumption of fructose or sucrose – a combination of fructose and sugar – leads to increases in fasting insulin levels and fasting glucose levels.
Recent trials have also found that replacing glucose-only starch with sucrose could increase the risk of adverse metabolic effects such as increased cholesterol and blood pressure. These adverse effects become more profound with increased proportions of added fructose in the diet.
“At current levels, added-sugar consumption, and added-fructose consumption in particular, are fueling a worsening epidemic of type 2 diabetes,” says DiNicolantonio.
Although fructose can be found naturally in whole foods such as fruits and vegetables, in these foods it exists in much lower concentrations than processed foods.
The authors report that approximately 75% of all packaged foods and beverages in the US contain added sugars.
“The mean daily consumption of fructose is now 83.1 g per person in the United States,” report the authors, “which is likely an underestimation because fructose is not required to be disclosed on nutrition labels and amounts that actually occur in processed foods are higher than once thought.”
At present, the dietary guidelines of the American Diabetes Association and the 2010 Dietary Guidelines for American do not recommend restricting the consumption of fructose-containing added sugars to any degree. In addition, both the 2010 Dietary Guidelines for Americans and the guidelines of the IOM allow for added sugars to make up part of daily calorie intake.
The authors recommend more restrictive recommendations in order to protect people from diabetes and its cardiovascular consequences. The World Health Organization’s (WHO) recommendation that added sugars should make up no more than 10% of daily calorie intake offers the level of restriction that the authors would like to see more of.
“There is no biological need for any added sugars in the diet, particularly those containing fructose,” they conclude. “At an individual level, limiting consumption of foods and beverages that contain added sugars, particularly added fructose, may be one of the most effective strategies for ensuring one’s robust future health.”
Last month, Medical News Today reported on a mouse study that found the fructose-glucose mixture found in high-fructose corn syrup had toxic effects on female mice when consumed in doses proportional to the diet of many Americans.