A new study found that sugar in sweetened beverages may be more harmful to health than sugar found naturally in foods as a whole, possibly raising the risk of type 2 diabetes.
Canadian researchers, including a team at St. Michael's Hospital in Toronto, analyzed 155 studies with a total of 5,086 participants examining the effect of various sources of fructose sugars on blood glucose levels in participants with and without diabetes,
Fructose is a sugar that is naturally found in a range of foods including whole fruits and vegetables, natural fruit juices and honey, but it is also added to foods such as soft drinks, breakfast cereals, baked goods, sweets and desserts such as "free sugars."
Conclusions published by The BMJ show that sweetened beverages and some other foods containing fructose can have a detrimental effect on blood sugar levels, which may increase the risk of type 2 diabetes.
Diabetes is a chronic disease that occurs when the pancreas does not produce enough insulin – the hormone that regulates blood sugar – or when the body can not effectively use insulin produced by it.
However, fruits and other foods containing naturally occurring fructose do not seem to have a detrimental effect on blood glucose levels.
In fact, scientists have found that fruit and fruit juices can have a beneficial effect on blood sugar and insulin control, especially in people with diabetes, probably because of the high fiber content in fruits, which helps slow down the release of sugars.
These guidelines already recommend restricting the consumption of free sugars, especially those found in sweetened beverages, with increasing data suggesting that fructose may be harmful to health.
Researchers note, however, that the review has some limitations, including small sample sizes in the studies included, short follow-up periods, and some studies involving a limited variety of foods.
"These findings can help make recommendations for important dietary sources of fructose in the prophylaxis and treatment of diabetes," said Dr. John Sievenpiper, lead author of the study. "But the level of evidence is low and higher quality research is needed."