Fructose, the most common sugar found in fruits, vegetables and other foods, has received a bad rap recently for its association with close relative, high fructose corn syrup (HFCS). Many studies have related high fructose corn syrup with the obesity epidemic in the US as its increasing amount in our diet has been linked to the rise in obesity in adults and children.
HFCS is derived from cornstarch and is a mixture of fructose and glucose. The amount of fructose in HFCS varies from 42 – 55%, the remaining sugar being glucose. Therefore, HFCS has the approximate composition of glucose and fructose that occurs in table sugar (sucrose) which are present in a 50:50 ratio. HFCS is the major sweetener in our diet and is also a major source of added calories. HFCS is used extensively to sweeten soft drinks, fruit drinks, sports drinks, teas and other processed drinks. It is also used in baked goods, jams, yogurts and other sweetened foods. HFCS is used because of its availability as a liquid and the ability to readily blend with food aand beverage constituents.
A recent paper has been published in the Annuals of Internal Medicine dispelling the myth that fructose in our diet contributes disproportionately to weight gain. In this paper, the results of 31 studies in 637 individuals were combined to determine the role of fructose in the diet on body weight changes. People in these studies ate diets that were matched for the number of calories but that differed in the amount of fructose. This important paper shows that when the calorie levels of the different diets were identical, there was no preferential effect for fructose to produce weight gain. A careful look at only those studies reporting weight gain with fructose intake identified that these diets while different in the amount of fructose, were not matched for calories. Weight gain occurred with diets that provided more calories, which makes sense. Fructose could not be solely blamed for the weight gain, because the fructose diets provided more calories.
In summary, fructose is a type of sugar that is found widely in fruits and vegetables as well as in HFCS. The Dietary Guidelines for Americans 2010 suggests that sugar, especially refined sugars should be consumed in moderation. Fructose, like all sugars can become a problem for weight gain when it is eaten in excess. So the mere presence of fructose, say as HFCS, does not dictate a health problem or weight gain, but like other sources of calories if it is consumed in excess then issues may arise. Specifically, the consumption of a diet high in fructose promotes the development of three of the clinical features associated with metabolic syndrome, namely, hyperlipidemia (excess fat in the blood), visceral adiposity (abdominal fat) and insulin resistance.