Fructose & health

Fructose, along with other sugars, is found naturally in many foods, such as honey, fruits and some vegetables. However, corn syrup is primarily fructose and table sugar contains fructose and glucose, and these are commonly used to sweeten processed foods. It is hard to over-consume fructose from unprocecessed or unrefined foods, but excessive intake of unnaturally sweetened foods such as soft drinks, some fruit drinks, cakes, biscuits etc can result in a diet high in fructose.
The scientific literature was reviewed by Elliot et al (published in the American Journal of Clinical Nutrition 2002; vol 76: p911-22) to explore whether fructose consumption might be a contributing factor to the development of obesity and accompanying abnormalities observed in the insulin resistance syndrome (which can develop into diabetes). They concluded that:

Unlike glucose, fructose does not need insulin to be transported into the liver to be broken down to produce energy - this in turn reduces the levels of an appetite control hormone called leptin. This combined effect of fructose (and its independance of insulin) may interfere with our ability to control our appetite and could increase the likelihood of weight gain. This may explain why some sweetened beverages can fail to make us feel full even though we are consuming lots of extra calories.
The route fructose takes to becoming energy can involve the production of undesirable blood fats known as triglycerides and LDL cholesterol, both linked to atherosclerosis.
Fructose consumption has been shown in animal models to induce insulin resistance, impaired glucose tolerance, high levels of blood fats (triglycerides), and high blood pressure. The data in humans is unclear, but there is some concern that too much fructose may exacerbate Syndrome X. This syndrome is the name for a group of risk factors which include abdominal obesity, high blood pressure and blood fats, and undesirable insulin levels.

More research is needed to determine just how detrimental fructose is to human health. Till we know for sure, when it comes to sweet foods, prefer wherever possible, a variety of naturally sweet whole foods such as dried fruit, freshly squeezed fruit juice, honey.

See also article on Sugar