I was very pleased to see that the World Health Organisation has recently taken a dietary tack, and is urging wide-scale reductions in the amount of sugar added to fast and processed foods. A potential consequence of consuming too much sweet stuff is an excess of the sugar-regulating hormone insulin, which in turn may precipitate a range of unwelcome effects including weight gain, high blood pressure and an increased susceptibility to diabetes.

However, conventional dietetic wisdom dictates that not all sugars have the same capacity to cause our body's chemistry to go awry. Nutritional scientists tell us that fructose, the principal sugar found in fruit, does not inflate levels of sugar or insulin in the system. Its seemingly benign effects mean that fructose has traditionally enjoyed a somewhat sugar-coated reputation.

Fructose's healthy image (and its relative cheapness) has given it a substantial and growing prominence as an additive in the American diet. An almost inevitable consequence of this is that fructose-sweetened foodstuffs (often in the form of what is known as high-fructose corn syrup) are becoming increasingly commonplace on this side of the Atlantic. I see this example of the Americanisation of our diet as a worrying trend. While it is often said that fructose does not upset our internal balance, the reality is that studies have found that it can impair the body's ability to handle sugar, and can reduce the effectiveness of insulin, too. What is more, animal experiments reveal that long-term consumption of fructose can indeed lead to elevated levels of both sugar and insulin. Taken as a whole, the science strongly suggests that fructose has diabetes-inducing potential.

The sweet sorrow fructose may inflict on the body does not end there. Studies show that fructose may push up blood levels of fats called triglycerides - believed to be an important risk factor for heart disease. Animal research has also found that fructose feeding can boost blood pressure.

One major hazard of dietary sugars is their capacity to react with protein molecules in the body, a chemical union that is believed to erode our health and well-being. So avoiding foods sweetened with fructose seems like a sensible precaution, though this may require some label reading.

One foodstuff that is rich in fructose (although its natural presence will mean it will generally not be declared on the label) is fruit juice. A half-pint of orange juice will provide the body with about three times as much fructose as a whole orange. I recommend that those in the habit of downing a glass of fruit juice in the morning swap this for a piece of whole fruit. Whether from fruit juice or processed foods, there's good reason to believe that fructose's reputation as a preferred form of sugar has turned sour.