Warning: we are drinking more and more sugary drinks

A study shows that fructose now makes up more than 10% of Americans' energy intake.

"Less than 20% of the fructose in the American diet comes from natural sources such as fruit and vegetables," says Dr Miriam Vos. These foods don't contain much fructose, and it comes with fibre and other nutrients; they are low in calories and reduce hunger, helping keep a healthy weight. By contrast, fructose added to foods and soft drinks raises calorie intake and leads to weight gain, because it doesn't come with fibre and other nutrients and doesn't curb appetite.

Data from 1977–1978 showed fructose intake of 37 g a day, 8% of total energy. The new study measured the amount and sources of fructose eaten by 21,483 American children and adults, by sex, age, ethnicity, income and body mass index. Average intake was 54.7 g a day, about 10.2% of energy. Teenagers aged 12 to 18 ate the most, 72.8 g a day, about 12.1% of their energy; a quarter of teenagers got at least 15% of their energy from fructose.

The biggest source was sugar-sweetened drinks (30%), followed by grain products (20%) and fruit or fruit juice (19%). The danger lies in drinking more soft drinks and juice instead of milk, especially among children, which means more sugar and less protein, calcium and vitamin D than their parents and grandparents had.

Fructose may increase fat build-up in the liver and raise blood triglycerides, obesity and insulin resistance. In short-term studies, more fructose was linked with higher triglycerides in healthy adults, and in children aged 6 to 19, eating sucrose was linked with higher triglycerides and lower "good" HDL cholesterol, both risk factors for heart disease. Fructose also raises uric acid in the blood, which increases the risk of gout directly, and of heart disease and high blood pressure indirectly.

In short: compared with other sugars, fructose raises cholesterol, triglycerides and uric acid, increasing the risk of heart disease and gout. So base your diet on vegetables, fruit and healthy proteins, and stay away from foods with added sugar. The study was published in Medscape Journal of Medicine in July 2008.