The authors say the original study provided hope that simple interventions could have an impact on obesity levels but they now believe these sorts of programmes need to be continuous if their long term effect is to be properly assessed.

Ten percent of the world's school age population is estimated to be overweight. In the UK it has been forecast that by 2010 nearly one in five boys and one in four girls will be obese.

Janet James and colleagues say a number of studies have shown the relationship between fizzy drinks and obesity, a link which has also been acknowledged by the World Health Organisation.

The Christchurch Obesity Prevention Project, also known as the Ditch the Fizz campaign, was run for a year in six junior schools in Southern England from August 2001. 644 children, aged between seven and eleven, took part. The project focussed on discouraging children from drinking fizzy drinks and promoting a healthy diet through four extra health education classes spread over the year.

At the end of the study the authors found significant differences in the proportion of overweight children in the control group and the intervention group.

Two years after the end of the study the researchers re-measured the childrens' height, weight and Body Mass Index, converting them into standard scores (Z scores). The Z score takes into account the child's age and gender and represents the deviation compared to an average child of the same gender and age.

They found the number of overweight children had increased in both groups although the prevalence was still higher in the control group. Three years later this gap was no longer significant.

Obesity is a very complex condition, say the authors, but they conclude:

It remains unclear whether specific interventions or those which focus on all aspects of the diet and physical activity are the most successful. Perhaps the true impact of any school based intervention can effectively only be evaluated if the interventions are continuous.

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Our data showed those people in the high-glycemic-index group were at greater risk of AMD progression, especially those already in the late stages, says first author Chung-Jung Chiu, DDS, PhD, scientist in the Laboratory for Nutrition and Vision Research at the USDA HNRCA and assistant professor at Tufts University School of Medicine. Participants who consumed the most refined carbohydrates were 17 percent more likely to develop blinding AMD than the group that consumed the least.

According to the authors, public health officials believe the condition could spur a public health crisis in the United States by 2020, when they predict the cases of AMD-related vision loss will have doubled to three million.

No one has been able to identify an effective noninvasive intervention that will slow the progression of AMD says Taylor, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts and Tufts University School of Medicine. We feel we have identified a risk factor that could postpone the debilitating loss of vision with very little economic or personal hardship. Based on our data, limiting refined carbohydrate intake, such as by limiting sweetened drinks or exchanging white bread for whole wheat, in at-risk elderly could reduce the number of advanced AMD cases by 8 percent in five years. This can equate to saving the sight of approximately 100,000 people.

The authors note that their findings warrant randomized controlled clinical trials.

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