Three popular diets were equally effective at reducing carotid atherosclerosis in obese people, researchers in Israel found.

Iris Shai and colleagues at the Ben-Gurion University randomly allocated 140 overweight and obese patients to one of three diets - low-fat, low-carbohydrate or Mediterranean - for two years. Twenty-six per cent of participants used lipid-lowering therapies and nearly one-third took BP medication, which continued throughout the study.

Patients recorded their diets using food diaries and questionnaires, while their BP and blood biomarkers were tracked. Researchers used ultrasound to and track changes in the thickness of the carotid artery wall at the start and end of the trial.

The data showed a 5 per cent regression in average carotid vessel-wall volume and a 1.1 per cent decrease in artery thickness. There was no difference in effectiveness between the three diets.

How significant are the results?
Previous studies had disagreed over whether lifestyle interventions could halt atherosclerosis, which increases the risk of MI and stroke.

The researchers said their data is some of the earliest to show the potential of dietary changes to prevent athero- sclerosis.

Sustained, moderate weight loss, rather than the macronu-trient content of the diets, is responsible for the reduction in carotid artery damage, the authors said. They said the changes appeared to be due to reductions in BP linked to weight loss. The effect was more pronounced among those patients who lost more than 5.5 kg of body weight and whose systolic BP decreased by more than 7 mmHg.

The British Cardiovascular Society said the study was 'very interesting' and gave a useful mechanistic insight into atherosclerosis. But honorary secretary Dr Charles Knight noted the study was 'relatively small'. Like many carotid trials the results were relatively modest in terms of carotid artery volume reduction, he added.

Should guidance change?

Co-author Dr Yaakov Henkin, of the Soroka University Medical Center, suggested changes in carotid atherosclerosis are predicted more accurately by diet-induced changes in BP.

Dr Knight said the study reinforced a 'powerful public health message' about the benefits of leading a healthy lifestyle. But the small size of the study and the lack of clinical endpoints meant the findings were not profound, he said.

He concluded: 'It would be wrong to give the public the view that their atherosclerosis was going to melt away if they lose weight.'

• Circulation Online 2010

Informing Patients
Weight loss diets led to a marginal reduction in carotid atherosclerosis among overweight people. The effect was greater where people lost weight and improved BP. Regression of atherosclerosis over two years was small.