Experts are to determine what diet is best to reduce the risk of heart disease and type 2 diabetes.

A four-year study will look at the impact of changes in dietary fat and carbohydrates on known risk factors for these diseases.

The Medical Research Council, which is carrying out the research, hopes the results can be used to inform public health policy.

The Food Standards Agency has given £2.7m to fund the research.

Metabolic Syndrome

People with Metabolic Syndrome have difficulties metabolising sugar in the normal way and can go on to develop diabetes and heart disease.

Up to a quarter of adults in the UK have one or more of the risk factors for developing Metabolic Syndrome.

These include obesity, high blood pressure and abnormal blood fat levels.

People who eat high fat diets and do little exercise tend to be at greater risk of developing the Metabolic Syndrome.

But less is known about foods that may help to reduce the risk.

A balanced, healthy diet low in fat and high in fruits and vegetables, along with regular exercise, has long been advocated for a healthy life.

But the MRC researchers go a step further and suggest the amount and quality of fat and carbohydrate in the diet might modify some of the features of the Metabolic Syndrome.

Lead researcher, Dr Susan Jebb, head of Nutrition and Health Research at MRC Human Nutrition Research in Cambridge, said: "Current dietary guidelines aim to reduce the levels of saturated fat in the diet, but many questions remain unanswered."

Fats and carbohydrates

Carbohydrates have an immediate effect on blood sugar when they are eaten and can be ranked as the glycaemic index.

The glycaemic index compares foods gram for gram for carbohydrate. Carbohydrates that breakdown quickly during digestion have the highest glycaemic indexes and blood glucose response is fast and high.

Carbohydrates that breakdown slowly release glucose gradually into the blood stream and have low glycaemic indexes.

The MRC researchers will look at two types of diets that vary in their fat and carbohydrate content.

Test diets

One type will be a low fat, high carbohydrate diet and the other will be a moderate fat diet where the saturated fats are replaced by monounsaturated fatty acids (MUFA).

A spokesman for the MRC explained: "Constructing test diets that take into account normal British eating habits can be difficult in practice.

"This project focuses on comparing the existing UK diet with diets either high in MUFA or low fat, with the carbohydrate content of the diet comprising either high or low glycaemic index, which will provide realistic and useful data to inform public health policy."

The scientists will recruit 650 volunteers from their research centre in Cambridge and four other centres - the University of Surrey, the University of Reading, London's King's College and Imperial College London.



http://news.bbc.co.uk/1/hi/health/3715539.stm