London (PTI): Want a healthy heart? Start eating like a caveman, for a study has revealed that a stone-age diet of berries, nuts, lean meat and fish can help reduce the risk of developing cardiovascular disease.

In their study, researchers at Karolinska Institute in Sweden found that people who ate the stone-age regime for just three weeks lowered their blood pressure and slashed levels of a substance known to cause deadly clots.

And, as an extra bonus, they also lost an average of two to three kgs in weight.

"The research proved that even short term use of the diet has favourable effects on the major risk factors for heart disease," Dr Per Wandell, who led the study, was quoted by 'The Daily Telegraph' as saying.

Our early ancestors survived on a diet lacking in cereals, dairy products and refined sugar for centuries before farming developed -- an era which accounts for a substantial phase of human history.

To test its benefits, 20 volunteers were put on caveman diet, which included fresh or frozen fruit, berries or vegetables, lean meat, unsalted fish, canned tomatoes, lemon or lime juice, spices and coffee or tea without milk or sugar, for three weeks.

All dairy products were banned as well as beans, salt, peanuts, pasta or rice, sausages, alcohol, sugar and fruit juice. However, the participants were allowed up to two potatoes a day. They were also given some dried fruit, cured meats and a portion of fatty meat as a weekly treat.

After three weeks, the volunteers who completed the study had lost an average of five pounds.

Moreover, the researchers found that systolic blood pressure, the higher of the two readings taken, had fallen by an average of just under five per cent in the participants, and levels of a clotting agent in the blood, which can cause heart attacks and strokes, also dropped by 72 per cent.

However, Dr Wandell warned that the lack of certain foodstuffs could have other impacts on overall health. "One negative effect was the decreased intake of calcium (present in dairy goods) which could be a risk factor for osteoporosis later in life."