Eating two or more servings of avocado every week cuts the risk of heart disease by a fifth, according to a new study.

Experts found that one avocado a week (equivalent to two servings) appears to slash the risks of coronary heart disease by 21 per cent compared to people who do not eat avocado.

Replacing half a serving per day of margarine, butter, egg, yoghurt, cheese or processed meats with the equivalent amount of avocado was also associated with a 16 to 22 per cent lower risk of heart disease.

Avocados contain dietary fibre, healthy monounsaturated fats and other key vitamins and minerals, including magnesium and vitamins C, E, and K.

The new study, published in the Journal of the American Heart Association (JAMA), included 68,786 women from the NHS Nurses' Health Study and 41,701 men from the Health Professionals Follow-up Study.

For the research, people were asked about their diets and filled in food frequency questionnaires at the start of the study, then every four years.

During a 30-year follow-up, 9,185 cases of heart attack and 5,290 strokes were recorded.

Dr Lorena Pacheco, lead author from the Harvard TH Chan School of Public Health in Boston, US, said: "Our study provides further evidence that the intake of plant-sourced unsaturated fats can improve diet quality and is an important component in cardiovascular disease prevention."

The research found that substituting half a serving a day of avocado for the equivalent amount of olive oil, nuts and other plant oils did not offer additional benefit.

No links were found between eating avocado and the risk of stroke.

Dr Cheryl Anderson, chair of the American Heart Association's Council on Epidemiology and Prevention, said: "We desperately need strategies to improve intake of American Heart Association-recommended healthy diets - such as the Mediterranean diet - that are rich in vegetables and fruits.

"Although no one food is the solution to routinely eating a healthy diet, this study is evidence that avocados have possible health benefits.

"This is promising because it is a food item that is popular, accessible, desirable and easy to include in meals eaten ... at home and in restaurants."