Becoming a vegetarian really could stave off a stroke or heart attack, according to new research.

A study of almost 2,000 people found those who ate nuts and beans instead of burgers had less 'bad' cholesterol.

It is the first to compare the health effects of red meat by substituting it for other specific types of foods.

Senior author Professor Meir Stampfer said: "Asking 'Is red meat good or bad?' is useless.

"It has to be 'Compared to what?' If you replace burgers with cookies or fries, you don't get healthier.

"But if you replace red meat with healthy plant protein sources - like nuts and beans - you get a health benefit."

His team at the Harvard T.H. Chan School of Public Health in the United States recommended adherence to healthy vegetarian and Mediterranean-style diets.

They could also boost environmental sustainability - as well as decreasing the risk factors for cardiovascular disease (CVD), said the nutritionists.

Lead author Dr Marta Guasch-Ferre said: "Previous findings from randomised controlled trials evaluating the effects of red meat on cardiovascular disease risk factors have been inconsistent.

"But our new study, which makes specific comparisons between diets high in red meat versus diets high in other types of foods, shows substituting red meat with high-quality protein sources lead to more favourable changes in cardiovascular risk factors."

The study, published in the journal Circulation, pooled data from 36 previous trials involving more than 1,800 participants who ate diets with red meat or more of other types of foods.

The list included chicken, fish, carbohydrates or plant proteins like beans and other legumes, soy or nuts.

It looked at concentrations of dangerous blood fats like cholesterol and triglycerides as well as blood pressure - that can all cause CVD.

Higher red meat consumption did lead to raised triglycerides - but there were no significant differences in any of the measures.

However, the researchers found diets high in plant proteins from beans, soy and nuts resulted in lower or LDL (lower density lipoprotein) cholesterol.

This was compared to those with lots of red meat.

The results back long-term epidemiological studies showing there are fewer heart attacks among those who eat plenty of nuts, fruit and vegetables instead of red meat.

They also suggest inconsistencies found in prior studies regarding the effects of red meat on CVD risk factors are partly due to the composition of other diets.

They recommended future research take specific comparisons into account.

The evidence comes as research shows CVD is the UK's second biggest killer - after dementia. It claims the lives of one-in-four men and one-in-six women.

It can be caused by smoking, eating a high-fat diet, being overweight, having high blood pressure or having high cholesterol.

According to Heart UK, eating a handful of nuts each day can help lower cholesterol and therefore reduce the risk of heart problems.

This is because nuts are rich in vegetable protein, fibre, unsaturated fats, vitamin E, magnesium, potassium, natural plant sterols and plant nutrients.

A handful of nuts, which is around 30-35g, a day has the power to lower cholesterol by an average of five per cent, says the charity. That is equivalent to 32 almonds, ten Brazil nuts, 28 cashews, four chestnuts, 21 hazelnuts, 21 macadamia nuts, 28 peanuts, 35 pistachios or 11 walnut halves.