More than 45,000 lives a year could be saved if everyone began eating meat no more than two or three times a week, health experts and Friends of the Earth claim today.

Widespread switching to low-meat diets would stop 31,000 people dying early from heart disease, 9,000 from cancer and 5,000 from strokes, according to new analysis of British eating habits by public health expert Dr Mike Rayner contained in an FoE report.

Dramatically reduced meat consumption would also save the NHS £1.2bn and help reduce climate change and deforestation in South America, where rainforests are being chopped down to grow animal feed and graze cows which are exported to Europe, the report states.

Eating too much meat, particularly processed meat, is bad for health because doing so can involve consuming more fat, saturated fat or salt than official guidelines recommend, the FoE say.

They do not advocate shunning meat altogether, but do urge people to eat meat no more than two or three times a week, with total weekly intake not exceeding about 210g – the equivalent of half a sausage a day. Average weekly intake at the moment is between seven and 10 70g portions.

Doing so would save 45,361 lives a year, according to research by Rayner and his colleagues in the British Heart Foundation health promotion research group at Oxford University.

They calculated that a switch to eating meat a maximum of five times a week would prevent 32,352 deaths, but another 2,509 people a year will die by 2050 if current meat consumption patterns continue. There are currently 228,000 deaths a year from three major conditions in which food intake plays a key role: heart disease, strokes or diet-related cancers, such as bowel cancer.

"We don't need to go vegetarian to look after ourselves and our planet, but we do need to cut down on meat," said Craig Bennett, FoE's director of policy and campaigns. "While the government has ignored the environmental aspect of high meat and dairy consumption, it can't ignore the lives that would be saved by switching to less and better meat."

Professor Steve Field, chairman of the Council of the Royal College of General Practitioners, agreed: "People shouldn't stop eating meat but they should eat less meat, especially processed meat, due to their salt and saturated fat content, and eat more fruit and vegetables."

Rachel Thompson, deputy head of science at the World Cancer Research Fund,, which has publicised the potential cancer risk of eating a lot of meat, said: "These figures add weight to what we have been saying about red and processed meat – that there is convincing evidence they increase the risk of developing bowel cancer, the third most common cancer in the UK. WCRF recommends eating no more than 500g of cooked red meat per week and to avoid eating processed meat – such as bacon, ham and salami."

Meat producers criticised the report. "The vast majority of consumers eat less than average recommendations of red meat already," said Chris Lamb of BPEX, which represents 20,000 pork producers in England. "It is over-simplistic to say that changing one element of the diet can have such a dramatic result. Red meat has a valuable role to play as part of a healthy, balanced diet."

Jen Elford, of the Vegetarian Society, added: "I find myself wondering why an organisation as courageous as Friends of the Earth can't bring itself to recommend a vegetarian diet. Of course less meat is better than more, but we can't address the scale of the environmental and health problems facing society without a wholesale shift away from animal protein."