Vegetarians have a higher risk of stroke than meat eaters, researchers have found.

Oxford University scientists, who tracked nearly 50,000 people for 18 years, believe low intake of the vitamins from meat may cause the additional risk.

The academics found vegetarians and vegans had a 20 per cent higher risk of stroke than meat eaters.

This is equivalent to three more cases of stroke per 1,000 people over 10 years, mainly due to a higher rate of haemorrhagic stroke - which occur when blood from an artery starts bleeding into the brain.

Vegetarians and vegans in the study had lower circulating cholesterol and lower levels of key vitamins - such as vitamin B12 - which could explain the link, the researchers said.

Popularity of meat-free diets is on the rise, with around 1.7million people in Britain now avoiding meat.

Vegan and vegetarian diets are linked to a lower risk of heart disease but may increase the risk of stroke, experts say

However, those avoiding meat also had significantly lower levels of coronary heart disease - which cause heart attacks and angina.

The researchers, writing in the British Medical Journal, said: 'Overall, the present study has shown that UK adults who were fish eaters or vegetarians had lower risks of ischaemic heart disease than meat eaters, but that vegetarians had higher risks of stroke.'

Vegetarians were found to have a 22 per cent lower risk of heart disease than meat eaters - the equivalent of 10 fewer cases per 1,000 people over a decade.

Pescatarians - those avoid meat but eat fish - had a 13 per cent lower heart disease risk.

The difference may be at least partly due to lower body weight, blood pressure and diabetes among vegetarians, the authors said.

The study looked at data on 48,188 people with an average age of 45 years.

Just over half were meat eaters, while a fifth ate only fish, and a third were vegetarian or vegan.

In the 18 years of follow-up there were 2,820 cases of heart disease and 1,072 of stroke.

Lead researcher Dr Tammy Tong, from the Nuffield Department of Population Health at Oxford, said: 'Additional studies in other large scale cohorts with a high proportion of non-meat eaters are needed to confirm the generalisability of these results and assess their relevance for clinical practice and public health.'

Meat eaters were more likely to suffer from heart disease, with experts claiming fans of sausages and steak are likely to be fatter, suffer high blood pressure and cholesterol, and struggle with tyoe 2 diabetes.

In a linked editorial published in the same journal, Professor Mark Lawrence at Deakin University, Australia, said the study's stroke risk should be kept in perspective.

WHAT DO EXPERTS THINK TO THE STUDY? In a linked editorial published in the same journal, Professor Mark Lawrence at Deakin University, Australia, said the study's stroke risk should be kept in perspective. 'It is based on results from just one study and the increase is modest relative to meat eaters,' he said. 'Shifting towards plant based dietary patterns for reasons of personal or planetary health does not necessarily mean becoming a vegetarian.' Dr Stephen Burgess of the University of Cambridge, said food studies are 'notoriously difficult' because 'it is hard to measure what people eat'. But he added: 'This is a reasonably high-quality one, with relatively detailed dietary information and a long follow-up period. 'Still though, this is an observational study, and so it tells us about differences between people who choose to be vegetarian compared with those who choose to eat meat, but it does not tell us what would happen if those who currently choose to eat meat instead decided to eat a vegetarian diet.' But he said the study shows that vegetarian diets - which are so often promoted for their supposed health benefits - may not be as healthy as thought. 'While the differences observed were small in magnitude, this study suggests that taking up a vegetarian diet may not be universally beneficial for all health outcomes,' he added. Tracy Parker, senior dietitian at the British Heart Foundation, said: 'Whether you're a committed carnivore, a veggie, or a vegan, one way to reduce your risk of heart and circulatory diseases is to ensure you're eating a balanced diet, packed with plenty of fruit and vegetables, wholegrains, beans, lentils, nuts and seeds.' Advertisement

'It is based on results from just one study and the increase is modest relative to meat eaters,' he said.

'Shifting towards plant based dietary patterns for reasons of personal or planetary health does not necessarily mean becoming a vegetarian.'

Dr Stephen Burgess of the University of Cambridge, said food studies are 'notoriously difficult' because 'it is hard to measure what people eat'.

But he added: 'This is a reasonably high-quality one, with relatively detailed dietary information and a long follow-up period.

'Still though, this is an observational study, and so it tells us about differences between people who choose to be vegetarian compared with those who choose to eat meat, but it does not tell us what would happen if those who currently choose to eat meat instead decided to eat a vegetarian diet.'

But he said the study shows that vegetarian diets - which are so often promoted for their supposed health benefits - may not be as healthy as thought.

'While the differences observed were small in magnitude, this study suggests that taking up a vegetarian diet may not be universally beneficial for all health outcomes,' he added.

'When considering cardiovascular health, switching to a vegetarian diet should not be seen as an end in itself, but should be considered alongside additional dietary and lifestyle changes.

'In isolation, the benefit of switching to a meat-free diet is not likely to be substantial.'

The research comes after a nutritionist last weak warned that the booming popularity of veganism may be putting the next generation's IQ at risk, because a lack of key nutrients in plant-based diets among pregnant women risks a baby's brain development.

Tracy Parker, senior dietitian at the British Heart Foundation, said: 'Whether you're a committed carnivore, a veggie, or a vegan, one way to reduce your risk of heart and circulatory diseases is to ensure you're eating a balanced diet, packed with plenty of fruit and vegetables, wholegrains, beans, lentils, nuts and seeds.

'For those who do eat meat, cutting back to less than 90g of red or processed meat a day is advised.

'Why not try bulking out a meat dish with beans or lentils, trying a new vegetarian recipe each week, or swapping your sugary snacks for fresh fruit or unsalted nuts.'