As a new study shows clear evidence that regularly eating red meat contributes substantially to premature death, the experts look at the statistics and discuss whether becoming vegetarian is the healthiest option.
By Lisa Salmon.
It's enough to make you choke on your bacon buttie - scientists say that eating red meat could cut your life short.
US researchers have found that eating high amounts of red and processed meat can lead to an earlier death, particularly from cardiovascular disease and cancer.
Not surprisingly, the Harvard Medical School findings have been questioned by the meat industry and some nutritionists, who say red meat is part of a healthy diet, and cutting it out could do more harm than good.
The Harvard research looked at the diets of more than 120,000 people over a period of up to 28 years, and concluded that one daily serving of unprocessed red meat (about the size of a deck of cards) was associated with a 13% increased risk of death, and one daily serving of processed red meat (two slices of bacon) was associated with a 20% increased risk.
The results also show that substituting other healthy protein sources, such as fish, poultry and nuts, was linked to a lower risk of death.
The study's lead author, Harvard research fellow An Pan, says: "More evidence has been added to the health risks of eating high amounts of red meat, which has been associated with type 2 diabetes, coronary heart disease, stroke, and certain cancers."
Last year, the Department of Health advised people who ate a lot of red meat - more than 90g a day - to cut down to the UK average of 70g a day. The advice followed the publication of a report, from the independent expert Scientific Advisory Committee on Nutrition (SACN), which reviewed evidence on the links between red and processed meat and bowel cancer. It concluded that eating those types of meat probably increases the risk of bowel cancer and people who eat around 90g or more should consider cutting down.
Pan stresses that risk factors including age, body mass index, physical activity and family history of heart disease or major cancers were taken into account in the Harvard study.
The study doesn't explain what specifically causes the association between red meat and increased mortality risk, although the researchers point out that red meat, especially when processed, contains ingredients that have been linked to chronic illness such as cardiovascular disease and cancer. These include heme iron, saturated fat, sodium, nitrites and certain carcinogens formed during cooking.
Pan adds: "Our study is not the first to report the association, and the consistency of our results with others further strengthens our conclusion."
The Vegetarian Society has, of course, welcomed the new study, although the Society's spokesperson Liz O'Neill points out that a large number of studies have reported positive health outcomes for vegetarians, so the Harvard findings are no surprise.
"The most important message for consumers is that they don't need to eat any red meat, or indeed animal flesh of any kind," she says. "A balanced vegetarian diet is delicious, nutritious and sustainable."
O'Neill says it's already known that vegetarians are less likely than meat eaters to suffer from diabetes, heart disease and other medical conditions, and adds: "This new study is a welcome endorsement of a meat-free lifestyle. A well-planned vegetarian diet really can make you feel better inside and out."
However, registered dietician Ursula Arens, a spokesperson for the British Dietetic Association, points out that both vegetarian and meat eating diets can be healthy.
"Billions of people eat meat in moderation and are healthy," she says. "Likewise, so are millions of people who don't eat meat, as long as they have access to other nutritious foods."
She stresses that meat is a healthy food with lots of positive nutrients, including protein, iron, zinc, and vitamins D and B12. But she also warns that too much meat leads to diets high in saturates, and processed meats are particularly high in salt/nitrites.
Arens points out that as well as the Harvard study finding increased risks with high meat intakes, it also showed better health in vegetarians and those who got protein from foods like nuts.
Suggesting that the findings should be treated with "some caution" in relation to other populations, as they were from a US population with very easy access to food and things like vitamin supplements, she adds: "The issue isn't whether meat is good or bad, it's how much? Two to three times per week is healthy, two to three times per day is bad."
The Meat Advisory Panel (MAP), a group of healthcare professionals and scientists who provide independent information about red meat and its role in the diet, says the Department of Health's recommended 500g of cooked meat a week is a reasonable target, but points out that most people don't need to cut down on red meat to remain healthy.
MAP member Dr Carrie Ruxton says the majority of people don't need to change their intake, with just a few exceptions.
"Women and girls could do with eating a bit more red meat, as there's quite widespread iron deficiency among this group," she says.
"Some blokes who eat very large portions of red meat every day could think about switching a few of those to fish or white meat."
Dr Ruxton is concerned that the Harvard study is observational, rather than a controlled experiment, and she explains: "This is just a snapshot. Lots of things contribute to the risk of early mortality, but the researchers have only pulled out one possible link.
"It's an interesting, valid study, but it's not the right kind of study to then jump to a public health message.
"It unnecessarily alarms a lot of people, who may change their diet and have a reduced iron intake and suffer cognitive function problems."
Dr Ruxton adds that a controlled trial published this year by US nutritionist Mike Roussell compared a group of people who ate a healthy low meat diet, with a group who ate a healthy high meat diet. Both groups experienced improvements in heart health indicators, with levels of 'bad' LDL cholesterol falling by around 10% in both groups.
"If meat was the problem, the high meat eating group should have had worse outcomes," she says. "But in fact, both diets performed the same way."
Red meat ratio The Department of Health now recommends eating no more than 70g of cooked red or processed meat a day.
Examples of a 70g portion of meat include: :: One medium portion of Shepherd's Pie and a rasher of bacon :: Two standard beef burgers :: Six slices of salami :: One lamb chop :: Two slices of roast lamb, beef or pork :: Three slices of ham