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Researchers ask 'Is meat killing us?' and their answer sounds like yes

'The evidence is consistent that increased intake of red meat, especially processed red meat, is associated with increased all-cause mortality'

Ian Johnston
Science Correspondent
Friday 06 May 2016 16:15 BST
Red meat has been designated as a 'probable cause' of cancer
Red meat has been designated as a 'probable cause' of cancer (Getty)

Eating red meat appears to increase your chance of dying and there is “sound” evidence that a vegetarian diet is healthier, according to researchers who carried out a review of recent studies on the issue.

In a paper entitled Is Meat Killing Us?, doctors from the Mayo Clinic in Arizona said a vegan diet had been shown to “reverse” cardiovascular disease, reduce blood pressure and the risk of getting diabetes.

Last year, in a controversial step, the World Health Organisation warned that processed meat caused cancer and red meat was also “probably” carcinogenic.

The Department of Health currently advises people who eat 90 grams of red and processed meat a day should reduce this to 70 grams, but officials also say red meat is a “good source of protein” and also provides iron, zinc and other useful minerals.

The review, published in the Journal of the American Osteopathic Association, covered studies that looked at the health of a total of 1.5 million people.

“Despite variability in the data, the evidence is consistent that increased intake of red meat, especially processed red meat, is associated with increased all-cause mortality,” the researchers concluded.

“Red meat also increases cardiovascular disease [CVD] and cancer mortality in Western cohorts [groups of people].

“A vegan diet has been shown to improve several parameters of health, including reversal of CVD, decreased body-mass index, decreased risk of diabetes, and decreased blood pressure in smaller studies.”

However they said eating fish and white meat was “not clearly associated with increased mortality” and “decrease[d] mortality when they replace red meat in the diet”.

The paper said the previous studies had some “limitations” – for example there have been no “large, long-term randomized controlled trials”.

However it added: “Avoidance of red and processed meats and a diet rich in plant-based whole foods including fruits, vegetables, whole grains, nuts, and legumes is a sound, evidence-based recommendation.

“If such a recommendation represents a difficult change for a patient, physicians should encourage limited animal products when possible and substituting red meat with plant-based proteins, fish, or poultry.”

A 2003 study found a "decreased risk of 25 per cent to nearly 50 per cent of all-cause mortality for very low meat intake compared with higher meat intake", the paper said.

And the life expectancy of people who had eaten a vegetarian diet for more than 17 years was also 3.6 years higher than "short-term vegetarians".

However Dr Carrie Ruxton, a dietician at the UK Meat Advisory Panel, said while eating a lot of red and processed meat was “statistically correlated with increased risk of mortality”, this “could be due to several lifestyle and dietary factors apart from meat, for example, low vegetable intakes, low fibre, low exercise, high fat intakes”.

“It is well known that people who eat a lot of red meat also tend to be male, older, smokers, overweight etc, so they already have a lot of risk factors,” she said.

Dr Ruxton pointed to a study which showed that watching television was “significantly correlated” with mortality rates.

“Of course, there is no reason why watching TV would cause someone to die, so we instinctively know that TV must be a marker for some other behaviour, e.g. sedentary lifestyle or overeating, which is driving the impact on mortality,” she said.

“It is exactly the same with red meat. There are no agreed mechanisms which point to how red meat could cause disease or death.

“Even the evidence on bowel cancer, which is the area with the most data -- as noted by WHO last year -- has not provided a consensus on mechanisms.”

Randomised controlled trials had showed that eating up to 130g of red meat a day as part of a balanced diet had “no negative impact on blood cholesterol, blood pressure, body weight or blood glucose levels”.

“Indeed on average these markers improved due to the overall healthiness of the diets. This tells me that red meat per se is not a problem – it is the type consumed (fatty, pies) and what you serve it with (chips instead of vegetables),” Dr Ruxton added.

And Dr Betsy Booren, vice-president of scientific affairs at the North American Meat Institute, said the review was "another example of taking weak correlation data from a few studies and trying to make a broader conclusion from it".

"The authors do not provide any reasoning for why they chose the studies included in their analysis, and they left out at least one recent study that contradicted their findings," she said. "It is also unfortunate that the authors chose not to include extensive research on the nutrition and health benefits of meat as well as potential health deficiencies from vegetarian diets."

But Lynne Elliot, chief executive of the Vegetarian Society, said the tide of public opinion was moving in their direction.

She pointed to the British Social Attitudes (BSA) survey which found three in 10 people in Britain said they had reduced the amount of meat they eat in the past 12 months with 58 per cent citing “health reasons".

“For people who want to improve their health, plant-based eating has a lot to offer," she said in a statement.

“This global review comparing meat and vegetarian diets appears to confirm the findings of similar British studies. Vegetarians have lower rates of significant health problems such as cancer (10 per cent lower) and heart disease (32 per cent lower).

“But UK studies also indicate that in addition vegetarians have lower rates of other common illnesses such as diabetes, kidney stones and high-blood pressure.”

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