Another major study claims to have identified strong links between eating red and processed meat and an increased risk of early death.
The study has been widely cited across the internet, accompanied by commentary that calls for a clamping down on red meat production and consumption.
In an editorial accompanying the study’s publication in the Archives of Internal Medicine this week, Barry M. Popkin of the University of North Carolina argued that greater deliberation needed to be given to the place of red meat in diets globally.
"There is a global tsunami brewing, namely, we are seeing the confluence of growing constraints on water, energy and food supplies combined with the rapid shift toward greater consumption of all animal source foods," Dr Popkin wrote.
He acknowledged that there are health benefits in eating some red and white meats (but not in processed meats), and so the answer did not lie in shifting to vegan or vegetarian diets.
"Rather, the need is for a major reduction in total meat intake, an even larger reduction in processed meat and other highly processed and salted animal source food products and a reduction in total saturated fat."
Researchers at the National Cancer Institute in the United States tracked 500,000 people aged 50-71 over 10 years, categorising them into five groups ranked on meat consumption.
The study found that the one-fifth of people who ate the most red meat (on average, 62.5 grams per 1000 calories per day) had a modestly increased chance of dying, and an increased chance of contracting heart disease or cancer, than the one-fifth who ate the least amount of meat (an average of 9.8 grams per 1000 calories per day).
The same conclusion was returned for those who ate large amounts of processed meat compared to those who didn't.
"For overall mortality, 11pc of deaths in men and 16pc of deaths in women could be prevented if people decreased their red meat consumption to the level of intake in the first quintile [one-fifth]," the researchers wrote.
"The impact on cardiovascular disease mortality was an 11pc decrease in men and a 21pc decrease in women if the red meat consumption was decreased to the amount consumed by individuals in the first quintile.
"For women eating processed meat at the first quintile level, the decrease in cardiovascular disease mortality was approximately 20pc."
Consumption of white meat was found to have a slightly positive impact on mortality.
Other recent studies have found correlations between consumption of red and processed meats and lung, bowel and breast cancer—although another research project found no connection between red meat and colon cancer.
Researchers are uncertain about why red meat consumption appears linked to increased risk of cancer, but a primary cause appears to be cooking meat at high temperatures, such as barbecuing.
The National Cancer Institute researchers also noted that high levels of saturated fat in some red meat have been linked to breast and colorectal cancer.
A factor not mentioned in the study is grain feeding’s apparently adverse impact on Omega 3 and Omega 6 ratios in red meat. Almost all beef in the US is lot fed.
However, Dr David Topping, a senior research scientist with CSIRO Food Futures and Preventative Health Flagships, questioned whether the result should also be considered in light of reduced fibre intake by big meat eaters.
"Previous studies have shown a dose-dependent lowering of colo-rectal cancer risk for dietary fibre and a number of studies have shown protective effects of fibre against a number of conditions," Dr Topping said.
He said that the fibre intakes of those in the study with the highest meat consumption were low—18.6 and 14.8 grams per day, men and women respectively—compared to 25 and 21 g/d for the men and women with the lowest meat consumption.
(Australians on average have a higher fibre consumption than their US counterparts, Dr Topping noted, at 27 g/d. However, the nation still has high levels of colorectal cancer. CSIRO believes this is to do with the type of fibre that Australians eat.)
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