Results from a huge study published in Archives of Internal Medicine have shown that consumption of a high level of red and processed meat is associated with a raised risk of early death.

Men who ate the most red meat – roughly equivalent to a quarter pounder burger a day – were 31% more likely to die within 10 years than men who ate less red meat.  Women eating similarly high quantities of red meat were 36% more likely to die than those who ate less red meat.

This prospective study assessed half a million people aged 50 to 71 years from six US states (California, Florida, Louisiana, New Jersey, North Carolina and Pennsylvania) and two metropolitan areas (Atlanta, Georgia and Detroit, Michigan).

A bumper 124-item food frequency questionnaire was used to collect information on what sort of foods and drinks had been consumed over the previous 12 months, and meat intake was calculated using this information and portion size data. Red meat included all types of beef and pork, white meat comprised chicken, turkey and fish and processed meat included bacon, red meat sausage, poultry sausage, luncheon meats, cold cuts, ham and hotdogs.

Participants were then followed up for 10 years, during which 47,976 men and 23,276 women died. Men and women who ate the highest amounts of red meat on – average 66-68 grams per 1,000 calories – were more likely to die during the 10-year follow up than those who ate much smaller quantities of red meat – less than 10 grams per 1,000 calories.

In addition, men who ate the most red meat were 22% more likely to die of cancer and 27% more likely to die of heart disease than men who ate little red meat, whereas the corresponding figures for women were 20% and 50%.

High processed meat intake – 16-19 grams  per 1,000 calories – also increased the risk of total, cancer and cardiovascular disease mortality. On the other hand, total mortality and cancer mortality decreased as white meat intake increased.

If red meat eaters changed their diet and cut the red meat in favour of white meat, 11% of deaths in men and 16% of deaths in women could be prevented.

The researchers had adjusted their analyses to take into account participants’ age, weight, smoking history and total food intake, increasing the chance that the higher mortality rate among red and processed meat eaters was in fact down to their diet and not the effect of another lifestyle factor.

However, participants who ate a lot of red meat were more likely a current smoker, have a higher body mass index and have a higher daily intake of energy, total fat and saturated fat than people who ate less red meat, and they tended to have lower physical activity levels and lower fruit, vegetable and fiber intakes.  As the authors acknowledge, “It’s unlikely we’re ever going to feed people meat and see what happens”.

The study authors suggest that the effect of red meat on mortality could be down to the carcinogens formed during the cooking of red meat. In addition, high intakes of red and processed meat raise blood pressure and thus cardiovascular risk, although the mechanism of this effect is unknown.

In an editorial that accompanies this article, Barry M Popkin, professor of nutrition at the University of North Carolina, Chapel Hill and head of the Division of Nutrition Epidemiology, points out that a high-protein, low-carbohydrate diet is just as healthy as a low-fat, high–carbohydrate diet, “[t]hus, the consensus is not that we should all become vegans or vegetarians”. Instead, he suggests, we should dramatically cut down our intake of processed meats and try to limit our consumption of meat overall.

Prof Popkin also highlights how cutting down meat intake could forestall the impending food crisis brewing as developing countries like China and India adopt a protein-heavy Western diet.

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Sinha R et al. (2009) Meat Intake and Mortality: A Prospective Study of Over Half a Million People. Arch Intern Med 169 (6): 562-571. Full text online: here