Eating more red meat, both processed and unprocessed, is associated with a 26% increased risk of dying from eight common diseases as well as risk of all cause mortality , according to data from a large 16-year US National Institutes of Health study. It also show reduced risks associated with substituting white meat, particularly unprocessed white meat.
Researchers examined data on almost 537,000 adults aged 50 to 71 and found the people who consumed the most red meat had 26% higher odds than those who ate the least of dying from a variety of causes. But people who ate the most white meat, including poultry and fish, were 25% less likely to die of all causes during the study period than people who consumed the least, researchers report.
"Our findings confirm previous reports on the associations between red meat and premature death, and it is also large enough to show similar associations across nine different causes of death," said lead study author Arash Etemadi of the National Cancer Institute. "We also found that for the same total meat intake, people who reported a diet with a higher proportion of white meat had lower premature mortality rates," Etemadi said.
For the study, researchers followed the health and eating habits of people from six US states and two metropolitan areas over about 16 years. They analysed survey data on total meat intake as well as consumption of processed and unprocessed red meat and white meat. Red meat included beef, lamb and pork, while white meat included chicken, turkey and fish.
Then, researchers sorted people into five groups from lowest to highest intake of red and white meat to see how this influenced their odds of death during the study period. They looked at deaths from nine conditions, including cancer, heart diseases, stroke and cerebrovascular disease, respiratory diseases, diabetes, infections, Alzheimer’s disease, kidney disease and chronic liver disease, as well as all other causes.
Overall, 128,524 people died, with cancer, heart disease, respiratory disease and stroke as the leading causes of death. Only Alzheimer’s disease risk was not linked to red meat consumption.
Certain ingredients in red meat, including compounds known as nitrates and a type of iron called heme iron, may help explain why it's linked to higher mortality rates for the other causes of death, the authors argue. The highest intake of heme iron was associated with 15% higher odds of premature death than the lowest intake, the study found.
Nitrates in processed meat were associated with a 15% increased risk of death from all causes, while with unprocessed meat nitrates were linked to a 16% greater mortality risk, the study also found.
The report says the study wasn't a controlled experiment designed to prove how the amount or type of certain meats might directly influence mortality. Other limitations include the reliance on survey participants to accurately recall and report on their eating habits and the lack of data on any changes in people's diets over time, the authors note.
Even so, the findings should reinforce the need for many adults to cut back on meat consumption, said Dr John Potter of the Centre for Public Health Research at Massey University in Wellington, New Zealand. Processed meat can produce cancer-causing chemicals, while saturated fats in meats can increase the risk of cardiovascular disease, Potter, author of an accompanying editorial, said by email. Choosing organic meat may not change the risk of premature death, Potter added.
"Mortality is higher with higher meat intake for every major cause of death except Alzheimer's," Potter said. "The really key issue in all this is that the current level of meat consumption, in most of the developed world and increasingly in low- and middle-income countries, is unprecedented in human history," Potter said. "We need to reduce meat consumption back to about one-tenth of our current level."
Abstract
Objective: To determine the association of different types of meat intake and meat associated compounds with overall and cause specific mortality.
Design: Population based cohort study.
Setting Baseline dietary data of the NIH-AARP Diet and Health Study (prospective cohort of the general population from six states and two metropolitan areas in the US) and 16-year follow-up data until 31 December 2011.
Participants: 536 969 AARP members aged 50-71 at baseline.
Exposures: Intake of total meat, processed and unprocessed red meat (beef, lamb, and pork) and white meat (poultry and fish), heme iron, and nitrate/nitrite from processed meat based on dietary questionnaire. Adjusted Cox proportional hazards regression models were used with the lowest fifth of calorie adjusted intakes as reference categories.
Main outcome measure: Mortality from any cause during follow-up.
Results: An increased risk of all cause mortality (hazard ratio for highest versus lowest fifth 1.26, 95% confidence interval 1.23 to 1.29) and death due to nine different causes associated with red meat intake was observed. Both processed and unprocessed red meat intakes were associated with all cause and cause specific mortality. Heme iron and processed meat nitrate/nitrite were independently associated with increased risk of all cause and cause specific mortality. Mediation models estimated that the increased mortality associated with processed red meat was influenced by nitrate intake (37.0-72.0%) and to a lesser degree by heme iron (20.9-24.1%). When the total meat intake was constant, the highest fifth of white meat intake was associated with a 25% reduction in risk of all cause mortality compared with the lowest intake level. Almost all causes of death showed an inverse association with white meat intake.
Conclusions: The results show increased risks of all cause mortality and death due to nine different causes associated with both processed and unprocessed red meat, accounted for, in part, by heme iron and nitrate/nitrite from processed meat. They also show reduced risks associated with substituting white meat, particularly unprocessed white meat.
Authors
Arash Etemadi, Rashmi Sinha, Mary H Ward, Barry I Graubard, Maki Inoue-Choi, Sanford M Dawsey, Christian C Abnet
[link url="http://www.reuters.com/article/health-meat-death-risks-idUSKBN18L2UG"]BMJ material[/link]
[link url="http://www.bmj.com/content/357/bmj.j1957"]BMJ abstract[/link]
[link url="http://www.bmj.com/content/357/bmj.j2190"]BMJ editorial[/link]