March 26, 2009 — Eating red and processed meat is associated with modest
increases in total mortality, cancer mortality, and cardiovascular disease
mortality rates, according to the results of a large, prospective study reported
in the March 23 issue of the Archives of Internal Medicine.
"High intakes of red or processed meat may increase the risk of mortality,"
write Rashmi Sinha, PhD, from the National Cancer Institute, National Institutes
of Health, Department of Health and Human Services in Rockville, Maryland, and
colleagues. "Our objective was to determine the relations of red, white, and
processed meat intakes to risk for total and cause-specific mortality."
The National Institutes of Health–AARP Diet and Health Study enrolled
approximately half a million people aged 50 to 71 years at baseline. A food
frequency questionnaire administered at baseline allowed estimation of meat
intake, and Cox proportional hazards regression models allowed calculation of
hazard ratios (HRs) and 95% confidence intervals (CIs) within quintiles of meat
intake.
Red meat included all types of beef and pork such as bacon, beef, cold cuts,
hamburgers, hotdogs, steak, and meats in pizza, lasagna, and stew. White meat
included chicken, turkey, and fish along with poultry cold cuts, canned tuna,
and low-fat hotdogs. Processed meats could include either red or white meats in
the form of sandwich meats or cold cuts as well as bacon, red meat and poultry
sausages, and regular hotdogs and low-fat hotdogs made from poultry. The authors
note that some of the meats may overlap in the 3 categories, but they were not
duplicated or used in the same models in the study analysis.
The models considered covariates of age, education, marital status, presence or
absence of family history of cancer (for cancer mortality only), race, body mass
index, smoking history, physical activity, energy intake, alcohol drinking, use
of vitamin supplements, fruit consumption, vegetable consumption, and use of
menopausal hormone therapy in women. Primary endpoints of the study were total
mortality and deaths caused by cancer, cardiovascular disease, injury and sudden
deaths, and all other causes.
During 10 years of follow-up, 47,976 men and 23,276 women died. Overall
mortality risks were increased for men and women in the highest vs the lowest
quintile of red meat intake (HR, 1.31; 95% CI, 1.27 - 1.35; and HR, 1.36; 95%
CI, 1.30-1.43, respectively) and processed meat intake (HR, 1.16; 95% CI, 1.12 -
1.20; and HR, 1.25; 95% CI, 1.20 - 1.31, respectively). Men and women with
higher intake also had increased risks for cancer mortality for red meat (HR,
1.22; 95% CI, 1.16 - 1.29; and HR, 1.20; 95% CI, 1.12 - 1.30, respectively) and
processed meat (HR, 1.12; 95% CI, 1.06 - 1.19; and HR, 1.11; 95% CI 1.04 - 1.19,
respectively).
Cardiovascular disease risk was increased for men and women in the highest
quintile of intake of red meat (HR, 1.27; 95% CI, 1.20 - 1.35; and HR, 1.50; 95%
CI, 1.37 - 1.65, respectively) and processed meat (HR, 1.09; 95% CI, 1.03 -
1.15; and HR, 1.38; 95% CI, 1.26 - 1.51, respectively). For the highest vs the
lowest quintile of white meat intake for both men and women, there was an
inverse association for total mortality, cancer mortality, and mortality from
all other causes.
"Red and processed meat intakes were associated with modest increases in total
mortality, cancer mortality, and cardiovascular disease mortality," the study
authors write. "In contrast, high white meat intake and a low-risk meat diet was
associated with a small decrease in total and cancer mortality."
Limitations of this study include possible residual confounding by smoking;
possible measurement error; and cohort predominantly non-Hispanic white, more
educated, with less smoking, less fat and red meat intake, and more intake of
fiber and fruit and vegetables than similarly aged adults in the US population,
limiting generalizability.
"These results complement the recommendations by the American Institute for
Cancer Research and the World Cancer Research Fund to reduce red and processed
meat intake to decrease cancer incidence," the study authors write. "Future
research should investigate the relation between subtypes of meat and specific
causes of mortality."
In an accompanying editorial, Barry M. Popkin, PhD, from the University of North
Carolina, Chapel Hill, discusses how the implications of reducing excessive meat
intake would relate to several major global concerns.
"Of equal importance is the role of clinicians as public health advocates," Dr.
Popkin writes. "Far too few clinicians speak out on topics such as this. What
the public hears is the side of the profession that is preaching vegetarian
diets and not the side of the profession that is discussing moderation as a
healthy option."
The Intramural Research Program of the National Institute of Health, National
Cancer Institute supported this study in part. The study authors have disclosed
no relevant financial relationships. Dr. Popkin is not a vegetarian and has no
financial conflict of interest related to any food product as it affects health.
Source : Arch Intern Med. 2009;169:543-545, 562-571.
