No association between meat intake and mortality in Asian countries.

The association between meat consumption and chronic disease incidence and mortality has been evaluated in hundreds of observational epidemiologic studies over the past 3 decades. However, there remains considerable scientific debate as to whether higher intakes of specific meat groups (eg, red meat, poultry, and fish) or individual meats (eg, beef, pork, and chicken) contribute independently to risk of certain diseases, including cancer and cardiovascular disease (CVD), or whether greater consumption of certain types of meat is part of a broader dietary and lifestyle pattern that is responsible for affecting disease risk. Adding to this debate are the inconsistencies and uncertainties in observational studies of diet and chronic disease. Much of the uncertainty in this field arises from issues at the study level, including challenges with confounding, measurement error, highly correlated dietary and lifestyle variables, and generally weak associations. Indeed, RRs from nutritional epidemiologic studies, including those of meat intake and disease risk, often hover around the null value of 1.0, and we commonly observe associations (including summary associations from meta-analyses and pooled analyses) with RRs ranging between 0.8 and 1.25— considered ‘‘weak’’ associations in the context of known and established causal relations. Most of the available data on meat consumption and chronic disease originate from studies conducted in North American and European populations; less is known about consumption trends and the relation between meat intake and chronic disease in Asian populations. Dietary and lifestyle characteristics in Asia appear to be transitioning to a more ‘‘westernized’’ pattern, with resulting changes in disease patterns as seen in Western countries (1, 2). In this issue of the Journal, Lee et al (3) examined temporal trends in meat consumption in Asia over the past few decades and analyzed the association between meat intake and mortality. First, Lee et al compared per capita consumption of meat, beef, pork, poultry, and fish/seafood in Bangladesh, China, Japan, South Korea, and the United States by using the FAO food balance sheets, which provide data on the food available for human consumption. The authors reported an overall increase in per capita meat consumption in Asian countries, and although per capita consumption of total meat, beef, and poultry is still considerably lower compared with the United States, the gap is slowly becoming narrower. Per capita pork consumption continues to increase in Japan, China, and Korea, with consumption amounts surpassing the United States in all 3 countries. Per capita consumption of fish and seafood in Asian countries is higher than in the United States. The authors hypothesize that chronic disease incidence and mortality rates will continue to increase because of the increasing trends of meat consumption, such as red meat, in Asian countries. However, a clear connection between red meat intake and chronic disease has not been established (4–7), and interpretation is complicated by numerous factors as mentioned above. Second, Lee et al (3) pooled prospective data from 8 Asian cohorts to estimate the association between meat intake and mortality. Specifically, they combined prospective cohort data from Bangladesh, mainland China, Korea, Japan, and Taiwan involving nearly 300,000 men and women. Food-frequency questionnaires along with other self-administered questionnaires were used to ascertain information on dietary, lifestyle, and anthropometric factors. The outcomes of interest were total mortality, CVD mortality, and cancer mortality. Specific causes of death within these categories were not analyzed. The authors pooled individual-level data across the cohorts to generate an overall estimate of RR. A pooled analysis is distinct from a metaanalysis, the latter of which combines ‘‘results’’ data across studies. In a pooled analysis, raw—or individual-level—data are combined. Thus, a pooled analysis may facilitate the utilization of unpublished participant-level data and a uniform statistical approach to analyze data across several different populations. Published pooled analyses are less common than meta-analyses because of the inherent challenge of gathering raw data from willing researchers or study centers. After pooling data across the cohorts, Lee et al (3) observed no significant increases in risk of all-cause mortality comparing the highest with the lowest intake categories of total meat, red meat, poultry, or fish. In contrast, most associations were in the inverse direction with significant decreased risks for poultry (among men and women) and fish (women), with a nearly significant decreased risk with greater intakes of red meat in women (upper CI: 1.00). Similar patterns of associations (most indicating a decreased risk) were observed for cause-specific mortality; comparing the highest with the lowest intake categories, significant decreased risks of CVD mortality with red meat (men) and cancer mortality with red meat and poultry (women) were observed. The only significant positive association in the overall analyses was