Red Meat and Health Getting to the Heart of the Matter
Total Page:16
File Type:pdf, Size:1020Kb
1.0 CPEUs and 1.0 ANCC Contact Hour Red Meat and Health Getting to the Heart of the Matter Lauren E. O’Connor, BS Wayne W. Campbell, PhD Consumption of red meat in the United States has pro- diabetes annually, with 90% of those cases being type 2 2 gressively declined over the past 35 years. This occurred in rather than type 1 diabetes. Importantly, CVD-related conjunction with public recommendations to reduce red mortality is 1.7 times more common in adults with diabetes 2 meat intake, based mainly on associations between higher compared with those without diabetes. red meat intake and increased chronic disease risk. This There are adaptable lifestyle practices that can reduce narrative review presents and discusses results from both cardiometabolic disease risk, including consumption of a observational cohort studies that focus on cardiometabolic healthy eating pattern. The Dietary Guidelines for Americans disease development and mortality and randomized con- often recommend reducing red meat consumption (no trolled trials that focus on cardiometabolic disease risk more than approximately 3Y4 servings per week, 2Y3oz factors. This review will also address the potential effect of per serving) to lower cardiometabolic disease risk. There categorizations of red meat and processed meats on our are other potential reasons to consider how much red 4 understanding of cardiometabolic health implications of meat to consume, such as cancer risk and environmental 5 consuming red meat. Nutr Today. 2017;52(4):167Y173 sustainability ; however, this brief narrative review will focus on cardiometabolic disease risk. The purpose of this narrative review is to summarize the evidence about the INTRODUCTION potential implications of consuming higher amounts of red meat on cardiometabolic disease development, re- Cardiometabolic disease risk refers to the chances of de- lated mortality, and the associated risk factors by com- veloping cardiovascular disease (CVD) or type 2 diabetes. paring results from observational cohort studies and More than 50% of the US population aged 19 years or older experimental randomized controlled trials. has dyslipidemia and/or hypertension, which are modifi- 1 able CVD risk factors, whereas approximately 27% of BUT FIRST, WHAT IS RED MEAT? the adult population is prediabetic, assessed by clinical measures of insulin-mediated glucose control.2 Each year, Red meat can be defined by (1) a technical meat science 735 000 and 610 000 Americans experience a myocardial perspective addressing the muscle fiber type and myoglobin infarction and CVD-related mortality, respectively.3 In the content of meat, (2) an agricultural perspective of animal United States, 1.4 million Americans receive a diagnosis of source, and (3) an industry perspective of meat processing. The 2015Y2020 Dietary Guidelines for Americans defines Lauren E. O’Connor, BS, is doctoral candidate, and Wayne W. red meats as ‘‘all forms of beef, pork, lamb, veal, goat, and Campbell, PhD, is professor in the Department of Nutrition Science, nonbird game (eg, venison, bison, elk).’’ Lean meats, in- Purdue University, West Lafayette, Indiana. Their research focuses on clusive of lean red meats, ‘‘contain less than 10 g of total understanding how dietary protein and exercise influence adult health as people age and the importance of eating a variety of protein-rich foods as fat, 4.5 g or less of saturated fat, and less than 95 mg of part of healthy eating patterns to improve body weight, body composition, cholesterol.’’ Unprocessed meats are preserved by refrig- and cardiometabolic disease risk factors. eration or freezing only, whereas processed meats are During the time when this article was written, W.W.C. received support for preserved by smoking, curing, salting, and/or the addition other research projects from the American Egg BoardVEgg Nutrition 6 Center, Beef Checkoff, Coca-Cola Foundation, National Dairy Council, of chemical preservatives. National Institutes of Health, Pork Checkoff, and USDA and had a con- As stated by the 2015 Dietary Guidelines Advisory Com- sulting arrangement with Coca-Cola Company. W.W.C. has served as a mittee, classification of meat, or red meat, throughout member of the 2015 Dietary Guidelines Advisory Committee and a member of the 2018 Physical Activity Guidelines Advisory Committee. scientific literature is inconsistent. For example, when L.E.O. received support from a National Institutes of Health training grant assessing dietary intake, researchers often classify red administered through Purdue’s Ingestive Behavior Research Center (NIH meat with processed meat, which has been defined as 5T32DK076540-08). ‘‘total meat’’7 or ‘‘red meat.’’8 More recently, researchers Correspondence: Wayne W. Campbell, PhD, Department of Nutrition Science, Purdue University, 700 West State St, West Lafayette, IN 47907 classify unprocessed red meat independently of pro- 7,9 ([email protected]). cessed red and white meats, which still causes discrep- Copyright * 2017 Wolters Kluwer Health, Inc. All rights reserved. ancies. For example, ‘‘beef, pork, or lamb as a sandwich DOI: 10.1097/NT.0000000000000225 or mixed dish’’ is seen categorized as unprocessed red \ Volume 52, Number 4, July/August 2017 Nutrition Today 167 Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. meat10; however, sandwich meats and mixed dishes (such United States, as shown by food availability data adjusted as pizza) can be prepared with processed meats. In this for estimated losses (Figure 1). narrative review article, we are limited by the definitions The concept of a healthy eating pattern, defined as a stated in each research article. combination of foods and beverages recommended for consumption to reduce chronic disease risk, was first in- RED MEAT DIETARY GUIDANCE AND troduced by the Dietary Guidelines for Americans starting INTAKE IN THE UNITED STATES in 2005. Throughout the evolution of these eating patterns such as the Dietary Approaches to Stop Hypertension The Dietary Guidelines for Americans, first released in (DASH) and the USDA’s Healthy Mediterranean-Style Eating 1980, provide evidence-based recommendations to pro- Pattern, red meat recommendations were explicitly or mote a healthy lifestyle and reduce chronic disease risk. implicitly presented in various food groups and recom- The guidelines are mandated by the US Congress to be mended amounts (Table 1). Assuming an average serving updated every 5 years by the US Department of Health size of red meat is 2 to 3 oz, as stated by the American and Human Services and the US Department of Agricul- Heart Association, these recommendations are equivalent ture (USDA) with help from a scientific advisory commit- to less than 1 serving of red meat per day; Americans typically tee of expert nutrition scientists (to see the scientific report consume approximately 1 oz above this quantity (Figure 2). of the 2015 Dietary Guidelines Advisory Committee and The 2010Y2015 Dietary Guidelines for Americans includes Y the 2015 2020 Dietary Guidelines for Americans,goto a specific ‘‘meat’’ ounce recommendation (assumingly red https://health.gov/dietaryguidelines/). One key message meat based on the other food groups included in the eating Y of the first 1980 1985 Dietary Guidelines for Americans patterns), but the 2005Y2010 Dietary Guidelines for American was to reduce total fat, saturated fat, and cholesterol in- and the 2015Y2020 Dietary Guidelines for American’s takes to decrease CVD risk. This recommendation was red meat intake recommendation is ambiguous. The based on, at the time, emerging positive associations be- Dietary Guidelines for Americans also emphasize that tween these nutrients and total blood cholesterol con- 11 protein sources, particularly meats, should be consumed centrations. To support this dietary goal, Americans were in lean forms. encouraged to choose lean protein sources. Although the Y 1980 1985 Dietary Guidelines for Americans did not REVIEW OF THE EVIDENCE explicitly suggest limiting red meat consumption, health- care professionals began recommending consumption of Recommendations to limit red meat consumption are mostly white meat rather than red meat to lower total and satu- based on evidence from long-term observational cohort rated fat intakes. This period coincides with a drop in total studies of humans’ eating habits. This type of prospective red meat intake matched by a rise in poultry intake in the study design, such as the Nurses’ Health Study, observes a FIGURE 1. Red meat and poultry approximate intake data over time. Data are adapted from the US Department of Agriculture’s Economic Research Service and are derived from food availability adjusting for food spoilage, plate waste, and other losses (https://www.ers.usda.gov/data-products/ food-availability-per-capita-data-system/food-availability-per-capita-data-system/#Loss-Adjusted%20Food%20Availability). \ 168 Nutrition Today Volume 52, Number 4, July/August 2017 Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. TABLE 1 History of Red Meat Recommendations in the Dietary Guidelines for Americans Healthy Eating Patterns Source Food Group Recommendation 2005Y2010 Dietary Guidelines for Meat and beans (poultry and fish included) 5.5 once-equivalents or G6 oz of meat, Americans healthy eating patterns poultry, and fish per day with 4-5 servings per week of nuts, seeds, and dry beans 2010Y2015 Dietary Guidelines for Meat (with separate food groups for 1.4Y1.8 oz/d Americans healthy eating patterns poultry and fish) 2015Y2020 Dietary Guidelines for Meats, poultry, and eggs 26 ounce-equivalents per week Americans healthy eating patterns group of people over time and relates their eating habits to versus lowest quintile of processed meats showed up to an whether they develop a disease (ie, type 2 diabetes diag- 18% increased risk of CVD-related mortality.12 Therefore, nosis or a CVD-related incident such as a stroke) or related the inconsistencies associating total red meat consumption mortality. Observational study designs can detect associa- with an increased CVD disease risk may be driven by the tions between these 2 variables but cannot confirm cau- grouping of unprocessed red meats with processed meats.