On May 8, 2015 the ASAS Public Policy Committee submitted comments regarding the Scientific Report of the 2015 Dietary Guidelines Advisory Committee (DGAC) to Tom Vilsack, Secretary of Agriculture, and Sylvia Mathews Burwell, Secretary of Health and Human Services. As a committee we felt strongly that these guidelines were written on misinformation and incomplete facts. Two main issues in the proposed guidelines were addressed within our comments: the value of lean meat in the diet and the committee’s lack of expertise regarding animal production and environmental sustainability. Please find our comments below.
Dear Secretaries Vilsack and Burwell:
On behalf of the American Society of Animal Science (ASAS), I am writing to provide comments regarding the Scientific Report of the 2015 Dietary Guidelines Advisory Committee (DGAC). ASAS has some significant concerns with the draft report provided by the DGAC. First, the draft neglects to acknowledge the important role that lean meat has in a healthy diet. Second, the DGAC has gone well outside of its scope and area of expertise to comment on animal production and environmental sustainability.
Lean Meat as an Important Part of a Healthy Diet
ASAS is very disappointed that the draft guidelines recommend the decreased consumption of lean meat. ASAS strongly believes that the committee neglected key scientific information regarding the important role lean meat plays in a healthy diet. This recommendation is unjustified due to the lack of scientific evidence and could have negative unintended consequences. For example, there is evidence that inadequate intake of animal-source protein, despite adequate consumption of plant-source protein and dietary energy, reduces whole-body and skeletal-muscle growth in young children (Murphy and Allen. 2003; Wu et al. 2014). Protein malnutrition during childhood may program nutrient metabolism to negatively impact growth and health of subsequent generations of the offspring (Wang et al. 2012).
With respect to adults, degenerative loss of skeletal muscle mass (sarcopenia) occurs with aging in both men and women (Beasley et al. 2013; Dillon 2013). As described in the DGAC Report, over the past 5 years, protein intake (per person basis) by Americans has declined progressively after peak values at 31- 50 years of age. This trend should be reversed to ensure adequate protein nutrition in adults. Lean meat is a major source of high-quality protein, and a reduction in dietary intake of lean meat will only exacerbate the problem of sarcopenia in the elderly.
Modern meat production practices have significantly lowered the fat content of meat, including the level of saturated fat. For example, the total fat content in lean cuts of beef is only 4.0%, which is similar to the value of 4.2% saturated fat in farm-raised salmon. Compared with the 1960s, a sirloin steak today has 34% less saturated fat. At the same time, lean meat provides high-quality protein, as well as other physiologically important nutrients that are absent from plant-source foods (including taurine, carnosine, heme iron, and vitamin B12). In addition, lean meat is rich in amino acids (e.g., arginine), which can effectively reduce obesity, ameliorate metabolic syndrome, and improve cardiovascular function in both obese humans and obese subjects with type-II diabetes mellitus. Consumption of meat promotes satiety, thereby decreasing excessive intake of dietary carbohydrates by humans to reduce synthesis and deposition of fat in the body.
While the draft mentions heme iron and vitamin B12, it fails to acknowledge that lean meat is an excellent food source of taurine and carnosine. These are powerful antioxidants and key regulators of muscular function. Plants do not contain taurine or carnosine. The absence of taurine from diets has been known for over 40 years to result in cardiac and retinal dysfunction in children (Chesney et al. 1998). Prolonged deficiencies in taurine and carnosine can also impact the overall health and vigor of adults (Budzeń and Rymaszewska. 2013; Wu 2013).
In addition to neglecting important nutritional factors of lean meat, the draft also contains conceptual errors on protein as a dietary nutrient. For example, the draft uses the term “lean protein” in numerous places. From a scientific perspective, there is no such a thing as “lean protein” in chemistry, biology or nutrition. Care must be taken to ensure that the final guidelines use correct and accurate scientific terms to describe protein and protein nutrition.
The draft also fails to make the distinction between plant- and animal-source foods in their values of protein nutrition for humans. Animal-source foods have a much higher value of protein nutrition than plant-source foods because animal-source foods have greater amounts and better proportions of amino acids than do plant-source foods. For example, to meet the daily dietary requirement for methionine plus cysteine by a 70-kg adult (1.33 g/day), the individual would need to consume daily 285 g of dry wheat flour but only 45 g of dry meat. The excessive amount of carbohydrates that would be consumed in the wheat flour can be converted into fat in the body, thereby contributing to development of obesity, dyslipidemia, and other disorders in metabolic syndrome.
Dietary Fat and Risk for Obesity, Cardiovascular Disease, and Cancer
The DGAC recommends limiting beef and other animal products, primarily because they contribute significantly to saturated fat intake in the U.S. However, a causal relationship between fat intake, obesity, cancer risk, and cardiovascular disease (CVD) has not been supported in recent scientific findings. In 2009, the Joint FAO/WHO Expert Consultation released their report, Fatty Acids in Human Nutrition. One of the contributions to their report was Review of Fat and Fatty Acid Requirements and Criteria for Developing Dietary Guidelines. The FAO/WHO report concluded that prospective and observational studies found no or small associations between total dietary fat and obesity, weight gain, CVD, or cancer. Similarly, randomized controlled trials (RCT) reported no evidence for beneficial effects of low-fat, high-carbohydrate diets on serum lipids, fasting serum glucose or insulin, compared with higher-fat, and lower-carbohydrate diets. Saturated fats increase LDL cholesterol, but also increase HDL cholesterol and decrease triglyceride levels. In contrast, substituting carbohydrates for saturated fat lowers HDL cholesterol and increases plasma triglycerides.
In contrast to lean beef, at least 60% of per capita beef consumption in the U.S. (30 kg/y) is consumed as ground beef. Ground beef contains as little as 3% total fat to an upper legal limit of 30% total fat. Statistics from July 2009 to July 2010 indicated that 31.4% of ground beef consumed in the U.S. contained 22-30% fat, while the next 34.8% of ground beef consumed contained 16-22% fat. In contrast, ground beef containing 10% or less fat comprised only 18.8% ground beef consumption. Because of its high fat content, ground beef is the most common source of monounsaturated fats (specifically oleic acid) for young adults. At the time the FAO/WHO report was published, the authors concluded that there was not sufficient new evidence to re-evaluate the dietary recommendations for monounsaturated fats. However, most reviews have concluded that increasing the intake of oleic acid increases HDL cholesterol with only small effects on LDL cholesterol. Additionally, the limited number of RCT that specifically examined the effects of ground beef on men and postmenopausal women concluded that ground beef containing 20 – 24% total fat increased HDL cholesterol without significantly affecting LDL cholesterol; the increased in HDL cholesterol was consistently greater in participants consuming ground beef naturally enriched with oleic acid. Furthermore, as reported in earlier RCT, ground beef consumption decreased plasma glucose and insulin, likely reflecting the replacement of dietary carbohydrates with fat.
Clearly, lean beef provides important essential amino acids, functional nutrients, and amino acids in the U.S. However, all recent scientific evidence indicates that the fat in beef, including ground beef, has no negative effects on risk factors for obesity, cancer, or CVD.
Out of Scope Consideration of Animal Production and Environmental Sustainability
The authority for the DGAC comes from Section 301 of Public Law 101-445 (7 U.S.C. 5341, the National Nutrition Monitoring and Related Research Act of 1990, Title III), which directs the Secretaries of Health and Human Services (HHS) and Agriculture (USDA) to jointly issue at least every five years a report entitled Dietary Guidelines for Americans. The law instructs that this publication shall contain nutritional and dietary information and guidelines for the general public. The DGAC’s consideration of environmental sustainability is not authorized, nor was it event contemplated, in the National Nutrition Monitoring and Related Research Act of 1990. All recommendations not directly related to nutritional and dietary information should be disapproved and not included in the final guidelines.
In addition to being out of scope, the DGAC neglected to use the latest science when considering the environmental footprint of animal agriculture. For example, recent studies have shown that increased intake of animal products by humans actually reduces human consumption of staple grains and, therefore, the demands for water and fertilizers for the production of food grains. It is estimated that an increase in human consumption of 1 kg animal products (primarily beef, milk and chicken as examples) results in decreases in human consumption of 2.79 kg plant-source foods (primarily wheat and potatoes as examples) and agricultural use of 698 L of water.
ASAS appreciates the opportunity to provide comment on the DGAC draft report and urges that the final report recognize the important role that lean meat has in a healthy diet, while avoiding out-of- scope issues such as environmental sustainability.
Debora L. Hamernik
Chair, Public Policy Committee American Society of Animal Science