This month’s newsletter was curated and edited by: Dr. J.W. Holloway and his Team

Synopsis

This discussion is preamble to a series of articles that will discuss in detail the nutrients supplied by the best food in the world, red meat. Red meat is the premium food because it provides readily absorbable nutrients in an abundance that is not available in any other food. These nutrients are classified as protein, fat, vitamins and minerals. The component content classifications for each nutrient are requisite for the human diet, for protein they are (the ten essential amino acids: threonine, tryptophan, histidine, arginine, lysine, leucine, isoleucine, methionine, valine, and phenylalanine). The components of fat are (the three essential fatty acids: linoleic, linolenic, and arachidonic), for vitamins (especially the B vitamins) and minerals (especially iron) respectively.

Analysis

Protein

Meat, especially red meat, is the preeminent source of human dietary protein. However, meat protein content can vary substantially. The average protein content is (22%) twenty two percent; however, it can be as high as (34.5%) thirty-four-point five percent, (chicken breast) or as low as (12.3%) twelve-point three percent, (duck meat) (Pereira and Vicente, 2013). Meat protein is of high digestibility to humans as shown by the Protein Digestibility-Corrected Amino Acid Scores (PDCAAS). The highest PDCAAS of (1.00) one has been reported for egg white and casein proteins. Meat scored (0.92) point nine two, while pinto beans, lentils, peas, and chickpeas widely considered important protein sources in vegetarian diets scored from (0.57) point five seven to (0.71) point seven one, and wheat gluten had a (0.25) point two five score (FAO/WHO,1991).

Meat proteins also are balanced in terms of proportions of the essential amino acids. Even the non-essential amino acids, which can be produced by the human body, must have the dietary precursors in order not to be limiting. Inadequate consumption of amino acids, the primary units of proteins, can lead to protein malnutrition. Red meat is rich in protein that is digestible and has balance in the essential amino acids while also affording the building blocks for the synthesis of non-essential amino acids thereby being pre-eminent as a protein source for humans (Williams, 2007). Vegetarians must combine cereal and legumes to get all the essential amino acids. Cereals like rice and wheat are especially poor in lysine while legumes have low contents of methionine (Elango, Ball, and Pencharz, 2009).

Current recommended dietary allowances (RDA) in America for protein of (0.95) point nine five grams per kilogram per day (g/kg/d) for children and (0.8) point eightg/kg/d for adults were based on nitrogen balance studies which, because of the clouding effect of endogenous nitrogen, are imprecise (Binnie et al., 2014). The more precise indicator, the amino acid oxidation method, indicates protein needs are much higher (Elango et al., 2010, 2012) in the order of (1.3) one point three to (1.55) one point five fiveg/kg/d for optimal growth and development of (6-10) six to ten year old children (Elango et al., 2011). The significant differential range average is above half again, the precise increase is (1.1) one point one to (1.5) one point fiveg/kg/d for muscle and bone maintenance to reduce risk of age-related disabilities in adults (Gaffney-Stromberg et al., 2009; and Paddon-Jones and Rasmussen, 2009).

Binnie et al. (2014) summarized the effects of higher protein diets on weight maintenance in adults by concluding that higher protein diets are more effective in weight maintenance because they are associated with greater levels of satiety and lower total caloric intakes. Also, meta analyses conducted by Siri-Tarino et al., 2010 and Chowdhury et al. (2014) of (45) forty five epidemiological studies and (27) twenty seven controlled clinical studies on dietary data from more than (600,000) six hundred thousand people in Europe, North America, and Asia did conclude that there is no cardiovascular benefit of replacing saturated fat with carbohydrate.

Role of Amino Acids in Sarcopenia

Sarcopenia is an age-related muscle-wasting syndrome common to all people that results in a reduction in muscle mass and strength possibly leading to physical disability and morbidity (Cruz-Jentoft et al., 2010). Sarcopenia can be exacerbated by simultaneous obesity (sarcopenic obesity) (Thornell, 2011) and by diabetes (Srikanthan, Hevener, and Karlamangla, 2010). Fundamentally, it is key to be pro-active in sustaining implementation of the prevention factors, in (3) three areas for uncomplicated sarcopenia, as muscle mass decreases about (0.5–1.0%) point five to one percent per year beginning at the age of (40) forty (Paddon-Jones et al, 2008). Factors thought to contribute to sarcopenia are age-related changes in food intake, changes in physical exercise, and chronic inflammation (Young et al., 2013). Treatment with testosterone and growth hormone only moderately alter the course of the disease, while treatment with growth hormone releasing hormone (GHRH) may have greater impact (Borst, 2004). However, a focused dietary intervention may have the greatest potential to counteract the onset of disease, or alter the course of sarcopenia (Young et al., 2013).

Increasing daily intake of protein above the requirement of (0.8) point eightg/kg/d can reduce muscle loss that normally occurs with age (Paddon-Jones et al., 2008). Protein quality is also important in this regard in that it contains large amounts of the functional amino acid leucine, which stimulates protein synthesis by mTOR signaling (Du et al., 2007). Paddon-Jones et al. (2008) reported that a moderate intake of lean beef could increase muscle protein synthesis in both young and elderly men and women. 

The most efficient intervention for reducing the effects of sarcopenia is resistance training (Young et al., 2013). Evans (2004) reported a synergistic effect of increased meat intake and resistance training allowing an increase in muscle mass in older men. In general, sarcopenia results from an imbalance in protein turnover. The mechanism underlying this synergistic effect involves the effect of the amino acid balance in meat on the activation of satellite cells resulting in muscle anabolism following resistance training (Thornell, 2011). 

Vitamins

Meat is an excellent source of several vitamins and minerals that are limiting in plant-based foods. A serving of red meat (100 g) one hundred grams provides about (25%) twenty-five percent of the RDA for riboflavin, niacin, vitamin B_6, and pantothenic acid and almost (2/3rds) two thirds of the RDA of vitamin B₁₂ (Williams, 2007). Meat is also one of the best sources for zinc, selenium, phosphorus, and iron. A serving of beef lean cuts (100 g) one hundred grams provide about (37%) thirty seven percent of selenium RDA, (26%) twenty six percent of zinc RDA, and (20%) twenty percent of potassium RDA (ARS-USDA, 2011). It is important to consider the influence of cooking techniques on vitamin and trace element contents considering that humans rarely eat raw meat. 

Cooking can cause significant losses of B vitamins (Lombardi-Boccia, Lanzi, and Aguzzi, 2005) with B₁₂ and thiamin among the most affected B vitamins as compared with riboflavin and niacin which are less affected (D’Evoli et al., 2009; and Riccio, Mennella, and Fogliano, 2006). Sources of these losses are: 1) water solubility: B complex vitamins are water soluble thus some cooking methods such as boiling may produce higher losses; and 2) thermal instability: B vitamins are thermally unstable thus shorter periods of cooking (stir frying) and grilling to doneness levels less than medium may reduce these losses (Lombardi-Boccia, Lanzi, and Aguzzi.  2005; and Yang and Science, 1994). 

Minerals

Dietary minerals are essential nutrients in human diets, and it is usually recommended by dietitians that they be supplied from foods in which they occur naturally so that they can be maximally absorbed in the gut. Although the prevalence of obesity is rapidly increasing, attaining the level of (33.8%) thirty-three-point eight percent for U.S. adults, many Americans are not meeting the recommended dietary allowance for many nutrients (Flegal et al., 2012; and ARS-USDA, 2011).

Of the commonly consumed protein foods, red meat is one of the best sources of readily absorbed iron and zinc. However, limited information is available regarding the content and natural variation in many nutrients in red meats or the extent to which that variation is the result of genetic differences or associated with meat palatability traits. Evaluation of relationships between the concentrations of these nutrients and sensory traits is essential for understanding the impact of this natural variation on traits like tenderness, juiciness, and flavor which are critical to consumer acceptance and satisfaction. The nutrient density of foods is immaterial if the foods are not acceptable to the consumer.

Conclusion

The primary nutritional problem in the world down through history and continuing today is the failure to consume adequate quantities of readily utilizable nutrients. This inherent nutritional deficiency continues today either because people cannot afford the most balanced food containing the essential, highly absorbable nutrients, red meat, or they chose not to consume it. The first limiting nutrient for growing young people and for growing-old people is protein. The problem in protein nutrition has several facets; quantity, absorbability, and quality (amino acid balance). Failure to satisfy the requirements of all these facets results in stunted growth for the younger, and muscle wasting in the older. The same situation exists for the critical nutrients of B vitamins and iron. Fortunately, red meat satisfies all these requirements. Some other foods supply some of these nutrients, but oftentimes lack the nutrient balance, absorbability, and quality of red meat. Even those that have the nutrient profile needed lack the palatability of red meats. Therefore, red meat is the best source of the nutrients we need the most because it combines nutrient content with palatability. Red meat is not only good it is good for you.