When I wrote the article on anti-nutrients, I allured to the idea that our perception of what food is, what should be and should not be classified as “healthy”, has changed drastically over the recent decades. Despite advances in technology and scientific research that have paved the way for us to have an in-depth understanding of food chemistry and its effects on our health, the same rise in scientific knowledge has given rise to a plethora of misinformation, peddled by people who may have vested interests in the food industry or by people who are neurotic influencers that gain a following through controversial and extremist content. In the end, I strongly believe that an acuity for truth and falsehood transcends science, and it is our responsibility to separate fact from fiction when controversy and confusion arise.   

To understand how critical certain foods are for humans, it’s important to look back in time, anthropologically speaking. Humans and our hominin ancestors have consumed meat for approximately 3 million years, as climate changes resulted in drier grassland and semi-forested region expansion, which resulted in a decrease in digestible plant foods but an abundance of grazing animals. Additionally, human genes have not changed since the paleolithic era and human beings, being animals, are influenced by the same environmental pressure as other animals. Therefore, changes in diet have had several important influences on our evolution, including cranio-dental changes (less emphasis on grinding and more on biting and tearing of flesh), bowel morphologic changes (stomach acidity and a reformed caecum and colon that cannot accommodate much fibre), and rising energy demands, which resulted in a heightened ratio between brain and body dimensions (Leroy et al, 2023) & (Pereira & Vicente, 2013).

The term “balanced diet” is frequently thrown into the conversation of what constitutes a healthy diet. For any diet to be “balanced”, it needs to ensure the adequate intake of all the essential nutrients that humans need to perform all daily life functions, including the myriad of biochemical ones that occur 24/7. These are divided into macro- and micronutrients, macro being ones we need in large quantities (protein, fats, and carbohydrates), and micro being ones we require in minute quantities (vitamins and minerals). Meat holds a special place in the hierarchy of food groups that constitute a healthy diet because it fulfills the protein requirements of humans, whilst providing a broad range of important micronutrients (Arshad, 2018). Meat is defined as: “skeletal muscle and associated tissues (nerves, connective tissue, fat, organs) from mammals, avian, and aquatic species”, so meat extends far beyond what we commonly associate the term meat with (red meat) (Bohrer, 2017).

For starters, protein provides energy, and its component (amino acids) are essential for the growth, maintenance, development and repair of tissues. Meat contains eight essential amino acids, as well as histidine and taurine (a different article will go into length about amino acids). Taurine is essential in newborn infants, as they don’t have the ability to synthesize it from cysteine, but this is contingent on the mother consuming adequate amounts of taurine as an infant will get this amino acid from breast milk (Baltic & Boskovic, 2015). The eight essential amino acids are the ones that humans cannot synthesize out of the twenty that are necessary to synthesize proteins. “Limiting amino acid” is the term given to a food which lacks an essential amino acid and meat distinguishes itself from other foods because it has no limiting amino acids. Those who rely on plant-based sources of protein, such as vegetarians, will need to diversify their intake of protein to meet the daily requirements of all amino acids (Pereira & Vicente, 2013). Below is a table, using cooked beef as an example, to illustrate the micronutrient content of meat; 

Additionally, meat contains a broad spectrum of micronutrients, including selenium, vitamins A, D and B12, zinc, folate, choline, and is particularly rich in iron. Iron and zinc have been given ample attention due to their higher concentrations found in meat as well as their critical roles in numerous physiological processes. The bioavailability of zinc has been shown to be 1.7 times higher than that of legumes, like beans, lentils, and peas, and iron is up to 2 times more bioavailable (Leroy et al, 2023). Dietary iron exists in two forms, heme, which is bound within a protoporphyrin ring and abundant in animal blood proteins, such as haemoglobin and myoglobin and non-heme iron, which is found primarily in plant-based sources of iron. Heme iron is known to be more bioavailable than non-heme iron because non-heme iron needs to be converted from ferric to ferrous iron and can also be inhibited by other compounds present in plant sources, such as phytic acid (Coffey & Ganz, 2017).  

A variety of other compounds found in meat also have therapeutic implications, including lipoic acid (an antioxidant), carnosine (composed of alanine and histidine, and acts as an antioxidant with antitumour properties), biogenic amines (formed from bacterial breakdown of amino acids and can improve gut health and cognitive performance), nucleotides (enhance immune function), glutathione (the chief antioxidant), and carnitine (a prerequisite for oxidation, improving athletic performance and brain development) (Abraham & Irshad, 2020). Below is a table, using cooked beef as an example, to illustrate the micronutrient content in meat.

Given that fat is one of three major macronutrients, it should be well noted how fat content in meat influences health. The fat content in meat varies greatly depending on the cut of meat and the type of feed that the animal consumed, as well as method of cooking. Meat contains unsaturated fatty acids (oleic, linoleic, linolenic, and arachidonic acid), which are components of mitochondria, cell wall and other metabolic sites. Cholesterol and the polyunsaturated fatty acids, DHA and EPA, are also readily found in meat. For example, 100 grams of beef contains 62 mg of cholesterol, 2.1 milligrams of linoleic acid, 1.4 mgs of linolenic acid, 1.1 mgs of arachidonic acid, and trace amounts of DHA and EPA (Arshad, 2018).

Despite saturated fat having a bad reputation for its potential role in cardiovascular disease, ruminant animals have intrinsic digestive characteristics that change the composition of fats in meat. Microbial enzymes promote the hydrolysis of unsaturated fatty acids into stearic acid, which has a neutral role in cardiovascular disease and can be converted by humans into oleic acid, the monounsaturated fatty acid found in olive oil. Both unsaturated and polyunsaturated fats have serious implications for brain health as the brain’s communication network is conducted by lipid-composed transmembrane transfer systems, which are rich in long-chain fatty acids, such as arachidonic and docosahexaenoic acids, and these are abundant in meat, particularly fish. (Pereira & Vicente, 2013) 

In this review, I did not cover the entire scope of the nutritional value of meat but my intention here was to highlight how important meat is, as part of a balanced diet and note its well-deserved place in the hierarchy of food groups. Despite humans having adaptations to consume both animal and plant sources of food, animal protein is a superior source of complete protein and bioavailable nutrients that people on plant-based/vegetarian diets can be at higher risk of developing deficiencies to.    

References

Abraham, J. & Irshad, A. (2020). Anxieties, concerns and facts about meat consumption and health: a short review. Journal of food and animal sciences, 1(2), 66-80.   http://dx.doi.org/10.51128/jfas.2020.A014

Arshad, M.S. (Ed.). (2018). Meat science and nutrition (pp. 61-73). IntechOpen. http://dx.doi.org/10.5772/intechopen.77045  

Baltic, M.Z. & Boskovic, M. (2015). When man met meat: meat in human nutrition from ancient times till today. Procedia food science, 5, 6-9. https://doi.org/10.1016/j.profoo.2015.09.002

Beef Cattle Research Council. (2023, June 27). Nutritional qualities of beef.https://www.beefresearch.ca/topics/nutritional-qualities-of-beef/

Bohrer, B.M. (2017). Review: nutrient density and nutritional value of meat products and non-meat foods high in protein. Trends in food science & technology, 65, 103-112. https://doi.org/10.1016/j.tifs.2017.04.016

Coffey, R., & Ganz, T. (2017). Iron homeostasis: an anthropocentric perspective. Journal of biological chemistry, 292(31), 12727-12734. https://doi.org/10.1074/jbc.R117.781823

Leroy, F., Smith, N.W., Adesogan, A.T., Beal, T., et al. (2023). The role of meat in the human diet: evolutionary aspects and nutritional value. Animal frontiers, 13(2), 11-18.  https://doi.org/10.1093%2Faf%2Fvfac093

Pereira, P.M.C.C. & Vicente, A.F.R.B. (2013). Meat nutritional composition and nutritive role in the human diet. Meat science, 93(3), 586-592. https://doi.org/10.1016/j.meatsci.2012.09.018