Substances or elements present in living body that provide nourishment and energy are called nutrients. These are essential for the maintenance and growth of the body (Kihara et al. 2017). Nutrients that are required in large amounts are termed as macronutrients while those that are required in smaller amount are called micronutrients (Pittia and Heer 2022). Proteins, carbohydrates, and fats are listed as macronutrients, while fibre, vitamins, and minerals are listed as micronutrients (Balami et al. 2019). A number of sources provide these nutrients to the body. These sources include meat, milk, fruits, vegetables, cereals, etc. (Langyan et al. 2022). Meat is a major source of protein for human needs (Papier et al. 2019). Mutton, beef, chicken, lamb, and fish are different types of meat (Owusu-Apenten and Vieira 2022). According to Statista, in 2022, poultry will be the most common type of meat, with 136 million metric tons. Other types are pork (121 million metric tons), beef and veal (72 million metric tons), and sheep (16 million metric tons). The trend over the last 6 years is shown below in the chart (< Production of meat worldwide by meat type 2022 _ Statista.pdf>).
Meat is a natural energy-rich food supplement that is also a major component of a healthy, balanced diet. It is also an essential component for human growth and development. It is a good supplier of protein, vitamin A, vitamin B complex vitamins, selenium, zinc, iron, and phosphorus. The average meat protein content is 23%, which differs with the type of meat (Ahmad et al. 2018).
The physiochemical properties of meat, such as pH, texture, colour, water holding capability, and cooking loss determine the meat quality along with consumer quality traits (Palanisamy et al. 2019). Meat contains an abundance of protein as a major constituent. Other components are water, ash, and fats (Geletu et al. 2021). The average protein content in meat is 22%, but it is present at 34.5% in chicken chest meat and 12.3% in duck meat [8]. The PDCAAS score of meat is 0.92, which is higher than that of other protein sources. PDCAAS is basically referred to as "protein digestibility corrected amino acid scores" (Huang et al. 2018). Compared with lamb and pork, beef meat has a high amino acid content (Sakomura et al. 2015). Figure 1 shows the production of meat in million matric tons from different sources.
Fats are macronutrients (López-Pedrouso et al. 2021). These are triglycerides (esters of alcohol glycerol, and fatty acids) (Ogori 2020). Fatty tissues are present in meat, which varies depending upon their location in the body (Ahmad et al. 2018). Fats provide protective padding to the kidney, heart, and other organs; insulation in the case of temperature irregularities; and energy deposition (Zhao et al. 2022). The amount of fat in the body ranges from 8–20%. Most fat is found in poultry skin (Peña-Saldarriaga et al. 2020).
Meat is also a source of different essential minerals, such as zinc, iron, and selenium, which play important roles in the growth and nourishment of the human body (Ahmad et al. 2018). Animal proteins have amino acid patterns according to human requirements. This pattern has all 9 necessary amino acids in adequate amounts (Sá et al. 2020). Proteins obtained from animal foods are easily digested and frequently available (Moughan 2021). Antinutritive factors such as tannins, protease inhibitors, and lectins limit the availability of proteins present in plant foods (Samtiya et al. 2020). The plant cell wall is also a major reason for the absence of plant proteins, as the human gastrointestinal tract lacks cellulase enzymes to break down cellulose and dietary fibres (Fujimori 2021).
According to DIAAS analysis, animal proteins have higher quality than plants. For example, milk powder has a DIAAS of 122, peas have 64, and wheat has 40 (Herreman et al. 2020). Soy protein is referred to for its high quality, but it also has a lower DIAAS score (90) than animal protein (Leyssens et al. 2017). Malnourished infants and children need sufficient supplies of proteins (Dipasquale et al. 2020). Protein deficiency has a negative impact on growth and development (Herring et al. 2018). Protein consumption should be maintained at moderate level. A very high intake of proteins increases the possibility of infants being small for gestational age (Rasmussen et al. 2020). The consumption of red meat and processed meat products can cause several diseases, including diabetes, cardiovascular diseases and inflammation. These compounds also cause adverse health effects, especially cancer (Libera et al. 2021).
However, developing countries are facing problems with contaminated food. These contaminants largely consist of heavy metals such as iron, lead, nickel, cobalt, chromium, cadmium and zinc (Orisakwe OE et al. 2020). A case study was conducted in Uganda to determined the presence of metals in beef meat (Kasozi et al. 2018). The Fe and Cu concentration in meet were found 184 and 160, respectively (Orisakwe O et al. 2017). Red meat contaminated with heavy metals is a major health threat that requires immediate decontamination strategies (Atangana 2020).
Zinc is a necessary cofactor in living cells. Zinc aids in the maintenance of cell structural integrity and the regulation of cell activity. Beef has a 127-ppm concentration of zinc (Jomova et al. 2022). When Zn absorbed into the body, its level becomes excessive. Zn dominates iron and copper, which leads to their deficiency. Zinc rich diets cause irregularities in lipid metabolism and gastrointestinal diseases (Leyssens et al. 2017).
Co in the form of vitamin B12 (Leyssens et al. 2017). It is present at an average of 0.25 ppm in meat (Kasozi et al. 2021). It helps in managing anaemia associated with improper absorption of vitamin B12 during ulcers (Al-Awami et al. 2019). Cardiovascular diseases, and neurological and endocrine disorders are caused by the toxicity of cobalt (Chen and Lee 2022).
The food lots and water drank by animals are major carriers of heavy metals that can enter the animal's body (Broomhead et al. 2020). Sewage and urban agriculture increase heavy metal accumulation in foods (Kasozi et al. 2021). The primary purpose of the consumption of meat and its products is to obtain nutrients, but they also carry hazardous metals (Salter 2018). The consumption of meat and its products also causes cancer, diabetes and CVD (Qian et al. 2020).