Factors that Influence Protein Requirements in Adults - Essay Example

Critically Discuss the Key Factors Influencing Protein Requirements in Adults Factors that Influence Protein Requirements in Adults Introduction Nutritional requirements and the identification of dietary components of food, in terms of quantity and quality, are aspects that form the foundation of clinical nutrition and nutritional science at large. Deliberations in this realm rarely occur without some extent of controversy, with protein being one of the principal nutrients characterised by debates and difficulties (Millward, 2013). A good source of protein is an important aspect of a healthy diet and it allows the body to grow and maintain the 25000 proteins that are part of the body encoding in the human genome and other nitrogenous compounds (Rand, et al., 2003). Together, these form the dynamic system of the body which contains the functional and structural aspects that help in nitrogen exchange to the environment (Joint, W. H. O., 2007). Thus the amount of protein that has to be consumed to meet these conditions of the body is termed as the protein requirement. Protein is the next bigger component of body tissues after water (Subar, et al., 2003). They are large molecules made of amino acids and are bonded together by peptides (Richards & Richmond, 2009). It is therefore important to take in proteins as they are used to maintain body tissue, which is constantly tearing and wearing out. A model on the protein needs is defined in terms of the organism metabolic demand and a demand of the diet that satisfies those needs for example efficiency of utilization (Elango, et al., 2010). The issue of protein intake in older adults is however controversial because some specialists warn that too much of it could cause toxicity while others argue that is important to take moderately high proteins to offset age related low energy intake and to maintain nitrogen balance (Millward, 2001). It is estimated that adults should take 0.75g (Young & Borgonha, 2000) of protein per kilogram of body weight to be on the safe side of nutrition deficiencies. These proteins should have a high digestibility and enough amounts of amino acids (Campbell, et al., 2008). These requirements can be satisfied by eating eggs, milk, fish and meat. Additionally legumes have a high amount of protein (Duranti, 2006). Since aging is associated with different physiologic and metabolic changes, the dietary protein requirements might also change. These changes may include decline in physical activity, changes in body composition due to loss of muscles, increased disease frequency in the older adults, decline in food intake, and decline in physical function capacity (Massey, 2003). These changes determine protein requirements in people but there are various ways of measuring the required protein intake in adults including protein content in food, biological value, digestibility, chemical score of protein, and protein efficiency ratio, so as to satisfy the needs. Factors affecting protein requirements in adults Digestibility and quality of proteins are important factors to determine whether dietary intake of proteins can furnish enough levels of the requirements on amino acids so as to satisfy the functioning of the body (Volpi, et al., 2003). The factors below influence the requirements of proteins in adults and the availability from protein sources. Changes in body composition The potential of growth in individuals is regulated through bone growth and adequate nutrition is essential for this; dietary protein has a major role in it (Paddon-Jones & Rasmussen, 2009). Skeletal muscle growth, the largest part of lean body mass is achieved through optimum nutrition and physical activity which lacks in the older adults (Houston, et al., 2008). Determining the protein requirements has its basis in nitrogen balance, which includes nitrogen excreted and that taken in food. Thus the real requirement for proteins intake is required for nitrogen rather than that of proteins. According to Hannan et al (2000), many women and men who are in their elderly stages and who take foods rich in proteins has helped to prevent the loss of lean muscle mass over some years. Similarly due to their nitrogen excretion through sweating or exhaustion of stored amino acids due to less food intake having protein rich food is essential. It is important to maintain lean muscle in older adults so as to prevent chronic health conditions (Chernoff, 2004). Nitrogen content varies in various foods thus older adults require a higher amount of nitrogen intake so as to prevent bone loss. If the body nitrogen is decreasing, which happens in the elderly persons, and then it means that they are having a deficient diet. Older adults are at a risk of being malnourished (Hickson, 2006)due to decrease in food intake thus it is important for them to retain a healthy nitrogen balance. It is however difficult to make the right measurements with sufficient accuracy of the requirements. Metabolic Demand This is the flow of amino acids through the pathways that maintain the function and structure of the body (Millward, 2003). This includes conversion of amino acids into metabolites and into nitrogenous products that are excreted through urine, sweat, faeces, and hair. This demand varies between individuals at different times and at different stages of life (Nieuwenhuizen, et al., 2010). The basal demand for nitrogen is equated to the loss in of it through all routes of the body after having a nutritionally adequate diet. These losses are representatives of instances where metabolic demands are met by protein from body tissues. If the body tissue pattern in amino acids is not similar to that of the metabolic demands, then the nitrogen losses include amino acids that are surplus to demand (Millward, et al., 2008). Pattern of amino acid demand is determined by age, sex and genotype, thus it is a crucial factor influencing protein requirements in adults. In young women for example, they have a higher amount of body fat compared to men thus their metabolic mass is lower. This does not however apply to less privileged communities where women undertake hard labour like the men. Protein requirements are essential in preserving body functions throughout the adult life (Walrand & Boirie, 2005). Biological Value Biological value is the measure of how food protein is efficiently absorbed from the digestive tract and turned into body tissue (Houston, et al., 2008). If a certain food consists of all the nine essential amino acids, then it should be absorbed and incorporated into the body proteins easily. As people age lean muscle diminishes and the ability to absorb all proteins that are ingested becomes a problem. Similarly the older adults have less body protein tissue due to tear and wear of their tissues (Schaafsma, 2000). It is therefore difficult to match between the amino acid pattern and the body tissue amino acid, thus many food proteins are not turned into body proteins. They are leftovers and are excreted as urea thus the biological value becomes low; ratio of retained nitrogen to absorbed nitrogen (Cannas, et al., 2004). Older people are vulnerable to various diseases that may hinder efficient absorption of food (Paddon-Jones, et al., 2008). Additionally their lack of physical activity may hinder the metabolic demand for proteins. Having low absorption capacity means that they have to supplement their proteins intake with something easily digestible and having a low metabolic demand for younger adults would mean a less requirement for protein intake as their bodies use reserve proteins. Lifestyle and environmental factors The best lifestyle characteristic that influences the demand for protein intake is physical activity. Different physical activities influence levels of food consumed as well as metabolic demands and body composition (Lichtenstein, et al., 2006). Physical activities play a major role in integrating intermediary metabolism and interchange of amino acids. Activity increases the demand for protein but its extent can be reduced through training and appropriate intake of energy. The opposite is true for adults. Since they are less active, the demand for protein in the body is lower (Phillips, et al., 2007). To add on this, most adults have the habit of smoking and taking alcohol which has an influence on the protein requirements intake and the demand. Detoxification of these chemical agents places an unbalanced demand on amino acid metabolism. There are certain medications like paracetamol that places a considerable demand for sulphur amino acids. Environmental challenges are sources of metabolic stress that induce immune responses in case of infections. Such exposures, at their most severe part, result in a total reordering of the metabolic priorities, changes in requirements for protein, nitrogen and amino acids, and losses (unbalanced) for the body system (Gaffney‐Stomberg, et al., 2009). Recovery from such instances also requires increased metabolic demands. Pregnancy and Lactation Extra energy is required during pregnancy and the total protein requirement for a woman who is estimated to gain more than seven kilograms and give birth to a three kilogram baby is high (Godfrey & Barker, 2000). This is because dietary proteins are converted into foetal, maternal, and placental tissues. This means that pregnant women have to undergo adaptation of protein metabolism due to these anticipations. These adaptive changes help in storing or conserving increased protein synthesis and nitrogen. Protein synthesis increases during the three trimesters of pregnancy with the third trimester having the highest increase (Godfrey & Barker, 2001). During the second half of pregnancy, there is an increase in insulin secretion thus an insulin resistance is observed. At the same time foetal protein synthesis increases remarkably. The resistance in insulin can be attributed to high levels of glucose circulation which potentially spares amino acids for protein synthesis. Lactating women lose proteins through breastfeeding and their need to regain them so as to accomplish the needs for growth for their children (Picciano, 2001). More so during the first six months of lactation where children depend solely on milk, women need to keep up the supply. Conclusion All these factors depend on digestibility. This is the extent to which food (protein) is digested. Animal proteins are digested faster than plant proteins because plant proteins have less digestive enzymes. This aspect is affected by thorough chewing and the method of cooking. Thus it determines the capacity of protein sources to meet the required demands of proteins in adults. It is therefore an important factor that revolves around all other factors discussed above and it is the most sufficient in estimating safe protein intakes for adults. 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