Nutrients can be defined as those substances that are assimilated by living organisms for the purposes of staying alive, for growth and development, normal breathing, locomotion, for reproduction, and excretion of waste substances for healthy wellbeing. Examples of nutrients include nitrate, carbon dioxide, phosphate, minerals, vitamins and proteins. Protein as one of the nutrients is to be discussed further. Welle (1999) defines protein as a linear polymer that is built from about twenty distinct amino acids whose type and sequence in a particular protein is determined by the DNA of the cell that creates them. The sequence of amino acids is very crucial because it determines the overall function and structure of a protein. Proteins are very important in the human body and can be obtained from different sources (Sikorski, 2001).
Protein constitutes of 40 percent of the human body's dry matter and is the second important nutrient for the human body after water which constitutes 60 percent of the human body. Proteins are known a the body's building blocks as they play very important role in repairing the worn out tissues as well as promoting growth of tissues due to cell division. Hormones and enzymes which are very crucial in carrying out a range of metabolic functions in the body are protein in nature. Antibodies are also protein in nature and are essential in human body since they defend the body against infections. Proteins are therefore one of the most essential nutrients required by human body such that they should be consumed adequately in one's daily diet (Insel et al., 2010).Proteins are crucial nutrients and therefore an integral part of healthy, balanced diet. Good quantities of proteins are always from the food taken as the main source. Appropriate amounts are essential for higher energy and stronger muscles. There are varied dietary sources of proteins and they include meat, fish and seafood, dairy products, eggs, nuts and seeds, beans, soya products, legumes, cereals such as oats, wheat and rice. There are two different types of proteins and they include complete proteins and incomplete proteins. All essential amino acids constitute of complete proteins. The complete type of proteins is obtained from a number of animal foods for instance, poultry, eggs, fish, meat, cheese and milk. Eggs are known to be the best source of complete proteins. Complete proteins can also be obtained from some plant products such as soybeans. Incomplete proteins include most plant foods for instance, seeds, vegetables, nuts, grains and legumes. Incomplete type of proteins comprise of small quantity of essential amino acids (Welle, 1999).
Since proteins are very important in the wellbeing of human body, ingestion of inadequate levels of proteins may bring about many effects, most of which are negative. For instance one may experience decreased energy, lowered immune functioning, hair loss, decreased body mass, bloating. However, inadequate intake of proteins can be beneficial to some extent, for instance can reduce the risk of cancer in human body. Decreased energy can result from insufficient oxygen in the blood stream and this is because hemoglobin which is a red coloring pigment in the blood is composed of a protein and iron. Hemoglobin is very important in carrying oxygen from the lungs to various parts of the body. Insufficient protein will bring about less hemoglobin and therefore less oxygen for respiration (Insel et al., 2010).One of the components that make up hair is a protein called keratin. Therefore inadequate intake of proteins may bring about less keratin in the body and this will cause hair loss. Antibodies are protein in nature such that if inadequate quantities of proteins are consumed, fewer antibodies will be available in the blood stream. Antibodies are very important in protecting the body from infections and therefore few antibodies will not effectively and sufficiently protect the body from infections hence low immunity functioning. Adequate proteins in the body prevent bloating as they bind with cells in the body to assist keep water in their cytoplasm. Since proteins are essential in building the body muscles, insufficient proteins will bring about loss of one's lean muscle mass and therefore decreased body mass. However inadequate intake of proteins will be beneficial in reducing risks of cancer as low proteins cause the body to produce lower levels of particular growth factor hormones (Welle, 1999).
Excessive intake of proteins has got its negative effects. Excess protein cannot be stored in the body like the case with excess carbohydrates but are usually eliminated in the form of urea. Excessive intake of proteins brings about increased excretion of calcium in urine during which urea is eliminated. Osteoporosis and bone loss is the consequence of decreased calcium in the body. However this problem can be fixed by regular intake of calcium in daily diet (Sikorski, 2001). Proteins are very important in healthy functioning of human body if it is taken adequately. Complete type of proteins is very important and should be included in every diet for the body to meet its appropriate requirements. However excessive intake of proteins can ring about excretion of calcium hence resulting in bone loss and osteoporosis. Insufficient intake of proteins will bring about many negative effects in one's health. However, in some cases in can be beneficial to take less protein since the risks of cancer can be reduced.