An In-depth Focus On Proteins

Proteins

Proteins are yet another essential nutrient required in large amounts(macro-nutrients). They serve various functions in the body that are vital to sustaining health. Proteins provide 4 Kilo calories per gram, similar to carbohydrates.

Structure

The building blocks of proteins are known as amino acids. It is these amino acids that combine in large numbers to form proteins. The diversity between proteins resonates from the sequence and number of amino acids contained. A protein’s structure principally constitutes long chains of amino acids (300 or more amino acids). The functions and characteristics of each protein are determined by the arrangement and placement of amino acids. Each amino acid contains a carboxyl (-COOH) functional group and an amino group (-NH2).

Amino acids can be classified as either:

Essential amino acids (indispensable amino acids)-the body cannot produce these amino acids. Therefore, they have to be provided in the diet. These amino acids examples include histidine, isoleucine, methionine, lysine, phenylalanine, leucine, valine, threonine, and tryptophan. There are nine of these types of amino acids.
Non-essential amino acids (dispensable amino acids)-the body can produce these amino acids.They include asparagine, serine, glycine, arginine, cysteine tyrosine, glutamic acid, proline, alanine, glutamine, and aspartic acid.

Proteins can either be complete proteins or incomplete proteins depending on the essential amino acids contained. Complete proteins have all 9 essential amino acids, while incomplete proteins lack one or more of the essential amino acids. Some protein sources such as beans are incomplete proteins because they do not have all essential nutrients, whilst others like poultry and fish are complete proteins because they contain all the essential nutrients. The amino acid that is in the most inadequate supply in an incomplete protein, is defined as a limiting amino acid.

Functions of Proteins

For growth and maintenance– Proteins are essential for the growth and maintenance of tissues. During normal circumstances, your body uses a similar amount of proteins to build and repair tissues. In other situations; however, the body needs more proteins, for instance, when one is ill, during pregnancy and when breastfeeding. Individuals who are in recovery from an injury ,those who engage in intense exercises and older adults also require increased amounts of proteins.
To maintain structural integrity – Certain proteins such as collagen and keratin serve structural functions. For example, keratin is found in your nails, hair, and skin and helps to keep them healthy. Collagen provides structure and strength for your muscles, connective tissues, and bones.
For transport mechanisms and storage functions– Proteins transport other nutrients such as cholesterol, vitamins, minerals, and oxygen .For example, oxygen is transported by haemoglobin from the lungs to tissues. Carrier proteins transport solutes binding to them, and transporting them across membranes. Ferritin (a protein), stores iron.
To facilitate bio-chemical reactions-Enzymes are proteins involved in diverse bio-chemical reactions in the body.They are play a role in the chemical reactions that promote growth, healing, energy production, digestion, reproduction, and blood coagulation, among others.
To maintain body pH– When you consume proteins, you regulate the basic and acidic levels in your body. Haemoglobin, a protein, used in the formation of red blood cells is significant in maintaining constant pH in the body. When pH rises(increase in base levels), haemoglobin loses hydrogen ions, and when pH decreases, (increase in acid levels) haemoglobin attracts the hydrogen ions, ensuring a constant pH.
To maintain body fluids-Proteins including globulin and albumin are significant in ensuring your body’s fluid balance by trapping and retaining water. Hence, your body does not get to have excess or insufficient body fluids.

Dietary Sources Of Proteins

Legumes such as beans, lentils
Meat
Fish
Poultry
Milk and dairy products
Eggs

How To Determine Quality Of Proteins

To determine a high-quality protein, various approaches can be employed including;

Assessing its digestibility-whether the body can utilize amino acids from a protein that has been digested and absorbed to meet its needs.
By determining its biological value– Biological value is a measure of how much of the amino acid content absorbed in the body becomes integrated into body proteins. If a protein has all the essential amino acids in the right amounts needed by humans, it is termed a high-biological value protein. When a protein lacks or has insufficient amounts of essential amino acids, it is referred to as a low-biological value protein.
Determining whether it is a complete protein – whether the protein has all the essential amino acids.

A high-quality protein therefore should be easily digested and absorbed, have high biological value, and be a complete protein.

You should note that consuming an incomplete protein in combination with 2 or more proteins (for example grains and legumes) ensures that you still obtain all essential amino acids. This is known as the use of complementary proteins. Most proteins obtained from plant sources are not high-biological value proteins ,while those proteins obtained from animal sources are mainly high-biological value proteins. For this reason, a vegetarian who only relies on proteins from plant sources may fail to meet their essential protein requirements. Nonetheless, by complementing the proteins, a vegetarian can obtain all the essential amino acids.

RDA

The quantity and amino acid composition, effects of physical activity, functions of energy in a meal, and how meals are distributed in a day are critical factors when establishing protein requirements. However, in general, protein requirements should range between 15%-20% of total calorie intake.

Of importance, individuals with high protein requirements such as those with illnesses or recovering from injury may need high protein in comparison to someone else who does not have these increased needs.Depending on one’s physical activity, protein needs may also vary. Someone involved in intense exercise needs a higher intake of proteins than a less active individual, due to the increased wear and tear of muscles during exercise.

Individuals with renal conditions are recommended to integrate a low-protein diet, which includes plant-based proteins. However, a dietitian can provide more guidance on the protein intake as per individual needs, to manage the condition.

Proteins are necessary for building muscles and ensuring growth. The inclusion of proteins from either plant or animal sources is imperative to ensure strong muscles and proper health.