While the recommended dietary allowance of protein for an average Indian adult is 0.8 to 1 gm per kg of body weight; the average intake currently is only about 0.6 gm per kg of body weight.
According to the National Sample Survey 2011-2012, there has been a decline in the per capita protein consumption in both urban (4 percent) and rural (11 percent) areas. This is in sharp contrast with the rest of the world—protein consumption across the globe is on the rise, averaging at 68 gm per person per day. This pushes India at the bottom end in terms of average protein consumption.
Science of Proteins:
There are a class of macronutrients that are unique and are abundantly present in all living organisms. Proteins are nitrogen-containing substances that are formed by amino acids. They as macromolecules which form the basis of growth and development in all living organisms including humans. Proteins majorly constitute the five elements - carbon, nitrogen, hydrogen, Sulphur, and oxygen.
How protein is produced? Proteins are synthesized at the cellular level, the information to produce a protein is encoded in the cell’s DNA. When a protein is produced, a copy of the DNA is made (called mRNA) and this copy is transported to a ribosome (protein production unit of the cell). Ribosomes read the information in the mRNA and use that information to assemble amino acids into a protein.
How much of human body is protein? Total protein in the body accounts for about 15%–20% of body weight. Remaining part of the body is predominantly water which is 65%, Minerals at 4-5% and Fat at 10-30%. Higher the protein which is lean muscle mass and lower the body fat it is better for health and performance.
Amino Acids
Proteins are made up of amino acids. There have been 20 amino acids identified that play a crucial role in human growth and metabolism. Twelve of these amino acids are termed nonessential, meaning that they can be synthesized by the body and do not need to be consumed in the diet. The remaining amino acids cannot be synthesized in the body and are described as essential meaning that they need to be consumed through diets.
EAA - Essential amino acids, also known as indispensable amino acids, are amino acids that humans cannot synthesize on their own. Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Leucine, Lysine are the essential amino acids. These amino acids must be supplied from an external diet because the human body lacks the metabolic pathways required to synthesize these amino acids. In terms of nutrition, the nine essential amino acids are obtainable by a single complete protein.
CEAA - Specific Non-Essential Amino acids (glutamine, arginine, cysteine etc) become essential due to a disease or transient condition are called conditionally essential amino acids in extreme trauma or stress from thermal injury, sepsis, surgery, or wounds.
What is a Complete Protein? A complete protein, by definition, contains all the essential amino acids. Complete proteins are usually derived from animal-based sources. The essential amino acids are also available from incomplete proteins, which are usually plant-based foods. And combinations of incomplete protein are mixed together to make a complete protein.
Plant vs Animal Protein:
Plants do not contain large quantities of proteins like animal sources because of their structural differences. To meet the requirements of the essential amino acids, a large amount of plant proteins have to consumed, to counteract the deficits. There are a very few plant sources that constitute the entire array of essential amino acids, and even if they did, it is a negligible proportion of it. Thus, an individual (i.e. vegetarian) who desires to get their protein from vegetable sources will need to consume a wide variety of vegetables, fruits, grains, and legumes to ensure consumption of all essential amino acids aiming to strike the balance every meal. Typically, on the contrary, all dietary animal protein sources can provide the complete spectrum of amino acids even when the quantity of consumption is stringent. Animal protein is an important dietary source of micronutrients, including vitamins, iron, and zinc.
Efficiency and Bioavailability of protein:
Determining the effectiveness and efficiency of a protein is accomplished by determining its quality and digestibility. Quality refers to the availability of amino acids that it provides. The term protein quality refers to the ability of a particular protein to provide a balanced pattern of essential amino acids.
A high-quality protein contains high concentrations of the essential amino acids. A low-quality protein is deficient or lacking in one or more of these amino acids. Although beans and eggs are similar, as far as protein density is concerned, the quality of egg protein is considerably better than that of the protein from beans.
Protein bioavailability indicates how well the protein from a specific food source can be used by the body. Or in other terms, Bioavailability generally indicates the percentage of just how much the body can make use of certain protein. A protein is considered highly bioavailable if it is easy to digest, absorb, and (after conversion into its constituent amino acids) can be made into other proteins.
Health-Span:
Protein and hence amino acids play a central role in affecting growth, reproduction, health span, physiology, and longevity. A gradual decline in muscle mass is observed from the third decade of life, hence adequate intake of protein is one of the key nutritional factors to maintain independence, predominantly by preventing loss of muscle mass and strength (sarcopenia), frailty and associated with comorbidities in later life. Several studies establish specific amino acid composition of the diet (protein quality) regulates metabolism, health, and longevity.
Muscle Building and Muscle Maintenance:
The potential muscle-related benefits achieved by consuming higher-protein diets has strong evidence. Dietary protein is the primary nutrient required for the structuring and remodeling of muscle tissue because of its ability to independently stimulate muscle protein synthesis. By building muscle there is an increase in the amount of tissue available to use and store glucose for energy. Muscles also serve as the body’s predominant amino acid reserve, supplying the needs for the body to produce wound-healing molecules, antibodies and other proteins that are important for sustaining health. The metabolic basis for increased muscle strength and size is the stimulation of muscle protein synthesis to a rate greater than that of muscle protein breakdown. Dietary protein intake stimulates muscle protein synthesis and, also decrease protein breakdown to some extent.
Fat Loss:
It has been established in several studies that under most conditions’ protein is more satiating than the consumption of carbohydrate or fat in humans and a high protein diet most frequently improves weight loss and body composition. Increased protein consumption is shown to increase glucose tolerance, reduce fat mass gain and also promoted rapid fat mass loss and insulin sensitivity. Proteins are more satiating than carbohydrate and fat, in the short term and, in the long term. A higher protein intake changes body composition in a way that spares fat free mass and also sustains weight maintenance.
Protein from food and protein supplements:
Protein must routinely come from food. But in food the costing is such carbohydrates are cheapest part of food and protein food are costlier. So, protein supplements are cost effective way to reduce the burden of protein deficiency.
To be continued in part 2.