Protein is needed by body every day although requirement may differ from age to age, and gender wise, as well as for persons with different physical activity. Infants require highest amount of proteins per kg of their body weight as they have a high rate of increase in their body weight. A large proportion of their body is composed of protein in the form of muscles and tissues. For this increase, they need high dietary proteins. Children also have very high level of physical activity as they are involved in playing games and learning new skills. Their protein requirement reduces as they grow older. Adults have somewhat lesser physical activity and no growth so their requirement per kg body weight is much less compared to children.
Among adults, those who are engaged in higher physical activity demands more protein requirement. Women who are pregnant and lactating need more protein in order to support the baby’s growth. Following requirements of protein are given in Dietary Guidelines provided by National Institute of Nutrition, ICMR for Indians.
Protein Requirements for Indians as per ICMR
How to meet the Requirements?
Protein contents of different food sources are different. Some foods are rich in proteins whereas others are not. Animal sources are rich in proteins. Meat, fish and poultry may commonly contain between 15 and 25% protein which is complete. Dry pulses and nuts also commonly contain between 20 and 25% protein but these have lower PDCAAS (Protein digestibility-corrected amino acid score- a method of evaluating the quality of a protein). Grains contain lesser protein between 10 and 15% but milled rice contains even less, around 7%.
Fig. taken from Pulse Cereals Grains partnership by Tanya Der, Western Canadian Functional Food Ingredients
Plant sources of proteins are not of high PDCAAS but their mixture will together slightly elevate the quality of proteins although they still fall short. One exception is soya protein. This is among the highest protein content foods as well as its value is as good as animal proteins. So when vegetarians are trying to improve their protein intake, they must always try to combine grains and pulses in their diet. For example, they should have idli or dosa in which there is pulse (udad) and rice together. It would also be better if they combine it with sambar prepared from dal. Some varieties of idli and dosa are also prepared with coarse wheat (rawa).
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Similarly it is better to eat roti with dal where wheat and pulse are combined. Even this combination of grain and pulse does not provide complete protein so it must be supplemented with either soya or milk & milk products like paneer or cheese. Some people consider eggs acceptable which also improves quality of plant proteins. Non-vegetarians must eat enough of meat, fish or poultry to supply enough proteins.
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Protein Contents of Different Food Sources
Sports persons and highly active persons need higher protein intake as there is a lot of wear and tear of their body proteins while they are extremely active and their muscles and other tissues need repair which needs a lot of proteins especially of branched chain amino acids containing proteins. Such proteins are high in whey proteins and soya; hence many such proteins supplements contain these sources.
Diet containing inadequate protein leads to undesirable conditions like protein energy malnutrition, obesity and other problems. Similarly, diet having excess protein also has many drawbacks. Thus, one must strike a balance in their protein intake.