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Protein intake
From CopperWiki
Proteins are necessary for maintenance of tissues, wear and tear and for sustaining growth. They are also used to make hormones and other physiologically active substances. Although proteins play a major role to keep us healthy by carrying out various bodily functions, we do not need very large quantities of it. So, how much protein does the body need and what determines this need?
[edit] Protein requirements
Definition
The protein requirement of an individual is defined as the lowest level of dietary protein intake that will balance the losses of nitrogen from the body in persons maintaining energy balance at modest levels of physical activity. Enough protein is needed in the diet to make up for the daily nitrogen losses in the urine, feces, skin, hair, nails, perspiration, and other secretions.
[edit] Calculation of protein requirements
The daily protein requirement in humans is calculated on the basis of the body weight of a person. Due consideration is given to other deciding factors. It is calculated in terms of grams per day for every kilogram of body weight. The requirements are generally determined in terms of egg protein. Requirements for other proteins are computed after making adjustment for the lower quality of dietary protein relative to egg.
Factors affecting protein requirements
- Age
- Sex
- Physical activity
- Physiological condition
Adults:
For normal healthy adults, requirement of egg protein is 0.8 grams of protein per kilogram of bodyweight. The requirement in terms of mixed vegetable protein is 1.0 grams per kilogram to account for some plant proteins being digested somewhat differently from animal proteins.
Growing children:
Children require more protein per unit body weight than adults because new tissues are being laid down during this period.
These new tissues require amino acids which are largely provided by the dietary proteins.
Thus, a young child of 1-2 years requires 1.2grams egg protein/kg or 2.0 grams of mixed vegetable protein/kg body weight.
Pregnant and lactating women:
It is to be expected that protein needs of women are greater during pregnancy and lactation. The protein requirement in these women is taken to include the needs associated with the deposition of tissues or the secretion of milk at rates consistent with good health. Hence, their requirements are greater than the non-pregnant, non-lactating women.
Athletes:
Athletes do not need to take very large quantities of proteins as very high levels can cause dehydration and other health problems. Though there is an increased demand for proteins in athletes, it has seen to be consistent with 1.2-1.4g of protein/kg body weight in case of endurance training. Persons engaged in strength training require higher levels in the range of 1.4-1.8g of protein/kg body weight.
Others:
Elderly people, adolescents, anyone undergoing severe stress (trauma, burns, hospitalization, and surgery), disease or disability need more protein.
A mixed diet solely based on plant proteins can also meet the protein requirement of adults and children, provided enough of the diet is consumed to meet the energy demand. For this, the protein content of the diet should contribute around 10%-15% of the total calories. For example, on a diet of 2,000 calories per day, at least 200 calories should come from protein or about 50 grams of protein (as 1gram protein provides 4 calories).
It must be emphasized that values for protein requirement are valid only when other nutrients, particularly calories are adequate in the diet. In other words, the diet must be well balanced to promote health and fitness.
