Protein intake is an indispensable requirement for the growth and maintenance of any living creature. Every cell in our body needs protein to carry out any function.

The amount of protein required for a person, however, is variable depending on many factors, namely, body weight, age, physical activity, health condition, environment, etc. Generally, protein intake should be in equilibrium with protein loss. Protein is lost in urine, feces, blood, sweat, skin, nails, hair etc. When protein intake is less than protein lost, it is called negative protein balance, whereas when it is the reverse it is called positive protein balance. Ideally, for normal adults a neutral protein balance should be attained.

Growing kids and pregnant and lactating women require more protein per unit weight than adults in normal condition and therefore they should be in positive protein balance. Growing kids and pregnant women actively gain muscle, bones, flesh and blood, and since for every cell in these tissues protein is a requirement, the recommended daily protein allowance is higher. Other conditions in which daily positive protein balance is needed include recovery stage after illness and when there is increased secretion of insulin, growth hormone, and testosterone.

As a general guideline, the recommended dietary allowance (RDA) for protein for adults is 0.8 grams per kilogram of body weight per day. The protein RDA refers to the daily average amount of protein most people (97 - 98%) need to stay healthy.

Table: Dietary Reference Intakes (DRIs): daily recommended intakes of protein for individuals. (Source: Food and Nutrition Board, Institute of Medicine)

Age, gender, life stage group Protein DRI (grams/day)
Infants
0–6 mo 9.1
7–12 mo 13.5
Children
1–3 years 13
4–8 years 19
Adult Men
9–13 years 34
14–18 years 52
19–30 years 56
31–50 years 56
51–70years 56
> 70 years 56
Adult Women
9–13 years 34
14–18 years 46
19–30 years 46
31–50 years 46
51–70years 46
> 70 years 46
Pregnant Women
14–18 years 71
19–30 years 71
31–50 years 71
Lactating Women
14–18 years 71
19–30 years 71
31–50 years 71

 

Note: Daily Reference Intakes (DRIs) have been developed, since 1996 by the Food and Nutrition Board, Commission on Life Sciences, National Research Council, to replace the Recommended Dietary Allowances (RDAs).


Protein related links
Food sources of protein: animal and vegetable protein sources and content.
Protein requirement: for kids, adults and pregnant and lactating women.
Soybean/tofu: nutritional value and health benefits
Essential and non essential amino acids: Definitions and Functions
L-Arginine: Food Sources, Health Benefits and Side Effects

 

References

Hamilton, E. M. N., Whitney, E. N., and Sizer, F. S. 1991. Nutrtion: Concepts and Controversies, 5th ed. West Publishing Co.,New York, USA.

Institute of Medicine. 2005. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academy Press. (Food and Nutrition Board, Institute of Medicine, National Academies).