The optimal daily protein intake varies widely between different individuals, and the amount and type of protein available in food is similarly variable, necessitating careful planning and tracking to ensure an optimal diet. Factors that should be taken into consideration when planning daily protein intake include age, gender, and pregnancy. Body type is also important when planning protein intake, as muscle tissue typically require more protein than other tissues. Certain activities — most commonly exercise — increase the body’s need for protein, and diet should be adjusted accordingly. Finally, the type of protein being consumed should be monitored, because not all proteins provide every essential amino acid.
All protein consists of some combination of eight different amino acids, which are used to build cells and for a variety of other crucial physiological processes. The human body cannot adequately synthesize these chemical compounds and must obtain them from food. Foods that come from animals or animal products almost always have a roughly even mix of different amino acids and are said to provide complete proteins.
Plant proteins, with a few rare exceptions, do not provide complete proteins. A diet that does not include animal products must mix different forms of plant protein for complete nutrition. Red beans and rice, in addition to being delicious, is a good example of a dish that mixes two incomplete proteins in such a fashion to provide an excellent boost to daily protein intake.
Everyone requires daily protein intake from external sources, but the amount that a given person requires depends on a variety of factors. People with greater muscle mass typically require more protein to repair and maintain that muscle. Men require more protein than women — 56 grams per day compared to 46 per day for women — partially because they tend to carry more muscle bulk and partially because they are simply larger on average. Children require less protein in absolute terms than do adults, but more as a percentage of their body weight, because they are still growing and building new tissues at a rapid pace. Pregnant women, too, require a very high daily protein intake, because they must supply nutrients to their unborn children.
Exercise and injury increase the body’s need for protein in the diet as well. No single set of guidelines for protein consumption to offset exercise is available. A broad consensus among physicians and athletes does support an increased level of protein intake for people engaged in vigorous exercise, both to speed recovery after exertion and to increase muscle building.
Anyone planning a program of diet and exercise should also be mindful of where his or her protein comes from. Red meat is an excellent source of protein but is also often very high in cholesterol. Lean meats, such as turkey or fish, may be better sources of protein. Vegetable protein, while requiring a bit more planning to ensure proper nutrition, typically also provides an excellent mix of other nutrients and fiber, both very helpful for maintaining health.