One important indicator of protein adequacy is muscle area of the thigh. In this study, muscle area of the thigh was reduced when people ate the RDA for protein. Although these results need to be confirmed in a larger group of people, the results are troubling indicators of insufficient protein intake. Insulin, hemoglobin and the fat burning enzymes in the muscle are all proteins that have important roles in regulating metabolism. Protein also helps in the maintenance of water balance and acid-base balance, regulation of the blood clotting process, prevention of infection and the development of immunity to disease.
Proteins also serve as carriers for nutrients in the blood such as free fatty acids.
If the body does not have adequate protein supplied by the diet, these functions can be impaired. Foods that are high in protein include meat, fish, poultry, dairy products and legumes, such as dry beans. Fruits, vegetables and grain products all have some protein, but the content varies. To insure adequate protein intake, health and nutrition professionals recommend eating a wide variety of animal and plant foods. If you are a vegetarian, you can still obtain adequate protein intake by planning your meals appropriately and including nuts, seeds and legumes, which can provide a good source of protein.