## The five main functions of protein __Construction.__ Protein is an important building block for bones, muscles, cartilage, and skin. Even hair and nails are made up mostly of protein. __Repair.__ Protein repairs damaged tissue. __Oxygenation.__ Red blood cells contain hemoglobin, a protein that transports oxygen throughout the body. __Digestion.__ About half of the dietary protein consumed daily goes to the production of enzymes that help digest food. __Hormone control.__ Protein plays an important role in regulating hormones, especially during puberty. > The physiological requirement for protein is 65 to 117 grams per day for men, and from 58 to 87 grams per day for women. > ## What does a deficiency lead to? Protein is made up of the building blocks of amino acids. Amino acids are needed to make muscle, bones, various enzymes, and hormones, and they are also a source of energy. Among the consequences of protein deficiency ===are: - Slowed metabolism - Reduced immunity - Depletion of muscle tissue - Anemia - Swelling, especially in the feet and ankles - Mood swings - Deterioration of skin, hair, and nails - Weakness - Insomnia - Slow growth (in children) ## What groups are typically protein deficient? __Vegetarians.__ This is because the primary source of protein is animal products. __People who follow strict diets.__ Malnutrition, mono-dieting, and rigid restrictions often lead to a shortage of vital nutrients, including protein. __Pregnant women.__ Protein is necessary for the formation of the fetus, so the need for it in expectant mothers increases dramatically. __Children and adolescents.__ This is because it is the building material for the growing body. In addition, protein helps to restore the energy that children expend in large quantities. __People who are physically active.__ Protein helps accelerate recovery from exercise, build muscle mass, maintain a healthy weight, and reduce hunger. ## Top sources of protein Animal products such as chicken, turkey, meat, fish, seafood, and dairy products are all good sources of protein. Other good sources include plant foods such as soy, quinoa, and amaranth. Nuts, seeds, and legumes are good sources of protein. Although they do not contain all essential amino acids, vegetarians should make sure to consume them. > Legumes, grains, seeds, and nuts contain phytic acid. Phytic acid binds minerals, making them unavailable for digestion, and also affects the function of some enzymes in the stomach, reducing the digestibility of protein and starches. Fermenting (soaking) foods can neutralize the action of this acid for at least seven hours. Phytic acid is also destroyed by phytase, which is activated during germination.