Functions of Protein

• You need proteins primarily as building blocks (structural components) for your body, but there are many more reasons why you depend on proteins so much. They act as enzymes to make your food more soluble, as antibodies to protect you from infections and as hormones to regulate your general body processes. You also need proteins for transport of other nutrients (like fats) throughout the body. Your body needs protein for growth in childhood and for maintenance as adults.
  
  

Protein Requirements

• In infancy, you require more protein per kg body weight as compared to adolescents and adults. Around 2.2 grams per kg weight is sufficient for babies. The Centers for Disease Control and Prevention (CDC) suggests 13 grams of protein per day for children ages 1 to 3 years. As you grow older, your protein requirements increase to about 19 grams for children ages 4 to 9, and 34 grams for children ages 9 to 13. (See References 1)
  
  As teenagers, your protein requirements increase as your body mass increases at an incredible rate and your body goes through so many changes. Adolescent girls between the ages of 14 and 19 require about 46 grams of protein daily, while adolescent boys require 52 grams per day.
  
  Adult women require 46 grams of protein daily for maintenance, but during pregnancy and lactation should increase protein intake to 71 grams per day. Adult men need 56 grams of protein daily. Although the current protein intake of elderly remain the same as those of adults, studies are being carried out by the Food and Agriculture Organization and the World Health Organization that reassess these values since elderly adults are not able to use as much protein from their diet as younger adults. (See References 2)
  
  

Sources of protein

• To get the best quality protein from your diet, eat adequate amounts of animal foods like meats, eggs, fish, milk and milk products. These are "complete protein foods" because of their essential amino acid content. One glass of milk contains about 8 grams of high quality protein. Make sure your children get enough milk for their growing bodies too. Meat contains about 21 grams of protein per 3 ounces. Choose leaner meats for a well-balanced, low fat, high protein meal.
  
  Consume grains and beans as "complimentary proteins." They are generally lacking in one or two essential amino acids but, when combined with other foods, they too are able to provide a complete protein meal. For example, rice lacks the amino acid threonine and beans lack the amino acid methionine, but when eaten together, they are a good source of protein.
  
  

Excess and Deficiency

• Many people eat high protein, low carbohydrate diets to lose weight, but according to a study published by Dr. Sachiko T in the American Heart Association Science Advisory, such diets should not be carried on for longer periods as they "compromise vitamin and mineral intake, as well as are potential for cardiac, renal, bone, and liver abnormalities overall." (See References 3)
  
  Protein energy malnutrition (PEM) is a body depleting disorder which can be very fatal for children. It generally effects children in developing countries only and is very uncommon in the United States.