Protein is a found throughout the human body in muscle, bones, hair, nails, skin and enzymes. It is the main structural component of the cells in our body. Amino acids are the basic building blocks of protein. Consumption of protein is required to maintain the body's protein as there are no amino acid stores to make new proteins. Without adequate protein, the body begins to breakdown muscle and tissue and can lead to kwashiorkor, or protein malnutrition.
Signs of Deficiency
Lack of protein in the diet initially causes fatigue, irritability and lethargy. If inadequate intake continues, loss of muscle mass, generalized swelling, decreased immunity, weakened cardiovascular and respiratory system and eventually death can occur. Other potential symptoms include diarrhea, changes in skin pigment, development of dermatitis or a rash and changes in hair texture, thickness and color.
Recommended Protein Intake
Treatment for protein deficiency is simply increasing protein intake with adequate caloric intake. The Institute of Medicine recommends at least 0.8 g of protein per kg of body weight every day. That's about 55 g of protein for a 150 lb. person. A 6 oz. piece of salmon at dinner provides over half of the protein needs for this individual, at 34 grams. Add a cup of lentils, 18 g of protein, with 1 cup of brown rice, around 5 grams, to meet the protein needs for the day.
Types of Protein
Protein is available from animal sources including milk, meat, fish, poultry and eggs, as well as plant sources such as beans, nuts, peas and soy. Harvard School of Public Health says the "protein package" is just as important as the protein itself. Plant sources come packaged with micronutrients and fiber. High fat meat and milk products may contain the micronutrients, but are also packaged with high amounts of saturated fat. Choose lean versions of animal protein as the healthier option.
Micronutrients in Protein Foods
Protein foods provide other nutrients in addition to the macronutrient. B vitamins like niacin, thiamin, riboflavin and B-6, as well as vitamin E, iron, zinc and magnesium can be found in these foods. According to the USDA, B vitamins play a role in energy release, the nervous system, red blood cell formation, as well as help build tissues; vitamin E helps protect against cell oxidation; iron is needed to carry oxygen throughout the body; magnesium helps build bones and release energy from muscle; while zinc is required for proper function of biochemical reactions and the immune system.
- “Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids”; Protein and Amino Acids; Food and Nutrition Board; 2005
- Harvard School of Public Health: Protein: Moving Closer to Center Stage
- MedlinePlus Medical Encyclopedia: Kwashiorkor
- ChooseMyPlate.gov: Why is it Important to Make Lean or Low-Fat Choices from the Protein Foods Group?
- U.S. Department of Agriculture Nutrient Database: Search: “Rice, brown, medium grain, cooked”