Proteins are organic compounds that contain carbon, hydrogen, oxygen, and nitrogen atoms; some proteins also contain sulfur.
Energy from Proteins
• 1 gram of protein supplies 4 kcal (the same as CHO).
• Proteins should supply 10-15% of your total daily kcals.
Classification of Proteins
Complete proteins (High-biological-value proteins) contain all of the essential amino acids. Complete proteins are primarily animal proteins, such as those in meats, poultry, fish, dairy products, and eggs.
Incomplete proteins (Low-biological-value proteins) lack one or more of the essential amino acids, usually lysine, methionine, and tryptophan. Most vegetables are incomplete proteins.
Essential amino acids
• The body cannot make essential amino acids. As a result, they must come from food.
• The nine essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
Nonessential amino acids
• "Nonessential" means that our bodies produce an amino acid, even if we don't get it from the food we eat.
• They include: alanine, asparagine, aspartic acid, and glutamic acid.
Functions of Proteins
Growth and replacement: clotting factor production, collagen synthesis, epithelial cell proliferation, fibroblast proliferation.
Immunity: antibodies, white blood cell production and migration, cell-mediated phagocytosis.
Fluid balance: intracellular osmotic pressure, albumin, maintenance of blood volume
Sodium and potassium balance.