Proteins are comprised of amino acids that are considered the basic building blocks of protein in the human body. About 10-35% of your daily calories should come from protein. Proteins aid in the development of blood, nails, skin, muscles, internal organs, and hair. Protein can be found in dairy products, nuts, beans, tofu, meat, poultry, fish, and eggs.
Protein has several important functions within the body. Protein aids in muscle building and growth, and assists in the transportation of nutrients, oxygen, as well as waste in the body. Protein is also essential in cell maintenance because it helps repair cells and assists in the production of new cells.
Important Points to Remember:
- Protein gives 4 calories per gram
- Not all proteins are complete
- Complete proteins can be made by combining plant proteins
- Eight essential amino acids: Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine
Complete proteins contain all eight essential amino acids, while incomplete proteins are deficient in one or more of these essential amino acids. Essential amino acids cannot be made in the body and therefore, must be supplied through diet. Complete proteins are found in animal foods; such as poultry, meat, fish, milk, eggs, and milk products like yogurt and cheese.
The only plant protein that is regarded as a complete protein is soybeans. Incomplete proteins are found in seeds, nuts, beans, grains, peas, and a small amount in vegetables. Nuts and seeds are considered to be incomplete proteins because they lack one or more of the essential amino acids.
Complete proteins can also be made by combining plant proteins to provide all the essential amino acids, known as a complementary protein. New research has shown that complementary proteins can be combined as long as they are eaten within the same day and they do not need to be consumed within the same meal to be used within your body.
Protein in Our Food Sources
Complete Proteins: Animal proteins, such as eggs, meat, poultry, fish, dairy products
Incomplete Proteins: Nut, seed, grain, legume, and vegetable proteins (can create complementary proteins by combining two or more incomplete proteins sources)
- Seeds and Nuts: walnuts, cashews, sunflower seeds, sesame seeds, pumpkin seeds, and various other nuts
- Grains: pasta, rice, oats, whole grain breads, barley, bulgur, buckwheat, rye, wheat, and cornmeal
- Legumes: peanuts, peas (dried), chickpeas, lentils, beans, and soy products (soybeans)
- Vegetables: broccoli and leafy greens
When two or more of these sources are combined, they should provide a sufficient amount of all essential amino acids.
Complementary Protein Examples
- Combine legumes with nuts/seeds- hummus (chickpeas & sesame paste), trail mix (peanuts & sunflower seeds)
- Combine grains and legumes- rice & beans, bean soup with a roll, peanut butter on whole wheat bread, tofu- vegetable stir-fry over rice or pasta
- Combine grains and nuts/seeds- whole wheat bun topped with sesame seeds, rice cakes with peanut butter, breadsticks covered with sesame seeds
Eating too much or too little protein can be problematic…
Excess Protein in Diet
- May cause stress on functions within your body
- May be dangerous for those with liver or kidney disease because they lack the ability to dispose of the waste products created by the metabolism of protein
- Body does NOT store excess protein
- May increase the risk of osteoporosis and kidney stones
Insufficient Protein in Diet
- Body will either let cells die or it will break down other tissues or muscles to get the protein that is required
- Will affect numerous bodily functions: Mobility & joint integrity, skin elasticity & muscle tone, enzymes and hormones, immune function & antibodies, turnover rate of cells in the heart, red blood cell production, bone cell synthesis, neurotransmitters & mood, sense of wellbeing/stamina, organ function & pH balance
References: CDC, RD 411- Protein Basics, http://www.bodyforlife2.com/incompletprotein.htm, Mayo Clinic, CNN, http://www.bodyhealth.com/html/biobuilde/key.asp. Nutrition Education for APRIL 2011. Produced by Meals on Wheels, Inc. of Tarrant County by Alexis Neal, a nutrition intern for Sherry Simon, R.D./L.D. For questions regarding nutritional information, please contact Sherry Simon, R.D./L.D., Director of Nutrition Services for Meals on Wheels, Inc. of Tarrant County at 817-336-0912 or email: email@example.com. Website: www.mealsonwheels.org.