Proteins are literally the building blocks of our bodies. They are in every body cell and form most body structures such as skin, nails, hair, membranes, muscles, teeth, bones and organs.
Protein is necessary for growth and tissue repair and for the immune system. All enzymes and most hormones contain protein. Protein regulates fluid and acid/base balance. It also transports nutrients in and out of cells.
Protein may also be used for glucose and energy if there is not enough carbohydrate and fat in the diet. Carbohydrate and then fat are the preferred sources of energy.
There are only 20 amino acids put together in different configurations to make up the thousands of kinds of proteins we need. Eleven of these amino acids can be manufactured by a healthy body. Nine must come from the foods we eat.
Great protein from food comes from both animal and plant sources. Animal sources like dairy products, fish, poultry, eggs and red meats contain all the amino acids that the body needs to make new proteins. These are called complete proteins. Plant sources lack one or more amino acids and are incomplete proteins. That means plant sources of protein like legumes, grains, nuts and seeds must be combined to make a complete protein.
In general, legumes (beans, peas and lentils) combined with grains, nuts and seeds make a complete protein. Examples: peanut butter and whole wheat bread, beans and brown rice, black-eyed peas and stone ground cornbread, hummus and whole wheat pita bread, chili and sesame seed crackers, bean burrito. Any plant protein can be made complete with the addition of a small amount of complete protein like milk, milk powder, cheese, eggs and, of course, fish, poultry or red meat. That means animal sources of protein can be the “garnish” of a recipe and not the main ingredient. Just a small amount of protein in any meal or snack helps give a feeling of fullness and satiety.
Soy and soy products like tofu, soy milk, soy flour, tempeh, miso, textured soy protein and meat alternatives have the amino acid quality of a complete protein. Availability of soy products is expanding in the United States. Although there are health questions about using soy exclusively as a protein source, soy in moderation is a healthy choice since it also has a wealth of other vitamins, minerals and phytochemicals. In 1999 the Food and Drug Administration approved food label claims for soy protein related to heart health. These claims state that 25 grams of soy protein daily included in a low saturated fat diet may help lower heart disease risk. Also, the American Academy of Pediatrics continues to recommend the use of soy protein-based infant formula for infants that cannot breast feed or take milk-based formula.
The health effects of isoflavones in soy are another issue however. There are mixed opinions in the scientific community related to isoflavones and reduction of risk from breast and prostate cancer, osteoporosis and menopause symptoms. While some studies have shown that isoflavones give protection against breast and prostate cancer, osteoporosis and relieving hot flashes in menopause, other studies are not conclusive.
Until the long-term safety of consuming large amounts of isoflavones is documented, consuming soy products with more than 100 milligrams of isoflavones is unwise. This would mean that about two servings of soy products like tofu or soy milk per day would give enough soy protein to be beneficial (25 g) but not too many milligrams of isoflavones to be harmful. Products like textured soy protein and meat alternatives (soy “meat” crumbles, imitation hamburgers, hotdogs, sausage, chicken patties and nuggets, bacon and cold cuts) have about the same amount of soy protein but less isoflavones. Reading food labels of soy foods is a must because products vary in amounts of protein and isoflavones.
Animal sources of protein offer a variety of choices for your health, budget and taste. Eggs and lowfat milk products are excellent and inexpensive sources of complete protein. Nonfat dry milk is an inexpensive way to add extra protein to many dishes like soups, puddings, casseroles, baked products and even milk. Just add 1/3 to 1/2 cup nonfat dry milk. Saturated fat and cholesterol in egg yolks can be eliminated in recipes by using two whites for one whole egg (or use egg substitutes). Of course without the color, thickening and emulsifying functions of the yolk, other ingredients in the recipes would have to be adjusted. The yolks, for those who eat them, are packed with high quality protein, iron, B vitamins and vitamins A, D, E and K. Egg yolks also contain the phytochemicals lutein and zeaxanthin.
Poultry and fish contain less saturated fat and cholesterol than red meats. Fish (especially fatty) and shellfish also contain large amounts of omega 3 fatty acids that help prevent heart disease. In addition to complete protein, lean red meats are rich in iron and zinc. All animal proteins contain B vitamins. In fact, vitamin B-12 comes only from animal sources. Lean red meats in moderation are a part of healthy eating. If you have elevated cholesterol or triglycerides be sure to check with your doctor or registered dietitian about dietary recommendations.
In general, the dietary reference intake (DRI) for protein is 46 grams for women and 56 grams for men daily. Most Americans get at least 70 grams or more per day. Excessive amounts of protein have been linked to heart disease, gout, kidney disease, certain cancers and calcium loss. More than twice the DRI for protein should not be consumed on a regular basis. For building muscle in strength training, eating a serving of protein along with carbohydrate 30–45 minutes after a workout can help build and repair muscle. The carbohydrate spares the protein from being burned as energy. Suggestions would be a tuna or turkey sandwich, lowfat yogurt, fruit and cottage cheese, egg on toast, cereal and milk, apple with cheese or peanut butter.
As far as serving sizes goes, two to three ounces equals one serving of lean meat, poultry or fish and is about the size of a deck of cards.
For additional resources on this topic, visit the resources section of www.thealabamabaptist.org.
Editor’s Note — Pat Hart Terry, Ph.D., is chairman of the department of nutrition and dietetics at Samford University in Birmingham and a registered dietitian.
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