L-1232
                                                                                                                       PROTEIN
                                                                                                                    Mary K. Sweeten*
                         The word "protein" comes from a Greek word                                       thatitprovides. Thebodycanmakesomeoftheamino
                    meaning"primary" or "tocome first." Early chemists                                    acids it needs, but other amino acids must come
                    gave protein this name because theyfelt that proteins                                 "ready-made"infoods. Theaminoacids thatthebody
                    were the most important of all substances in the or-                                  must have "ready-made" are called essential amino
                    ganic kingdom. All living things, both plant and ani-                                 acids. There are eight ofthese essential amino acids.
                    mal, contain protein. Today we know that protein is                                        A protein that provides all of the eight essential
                    one ofsix key nutrients necessary for good health in                                  aminoacidsiscalledacompleteprotein. Aproteinthat
                    humans. Proteins, minerals, vitamins, carbohydrates,                                  lacks one or more ofthe essential amino acids is called
                    fats and water make up these six key nutrients.                                       an incomplete protein. The body needs some ofboth
                    Function                                                                              kinds ofproteins. Some foods provide complete pro-
                                                                                                          tein while others provide incomplete protein.
                         Themainfunction ofproteininthebodyis tobuild                                          Most proteins that come from animal sources
                    and repair tis ues. The nutrient protein is needed by                                 (meat, poultry, fish, eggs, cheese and milk) are com-
                    everycellin thebody. As achildgrows, hismusclesare                                    plete proteins, while most plant proteins are incom-
                    builtfrom proteins. Adults also need protein to repair                                plete. Theplantproteins, whichareimportantsources
                    theirmuscles as well as othertissues. Proteins are also                               ofincomplete proteins, can be combined with animal
                    important in enzymes, which start chemical reactions                                  foods to provide all the essential amino acids.
                    so thebodycanusethefood you eat. Proteincanactas
                    a regulating substance. Finally, protein canbeusedto                                  Protein Requirement
                    provide energy. When carbohydrates, sugars and                                             Everyone needs some protein each day, but the
                    starches, andfats areavailable, however, the bodywill                                 amount needed daily depends on body size, rate of
                    usetheseforenergyandallowproteintobeusedforits                                        growth, and individual repair and maintenance re-
                    other functions.                                                                      quirements. The NationalResearch Councilhas setup
                    Protein Structure                                                                     recommendedamountsofproteinfor eachsexandage
                                                                                                          group. The accompanying chart lists the recom-
                         Proteinis oneofthe mostabundantcomponentsin                                      mendedamountofproteinfor each sex andage group
                    the body. Most ofthe body's protein is located in the                                 as well as recommended amounts for consumption
                    muscle tissue. Different kinds ofprotein occur in the                                 during pregnancy and lactation periods.
                    blood, soft tissues and teeth.                                                       Sources of Proteins
                         Forexample, proteinsaremadeupofsmallerparts
                    called amino acids. These acids act as building blocks.                                    Most foods contain some protein, but some are
                    Theyjointogethertomakeaprotein. Theremaybeas                                         better sources of protein than others. Animal foods,
                    manyas 280oras few as 2 amino acids that make up a                                   such as meat, fish, poultry, eggs, cheese and milk,
                    protein, butmostproteinsinfoods andin thebodyare                                     which have complete proteins, are the best food
                    made up of12 to 22 amino acids.                                                      sources ofproteins. Drypeas, beans, nuts andpeanut
                   Nutritive Value Of Proteins                                                           butter which contain almost-complete proteins are
                                                                                                         also good sources. Cereal and pasta products, impor-
                        Since proteins are made up of amino acids, the                                   tant sources ofincomplete proteins, can be combined
                   nutritivevalueofaproteindependsontheaminoacids                                         with animalfoods to give all the essential amino acids.
                                                                                                         Eatingavarietyoffoodsthatfurnish proteinsis impor-
                                                                                                         tant to good nutrition.
                   *Exten ion foods and nuhition specialist, TheTexas A&M Univer-                              Recently a number of textured soybean products
                     sity  ystem.                                                                         have appeared on the market. Sophisticated methods
                                                                                                  14.13
          Texas Agricultural Extension Service. The Texas A&M University System. Daniel C. Pfannstiel, Director. College Station
                         Recommended Daily Dietary                                       Include a protein-rich food at each meal. Milk
                                                                                     group foods and bread and cereal group foods eaten
                             Allowances for Protein                                  duringthe dayalso will add protein even though they
                                                                                     are not meat group foods.
                                                    Ages         Protein                 Studies indicate that consumers spend from 30 to
                  Class                           (Years)       (Grams)              40percentofthefood dollaron meatgroupfoods. By
                                                                                     usingless expensive cuts ofmeator substitutingmeat
                  Children                            1- 3           23              alternates like eggs, dry beans and peas, nuts and
                                                      4- 6           30              peanutbutter, theconsumercanassureadequatepro-
                                                      7-10           36              tein at a lower cost. Less expensive cuts ofmeat pro-
                                                                                     vide as much protein as higher cuts ofmeat, but they
                  Males                             11-14            44              are usually less tender. Combining high-quality ani-
                                                    15-18            54              mal proteins with incomplete vegetable protein or
                                                    19-22            52              textured vegetable protein products is anotherway to
                                                    23-50            56              insure good nutrition and still economize on the food
                                                     51+             56              bill.
                  Females                           11-14            44                  Usealowtemperatureandcookprotein-richfoods
                                                    15-18            48              longer. High temperatures toughen the protein and
                                                    19-22            46              result in an undesirable product. Use moist heat
                                                    23-50            46              method ofcooking such as stewing, braising or pres-
                                                     51+             46              sure cooking when cooking less tender, inexpensive
                  Pregnancy            Amountfor age +               30              cutsofmeatorfowl. Thisis themethodrecommended
                                                                                     for less tendermeatbecausemoistheathasa tenderiz-
                  Lactation            Amount for age +              20              ing effect.
                                                                                         Most protein-rich foods require refrigeration to
                                                                                     prevent spoilage. Nuts, dry beans and peas, peanut
                                                                                     butter and some cheeses can be stored safely at room
                of extraction, handling and fortifying soy products                  temperatures.
                help them comeclose to meatin the kind and amount                        Eat a well-balanced diet that promotes health to
                ofaminoacids present. Meatanalogs -           texturedveg-           insure protein and other nutrients in the correct
                etableproteinproducts- madetolook, cookandtaste                      amounts each day.
                like meat, have a low saturated fat contentand almost
                no cholesterol. If these products are fortified with
                vitamins and minerals they can be close to meat in                                           References
                nutritive value. Although textured vegetable protein                Recommended Daily Dietary Allowances. Washing-
                productsareversatile, abetteraminoacidbalancemay                         ton, D. C.: Foods and Nutrition Board,            ational
                beobtainedbyaddingaminoacidsfrom othersources,                           AcademyofSciences-             ational Research Coun-
                such as vegetable proteins, or meat or other animal                     cil, 1973.
                materials to texture vegetable protein products.
                Meal Planning                                                       Robinson, Corinne H., Proudfit-Robinson's Normal
                    In ure that you get all the protein you need each                   and Therapeutic Nutrition. Thirteenth Edition.
                day by following the Daily Food Guide for the four                      NewYork: The Macmillan Company, 1967.
                basic food groups.
                    The Daily Food Guide recommends that you eat                     "SoybeansinFamily Meals," USDABulletin H & GB
                two ervings ofmeatgroupfoods each day. A serving                         208.
                from the meat group is three ounces of lean cooked
                meat, fish or poultry. One-halfserving ofmeat group                  Wilson, Eva D.; Katherine H. Fisher; and Mary E.
                foods is 1 egg, % cup of dried peas or beans or 2                        Fugua. Principles of Nutrition. Second Edition.
                tablespoons ofpeanut butter.                                             NewYork: John Wiley and Sons, Inc., 1967.
                Educational proarams conductedby the Texas AgriculturalExtension Service serve people ofall ages regardless ofsocio-economic levels, race,
                color, sex, religion or national origin.
                Cooperative Exten ion Work in  griculture and Home Economics, TheTexas A&M University System and the United State Departmentof
                 gJiculture coop rating. Distributed in furtherance of the Acts ofCongress of May 8, 1914, as amended, and June 30, 1914.
                30M -  3-76, Revis d                                                                                                          F&