The Body’s Building Blocks

 Explain the difference between essential and nonessential amino acids.  Discuss the functions of protein.  Identify animal and plant food sources of protein.  Calculate your daily protein needs.  Describe problems associated with protein deficiencies and excesses.

 Protein is an energy-yielding nutrient composed of carbon, hydrogen, oxygen and nitrogen.  The presents of nitrogen is what distinguishes it from carbohydrates and fats.

 Are the building blocks of protein molecules.  Most proteins are made up of different patterns and combinations of 20 amino acids, which are linked in strands.  The human body has at least 30,000 types of protein.  Each type performs a specific job.  The number and order of amino acids in which they are linked determine the protein type.

 Are combined in different sequences to form different proteins..  Can be arranged one after another in a straight line.  They can also be stacked up and branched to resemble a tree.

 Found in the nucleus of every cell.  Provides the instructions for how the amino acids will be linked to form the proteins in your body.

 The process in which protein molecules can change their shape and take on new characteristics.  Factors that can denature proteins include: ◦ Heat ◦ Acids ◦ Bases ◦ Alcohol

 Cook an egg – Heat applied to an egg will change the runny structure to a solid mass.  Marinate a roast – Soaking a roast in an acidic marinade make the meat more tender  Once proteins are denatured, they can never return to their original state.

 For good health all 20 amino acids are need in the body.  The body can only synthesize 11 of the amino acids from the other amino acids.  Synthesize means your body can use one or more compounds to make a new and different compound.

 Nonessential amino acids are the amino acids your body can make.  Essential amino acids are the 9 remaining amino acids that the body is unable to make and must be supplied by the foods in our diet.

 Build and Maintain Tissues  Make Important Compounds  Regulate Mineral and Fluid Balance  Maintain Acid-Base Balance  Carry Vital Substances  Provide Energy

 The two types of protein sources are: ◦ Animal ◦ Plant  Factors that influence which protein sources we select: ◦ Availability ◦ Cost ◦ Health concerns ◦ Food preferences ◦ Religious beliefs ◦ Environmental

 Beef  Veal  Pork  Lamb  Poultry  Fish  Eggs  Dairy Products

 USDA reports that U.S. citizens eat an average of 200 pounds of meat, poultry and seafood annually.  Meat is an excellent source of protein.  Important to remember that some meat products and some dairy products can be very high in fat.  The cost of protein from animal sources is high.

 Grains  Nuts  Seeds  Legumes ◦ Black-eyed peas ◦ Kidney beans ◦ Black beans ◦ Lentils ◦ Chickpeas ◦ Lima beans  Soybeans ◦ Tofu

 Mainstays of a vegetarian diet include: ◦ Fruits ◦ Vegetables ◦ Grains ◦ Nuts ◦ Seeds  Some vegetarians also eat: ◦ Dairy products ◦ Eggs

 Today many people choose to avoid eating foods from animal sources.  Interest in vegetarianism seems to be growing in popularity, especially in young people.

 Vegans: Eat no foods from animal sources. Their diet is limited to foods from plant sources.  Lacto-vegetarians: eat animal protein in the form of milk, cheese, and other diary products.  Lacto-ovo vegetarians: eat animal protein in the form of dairy products and eggs. Do not eat meats, fish or poultry.  Semivegetarians: Eat dairy products, eggs, poultry and seafood. Eat little or no red meat.

 Most fats in plants protein are polyunsaturated.  Plant foods contain no cholesterol and general high in fiber.

 Religious  Health  Socioeconomic  Environmental  Humanitarian

 Proteins in various foods sources differ in their quality.  The quality of protein is either: ◦ Complete ◦ Incomplete

 Means all the essential amino acids humans need are present in the proteins.  Sources include: ◦ Animal foods ◦ Eggs ◦ Milk ◦ Cheese ◦ Yogurt

 Proteins that are missing or short of one or more of the essential amino acids.  Proteins provided by plant sources.  Your body needs the right balance of all 20 amino acids.  If one or more of essential amino acids are missing, your cells will not be able to make needed protein.

 Two or more incomplete proteins that can be combined to provide all the essential amino acids.  A general guideline is to combine grains, nuts, or seeds with legumes. ◦ Peanut butter on whole wheat bread ◦ Corn tortilla with refried beans ◦ Hummus  Another way to extend the quality of incomplete protein foods is to combine it with complete proteins. ◦ Small amount of meat with a large amount of rice.

 Strict vegetarians must be very careful about using complementary proteins.  Diets that provide only one source of incomplete proteins are harmful to long-term good health.

 The body does not store protein, so it needs protein everyday.  The amount required is based on: ◦ Age ◦ Gender ◦ Body size ◦ State of Health  Most need less than what they consume a day.

 As children and teens grow, their bodies are building new tissue as well as maintaining existing tissues.  Have a higher proportional need for protein than adults who are no longer growing.

 Need extra protein to support the growth of their babies.  Women who are breast- feeding need extra protein as well.  The protein is required to produce milk.

 Vary between males and females  Men generally have a higher percentage of lean tissue than women.  Therefore, teens and adult males usually require more protein than females of similar age and body size.  The more lean tissue a person has, the more protein will be needed to maintain it.  Illness and injury increase the need of protein.

 52 grams per day for 14 to 18 year old males.  46 grams per day for 14 to 18 year old females. ◦ RDAs are designed for healthy individuals who eat adequate amounts of carbohydrates and fats and choose high quality sources of protein.

 Well-trained athletes do need a little more protein to build muscle and supply energy. ◦ But using protein supplements or large chucks of protein are not needed. ◦ An extra half a glass of milk or a small piece of chicken will be enough to provide the extra protein needed.  People who exercise occasionally do not need extra protein.  Most of an athletes calories should come from carbohydrates.

 Best ways to meet protein needs is to follow the recommendations of MyPyramid.  Meat and milk groups are the primary source.  Include two to three daily servings from the milk group per day.  And two to three daily servings are recommended for the meat, poultry, fish, dry beans, eggs and nuts group.

 Avoid the health risks of a diet high in saturated fats.  Choose low fat protein foods.  Trim visible fat from meats and remove skin from poultry.  Use low fat cooking methods.  Avoid adding high fat cooking oils, sauces and gravies to protein foods.

 A lack of protein and a surplus of protein can both cause health problems.  Nitrogen balance is a comparison of the nitrogen a person consumes with the nitrogen he or she excretes. ◦ Nitrogen equilibrium means a person excretes the same amount of nitrogen they take in. Most healthy adult are in nitrogen equilibrium. ◦ Positive balance is when a person is building new tissue takes in more protein than he or she excretes.

◦ Negative balance is a person whose body is wasting due to starvation. The tissues are deteriorating would be losing more nitrogen than being consumed.

 A sickness caused by a lack of essential nutrients.  Protein-energy malnutrition is a condition caused by a lack of calories in the diet.

 Most people in the US consume more than the RDA for protein.  On the average: ◦ Women eat almost one and one-half times the RDA for protein. ◦ Men eat nearly twice the RDA for protein.

 Liver and Kidney Problems ◦ Creates extra work on these organs causing them to age prematurely. ◦ Extra work on the kidneys cause special problems for diabetics.  Calcium Loss ◦ Studies have shown diets high in protein from animal sources may contribute to calcium loss in the bones.  Excess Body Fat ◦ Excessive amino acids convert to body fat.