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What are proteins?Protein: Greek word proteios of prime importanceVersatile and vital cellular working molecules- no life without proteinsNutrition & Proteins: Very crucial roleThe Proteins and Amino AcidsThe Structure of ProteinsContain Carbon, hydrogen, oxygen & nitrogen to arranged as strands of amino acids.Protein builds, maintains, and replaces the tissues in our body. Muscles, organs, and immune system made up mostly of protein Amino acids: Building block of proteinCarbon atom with amine group and acid groupSide chain20 amino acids with its ownDifferent side chain makes different proteins

How Do Amino Acids Build Proteins?Long necklace with different beads: Each amino acid (AA) is hooked to another AA through Peptide bond amine group of one AA & acid group of next AA. Side chain gives protein unique structure. Essential or indispensable amino acids: What are they? Ten of them:??Recycling of amino acids: Protein rich food. Protein from animals: Milk & meat: CompleteProtein from plants: Incomplete

Essential Amino Acids Mnemonic Phenylanine, Valine, Threonine, Tryptophan, Isolucine, Methionine, Histidine, Arginine, Leucine, Lysine. (P V T T I M H A L L). Pvt. Tim Hall. Pvt. Tim Hall to recall all 10 acids.

The Coiling and Folding of a Protein Molecule

The Variety of Proteins Collagen: Protein present in connective tissueEnzymes: Responsible for chemical changesHemoglobin: In RBC: Oxygen carrierHormones: Insulin20 AAs group together to form various proteins.Amino acid sequence is hereditaryAlterations to sequenceSickle-cell disease : 6th amino acid is valine Not glutamic acidNutrients and gene expression ??Normal Red Blood Cells and Sickle Cells

Protein DigestionStomachDenatures protein in foodUncoil proteins strandsEnzymes attack peptide bondsSmall intestinePolypeptidesFurther break down: dipeptide & tripeptideAmino acids & energy Common misconceptions :Enzyme consumptionDenaturation of ProteinsDenaturing agents: heat, radiation, alcohol, acids & bases, saltsDangers of denaturation: destroys body protein

The Importance of ProteinAmino acids must be continually availableBuilding of new proteinsAmino acids are needed each dayProtein turnover: breakdown, recovery and synthesis everyday in the bodyRoles of Body ProteinsRegulation of gene expressionProviding structure and movementMuscle tissueOther structural proteinsBuilding enzymes, hormones, & other compoundsBuilding antibodiesEnzyme Action

Roles of Body ProteinsTransporting substancesHemoglobin and lipoproteinsMaintaining fluid and electrolyte balanceEdemaMaintaining acid-base balanceBlood clottingProviding energy and glucoseProteins Transport Substances Into and Out of Cells

Three Different Energy Sources

Amino Acids to GlucoseNo storage compound for protein: Glucose-glycogen, fat- triglyceridesOversupply of amino acidsRemove amine group& excreteUse rest of residues to store fatty acids and glycogenProtein and Amino Acid SupplementsProtein supplementsDo not improve performanceNot effective for weight lossAmino acid supplementsBody designed to work with whole proteinsNo safe level of amino acid supplementationPeople Most Likely to Be Harmed by Amino Acid Supplements

How Much Protein Do People Really Need?DRIDepends on body sizeInfants and growing childrenRecommended intakeVegetarians 10-30% of calories from proteinBodys healthQuality Nitrogen BalanceNitrogen excreted as compared to nitrogen eatenLevels in healthy adultsVariation in nitrogen balance - Nitrogen equilibrium: healthy college student, young retireePositive balance: input greaterExample: Growing child, pregnant woman, athletes, body buildersNegative balance: output greaterExample: patients, astronaut Nitrogen Balance

Which Foods Provide High Quality Protein?High-quality proteinsEnough of all essential amino acidsLimiting amino acids supply: Body manufactures , how long?Complementary proteinsProtein digestibilityAnimal proteins: easy absorption >90%Legumes: 80-90%

Complementary Protein Combinations

Protein Deficiency and ExcessWorlds leading form of malnutritionCombined with energy deficienciesProtein-energy malnutrition (PEM)Locations of prevalence :Africa, E & SE Aisa, central & south America, Middle EastEffects of PEMChildren and adults:33,000 children/dayTwo formsProtein Deficiency and ExcessMarasmusCommon in childrenMuscle wastingImpairments Disease conditionsPreventing death not possibleHeart failure

Protein Deficiency and ExcessKwashiorkorWeaning of babiesFluid balance is diminishedChanges in body : fluid leak, edema, swelling of bellyRisk of infectionPEM at home, USA:14 million children

Protein Deficiency and ExcessOverconsumption of protein-rich foodsPossible health risksU.S. protein intakes: Sometimes too muchHeart disease: vitamin B deficiencyKidney disease: increase in kidney workloadAdult bone loss: calcium deficiency /osteoporosisCancer: moderate risk of colon & rectum cancer Getting Enough but Not Too Much ProteinProtein-rich foodsProtein is critical to nutritionDisplacement of other necessary foodsAdvantages of legumesProteinVitamin and mineral sourceSoybeans Top Contributors of Protein to the U.S. Diet

A Legume

Vegetarian DietsReasons to choose a vegetarian lifestyleCategorization of vegetariansBy foods they choose to eatReasons why meat eaters choose to eat meatVegetarian and Meat-Containing Diets: What Are the Benefits and Pitfalls?Terms Used to Describe Vegetarians and Their Diets

Positive Health Aspects of Vegetarian DietsOther health behaviors associated with being vegetarianObesity Heart diseaseBlood lipids HypertensionCancer Other health benefits

Positive Health Aspects of the Meat Eaters DietCritical times in lifeExamplesPregnancy and infancyChildhoodAdolescenceAging

Planning a Vegetarian DietVegetarian food guidesEnsure adequate intakes ProteinIronZincCalciumVitamin B12Vitamin DOmega-3 fatty acidsMy Vegetarian Food Pyramid

Nutrients in Nonfat Milk and Light Soy Milk