Lect10+Protein2 - Protein •  What are Proteins • ...

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Unformatted text preview: Protein •  What are Proteins? •  Functions of Protein •  Digestion of Protein •  How much do we need? •  What are the consequences of too much or too little? Digestion Stomach: Gastrin: HCL, pepsin Small Intestine: Pancreatic trypsin, chymotrypsin Brush border peptidases transporters for individual amino a cids immune system becomes weak without p rotein absorption of nutrients will become d ifficult for cancer patient--variety of GI p roblems put into acid: causes shape to change mucus and hormones protects stomach from acid How much protein do we need? It depends on: 1.  Quality of the protein: a. Complete/Incomplete b. Digestibility Protein Complementation 2. State of the person Other Examples? amino acid proportions 1 ! Protein Digestibility State of the Person •  Nitrogen Balance: Nin = Nout •  Positive N balance: Nin > Nout •  Negative N balance: Nin < Nout u ndigested proteins: feces digestibility and amino acid sequence nitrogen in=amino acids eating nitrogen out=urine nitrogen (i.e. malnourished, sick, people who have burns, ) RDA for adults is 0.8 g protein /kg body wt/day •  If you weigh 154 lb (70 kg) •  You need 56 g protein per DAY •  Examples: –  3 oz Canned tuna –  8 oz Yogurt –  1 large bagel –  1 Egg 22 g 15 g 11 g 6g does not take into digestibility 2 ! Protein Requirements •  Endurance & strength training athletes need: 1.2 - 1.8 g/kg body wt/day –  Why? Protein Deficiency •  Occurs: starvation –  Very-low energy diets –  Severe illness, infection or burns –  Blood loss •  Vegetarians need slightly higher levels –  Why? •  Results in: stunting of children –  Loss of immune function –  Dysfunction of rapidly turning over tissues missing fiber and vitamins high saturated fats come with animal p rotein coconut and palm oil have saturated fat when in excess, protein turn into fat o r carbon compounds need water to flush ammonia out of system Protein-energy Malnutrition •  Kwashiorkor/Marasmus •  Low protein density diet •  Energy needs are marginally met •  Characteristics: –  apathy, listlessness –  failure to grow, poor weight gain –  change in hair color, flaky skin –  fatty infiltration in the liver –  massive edema in the abdomen and legs High Protein Intake Concerns: 1.  Diet may be low in plant foods 2.  Diets high in animal protein 3. Dehydration –  excrete excess N in urine as urea, –  need extra water for urine –  concern for athletes 3 ! Individual Amino Acid (AA) Supplements •  Imbalances and toxicity (esp. with methionine and tyrosine) Words to know: Amino acid Limiting amino acid Transcription/ Translation Protein shape Fluid balance Urea Protein quality Digestibility Nitrogen balance Protein/energy malnutrition Kwashiorkor Marasmus •  Overwhelm the absorptive mechanism: excess of one AA can hamper absorption of other AA (arginine competes lysine) •  Digestion more efficient with whole proteins e gg white can better proteins we absorb more amino acids when we digest it 4 ! ...
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