NUT 10 - Week 2 - Prof Fetter PDF

Preview

Summary

Prof Fetter...

Description

04/09/19 How Your Body Processes Protein Learning Objectives 1. Understand how the body uses protein and amino acids to build and refresh the body’s own proteins. 2. Describe the significance of protein turnover and its implications for protein inadequacy in the diet. 3. Understand how the body deals with excess protein/amino acids. 4. Explain stages of growth and the consequence of protein deficiency during these stages, including resulting symptoms. 5. Explain why protein is needed as an essential nutrient and how protein requirement is established. 6. Determine the protein requirement for an individual using the RDA for protein and identify factors that impact the RDA for protein. Body Cells and Protein ● Mitochondria ○ site where energy nutrients are metabolized for energy use ● Nucleus ○ contains DNA ■ set of cell instructions that determine specific proteins made in cell ● Endoplasmic Reticulum ○ site where proteins are built from amino acids ○ located right outside nucleus Protein as an Essential Nutrient ● Dietary Protein ○ EAA (essential) & NEAA (nonessential) breaks down into amino acids ○ Amino Acid: basic unit of protein ○ amino acids are used to replenish body muscles, cells, or the liver ● Protein Synthesis ○ Protein Turnover ■ our body is constantly using pool of amino acids to build up proteins ■ our body is also breaking ourselves down when proteins expire ■ aka “recycling” amino acids ■ process of protein turnover is not 100% efficient; amino acids “leak” out ○ Fast Turnover ■ immune system - white blood cells ■ helps us when we get sick ■ occurs in a few days ○ Medium Turnover ■ muscle, skin, red blood cells

●

■ occurs in weeks ○ Slow Turnover ■ brain, central nervous system ■ we want to keep our HQ in tip top shape; breaking down proteins in the brain and CNS will hella mess with us ■ rarely turns over Deadend Protein ○ do not turn over at all ○ ex. hair, nails, skin cells, stool ○ loss of protein (N and EAA) must be replaced

Protein Deficiency ● most of us tend to get more than enough protein in the U.S. ● not consuming enough protein in general or incomplete proteins ● Growth Stages ○ Critical Period ■ gestation to toddler ■ during gestation to the first 2 years of life, brain development is crucial ■ cell growth by increased cell numbers ■ protein deficiency can most affect the brain during this stage because the brain itself is developing and rapidly growing ● mental retardation, stunting of growth ○ Later Development ■ childhood ■ brain is at 95% adult weight by age 6 ■ cell growth by cell size increases ■ protein deficiency can stunt growth; some damage can be reversed ● edema (fluid balance disrupted) ● body is not able to properly regulate water flowing in/out of cells ● intestinal problems (slower protein turnover in intestinal tract) ● distended abdomen (fatty liver) ○ fluid accumulation in peritoneal cavity ○ fat requires a special carrier to transport it; requires protein ● infections (unable to ward off pathogens as well) ○ high turnover proteins affected most dramatically ● Protein Deficiency Conditions ○ Protein-Calorie Malnutrition ■ occurs because not enough calories are consumed in general ○ Kwashiorkor ■ second child causes first child to not thrive as readily ■ first-born children in underdeveloped countries after they are weaned from their mother’s breast milk and given a plant-based diet with incomplete proteins; infant retains fluid

○

Protein Deficiency ■ amount of protein going in is being used for energy; not enough protein to replenish body tissues that the person needs ■ inadequate energy intake

How Much Protein Do You Need? ● Why do you need protein? ○ 9 essential amino acids ○ Nitrogen source ● RDA for Protein ○ how to calculate protein RDA ■ calculate a minimum ● use an “average” person ● determine minimum protein requirement ● measure nitrogen loss/day ● convert to protein replacement need ● 16% of all protein’s weight is nitrogen ● minimum protein requirement must be eaten as “perfect protein” ○ egg whites or breast milk ■ adjust for population variability ■ adjust for protein quality ● not just eating perfect proteins ● egg whites are 100% (aka perfect) ● 70% is the typical protein in your diet ● no difference between adult males and females ○ MEMORIZE THIS NUMBER: 0.8g protein/kg body weight/day = RDA 04/11/19 More Protein! Factors That Change Protein Needs ● Growth ○ when someone is going through rapid stages of growth, they need more protein ○ creating all new cells requires a lot of building materials from our food (nutrients) ○ RDA for adults: 0.8g protein/kg body weight; children’s RDA is almost doubled ● Pregnancy & Lactation ○ require an additional 25g/day above individual’s RDA ● Injury & Illness ○ severe burns have a much higher need for protein; burn increases rate of oxidizing calories ● Athletes ○ there is research to support that athletes have a greater need for protein ○ no specific RDA for athletes ○ exercise can increase RDA up to 50% above standard RDA

○

we need protein for muscle repair after exercise (best if within 1 hr)

Daily Values ● amount listed on the food label (one size fits all 2,000 calorie diet) ● 12% of daily fat, 14% dietary fiber, 20% added sugars ● Americans consume more than enough protein, so FDA decided that protein does not need the same daily value percentage on labels (makes it vague so people don’t overcompensate) ● daily value of protein is 50 grams ● How to Calculate % Daily Value for Protein ○ 3g of protein per serving / 50g (total daily value) x 100 = 6% ● “Good” Protein source is above 20% of daily amount of protein Making Protein Choices ● food proteins differ in their essential amino acid compositions ○ incomplete vs. complete protein ● Complete Protein ○ contains all 9 EAA (essential amino acids) ○ easy to digest ○ almost all animal sources; soy is the plant outlier ○ Soy ■ plant-based, complete protein ○ Beef and other meats ■ beef, egg, poultry, dairy, fish ○ Crickets and Mealworms ■ sustainably produced; contains all 9 EAA ● Incomplete Protein ○ low in one or more of the 9 EAA in amounts proportional to need ○ Beans ■ kidney, garbanzo, legumes ○ Nuts and Seeds ■ almonds, sunflower seeds ○ Grains ■ rice, flour, bread, pasta Protein Quality ● the way to measure protein quality is based on the essential amino acid content ● Protein Efficiency Ratio (PER) (indirect measure) ○ feed test protein diet to lab rats ○ measure how much weight is gained relative to protein eaten (determined from amount of food consumed) ○ PER = weight gained / protein eaten ○ High PER Proteins

●

●

●

■ fish, milk, beef (in the middle) ○ Low PER Proteins ■ wheat, corn Chemical Score (direct measure) ○ compare food protein EAA levels relative to egg white protein EAA levels ○ divide amounts of amino acids found in egg white by white flour protein ■ Lysine: egg white 7.0 --- white flour protein 2.1 → 2.1 / 7.0 x 100 = 30% ○ quality of a protein is only as good as the lowest amino acid amount Limiting Amino Acid (LAA) ○ the EAA in a food protein that is the lowest amount relative to need ■ all incomplete proteins have an LAA ○ food example: white flour protein ■ limiting amino acid is Lysine Compare Nitrogen and EAA Needs ○ how much of a protein requirement must be as EAA? ■ Adult: 0.09g EAA/kg (11% of protein need) ■ Infant: 0.7g EAA/kg (40% of protein need)

Vegetarian Diet ● Complementary Proteins ○ incomplete proteins have low amounts of one or more amino acids ○ by pairing different incomplete proteins, you can get all the EAA you need ○ rice is low in one EAA, but high in another; beans are high in the EAA that rice is low in, but low in the EAA that rice is high in. if you eat rice and beans, a-ok! ● research has shown that people who consume a higher amount of protein from vegetables (vs. animal products) also decrease risk of chronic disease risk (cardiovascular disease, cancer, type II diabetes) ● Vegetable Protein Sources ○ grain + legume → complete protein ○ 1 ¼ cup of rice and cup of beans makes up a complete protein meal!...