Proteins Patty Maloney MSN/Ed 1 Chapter 6

Proteins Proteins-organic compounds formed by linking many smaller molecules of amino acids. Amino acids-organic compounds made of carbon, hydrogen, and oxygen. Protein in food is our only source of amino acids, which are necessary for every aspect of human life. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.2

Amino Acids: Building Blocks Each protein is composed of hundreds of amino acids When protein foods are eaten, proteins are broken down into amino acids Amino acids are reassembled in the body to form a variety of proteins 3

Functions of Proteins Growth & Maintenance ; replacement of cells. Creation of Communicators and Catalysts; hormones, blood clotting. Immune System Response; defense system. Fluid & Electrolyte Regulation Acid-Base Balance. Transportation of Nutrients Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.4

The protein in foods are categorized by the essential amino acids they contain. Complete protein-contains all nine essential amino acids to support growth and maintenance. Sources-animal-derived foods, including meat, poultry, fish, eggs, and dairy products. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.5 Protein Foods

Protein Incomplete Proteins-lack one or more of the nine essential amino acids. Does not supply sufficient amount of amino acids to support life. Plant foods are incomplete sources, grains and legumes are better sources. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.6

Classes of Amino Acids Essential amino acids – 9 (lycine) Body cannot manufacture, must come from diet Conditionally essential amino acids – 5 (cysteine) Body can synthesize from indispensable, do not have to come from diet (may be lacking in disease process). Nonessential amino acids – 6 (alanine) Normally synthesized but some health conditions may require dietary intake (Table 5-2). 7

A Healthy Balance Protein balance Catabolism: breakdown of proteins Anabolism: resynthesis of proteins Nitrogen balance (intake = excretion) Nitrogen equilibrium (ideal) Positive nitrogen balance: body stores more protein than it excretes (ie, growth, preg, lact) Negative nitrogen balance: body takes in less protein than it excretes (ie, malnutrition, illness) 8

Food Source of Proteins 9

Food Sources of Protein Complete proteins – contain all 9 essential amino acids Meat, fish, eggs, seafood (animal) Soy (plant) Incomplete proteins (lack one or more essential amino acids). Plant-origin foods Grains Legumes (peas, beans, peanuts, lentils) Nuts Seeds Fruits and vegetables 10

Vegetarian Diets Approx. 3-5% of population Reasons = religious beliefs (buddhism, hinduism, 7 th day Adventist), animal cruelty concerns, environmental concerns, aversion to animal products 11

Vegetarian Categories Vegan -includes all plant foods, grains, legumes, fruits, vegetables, seeds and nuts. Excludes all animal-derived foods. Lacto-vegetarian -includes all plant foods plus dairy products, (milk, cheese, yogurt, and butter). Excludes animal meat, (meat, fowl, fish, and eggs). Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.12

Vegetarian Diets Ovo-lacto vegetarian- includes all plant foods, dairy products, and eggs. Excludes animal meat. Pescetarian- includes all plant foods, dairy products, eggs and fish. Excludes meat and fowl. Flexitarian- includes all plant foods, dairy, and eggs, with occasional consumption of meat, fowl, or fish. No exclusions, but minimal consumption of animal meat. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.13

Digestion of Proteins Mouth – mechanical digestion, chewing Stomach: enzymes to breakdown protein into amino acids Pepsin ** Hydrochloric acid Small intestine Pancreatic secretions aid digestion Trypsin, chymotrypsin, carboxypeptidase Intestinal secretions Aminopeptidase, dipeptidase 14

Summary of Protein Digestion 15

Body Needs for Protein Tissue growth * more protein needed during growth periods * fetus, infant, children, adolescents Additional needs caused by illness * More protein needed during illness (fever, traumatic injury, burns, surgery) 16

Dietary Deficiency Kwashiorkor Protein energy malnutrition Occurs after child is weaned from breast feeding Not enough protein to support growth Clinically the child looks chubby, especially in abdomen (fluid retention) Endemic in areas where diet lacks protein Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.17

Kwashiorkor Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.18

Marasmus Protein Energy Malnutrition Too few calories and insufficient protein Person appears to be wasting away Commonly seen in developing countries Seen in debilitating diseases such as cancer or AIDS Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.19

Marasmus Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.20

Dietary Guides Recommended Dietary Allowances (RDAs) Relate to age, sex, weight Highest at birth and slowly decline into adulthood Men and women: 0.8 g/kg of desirable weight 21

Dietary Guides First, convert lb. to kg. 200 lb divided by kg (round to 91 kg) Convert your body weight (lb.) to kg 22

Calculating Protein Needs Calculation: Recommended protein intake = 0.8 g/kg 1 kg = 2.2 lb. Calculate: 220 lb. man 220 divided by 2.2 = 100 kg 100 kg multiplied by 0.8 g = 80 g protein 23

Calculating Protein Needs Calculation: Your body weight = _______ lb. ______ lb. divided by 2.2 = ______ kg ______ kg. multiplied by 0.8 = _______ ** this equals # protein grams per day recommended for you 24

Dietary Guides, cont’d Dietary Reference Intakes (DRIs) from National Academy of Sciences 10% to 35% of total caloric intake from protein (children and adults) 25

Summary Protein provides the body with its primary tissue-building units, amino acids 20 common amino acids Nine of the 20 amino acids are essential in the diet Body can manufacture the remaining 11 amino acids Complete proteins are foods that supply all the indispensable amino acids 26

Summary, cont’d Complete proteins are usually of animal origin Plant foods are considered incomplete proteins because they lack one or more of the indispensable amino acids (with the exception of soy) Vegetarian diets can be strict with only plant proteins (vegan), whereas other variations include dairy, egg, and sometimes fish 27

Summary, cont’d Clinical influences on protein include fever, disease, surgery, or other trauma to the body Protein needs are calculated based on RDA standards related to age, sex, and weight, which for both men and women is set at 0.8 g of high quality protein per kilogram of body weight per day 28

Summary, cont’d Adjustments for protein intake are required for infants and pregnant and breastfeeding women Adjustments also may be necessary for individuals following a vegan diet Adjustments are made for critical illness 29