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Proteins and Amino Acids in Nutrition

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Title: Proteins and Amino Acids in Nutrition


1
Proteins and Amino Acids in Nutrition
  • Dr. David L. Gee
  • FCSN 245
  • Basic Nutrition

2
  • Biologically
  • proteins are the most important molecues in the
    body
  • action molecues
  • Nutritionally (at least in the US)
  • proteins are of the least concern for
    macronutrients in the diet
  • protein deficiency very unusual
  • excess protein generally not a problem

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4
Protein Structure
  • Polymer of amino acids
  • Amino acid structure
  • amino group (N)
  • acid group
  • side chain

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Amino Acids
  • 20 different amino acids
  • Differ by type of side chain
  • Water soluble AA
  • charged side groups
  • Can form ionic bonds
  • sulfer containing side groups
  • Can form disulfide bonds
  • Fat soluble AA
  • Fat soluble AA interact/dissolve with each other
  • These interaction/bonds between AA side chains
    cause proteins to form specific shapes

9
Protein Structure
  • Primary Structure
  • sequence of amino acids
  • Secondary Structure
  • helical coil

10
Protein Structure
  • Tertiary Structure
  • folding of coil
  • 3-dimensional structure
  • Determined by AA sequence
  • Specificity of a proteins function
  • Diversity of protein functions

11
Other Amino Acid Facts
  • 9 Essential amino acids
  • Amino acids that cannot be made and must be
    consumed in the diet (dietary essential)
  • peptide bonds link amino acids together
  • proteins typically contain a few hundred amino
    acids
  • infinite combinations of amino acids
  • tremendous diversity of protein types

12
Protein Synthesishow proteins are made
  • DNA, genes, chromosomes
  • where the information is stored
  • Transcription
  • making a copy of the information
  • messenger RNA
  • Translation
  • reading the information and making the protein

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15
Genetic Disorderserrors in the stored
information
  • Examples
  • Sickle Cell Anemia
  • Cystic Fibrosis
  • Familial Hypercholesterolemia
  • LDL-receptor
  • Human Genome Project
  • Map the genome
  • 20-25,000 genes in human genome (10/04)
  • Fix the genes ???

16
Have you eaten GM foods?Are GM foods safe?
  • 2003 survey of US consumers
  • Non-partisan Pew Initiative on Food and
    Biotechnology
  • 48 opposed to GM foods, 25 in favor
  • 2001 58 opposed to GM foods
  • 24 say theyve eaten GM foods
  • 58 say they havent

17
Genetic Modified Crops Prevalence
  • In 2003 (USDA) genetically modified crops
    accounted for
  • 40 of all corn
  • 81 of soybeans
  • 73 of cotton
  • In 2002
  • 35 of corn
  • 55 of soybeans
  • Grocery Manufactures of America (2003)
  • 70-80 of processed foods contain GMO
  • USDA approval for
  • potatoes, tomatoes, melons, beets
  • nicotine free tobacco

18
Genetic EngineeringFood and Health Issues
  • Traditional animal and plant breeding
  • Alteration of genetic material with tools of
    biotechnology
  • Advantages
  • speed
  • more specific, less random
  • interspecies gene transfer

19
Benefits of Genetically Engineered Foods
  • Reduce use of pesticides
  • Bacillus thuringiensis (Bt)
  • natural pesticide used by organic farmers
  • Bt produces a protein toxic to insect larvae
  • Gene for Bt toxin incorporated into corn, etc.
  • Corn plant produces Bt protein toxin

20
Benefits of Genetically Engineered Foods
  • Reduce erosion of topsoil due to tilling
  • tilling for weed control
  • Monsantos Roundup (glyphosate)
  • inhibits plants ability to make tryptophan
  • tryptophan is an EAA for humans
  • Roundup resistant plants (soybeans)
  • spliced bacterial gene into plant that is
    resistant to effect of Roundup (still able to
    make tryptophan)

21
Benefits of Genetically Engineered Foods
  • Improved nutritional quality of plants
  • golden rice
  • rice with B-carotene gene
  • improved protein quality quantity
  • higher in vitamins
  • Improved sensory properties
  • Tomato and strawberry flavor texture

22
Genetically Engineered FoodsEnvironmental
Concerns
  • Pesticide resistant insects
  • Unintentional environmental effects
  • monarch butterfly larvae - lab study
  • affect beneficial insects (ladybugs)
  • development of superweeds, superbugs
  • Control of Food Production
  • Terminator gene
  • GMO plants with gene to produce sterile seeds
  • Biotech firms with too much control?

23
Genetically Engineered FoodsHealth
Issues(Theoretical problems?)
  • Lack of long term feeding trials
  • animal studies, human studies
  • Food allergies
  • antifreeze protein from fish
  • Labeling Issue
  • Pros consumer has the right to know
  • Cons unnecessary, no evidence of
    environmental/health concerns, will hurt sales
    and stymie further development

24
Protein Functions
  • Enzymes related proteins
  • Catalysts
  • Membrane transporters
  • Cell receptors

25
Transport Proteinssodium pumps
26
Protein Functions
  • Structural Proteins
  • Muscle fiber proteins
  • Connective proteins

27
Protein Functions
  • Hormones
  • Protein Hormones
  • Insulin
  • Glucagon
  • Amino Acid Derived Hormones
  • serotonin
  • adrenaline

28
Protein Functions
  • Antibodies Immune System
  • impaired immune system with protein deficiency
  • Fluid Balance
  • albumin
  • edema

29
Protein Functions
  • Acid-Base Balance
  • buffer
  • acidosis alkalosis
  • Energy Glucose
  • Unlike fats, amino acids can be converted into
    glucose (required for CNS/brain function)
  • starvation
  • low carbohydrate diets
  • body cannibalizes body proteins to make glucose

30
Protein and Nutrition
  • Daily protein needs
  • Quantity of protein
  • Quality of protein
  • Protein Quality
  • How well a protein meets the bodys need for
    health, growth, etc
  • Digestibility
  • Amino acid composition
  • Essential Amino Acids composition

31
Protein Quality
  • Measures of protein quality
  • Biological Value (BV)
  • Measures body retention of food protein
  • BV100 gt 100 of food protein retained
  • Protein Efficiency Ratio (PER)
  • Measures ability of protein to support growth
  • g growth/g protein fed
  • PER3 gt 3g growth per g or protein fed

32
Protein Quality BV
33
Protein Quality PER
34
Protein Quality
  • Vegetarian Diets
  • Is there a protein problem?
  • Plant proteins are Incomplete proteins
  • Complementary Proteins
  • Example Mexican Food
  • Tortilla low lysine, hi methionine
  • Beans low in methionine, hi lysine

35
Tortillas Rice with Refried Beans
36
Hummus (garbanzo beans) and Pita Bread (wheat)
37
Peanut butter (legume) sandwich (wheat)
38
Vegetarian DietsWhy become a vegetarian?
  • Health benefits
  • Environmental concerns about meat based diets
  • Animal welfare/ethical considerations
  • Economic reasons
  • World hunger issues
  • Religious beliefs

39
Vegetarian DietsPotential Health Benefits
  • Obesity
  • of obesity lower in vegetarian populations
  • Cardiovascular Disease
  • Risk of CHD 31 lower in vegetarian men and 20
    lower in vegetarian women
  • Lower LDL-C, lower HDL-C
  • Hypertension
  • 42 non-veg with hpt, 13 vegetarians
  • Also lower prevalence for
  • Diabetes
  • Cancer

40
Vegetarian DietsConsumer Trends - 2000
  • 2.5 of adult Americans are vegetarians
  • 4.8 million people
  • Slightly less than 1 are vegans
  • 20-25 of adult Americans eat 4 or more meatless
    meals weekly

41
What do vegetarians in the United States
eat?Am J Clin Nutr. 78S626-632 (2003)
  • Continuing Survey of Food Intake by Individual
    (CSFII) 1994-1996
  • gt13,000 subjects
  • 2 day food records
  • 2.5 considered themselves as vegetarian
  • 36 of self-defined vegetarians actually consumed
    no meat
  • 4 of total consumed no meat

42
What do vegetarians in the United States
eat?Characteristics of Self-defined Vegetarians
  • Vegetarians were thinner
  • BMI 23 vs 26
  • Consumed more CHO
  • 57 vs 50
  • Less fat and saturated fat
  • 27 vs 33 and 9 vs 11
  • More vitamin A, carotene, vitamin E, vitamin C,
    folate, dietary fiber and less cholesterol

43
Vegetarian Diets Types
  • Non-red meat vegetarian
  • poultry, fish, dairy, eggs OK
  • Nutritional Benefits
  • Less fat, saturated fat, cholesterol
  • Nutritional Concerns
  • no special nutritional problems
  • May not be any better than typical US diet
  • may be high in fat, satd fat, salt
  • cooking methods
  • junk foods, convenience foods

44
Vegetarian Diets Types
  • Lacto-ovo vegetarian
  • Milk eggs OK
  • Nutritional Benefits
  • Like non-meat vegetarians
  • Nutritional Concerns
  • No special nutritional problems
  • May be high in fats, satd fats
  • cheese eggs

45
Vegetarian Diets Types
  • Strict Vegetarian Vegan
  • no animal foods
  • Nutritional Benefits
  • Low fats, high fiber, plant-based
  • Nutritional Concerns
  • protein quality
  • probably OK, quantity may be an issue
  • calcium
  • no dairy, plant sources (leafy greens, soy),
    fortified foods (soy, rice milk)
  • iron
  • no meat, plant sources (leafy greens), cereals
  • vitamin B-12
  • probably OK, cereals supplements

46
Protein Deficiency
  • Protein - Energy Malnutrition
  • gt 500 million children with PEM
  • 33,000 die per day with PEM
  • Two major forms of PEM
  • Kwashiorkor
  • Marasmus

47
Protein Deficiency
  • Kwashiorkor
  • Ghana the evil spirit that infects the first
    child when the second child is born
  • Protein low, Calories OK
  • Symptoms
  • edema
  • enlarged fatty liver
  • light colored hair
  • low tyrosine/melanin
  • skin lesions

48
Protein Deficiency
  • Marasmus
  • Both Protein and Calories low
  • inadequate food intake
  • Symptoms
  • wasting of lean and fat tissue
  • weak, anemic, low metabolism
  • death due to secondary infections

49
Protein Needs
  • RDA 0.8g Pro/kg BW
  • Or 15 of calories
  • M 55 gP/d F 45 gP/d
  • Safety factor accounts for
  • individual differences
  • varied protein quality
  • average requirement 0.5-0.6gP/kg
  • Typical Intake 65 - 110 gP/d

50
Athletes Protein Needs ?
  • Most sport nutritionists recommend
  • 1.0 to 1.5 g protein/kg BW
  • RDA 0.8 gP/kg BW
  • Example of athletes protein needs
  • 175 lb 80 kg athlete
  • 80 kg x 1.5gP/kg
  • 120 g protein needed per day
  • So do athletes need to supplement their diets?
    Usually not.
  • 3500 Cal/d x 15Pro 525 Cal Pro
  • 525 Cal P / 4 Cal/gPro
  • 131 g pro in normal diet

51
For maximal muscle gain
  • Adequate protein
  • 1.2 1.5 gPRO/kg BW
  • 175 lbs 80kg 96-120gP/day
  • If 3000 Cal diet 13-16 of Calories
  • Adequate energy, especially Carbs
  • 6-7g CHO/kg BW
  • 175 lbs 480 560 g CHO
  • If 3000 Cal diet 64 - 75
  • Proper cellular hormonal balance
  • Genetics
  • Weight training
  • Cheating (anabolic steroids, androstenedione
    (prohormone)
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