Transcript Class 4 6-7 vitamin energy balance 2013

Chapter 7
Vitamins
“In the middle of difficulty lies opportunity.”
Albert Einstein
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1
Key Concept
• Vitamins are noncaloric essential nutrients
necessary for many vital metabolic functions and
the prevention of associated deficiency diseases.
• Recommendations for nutrient intake by healthy
population groups are based on gender and age
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2
Discovery: Early
Observations
• Vitamins were discovered while searching for
cures for classic diseases
– Dr. James Lind and scurvy
• Sailors dying on long voyages without fresh
food
• Lemons and limes provided, no one became
ill
• British soldiers got the nickname “limeys”
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3
Definition of Vitamin
• It must be a vital, organic substance that is
only necessary in extremely small amounts
– mg or mcg.
• It cannot be manufactured by the body in
sufficient quantities to sustain life, so it
must be supplied by diet.
• The body uses vitamins to make coenzymes
required for some enzymatic function.
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4
Function of Vitamins
• Metabolism: Enzymes and coenzymes
• B vitamins are part of coenzymes
– Coenzymes needed to perform certain
functions, such as:
• Glucose metabolism
• Protein metabolism
• Fatty acid metabolism
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5
Functions of Vitamins, cont’d
• Tissue structure and protection
– Vitamin C
• Prevention of deficiency diseases
– Scurvy (lack of vitamin C)
– Beriberi (lack of thiamine [B])
– Pellagra (corn and rice are low in niacin, a B
vitamin)
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6
Periodontal Disease in Scurvy
EAT
YOUR
VITAMIN
C
EVERY
DAY!!
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7
Vitamin Metabolism
• Fat soluble vitamins
– Vitamins incorporated with absorbed fat and
transported by chylomicrons in the lymph
– Best absorbed when eaten with fat
– May be stored for long periods in fat tissues
• Water soluble vitamins
– Easily absorbed and transported by the portal
circulation to the liver
– Not stored, so must be eaten on regular basis
(exceptions: B12 and B6)
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8
Fat-Soluble Vitamins:
Vitamin A (Retinol)
• Functions
– Vision- adjusts to light levels
– Tissue strength and immunity – prevents macular
degeneration
– Growth – skeletal and soft tissue
Toxicity symptoms – liver damage
• Food sources – orange foods, broccoli, tomato
juice, and beef liver
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9
Vitamin D (Cholecalciferol)
• Functions
– Absorption of calcium and phosphorus
– Bone mineralization
• Deficiency disease: Rickets and osteoporosis
• Food sources – egg yolk, liver, fatty fish
• Ultraviolet light makes the precursor to Vitamin D
in our skin, so get 15 minutes of sunshine a day!
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10
Child with Rickets
Low Vitamin D
prevents
Calcium
absorption;
leads
to weak bones
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11
Vitamin E (Tocopherol)
• Functions
– Antioxidant function
– Relation to selenium metabolism
• Deficiency disease: Hemolytic anemia
• Food sources – plant oils, soy, shrimp, cod,
wheat germ, sunflower seeds
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12
Vitamin K
• Functions
– Blood clotting
– Bone development
• Food sources – Brussel sprouts, leafy
green vegetables, liver
• Produced in our colon by bacteria
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13
Water-Soluble Vitamins:
Vitamin C (Ascorbic Acid)
• Functions
– Connective tissue building
– General body metabolism
– Antioxidant function
• Deficiency disease: Scurvy
• Toxicity symptoms – GI “distress”
• Food sources – fruits
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14
Thiamin (Vitamin B1)
• Functions
– Gastrointestinal system
– Nervous system
– Cardiovascular system
– Helps store fat as energy
• Deficiency disease: Beriberi
• Levels are low in alcoholics
• Food sources – spinach, green peas, tomato juice,
watermelon, lean ham & pork chops, soy milk
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15
BERIBERI
UNABLE TO
STORE FAT,
NO
DEMENTIA
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16
Riboflavin (Vitamin B2)
• Functions
– Energy production
– Normal vision, & skin health
– Tissue protein building
• Deficiency disease – tissue inflammation, poor
wound healing
• Food sources – spinach, broccoli, mushrooms, eggs,
milk, liver, oyster, clams
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17
Niacin (Vitamin B3)
• Functions
– Energy metabolism
– DNA repair
• Deficiency disease: Pellagra
• Toxicity symptoms – flushing skin
• Food sources – spinach, tomato juice, lean
ground beef, chicken breast, canned tuna,
liver, shrimp
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18
Niacin Deficiency: Pellagra
DERMATITIS,
DIARRHEA,
DEMENTIA
AND DEATH
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19
Vitamin B6 (Pyridoxine)
• Functions
– Protein metabolism
– Neurotransmitter
• Deficiency disease – microcytic, hypochromic anemia
& abnormal CNS function
• Food sources – bananas, watermelon, tomato juice,
spinach, acorn squash, potato, white rice, chicken
breast
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20
Folate
• Functions
– Aids in: DNA synthesis; Regulation of blood
homocysteine levels
• Deficiency diseases: Megaloblastic anemia,
Neural tube defects
• Food sources – tomato juice, green beans,
broccoli, spinach, asparagus, okra, black eyed
peas, beans (navy, lentil, pinto, & garbanzo)
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21
Cobalamin (Vitamin B12)
• Functions
– Regulation of blood homocysteine levels
– Heme synthesis
– Nervous system functioning
• Deficiency disease: Pernicious anemia
• Food sources – meats, poultry, fish, shellfish,
milk, eggs
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22
Choline
Associated with the B-complex vitamins
– Functions
• Structural integrity of cell membranes
• Neurotransmission (ACH)
– Deficiency disease: Liver damage
– Food sources- milk, eggs, liver, peanuts
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23
Phytochemicals
• Bioactive molecules with health benefits -those plant
compounds that act as antioxidants or hormones
• Need to have seven colors on your plate for benefits!
• Seven colors with corresponding phytochemical
• Lycopene, zeaxanthin, anthocyanin, betacarotene, flavonoids, glucosinolate, allyl
sulfides
• Only found in whole foods
– (grains, fruit and vegetables)
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24
BENEFITS
• What are some of the beneficial effects of
phytochemicals that have been documented?
– Reduced risk of chronic disease,
– Protection against coronary heart disease
– Improved overall colon function
– Prevention of age-related macular
degeneration and cancer
– Increased antioxidant status
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25
Vitamin Supplementation
• Ongoing debate
• Biochemical individuality
– Life cycle needs
• Pregnancy & lactation – folic acid & vitamins
• Infancy – Vitamins K & D
• Children and adolescents – need all during
growth spurts
• Aging – need more vitamins b/c eat less food
and absorb less nutrients
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26
Vitamin Supplementation,
cont’d
• Megadoses
– Toxic effects
• Fat soluble are stored
• Vit B6 – ataxia and nerve damage
• Vit C leads to GI issues, kidney stones and
decreased immune function
– “Artificially induced” deficiencies
• Supplementation principles
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27
Summary
• Vitamins are food substances required in very
small amounts.
• Body cannot make vitamins, but a well-balanced
and varied diet usually supplies sufficient intake.
• Fat-soluble vitamins are A, D, E, K.
• Water-soluble vitamins are C and B-complex.
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28
Summary, cont’d
• Possibility of toxicity is increased for fat-soluble
vitamins compared with water-soluble vitamins.
• Water-soluble vitamins C and pyridoxine (B6) in
megadoses can be harmful.
• Phytochemicals are found in whole and unrefined
plant foods.
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29
Basic Energy Needs
• The body uses most of the daily energy supply for
constant use in voluntary and involuntary activity
• Voluntary work and exercise
– Includes all physical actions related to usual
activities and additional physical exercise
– Seems to require most of the energy output, but
is usually not the case
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30
Basic Energy Needs, cont’d
• Involuntary work: includes all activities of the body
that are not consciously performed
– Circulation, respiration, digestion, absorption
– Requirements include:
• Chemical energy: in many metabolic products
• Electrical energy: in brain and nerve activities
• Mechanical energy: in muscle contraction
• Thermal energy: to keep the body warm
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31
Basic Energy Needs, cont’d
• Fuel is provided in the form of nutrients
• Only three energy-containing nutrients:
– Carbohydrate is primary fuel
– Fat assists as storage fuel
– Protein is a back-up fuel source
• Alcohol also provides energy but is not a nutrient
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32
Measurement of Energy
• Calorie: Amount of energy in food or expended in
physical actions
• Kilocalorie (1000 calories or 1 Calorie): Amount
of heat necessary to raise 1 kg of water 1° C
– Large Calorie unit used in nutrition science to
avoid dealing with large numbers
– Abbreviation: kcalorie or kcal or Cal
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33
Fuel Factors
•
•
•
•
Carbohydrate: 4 kcal/g
Fat: 9 kcal/g
Protein: 4 kcal/g
Alcohol: 7 kcal/g
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34
Caloric and Nutrient Density
• Density: The degree of concentration of material
in a given substance
• Caloric density: Concentration of energy in a
given amount of food (think of the bakery!)
– Foods high in fat have the highest caloric
density
• Nutrient density: Concentration of all nutrients in
a given amount of food (Think of an apple)
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35
Energy Intake
• The body’s energy balance depends on
energy intake in relation to energy output
• Energy intake
– Three macronutrients are stored as:
• Glycogen
• Adipose tissue
• Muscle mass
– Energy intake is the calculated energy value
of actual food consumption
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36
Energy Output
• Activities to sustain life require energy from food
and body reserves
• Three demands for energy determine the body’s
total energy requirements
– Resting energy expenditure (REE)
– Physical activity
– Thermic effect of food (TEF)
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37
Resting Energy Expenditure
• Sum of all internal working activities
of the body at rest
• Expressed as kcal/day
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38
Measurement of Resting
Metabolic Rate
• How are resting metabolic rate (RMR) or basal
metabolic rate (BMR) measured?
– Indirect calorimetry
• Metabolic rate calculated on the basis of the
rate of oxygen utilization
– Thyroid function test – responsible for body
metabolism
• Measures the activity of the thyroid gland
and the blood levels of the hormone
thyroxine
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39
Measurement of Resting
Metabolic Rate, cont’d
• General formula
– Men
• 1 kcal x kg body weight x 24 hours
– Women
• 0.9 kcal x kg body weight x 24 hours
Calculate your Basal Metabolic Rate
1 kg = 2.2 pounds
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40
Factors Influencing Basal
Metabolic Rate
• Lean body mass (muscles and organs)
– Greater metabolic activity in lean tissues
• Growth periods
– Growth hormone stimulates cell metabolism
and raises BMR
• Body temperature
– Fever increases BMR
• Hormonal status
– Example: Hypothyroidism = Decreased BMR
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41
BODY MASS INDEX
Body mass index (BMI) is measure of body fat based on
height and weight that applies to both adult men and women.
BMI Categories:
Normal weight = 18.5-24.9
Overweight = 25-29.9
Obesity = BMI of 30 or greater
Calculate your BMI
BMI = weight in pounds x 703 / inches squared
Ex: 150 pounds x 703 = 105450
5’ 8” = 68 inches x 68 inches = 4624
105450/ 4624 = 22.8 BMI
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42
Physical Activity
• Energy expenditure for physical activity goes above
and beyond energy used for resting energy needs.
• Energy output during physical activity varies widely
across individuals.
• 3500 extra calories = 1 pound;
– That is 500 extra calories per day to gain 1 pound
in a week or exercise 500 calories off per day to
lose 1 pound in a week
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43
Physical Activity Level
Factors
• Categorize physical activity level
(PAL) according to standard values
–
–
–
–
–
1.2: Chair or bed bound
1.4-1.5: Sedentary
1.6-1.7: Very light
1.8-1.9: Moderate
2.0-2.4: Heavy
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44
Thermic Effect of Food
• Extra energy for digestion, absorption, and
transport is required after eating.
• 5% to 10% of the body’s total energy needs for
metabolism relate to the processing of food.
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45
Total Energy Requirement
• Total energy requirement: Resting energy
expenditure + Physical activity + Thermic Effect
of Food
• To maintain daily energy balance:
– Food energy intake = Body energy output
– Intake > output = Weight gain (extreme:
obesity)
– Intake < output = Weight loss (extreme:
anorexia)
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46
Life Cycle
• Growth periods
– Extra energy per unit of body weight is
necessary to build new tissue
– Infancy, adolescence, pregnancy
• Adulthood
– Energy needs level off
– With aging, energy needs decline
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47
Gradual Reduction of Kilocalorie
Needs During Adulthood
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Dietary Reference Intakes
• Dietary guidelines for healthy Americans indicate
energy needs based on three recommendations:
– Maintain body weight in a healthy range
– To prevent gradual weight gain over time, make
small decreases in food and beverage calories and
increase physical activity
– Make recommended intakes within energy needs
• USDA Food Guide
• DASH eating plan
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49
Summary
• Energy is the force or power to do work.
• Energy is measured in “large” calories, or
kilocalories.
• Metabolism is the sum of the body processes
involved in converting food into various forms of
energy.
• When food is not available for energy, stored
energy is used in the form of glycogen, fat, and
tissue protein.
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50