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Human Nutrition
How our diet determines Health
& Wellness
Why should we care?
• Nutrition (and physical
activity) contributes
to wellness
• Wellness = the
absence of “disease”
– Physical
– Emotional (including
mental)
– Spiritual
Why should we care?
Optimal nutrition prevents disease
1. Nutrient deficiency diseases
•
Goiter, scurvy, pellagra, rickets
2. Diseases influenced by nutrition**
•
Chronic diseases (heart disease, odesity, Type II
diabetes)
3. Diseases in which nutrition plays some role
•
Some cancers, Osteoporosis
Example: Obesity
• An emerging problem,
just within last two
decades
Table 1-5
Page 24
Table 1-6
Page 25
Optimal Nutrition
•
•
Largely because of 2 and 3, acquiring
optimal nutrition has become a national
goal
Goals of Healthy People 2010 (promoted by
USDHHS)
1. Increase quality and years of healthy life
2. Eliminate health disparities
Another reason: Omnivore’s
Dilemma
• Knowing what to eat, how much to eat, and
in what setting to eat is BASIC
– We’ve been doing it pretty well for tens of
thousands of years.
– Within the last 50 years or so, we’ve
forgotten how to do it.
– Due almost entirely to corporations that make
money from selling us food products.
What are Nutrients?
• Organic* (contain Carbon) &
Inorganic molecules in food
that are critical to human
growth and function
–
–
–
–
–
–
Carbohydrates *
Lipids (Fats and oils) *
Proteins *
Vitamins *
Minerals
Water
Divisions of Nutrients
• Macronutrients
– provide energy to do
work*
– Fats, Carbs, Proteins
– Required in large
amounts
– Broken down & stored
or rebuilt
• Micronutrients
– Provide specialty parts
for enzymes
– Vitamins and minerals
– Required in much
smaller quantities
– Used primarily “as-is”
Energy of macronutrients
• Measured in
kilocalories (kcal) =
Energy required to
raise the temp. of 1g
of H2O by 1°C.
• Via bomb calorimetry
• On food labels,
“Calorie” usually
means kcal.
Energy Density of Two Breakfast Options Compared
LOWER ENERGY DENSITY
HIGHER ENERGY DENSITY
This 450-gram breakfast delivers 500
kcalories, for an energy density of 1.1
(500 kcal ÷ 450 g 1.1 = kcal/g).
This 144-gram breakfast also delivers
500 kcalories, for an energy density of 3.5
(500 kcal ÷144 g = 3.5 kcal/g).
Carbohydrates
• Primary source of Energy during activity
(especially for our brain)
• C, H and O in ratio of 1:2:1
• Provides 4 kcal/g
Fats (Lipids)
• Triglycerides, phospholipids
• Important source of Energy during rest
and low intensity activity
• Provide 9 kcal/g (far fewer Oxygens)
Proteins
• Contain C, H, O & Nitrogen (N)*
• Constructed of chains of Amino Acids (AA)
• Energy source only in dire need; 4 kcal/g
Proteins
• Important for:
–
–
–
–
Bone structure (organic part of bones is protein)
Regulating metabolic rate & fluid balance
Repairing muscle & bone
Build cells and tissues
Table 1-2
Page 9
Calculating Energy of foods
• 1 slice bread with 1 tbsp. peanut butter
–
–
–
–
Carbs: 16g * 4 kcal/g
Protein: 7g * 4 kcal/g
Fat: 9g * 9 kcal/g
Total
= 64 kcal
= 28 kcal
= 81 kcal
= 173 kcal
Vitamins
• Micronutrients (only need a little; e.g. mg,
µg)
• Organic compounds that assist in
regulating body processes and using E (do
not supply E)
• 2 types based on solubility
– Fat-soluble
– Water-soluble
Fat-soluble vitamins
• Vitamins A, D, E, K
• Easily dissolve in fats and oils
• Easily stored in adipose tissue (fat cells)
throughout the body
– Unnecessary to ingest or synthesize these
every day
Water-soluble vitamins
• Vitamins C, B (thiamin, B6, riboflavin,
folate, etc.)
• Must ingest or synthesize these every day
– Your kidneys filter them from the blood & you
excrete them in urine
Minerals
•Inorganic compounds (no Carbon)
•Remain intact (maintain same structure
regardless of their environment)
• Major
–
–
–
–
–
–
Sodium (Na+)
Chloride (Cl-)
Potassium (K+)
Calcium (Ca2+)
Phosphorous (P)
Magnesium (Mg2+)
• Minor
–
–
–
–
–
–
–
–
Iron
Zinc
Iodine
Selenium
Copper
Flouride
Chromium
Molybdenum
Minerals
• Essential to:
– Bone deposition (Ca, P, Mg)
– Delivering O2 to cells and removing CO2 (Fe)
– Initiating & sustaining muscle contraction (Na,
K, Ca)
– Propagating nerve impulses (Na, K, Ca)
– Fluid balance & blood pressure (Na, K, Cl)
H2 O
~ 2/3 of total body weight
• Dissolves organic and inorganic molecules
making a solution (~55% of blood volume is water)
• Needed for chemical reactions
– Hydrolysis and dehydration synthesis
• High heat capacity
– Absorbs and retains heat without changing temp.
or state = stability!
– Great medium for cooling the body
• Effective lubricant
– Reduces friction
Determining Nutrient Intake
Naive vs. Accurate View of Nutrient Intakes
Danger
of toxicity
Marginal
Tolerable
Upper Intake
Level
Safety
Safety
RDA or AI
RDA
Marginal
Danger
Danger
of
deficiency
Naive
view
Accurate
view
Estimated
Average
Requirement
Dietary Reference Intakes
Dietary Reference Intakes
• DRIs consist of 4 values:
1. Estimated Average Requirement (EAR)
2.Recommended Dietary Allowances (RDA)
3.Adequate Intake (AI)
4.Tolerable Upper-Intake Level (UL)
Dietary Reference Intakes
• Estimated Average
Requirement (EAR)
• Average daily intake
(ADI) level of a
nutrient that meets
the needs of 1/2 of
the people in a
particular category
Dietary Reference Intakes
• Recommended Dietary
Allowance (RDA)
• The ADI level
required to meet the
needs of 97 – 98% of
people in a particular
category
Dietary Reference Intakes
• Adequate Intake (AI)
• Recommended ADI level for a nutrient
• Based on observations and estimates from
experiments
• Used when the RDA is not yet established:
calcium, vitamin D, vitamin K, fluoride
Dietary Reference Intakes
• Tolerable Upper Limit (UL)
• Highest ADI level that is not likely to
have adverse effects on the health of
most people
• Consumption of a nutrient at levels above
the UL is not considered safe
– Anything consumed in excess is potentially
dangerous
Dietary Reference Intakes
• Estimated Energy Requirement (EER)
• Average dietary energy intake (kcal) to
maintain energy balance (neither gaining
nor losing weight)
• Based on age, gender, weight, height,
level of physical activity
Dietary Reference Intakes
• Acceptable Macronutrient Distribution Range
(AMDR)
• Describes the portion of energy intake that
should come from each macronutrient
Nutrient
AMDR
Carbohydrate
45 - 65%
Fat
20 - 35%
Protein
10 - 35%
Your Goal
• Create a diet plan that is:
– nutritionally adequate
– allows you to maintain a healthy weight
– support your daily physical activities