L13 Intro to Nutrition Flashcards
What is the #1 risk factor for disease and
premature death in America?
What is the cure?
Diet
Heart disease, cancer, stroke and
diabetes mellitus account for 60% of
all deaths worldwide and is predicted
to increase to 75% by 2020
No cures in sight, prevention, in
the form of good nutrition, is our
best option
What are three classifications for nutrients?
Macronutrients provide the
energy (Calories), essential fatty
acids and essential amino acids
needed for life
Micronutrients are needed in
smaller amounts and include
vitamins and minerals
Nonessential micronutrients
(e.g. phytochemicals found in
fruits and vegetables) are not
necessary but often promote
good health.
Water
What are Dietary Reference Intakes (DRIs) and what are they used for?
DRIs include:
Estimated Average Intake (EAR)
Recommended Dietary Allowance (RDA)
Adequate Intake (AI)
Tolerable Upper Intake Level (UL)
(DRIs) are used to estimate amount of nutrients
needed to prevent deficiency diseases and maintain optimal health and growth.
What is EAR?
RDA?
AI?
EAR is the quantity of nutrient required to
meet the needs of half the population.
The RDA is the EAR plus 2 standard
deviations: meets the needs of 97-98% of the population.
AI is used rather than EAR when needs
criteria have not been decided upon. AI is
determined by identifying populations with
the lowest intake and yet are free of any
signs of nutrient deficiency
Why are vitamins important?
They’re usually cofactors for enzymes.
Are DRIs qualitative or quantitative?
How should DRI information be used?
What factors influence DRIs?
Quantitative nature of DRIs can
convey the false impression that the
values are precise.
DRIs should be interpreted as
average intakes needed over a
period of 2 to 3 days and should
not be taken literally as
amounts/day
DRIs vary depending on:
• Age (10 life-stage groups) plus pregnancy and lactation
• Gender
• Body weight, energy consumption and protein intake
What criteria were used to considered in setting the DRI for Vitamin C?
Which was used?
Criteria considered: Amount Vit C needed to:
• Prevent scurvy
• Achieve tissue saturation
• Maximize absorption of nonheme iron
• Minimize risk of gastric cancer
• Provide reasonable stores in neutrophils
The committee decided to base the DRI on the amount that provides reasonable stores in neutrophils
Neutrophils have highest vitamin C levels of any cell
How are % Daily Values determined?
What DVs are considered low and high?
The daily value (DV) for a nutrient is the
population based average of the nutrient’s
RDA or AI.
Percent daily value (%DV) is the amount of
nutrient in one serving of food expressed as a
percentage of the DV (based on a 2,000-
kcal/d diet)
%DV helps one decide if a serving of food is
high or low in a nutrient
• 5% or less is low
• 20% or more is high
Use the %DV to make food choices:
• Limit these: fats, cholesterol and Na
• Get enough of these: fiber, vitamins and
minerals
What are the two overarching goals behind Dietary Guidelines?
1) Maintain calorie balance over time to achieve and sustain a healthy weight (Stay within 5 to 10 # of weight at age 20) (rule of thumb)
• Be physically active everyday (30 min decreases risk of chronic disease, 60 min prevent weight gain and 90 min to sustain weight loss)
2) Focus on consuming nutrient dense foods and beverages
• A healthy eating pattern limits intake of sodium, solid fats, added sugars (SOFAS) and refined grains (i.e. junk food) and emphasizes nutrientdense foods and beverages—vegetables, fruits, whole grains, fat-free or
low-fat milk and milk products, seafood, lean meats, poultry, eggs, beans, peas, nuts and seeds
• Rather than SOFAS which is stated in terms of nutrients, would be clearer to say reduce consumption of red meat, cheese, butter and sugar
What are some general guidelines to a healthy diet?
• Avoid oversized portions
• Make half your plate fruits and vegetables
• Switch to fat-free or low-fat (1%) milk
• Make at least half your grains whole grains
• Compare sodium in foods like
soup, bread and frozen meals-
–and choose foods with lower numbers
• Drink water instead of sugary
drinks
What term describes the amount of energy in food?
How is the amount determined?
How much energy/g is contained in carbs, protein, fat and alcohol?
The energy in food is measured in terms of calories
• In nutrition, calories usually refer to kilocalories (kcal or Cal)
Two methods of measuring caloric content of food:
• 1) Energy content of food is based on the heat released by total combustion of a food in a bomb calorimeter
• 2) Macronutrient-fuel factors can be used to determine the number of calories in food if one knows the grams of each of the macronutrients in the food
Carbs: 4Cal/gram
Protein: 4 Cal/gram
Fat: 9 Cal/gram
Alcohol: 7 Cal/gram
Example:
• A McDonalds Big Mac has 45 gm carbohydrate, 25 gm protein, and 29 gm fat.
• Using the fuel factors one can calculate that a Big Mac has 541 calories and that 48% of the calories come from fat.
What is the estimated energy requirement?
What is energy balance?
“Estimated Energy Requirement” (EER) is the average caloric intake needed to maintain energy balance in 50% of the adult population. (EER depends on goal to maintain weight, gain or lose weight)
Energy balance is the difference between daily energy
intake and energy expenditure
Energy Balance = Energy Intake – Energy Expenditure
What are the 3 categories of body energy expenditure?
- Resting metabolic rate (RMR) formerly known as basal metabolic rate (BMR)
- Physical activity (MET)
- Thermic Effect of Food (TEF)
Metabolic rate is reported in terms of
calories burned/day
Fuel* + O2 → CO2 + H2O + EnergyATP + Heat
*Fatty acids, glucose and amino acids
How is metabolic rate estimated?
Metabolic rate is estimated using
direct or indirect methods:
Direct calorimetry measures the heat given off by an
individual in a closed environmental chamber
• Direct calorimetry is expensive, time consuming
and cumbersome
Indirect calorimetry measures oxygen consumption or both
oxygen consumption and carbon dioxide production.
• This data is used to estimate metabolic rate
What is RMR and what does it represent?
RMR is equivalent to the number of calories used by a fasting individual at rest
• RMR usually makes up the largest portion (45 to 70%) of our total daily energy expenditure
RMR represents the energy required to run the body’s infrastructure
• Maintenance of cellular integrity (e.g. protein turnover)
• Ion transport (e.g. Na+, K+-ATPase)
• Body temperature
• Internal organs (energy to run heart, lungs, kidney etc)
The energy needed to power RMR is equivalent to that given off by a lit candle
What is the Thermic Effect of Food (TEF)?
How does the TEF differ between macronutrients?
TEF is defined as the increase in the metabolic rate induced by eating.
- The TEF is the difference between the postprandial metabolic rate and the RMR
- It is hypothesized that TEF represents the energy spent to digest, absorb, distribute, and store ingested nutrients.
- TEF is estimated to account for ~10% of the daily caloric intake if eating a mix of all three macronutrients
The postprandial increase in metabolic rate
depends on the macronutrient consumed.:
•Protein metabolism results in the largest
increase in MR due to urea synthesis,
gluconeogenesis, etc.
•Increase in MR following carbohydrate
consumption is due to absorption and
glycogenesis
