Exam 2: Nutrition Flashcards
Nutrients
Nutrients provides structural or functional components or energy to the body.
Essential nutrients must be obtained from the diet.
Body unable to produce sufficient quantity to meet needs.
Important compounds which do not participate in metabolic pathways include antioxidants and dietary fiber.
Food Regulation
Limited primarily to labeling and purity.
US Department of Agriculture (USDA) regulates safety, quality, and labeling of meat, poultry, and eggs.
Food and Drug Adminsitration (FDA) regulates all other foods.
Nutrient Recommendations
Made by the Food and Nutrition Board of the Institute of Medicine.
Dietary Reference Intakes (DRI) value for any given nutrient is continually reevaluated.
Goal to determine the amount high enough to prevent impairment of health even if intake is inadequate for a short period.
There are four seperate recommendations:
- Estimated average requirement (EAR)
- Recommended dietary allowance (RDA)
- Adequate Intake (AI)
- Tolerable Upper Intake Level (TUL)
Nutritional Supplements
Labeling and advertising limited to structural claims and cannot make disease claims.
Estimated Average Requirement
(EAR)
Average daily intake level needed to meet the requirement of half of healthy individuals in a particular life stage and gender group.
Recommended Dietary Allowance
(RDA)
Average daily intake level needed to meet the requirement of 97.5% of healthy individuals (mean ± 2 SD) in a particular life stage and gender group.
Applies to most micronutrients (vitamins and minerals).
RDA values have been set for carbohydrates and proteins but not most fats except for n-6 and n-3 polyunsaturated fatty acids.
Adequate Intake (AI)
Recommended average daily intake level based on observed or experimentally determined approximations by groups of healthy people that are assumed to be adequate.
Used when RDA cannot be determined.
Most commonly seen for young infants.
Tolerable Upper Intake Level
(UL or TUL)
Highest average daily intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population.
Nutrition Facts Label
Required on most types of packaged foods.
Contains 2 types of information in the US:
Nutrient content and list of ingredients
Based on serving size and number of servings per container
-
Items above the heavy line:
-
Macronutrients
- 100% daily value (%DV) represents an upper limit (DRV)
- No RDA for these nutrients
-
Fiber
- 100% daily value (%DV) based on recommendation of 25 g/day
- Sugars ⇒ mono- and disaccharides
- Remainder of carbs are complex carbs = total less sugars and fibers
- Sodium
- Cholesterol
-
Macronutrients
-
Items below the heavy line:
- %DV is the mininum value for any individual
- Based upon the highest RDA among age groups for micronutrients
- Denominator used is RDI
- Would be higher for someone with a lower RDA
- %DV is the mininum value for any individual
Food Label Revisions
- Newer values for daily requirements used to calculate %DV
- Added sugars now included
- Vit D & potassium added. Vit A & C removed
- Calories from fat removed ⇒ type more important than amount
-
Serving sizes revised to reflect what is actually eaten
- Things usually consumed in one sitting now reported as single serving per container
- Larger packages should clearly indicate “per serving” vs “per package”
- Calories and serving sizes more prominent
Reference Daily Intake
(RDI)
The highest RDA value among the different age and gender groups.
Used to determine the micronutrient amount per serving for food labels.
Basal Metabolic Rate
(BMR)
The energy needed to carry out fundamental metabolic functions.
- Measured with subject fasted, laying quietly in a room of comfortable temperature
- Varies with age and sex
- Lean body mass major determinant (men with less body fat)
- Values normalized for surface area
Acceptable Macronutrient Distribution Range
(AMDR)
The breakdown of the % of total calories provided by fat, carbohydrate, and protein.
Healthy Eating Index
(HEI)
Used to assess whether individuals or populations are compliant with recommendations.
If they are, does this translate to getting enough nutrients.
Score on 0-100 scale.
All components of the nation’s intake inadequate (20% to 82%) except for proteins.
Allergy vs Intolerance
Food allergies are immune responses which can be life threatening.
Most common are eggs, peanuts, and milk.
Food intolerances are non-immune responses.
Nutrition in Infancy
Ideal infant nutrition based on human milk.
Must provide for the greater metabolic needs and growth rates.
Nutrition in 1 to 10 y/o Child
- Most children with access to a varied diet will choose adequate amounts of all nutrients.
- Major concerns:
- iron deficiency anemia in 1-3 y/o
- inadequate calcium intake for good bone development
- inadequate protein intake in vegan children and those with allergies
- over-nutrition (obesity)
Nutrition in Adolescence
- Adolescence associated with intense anabolism
- Food habits can produce deficiencies in some nutrients:
- Vit A & B6
- Calcium
- Iron
- Zinc
- Folate
- Excess fats and sodium common
- Eating disorders a concern
- Obesity can be a significant problem
Effects of Health on Nutrition
Nutrition in the Elderly
Nutritional requirements unchanged or even increased (e.g. protein) at a time when total food consumption decreases resulting in unmet needs.
- High probability of malnutrition
- Decreased appetite ⇒ insufficient essential nutrient content in calorically adequate meals
- Changes in vitamin and mineral absorption ⇒ changes dietary requirements
-
Greatest risk for inadequacy:
- Proteins
- Vit B12
- Calcium & Vit D
- Vit C
- Zinc
- Age-related achlorhydria ⇒ reduced output of stomach acid
Nutritional Problems With Aging
- Sensory change: loss of smell, taste may make foods less appealing.
- Physical limitations can affect nutrition by affecting ease of obtaining and preparing foods.
- Social factors: Social isolation, loneliness, depression may result in inadequate diet, problems with transportation, financial problems.
Vegetarianism
- Subject to individual preference and varies in strictness
- vegan ⇒ no meat or dairy
- lacto-ovo-vegetarianism ⇒ allows eggs and dairy
-
Nutritional benefits:
- lower saturated fats
- higher fiber intake
- higher antioxidants
- lower body weight
- lower incidence of heart disease
-
Nutritional concerns:
- deficient in some amino acids
- may be deficient in Vit B12, calcium, Vit D, iron, zinc
- Compensation for any deficiencies important in infants and children
Drug-Nutrient Interactions
Drugs may interact with foods favorably or unfavorably.
Many drugs can cause nutritional problems.
Foods can interfere with or potentiate the actions of some drugs.
Tyramine and MAO inhibitors
-
Tyramine = monoamine that can induce the release of norepi from SNS terminals
- Leads to ↑ BP and HR
- Derived from tyrosine in foods via fermentation or decay
- Tyramine metabolized by monoamine oxidase
- Patients taking MAO inhibitors may have elevated tyramine levels
- Results in risk for increased BP ⇒ hypertensive crisis
Energy Measurement
1 Calorie = 1,000 calories
Often labeled as kcal.
Becoming common to replace kcal with kilojoules
1 Cal = 4.184 kJ
Metabolic Rate
The rate per hour that we expend calories by merely subsisting i.e. just sleeping.
Expenditure proportionally higher if awake and active.
Protein Oxidation
RQ = 63/77 = 0.82
Protein oxidation is not evaluated with RQ but rather through measurement of urea excretion.
Test called urinary urea nitrogen or UUN.
Total Energy Expenditure
(TEE)
The total of all calories expended over the course of a 24-hour day.
~ 60% of TEE is due to basal metabolism aka basal energy expenditure (BEE).
BMR
vs
RMR
Basal metabolic rate (BMR) refers to a very specific set of conditions ⇒ at rest, fasted, not subject to stimuli, etc.
Not always practical to measure.
Resting metabolic rate (RMR) measured under more realistic conditions and regarded as “close enough” to BMR.
Metabolic Rate
Determination
Metabolic rates can be estimated based on crude estimates or using emperical equations.
Estimated BMR for a man is 1 kcal/kg/hr and that of a woman is slightly less.
-
Empirical equations are based on population averages.
- Harris-Benedict equations most common
- Uses height, weight, age, and set of constants.
- Different equations used for men and women.
- Can be determined by measuring the oxygen consumed or carbon dioxide produced.
- Factors exist that relate liters of gas respired to Calories expended
- Normalized to Cal/hr or Cal/kg-hr
Indirect Calorimetry
Amount of O2 consumed and CO2 produced used to estimate the number of kcal expended over time.
Used to estimate RMR or BMR.
Respiratory Quotient
Ratio of CO2/O2
Determines what proportion of calories used comes from fats vs carbs.
RQ ≈ 0.85 in a typical american diet.
Typically get 50% of non-protein-derived energy from carbs and 50% from fats.
Patients with severe dyspnea/hypercapnia may benefit from burning fats d/t lower RQ.
Macronutrient Caloric Content
-
Carbohydrates
- Max 4.1 Cal/g possible
- 98% efficiency of digestion/absorption
- Corrects to 4 Cal/g
-
Fats
- Max 9.4 Cal/g
- 95% absorbed
- Corrects to 9 Cal/g
-
Proteins
- Max 5.6 Cal/g
- Only 92% absorbed
- Only 75% of absorbed protein catabolized to CO2
- Corrects to 4 Cal/g