Nutrition Lecture 3

Dietary Reference Intakes (DRIs)

• DRIs are scientifically-based reference values for nutrient intake
• They help create nutrition labels and dietary guidelines
• Key components include RDAs, AIs, ULs, EARs, AMDRs, and DVs

Recommended Dietary Allowance (RDA)

• RDA is the average daily intake needed for 97-98% of healthy individuals in a specific age/gender group
• Purpose: prevent nutrient deficiencies
• Example: RDA for calcium (adults 19-50): 1000 mg/day

Adequate Intake (AI)

• AI is used when an RDA cannot be determined due to insufficient scientific evidence
• It's based on observed intakes in healthy individuals
• Example: AI for fiber in women: 25 g/day

Tolerable Upper Intake Level (UL)

• UL is the highest daily intake unlikely to cause adverse effects
• Purpose: prevent nutrient toxicity
• Example: UL for vitamin D in adults: 4000 IU/day

Estimated Average Requirement (EAR)

• EAR is the average daily intake needed for 50% of individuals in a specific group
• It's used to assess population-level nutrient adequacy
• Example: EAR for iron (women 19-50): 8.1 mg/day

Acceptable Macronutrient Distribution Range (AMDR)

• AMDR is the range of macronutrient intake associated with reduced chronic disease risk
• It provides essential nutrients and energy
• Example: Carbohydrates should be 45-65% of daily calories

Daily Value (DV)

• DV is a reference value on food labels, usually based on a 2000-calorie diet
• Example: 20% DV for iron means the product provides 20% of the recommended 18 mg/day iron

Biochemical Assessments

Hemoglobin A1c (HbA1c)

• HbA1c measures average blood glucose over 2-3 months
• Reflects long-term glucose control
• Normal range: below 5.7%
• Prediabetes range: 5.7% to 6.4%
• Diabetes diagnosis: 6.5% or higher

Renal Function Tests (RFTs)

• RFTs evaluate kidney function using biochemical markers like:
  • Creatinine: muscle metabolism waste product; elevated levels = impaired kidney function; normal range: 0.6–1.2 mg/dL
  • Blood Urea Nitrogen (BUN): measures urea in blood; high levels = kidney issues; normal range: 7–20 mg/dL
  • Glomerular Filtration Rate (GFR): assesses kidney blood filtration; critical value: below 60 mL/min/1.73 m² = chronic kidney disease

Liver Function Tests (LFTs)

• LFTs measure enzymes and proteins to assess liver health
  • ALT (Alanine Aminotransferase): liver inflammation; normal range: 7–56 U/L
  • AST (Aspartate Aminotransferase): liver damage; normal range: 10–40 U/L
  • ALP (Alkaline Phosphatase): bile duct obstruction or liver disease; normal range: 44–147 U/L
  • Bilirubin: jaundice or liver dysfunction; normal range: 0.1–1.2 mg/dL

Lipid Panel

• Lipid panel assesses cardiovascular risk by measuring lipids in the blood
  • Total Cholesterol: desirable level < 200 mg/dL
  • LDL ("Bad" Cholesterol): desirable level < 100 mg/dL
  • HDL ("Good" Cholesterol): desirable level ≥ 40 mg/dL
  • Triglycerides: desirable level < 150 mg/dL

Nutrition Assessment Technology & Software

Body Composition Analysis Tools

• Bioimpedance Scales (BIA): estimate body composition (fat, lean mass, water) using electrical current
• Applications: clinical, fitness; weight loss, muscle gain, hydration tracking
• Fat Calipers: measure subcutaneous fat using skinfold pinching; cost-effective but accuracy depends on technique
• Dual-Energy X-ray Absorptiometry (DEXA): gold standard for precise body composition, bone density, fat, and muscle; expensive and less portable

Glucose Monitoring Tools

• Blood Glucose Monitors: portable devices using finger-prick blood samples for immediate glucose level readings
• Continuous Glucose Monitors (CGM): track glucose continuously via a sensor under the skin; provide real-time data via smartphones/apps

Other Monitoring Tools

• Blood Pressure Meters: measure blood pressure
  • Manual (Aneroid): uses stethoscope and gauge
  • Digital: automatic inflation and display
  • Wrist Monitors: portable but less accurate than upper-arm
  • Key Measurements: Systolic (during heartbeat) and Diastolic (between heartbeats)
• Wearable Fitness Trackers: monitor physical activity, heart rate, and energy expenditure (steps, calories, activity)
• Examples: Fitbit, Apple Watch, Garmin
• Smart Kitchen Scales: digital scales that connect to apps to track food portions and nutritional content

Food Tracking Apps

• Mobile apps for logging food intake and tracking nutrients
• Features: barcode scanning, calorie/macronutrient/micronutrient tracking, recipe/meal planning

Anthropometrics (Physical Measurements)

• Anthropometry is the science of measuring human body dimensions, forms, and functional capacities to assess nutritional status and health risks

Key Anthropometric Measures

• Weight: total body mass; doesn't differentiate fat/muscle. Applications: overall size change tracking with other measurements.
• Body Fat Percentage: proportion of body weight from fat; Healthy ranges differ for males and females
• Body Mass Index (BMI): measure of weight relative to height. Formula: Weight (kg) / Height² (m²). Categories: Underweight, Normal Weight, Overweight, Obese. Limitations: doesn't distinguish fat/muscle.
• Mid Upper Arm Circumference (MUAC): upper arm circumference (shoulder to elbow midpoint). Applications: malnutrition detection, especially in children, pregnant women, and the elderly. Cut-off values vary by age/population
• Waist-to-Hip Ratio (WHR): waist circumference / hip circumference. Applications: cardiovascular and metabolic risk predictor. High WHR = increased risk of heart disease and type 2 diabetes.

Food Labels

• Food labels provide nutritional information for informed dietary choices

Key Elements of a Food Label

• Nutrient Facts Panel: on back/side, detailed nutrients, calories, %DV
• Front of Package Warning Labels (FOPWL): highlights calories, fats, sugar, health claims

Nutritional Assessments

• Nutritional assessment: comprehensive evaluation of food intake, nutrient consumption, and overall health
• Types of Assessments:

Direct Methods (ABCD Approach)

• A: Anthropometry: measures body dimensions (height, weight, BMI, MUAC)
• B: Biochemical/Biophysical: analyzes blood/urine/tissue samples for nutrient concentrations
• C: Clinical: complete physical examination for deficiency/excess signs
• D: Dietary: examines food intake, eating patterns, and diet history

Indirect Methods

• Assesses broader nutritional environment via mortality rates, health service statistics, infection rates, and economic factors

Conducting a Dietary History

• Detailed food intake, eating habits, and dietary preferences to identify nutritional imbalances
• Key Components: 24-hour recall, food frequency questionnaires, meal patterns, preferences/restrictions, cooking/shopping habits

Assessment Tools and Techniques

• Nutrient/Additive Scavenger Hunt: identify nutrients/additives in food products using labels

This quiz explores the concept of Dietary Reference Intakes (DRIs), focusing on key components such as Recommended Dietary Allowance (RDA), Adequate Intake (AI), Tolerable Upper Intake Level (UL), and Estimated Average Requirement (EAR). Understand how these values guide nutrition labels and dietary guidelines for maintaining health and preventing deficiencies.