S

L 39 Nutrition in Preventive Medicine — Lecture 39 Notes (Comprehensive)

Introduction

  • Course: BIOCD 0553, 2025, Lecture 39, Dr. Martinez-Guryn
  • Topic: Nutrition in Preventive Medicine
  • Overall objective: Understand the role of preventive nutrition in obesity, cardiovascular disease, cancer, osteoporosis, and pregnancy
  • Assigned readings: Dietary Guidelines for Americans 2020-2025 (Executive Summary, Infographic)
  • Key messages from Dietary Guidelines for Americans 2020-2025:
    • Follow a healthy dietary pattern at every life stage
    • Customize and enjoy nutrient-dense foods that reflect preferences, culture, and budget
    • Focus on meeting food group needs with nutrient-dense foods within calorie limits
    • Limit added sugars, saturated fat, sodium, and limit alcoholic beverages
    • Non-dietary recommendations: abstain from smoking; avoid excess sun exposure
  • Emphasis: Nutrition as a cornerstone of public health and individual health promotion

Causes of Mortality in the United States

  • Ten leading causes of death (2015–2020) per CDC/NCHS data; total deaths: ~2.8 million (2017) and ~3.3 million (2020)
  • Leading causes in this period: heart disease and cancer; COVID-19 ranked third in 2020
  • Important point: many deaths are preventable through lifestyle modification and preventive nutrition
  • Review questions highlighted: which is the most/second most common cause; which of the top ten could be prevented by diet/lifestyle

Obesity

  • Definition: obesity is a chronic medical condition with excess adiposity and increased morbidity/mortality from T2DM, CVD, MASLD (formerly NAFLD), sleep apnea, cancer
  • 3.1 Clinical Assessment of Obesity
    • Body Mass Index (BMI) used to classify weight status
    • Example calculation (women, 5'3" and 160 lb):
    • Convert weight: 72.73 ext{ kg}
    • Height: 63 in = 1.60 ext{ m}; height^2 = 2.56 ext{ m}^2
    • BMI: ext{BMI} = rac{72.73}{(1.60)^2} \approx 28.4
    • BMI = weight(kg) / height(m)^2
    • Note: BMI classifications are largely based on European ancestry; they may underestimate risk in other populations
  • 3.2 Risk Factors for Obesity
    • Modifiable vs non-modifiable risk factors (examples are discussed in class materials)
  • 3.3 Strategies for Prevention (Treatment) of Obesity
    • Three-fold approach: diet, exercise, behavior modification
    • Weight gain prevention criteria:
    • Normal weight BMI (18.5–24.9) with no additional risk factors
    • Overweight BMI (25.0–29.9) with no additional risk factors for CVD
    • Overweight/obese individuals who are not ready for weight loss yet but could gain benefits from prevention
    • Weight-loss therapy criteria:
    • BMI 25.0–29.9 with 1 CVD risk factor (e.g., diabetes, hypertension, hyperlipidemia, high-risk waist circumference)
    • BMI ≥ 30 kg/m^2
    • Initial target weight loss: 5–10% of baseline body weight within 6 months
    • Dietary recommendations for weight loss (as per ADA guidelines and expert guidelines):
    • Women: 1,200–1,500 kcal/day; Men: 1,500–1,800 kcal/day (caloric targets adjusted for individual weight and needs)
    • Energy deficit: 500 kcal/day or 750 kcal/day
    • Use evidence-based diet patterns that create an energy deficit while providing essential nutrients
    • RDN monitoring: assess energy intake and nutrient adequacy; adjust plan as needed
    • Resting metabolic rate (RMR) measurement via indirect calorimetry is preferred when possible; Mifflin–St Jeor equation commonly used to estimate RMR when indirect calorimetry is unavailable:
      • Men: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age + 5
      • Women: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age - 161
    • Total energy needs: Total\ Energy\ Needs = BMR \times AF where AF (activity factor) ranges:
      • Sedentary: 1.0–1.4
      • Low active: 1.4–1.6
      • Active: 1.6–1.9
      • Very active: 1.9–2.5
    • Example: 40-year-old, 5'4" (64 in) female, 160 lb, lightly active
    • Weight: 72.7\text{ kg}; Height: 162.6\text{ cm}; BMR ≈ computed per Mifflin–St Jeor; Total energy ≈ BMR × 1.4 ≈ 1,935 kcal/day
    • If aiming for 10% weight loss in 6 months: ~7.3 kg (16 lb) target; rough calculation using 1 lb ≈ 3,500 kcal; daily deficit ≈ 333 kcal/day (noting that changes in body composition will alter RMR over time)
    • Macronutrient composition and diet types
    • No single macronutrient is consistently superior for long-term weight loss or weight regain prevention (evidence from andeal.org and JAMA analyses)
    • Diets discussed: moderate-fat/moderate-protein/high-carb; high-fat/high-protein/low-carb (Atkins; not recommended here); very low-fat/moderate-protein/high-carb (Dean Ornish/vegetarian-based)
    • Intermittent fasting (IF) / energy-restriction patterns: IMF (≥60% energy restriction 2–3 days/week) or time-restricted feeding (e.g., 8:00–18:00 window)
    • Long-term superiority of any pattern unclear; adherence appears to be key determinant of weight loss
    • Beverages contribute to calorie intake; track liquid calories as part of weight-loss plans
    • Portion control and portion-size trends: late 20th–early 21st century have seen substantial increases in portion sizes; reference to NHLBI resources
    • Other beneficial diets for weight management include Mediterranean and DASH; paleo and ketogenic approaches are not recommended for weight loss due to lack of long-term efficacy and potential adverse lipid effects
  • 3.4 Ten Steps to Treating Overweight and Obesity in the Primary Care Setting 1) Measure weight and height to determine BMI 2) Measure waist circumference 3) Assess comorbidities 4) Determine if treatment is warranted 5) Assess patient readiness/motivation to lose weight 6) Decide which diet to recommend 7) Set a physical activity goal with the patient 8) Document goals for diet, exercise, behavior change; review weekly food/exercise diary 9) Provide dietary information to patient 10) Track achievement of goals
    • Source: NHLBI/NAASO Practical Guide (2000)

Cardiovascular Disease (CVD)

  • 4.1 Etiology and Pathogenesis
    • Atherosclerosis as a process involving vascular wall cells, circulating blood cells, and hemostatic factors
    • Early lesions: LDL-cholesterol uptake by macrophages → foam cells; macrophage-derived cholesterol accumulation
    • Smooth muscle migration and fibrous cap formation; plaque rupture/fissuring → platelet aggregation → lumen occlusion
    • Clinical endpoints: myocardial infarction (MI) and stroke
  • 4.2 Risk Factors for Cardiovascular Disease
    • Non-modifiable risk factors (examples): age, family history, genetics, sex
    • Modifiable risk factors (examples): obesity, dyslipidemia, hypertension, smoking, physical inactivity, diabetes
  • 4.3 Role of Diet in the Prevention and Management of Hyperlipidemia
    • Hypercholesterolemia is a key modifiable risk factor for heart disease
    • Dietary fats consist of saturated, monounsaturated, and polyunsaturated fats
    • TLC (Therapeutic Lifestyle Changes) diet recommendations:
    • Reduce saturated fat to <7% of total calories; limit cholesterol to <200 mg/day
    • Increase plant stanols/sterols (2 g/day) and soluble fiber (10–25 g/day)
    • Maintain optimum body weight and increase physical activity
    • TLC Diet guidance (NCEP):
    • Total fat: 25–30% of calories
    • Saturated fat: ≤7% of calories
    • Monounsaturated fat: 25–30% of calories
    • Polyunsaturated fat: ≤10% of calories
    • Cholesterol: ≤200 mg/day
    • Protein: ~15% of calories
    • Carbohydrate: 50–60% of calories
    • Fiber: 20–30 g/day; Soluble fiber: 10–25 g/day
    • Clinical measures to monitor: Total cholesterol, LDL, HDL; normal ranges are context-dependent; (table placeholders exist in slides for values)
  • 4.4 Role of Diet in the Prevention and Management of Hypertension
    • Hypertension prevalence: ~48.1% of adults; risk increases with age; by age 60, >50% hypertensive
    • Major mortality/morbidity from stroke and MI; renal failure also linked
    • Public health focus: modify obesity, salt intake, alcohol consumption, and physical inactivity
    • Sodium restriction: Dietary Guidelines recommend ≤2.3 g/day sodium (approx. 1 teaspoon salt = ~6 g, ~2.3 g sodium) with the DASH plan
    • DASH Eating Plan (2,000 kcal/day) general guidelines:
    • 1,500–2,300 mg sodium/day depending on target; avoid high-sodium foods (>300 mg per serving); minimize table salt; limit eating out; emphasize healthy fats
    • Mediterranean Diet as an alternative beneficial pattern for CVD and hypertension: emphasis on olive/canola oil, fish ≥2x/week, plant-forward foods, herbs/spices, reduced red meat, high vegetables/fruits/whole grains, moderate dairy, and optional moderate red wine

Cancer

  • 5.1 Pathobiology of Cancer
    • Cancer is a cluster of diseases characterized by uncontrolled cell growth and spread (metastasis)
    • External (chemicals, radiation, viruses) and internal (hormones, inherited mutations) factors contribute
    • Nutrients play roles in cancer-related biological processes (e.g., zinc modulating gene expression via zinc finger proteins)
  • 5.2 Diet and Cancer
    • Public interest in dietary factors as pro- or anti-cancer agents has surged; about one-third of cancer mortality is diet-related
    • WCRF/AICR 2007 report (Foods, Nutrition, Physical Activity, and Prevention of Cancer) and Continuous Update Project (CUP) updates
    • Strong evidence summary from WCRF/AICR on diet, nutrition, physical activity, and cancer prevention (examples):
    • Red meat: probable increased risk for colorectal cancer; processed meat: convincing increased risk
    • Whole grains: probable decreased risk
    • Alcohol: convincing increased risk for breast, colorectal, oral, esophageal, and liver cancers
    • Coffee: probable decreased risk for liver and endometrial cancers
    • Adult attained body fatness linked to several cancers (kidney, endometrial, breast, colorectal, hepatic, pancreatic)
  • Cancer Prevention Recommendations (WCRF/AICR): 10 items
    1) Be a healthy weight; avoid excess weight gain
    2) Be physically active; integrate activity into daily life
    3) Eat whole grains, vegetables, fruits, and beans
    4) Limit fast foods and processed foods high in fat, starches, or sugars
    5) Limit red meat and avoid processed meat
    6) Limit sugar-sweetened drinks; drink water ideally
    7) Limit alcohol consumption; best to not drink for cancer prevention
    8) Do not use supplements for cancer prevention; meet nutritional needs through diet
    9) Breastfeed your baby if possible
    10) After cancer diagnosis, follow WCRF recommendations if possible

Osteoporosis

  • 6.1 Natural History of the Skeleton
    • Osteoporosis: decrease in bone mineral density (calcium), leading to bone fragility and increased fracture risk
    • Common fracture sites: spine, wrist, hip
  • 6.2 Dietary Factors
    • Key nutrients and factors: Calcium, Vitamin D, Vitamin K, caffeine, sodium, phosphorus, alcohol, protein, vitamin A, vitamin C, trace minerals (Mg, Cu, Zn, Si, B), isoflavones (soy)
  • 6.3 Non-Dietary Factors
    • Sex, family history/genetics, race/ethnicity, age, exercise, estrogen status, body weight, smoking, medications (e.g., glucocorticoids)
  • 6.4 Calcium and Vitamin D
    • Prevention focuses on maximizing peak bone mass and minimizing postmenopausal bone loss
    • Adequate calcium/vitamin D intake across life stages is essential; dairy (milk) is a major calcium source; one cup of milk ≈ 300 mg calcium
    • Other calcium sources: tofu, certain fish (salmon, sardines)
    • Optimal vitamin D status is essential for calcium utilization; sun exposure contributes to endogenous synthesis; 5–15 minutes of midday sun during spring–fall is often sufficient for many individuals
    • Calcium intakes vary by life stage; refer to DRIs for specifics (Table S-1 in the slides; note: table formatting in source is complex)

Preventive Nutrition in Pregnancy

  • 7. Preventive Nutrition in Pregnancy
  • 7.1 Folic Acid (Vitamin B9) and Prevention of Neural Tube Defects (NTDs)
    • Neural tube forms 21–28 days post-conception; NTDs include spina bifida and anencephaly
    • Adequate periconceptional folic acid nutrition significantly reduces NTD incidence
    • Recommendation: daily multivitamin containing 0.4 mg folic acid beginning before conception; avoid smoking and alcohol
    • Dietary folate alone is not sufficient; synthetic folic acid supplementation is advised in addition to dietary folate
    • Q: Dietary items that contribute most to daily folic acid intake?
  • 7.2 Fetal Alcohol Syndrome (FAS)
    • FAS caused by chronic maternal alcohol exposure during pregnancy; features include low birth weight, craniofacial abnormalities, intellectual disability
    • FAS is completely preventable by avoiding alcohol during pregnancy; effects are irreversible
  • 8. Nutrition Guidelines for Disease Prevention and Health Promotion (summary from Dietary Guidelines)
    • Reiterate the four core dietary principles above
    • Adherence measured by the Healthy Eating Index (HEI)
    • Important note: All women of childbearing age should consume 0.4 mg folic acid per day to reduce risk of NTDs
    • 1992 CDC MMWR guidance: 400 mcg synthetic folic acid daily for women capable of becoming pregnant, in addition to food folate
  • HEI (Healthy Eating Index)
    • Tool to evaluate how well a set of foods aligns with the Dietary Guidelines
    • Scoring: 0–100; higher score = higher diet quality
    • HEI introduced in 1995; used to monitor national adherence

Healthy Eating Index (HEI) and Diet Quality Across Life Stages

  • HEI-2015: maximum total score = 100
  • Age-group adherence (summary from slides):
    • Ages 2–4; 5–8; 9–13; 14–18; 19–30; 31–59; 60+; scores shown in figure indicate variable adherence levels across life stages
  • Resources for more information on nutrition in health and disease (web resources):
    • Eatright.org (Academy of Nutrition and Dietetics)
    • Nutrition Reviews (I.L.I.S. content)
    • American Journal of Clinical Nutrition (AJCN)
    • Annual Review of Nutrition

Practical Tools, Formulas, and Examples (Summary of Key Calculations)

  • BMI (used to assess obesity and overweight status):
    • BMI = rac{weight\ (kg)}{(height\ (m))^2}
  • Mifflin–St Jeor equations for estimating resting metabolic rate (RMR):
    • Men: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age + 5
    • Women: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age - 161
  • Total energy needs (approximate):
    • Total\ Energy\ Needs = BMR \times AF
    • Activity factor (AF): Sedentary 1.0–1.4, Low active 1.4–1.6, Active 1.6–1.9, Very active 1.9–2.5
  • Example (provided in notes): 40-year-old, 5'4", 160 lb, lightly active
    • Weight: 72.7\text{ kg}; Height: 162.6\text{ cm}; AF ≈ 1.4; Estimated daily energy ~1,935\text{ kcal}
  • Weight loss planning (conceptual)
    • Target: 5–10% weight loss in 6 months
    • Rough rule (older guidance): 1 lb fat ≈ 3,500 kcal; 500 kcal/day deficit ≈ 1 lb/week; 6 months ≈ 24 weeks → ~24–25 lb potential weight loss with perfect adherence (note: individual variability and RMR changes occur)
  • Macronutrient diet patterns (overview)
    • No single macronutrient consistently superior for long-term weight loss
    • Various patterns: moderate-fat/moderate-protein/high-carb; high-fat/high-protein/low-carb (e.g., Atkins) – not recommended by this course; very-low-fat/moderate-protein/high-carb (Dean Ornish/vegetarian) – included as examples
    • Intermittent fasting (IF) / energy-restriction patterns: evidence on long-term benefits limited; adherence and personalization are key

Practical Dietary Guidance Highlights

  • Beverage consumption matters; liquid calories affect energy balance
  • Portion size awareness is crucial due to gradual increases in U.S. portion sizes over the last two decades
  • DASH Diet details:
    • Emphasizes fruits, vegetables, low-fat dairy; rich in potassium, magnesium, calcium; adequate protein and fiber
    • Sodium target: generally 1,500–2,300 mg/day depending on plan; practical tips include avoiding table salt and limiting high-sodium foods
  • Mediterranean Diet details:
    • Emphasizes olive/canola oil; at least two servings of fish per week; plant-forward foods; herbs/spices rather than salt; decreased red meat; increased vegetables, fruits, whole grains; moderate dairy; optional red wine in moderation
    • Associated with improved heart health outcomes
  • Key public health messages throughout: smoking cessation and sun exposure moderation as non-dietary health determinants

Tables/Reference Points (as described in transcript)

  • TLC Diet macronutrient targets (NCEP guidelines):
    • Total fat: 25–30% of calories
    • Saturated fat: ≤ 7% of calories
    • Monounsaturated fat: 25–30% of calories
    • Polyunsaturated fat: ≤ 10% of calories
    • Cholesterol: ≤ 200 mg/day
    • Protein: ~15% of calories
    • Carbohydrate: 50–60% of calories
    • Fiber: 20–30 g/day; Soluble fiber: 10–25 g/day
  • DASH Sodium targets (for 2,000 kcal/day baseline):
    • General: 1,500–2,300 mg sodium/day depending on plan
    • Specific guidance: limit foods with >300 mg sodium per serving; avoid table salt; prefer fresh, minimally processed foods
  • Calcium and Vitamin D (osteoporosis context):
    • Calcium sources: dairy (one cup milk ≈ 300 mg calcium), tofu, some fish (salmon, sardines)
    • Vitamin D status: optimal status important for calcium utilization; sun exposure provides a portion of needs; 5–15 minutes midday sun in spring–fall suffices for many individuals
    • Calcium DRIs vary by life stage (AI/EAR/RDA/UL ranges provided in Table S-1; refer to the source for exact values by age and sex)
  • Folic acid and pregnancy: 0.4 mg folic acid per day beginning before conception; supplement to achieve 400 mcg/day synthetic folic acid in addition to dietary folate
  • Important public health note: Healthy Eating Index (HEI) measures adherence to the Dietary Guidelines; HEI scores range 0–100; higher scores indicate better alignment

Connections to Foundational Principles and Real-World Relevance

  • Preventive nutrition intersects with epidemiology (mortality data), behavioral science (behavior modification in obesity treatment), and public health policy (Dietary Guidelines, HEI, DASH/Mediterranean patterns)
  • Weight management is multifactorial: energy balance, diet quality, portion sizes, physical activity, behavior modification, and adherence
  • Sodium, potassium, calcium, vitamin D, and folate play central roles in cardiovascular and skeletal health, as well as fetal development
  • Dietary patterns (DASH, Mediterranean) link to lower risks for hypertension and CVD, and are practical, culturally adaptable strategies
  • Nutritional status across the life cycle (pregnancy, infancy, childhood, adolescence, adulthood, older age) influences disease risk and health outcomes; emphasis on periconceptional nutrition and fetal health
  • Ethical and practical implications: access to healthy foods, cultural relevance, affordability, and education influence the ability to follow guidelines; public health messaging emphasizes equity and feasibility

Quick Reference Equations and numeric anchors

  • BMI: BMI = \frac{weight\ (kg)}{(height\ (m))^2}
  • Mifflin–St Jeor (RMR):
    • Men: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age + 5
    • Women: BMR = 10\times weight{kg} + 6.25\times height{cm} - 5\times age - 161
  • Total energy needs: Total\ Energy\ Needs = BMR \times AF with AF categories as above
  • Caloric deficit rule of thumb (older guidance): 1 lb fat ≈ 3500 kcal; ~500 kcal/day deficit yields ~1 lb/week
  • Sodium targets: ≤ 2300 mg/day (general); DASH plan allows lower targets depending on calories
  • Calcium source example: 1 cup milk ≈ 300 mg calcium
  • Folic acid supplementation in preconception: 0.4 mg/day (400 mcg/day) synthetic folic acid in addition to dietary folate

Summary of Public Health Messages to Remember

  • Obesity prevention and treatment rely on a balanced approach to diet, physical activity, and behavior change
  • Heart disease and cancer remain the top causes of death in the US; many deaths are preventable through diet and lifestyle
  • Dietary patterns (DASH, Mediterranean) are practical, evidence-based strategies to improve cardiovascular health
  • Public health guidelines emphasize weight management, nutrient-dense foods, and limiting processed foods, added sugars, sodium, and alcohol
  • Pregnancy health depends on periconceptional nutrition and avoidance of alcohol; folic acid supplementation is essential to prevent NTDs
  • The HEI provides a standardized measure of diet quality relative to dietary guidelines and can guide population and individual improvements

Resources for Further Study

  • Dietary Guidelines for Americans 2020-2025 (Executive Summary & Infographics)
  • NHLBI guidelines: TLC diet details and cardiovascular risk management
  • WCRF/AICR: Diet, Nutrition, Physical Activity, and Cancer: Global Perspective; interactive diet-cancer risk matrix
  • Mifflin–St Jeor equation and other BMI-based assessment tools
  • DASH Diet guidelines and Mediterranean diet resources