Study Notes on Diet, Health, and Chronic Diseases

Chapter 18: Diet and Health Nutrition and Infectious Diseases

Advances in Medical Science

  • Medical science advancements have led to an increase in average life expectancy, primarily through immunizations and antibiotics.

The Immune System

  1. First Lines of Defense: The body utilizes several barriers to fight off infections, which include:

    • Skin

    • Mucous membranes

    • Gastrointestinal (GI) tract

  2. Secondary Mechanisms: If these barriers fail, the cellular components of the immune system are activated.

    • Foreign Cells: The cells that prompt an immune response are referred to as antigens.

  3. Types of White Blood Cells: The two major categories of white blood cells involved in combating infectious diseases are:

    • Phagocytes

    • Lymphocytes

    • Explanation: The organs central to the immune system include the spleen, lymph nodes, and thymus. Antigens can be bacteria, viruses, toxins, or proteins from allergens.

Matching Types of White Blood Cells to Function

  • Lymphocytes:

    • T-cells: Recognize antigens and produce cytokines to destroy particles with foreign antigens. They are highly specific and possess memory. They also participate in transplant rejection.

    • B-cells: Produce antibodies, known as immunoglobulins, that specifically target pathogens.

  • Phagocytes:

    • Neutrophils and macrophages are the initial responders to an infection. They engage by engulfing and digesting pathogens through phagocytosis.

    • Release oxidative molecules that kill microbes.

Nutrition and Immunity

  • The immune system is sensitive to nutritional changes and can be negatively affected by both overnutrition and undernutrition.

  • Immune responses necessitate an increased nutrient supply for:

    • Antibody synthesis

    • Cytokine production

    • Cell multiplication

    • Infectious diseases increase nutrient needs while often decreasing food intake, creating a synergistic downward spiral.

Selected Nutrients and Their Roles in Immune Function

  • Protein: Critical for maintaining healthy skin and epithelial tissues (barriers to infection) and for the synthesis and function of immune organs and cells, including antibody production.

  • Omega-3 Fatty Acids: Promotes the resolution of inflammation through the production of lipid mediators known as resolvins and protectins, enhancing host defense.

  • Vitamin A: Supports healthy epithelial tissues, immune cell replication, antibody production, and anti-inflammatory actions.

  • Vitamin D: Regulates T-cell responses and aids in antibody production.

  • Vitamins C and E: Act as protectants against oxidative damage.

  • Vitamin B6: Essential for effective immune responses and antibody production.

  • Vitamin B12 and Folate: Important in supporting cell replication and specialization for immune cell and antibody production.

  • Selenium: Provides protection against oxidative damage.

  • Zinc: Maintains effective immune responses and is involved in antibody production.

Inflammation and Chronic Diseases

  • The immune system's response to infection or injury involves:

    • Enhanced blood supply to affected areas.

    • Increased blood vessel permeability.

    • Phagocytes engulfing pathogens and producing oxidative molecules for destruction.

  • Chronic Inflammation: Linked to various health issues, particularly obesity, and other harmful factors.

Chronic Diseases

  1. Chronic Disease Causation: Many of the top ten leading causes of death stem from chronic diseases influenced by:

    • Lifestyle factors such as diet, physical inactivity, overweight, tobacco use, and substance abuse.

  2. Risk Factor Interaction: Chronic diseases typically develop from multiple risk factors that can interplay synergistically.

    • Example: Cigarette smoking elevates heart disease risk among predisposed individuals.

Leading Causes of Death in the U.S.

  • Ten leading causes of death are relevant in understanding chronic diseases and their dietary and lifestyle factors impacting health.

Dietary Risk Factors and Chronic Diseases

Examples of Risk Factors

  • Dietary Risk Factors for Chronic Diseases:

    • High added sugars in diets contribute to diabetes, hypertension, and obesity.

    • High salt (sodium) in diets is linked to hypertension and stroke.

    • Diets high in saturated or trans fats correlate with multiple chronic diseases.

    • Diets low in fruits, vegetables, and fiber impact various chronic diseases.

    • Lack of essential vitamins and minerals can elevate chronic disease risks.

  • Non-Dietary Risk Factors: Conditions such as age, genetics, environmental contaminants, a sedentary lifestyle, and smoking all contribute to diseases like cancer, hypertension, diabetes, and cardiovascular diseases.

Interrelationships among Chronic Diseases

  • Cardiovascular Disease: Encompasses heart diseases and blood vessel diseases, with coronary heart disease (CHD) being the most prevalent form, typically attributed to atherosclerosis.

    • Atherosclerosis: Characterized by the accumulation of lipids and other materials in arteries, forming plaques that can cause cardiovascular events.

Definitions Related to Cardiovascular Health

  • Inflammation: An immune response that can lead to tissue damage and contributes to plaque formation in arteries, ultimately resulting in heart disease.

Risk Factors for Coronary Heart Disease (CHD)

  • Major Non-Modifiable Risk Factors: Increasing age, male gender, and family history of early heart disease.

  • Major Modifiable Risk Factors: High LDL cholesterol, low HDL cholesterol, hypertension, diabetes, obesity, physical inactivity, and a diet high in saturated fats and low in vegetables, fruits, and whole grains.

Standards for CHD Risk Factors

  • Total Blood Cholesterol levels are classified into desirable, borderline, and high-risk categories based on milligrams per deciliter (mg/dL). For example:

    • Desirable: Total blood cholesterol <200 mg/dL

    • High risk: Total blood cholesterol >=240 mg/dL

  • BMI classifications correspond as follows:

    • Normal: 18.5–24.9

    • Overweight: 25–29.9

    • Obese: >=30

Hypertension

  • Chronic Hypertension: Risks for heart disease increase with blood pressure elevations, which can injure arterial walls and accelerate plaque formation.

  • Underlying causes are multifactorial, including factors like cardiac output and sodium intake.

Recommendations for Reducing CHD and Hypertension Risk

Dietary Changes

  • Emphasize a nutrition plan that includes:

    • Abundant fruits, vegetables, whole grains, low-fat dairy, fish, legumes, and minimal sweets and red meats.

    • Limit saturated fats to <10% and trans fats to <1% of total kcalories.

    • Limit sodium intake to 1500 mg per day.

  • Alcohol consumption should be moderated based on gender-specific recommendations.

  • Physical Activity Guidelines: Encourage regular aerobic activity to help with weight control and cardiovascular health.

Diabetes Mellitus

  • The rise in diabetes incidence, especially type 2, has paralleled increases in obesity and sedentary lifestyles. Diabetes is recognized as a leading cause of death, often leading to complications such as cardiovascular disease.

Types of Diabetes

  • Type 1 Diabetes: Typically autoimmune, occurring in younger populations.

  • Type 2 Diabetes: More common, usually develops in older individuals, often associated with obesity and lifestyle factors.

Recommendations for Managing Diabetes

  • Dietary management for diabetes involves regulating carbohydrate intake, maintaining even spacing of meals, and monitoring glucose levels closely.

  • Patients should adhere to the Dietary Guidelines for Americans, particularly concerning saturated fat and trans fat intake.

Cancer

  • Cancer remains a significant health challenge, ranking just below cardiovascular disease in mortality.

  • Carcinogenesis refers to the process that transforms normal cells into cancerous cells, driven by genetic mutations and environmental factors.

Environmental and Dietary Contributors to Cancer

  • Factors include radiation, pollution, tobacco, and dietary components.

  • High consumption of red and processed meat has been linked to increased cancer risks, particularly colon cancer due to carcinogenic substances formed when meat is cooked at high temperatures.

Cancer Prevention Measures

  • A robust diet rich in fruits, vegetables, and fiber along with regular physical activity can reduce cancer risk by enhancing immune function and preventing oxidative stress that can damage cellular DNA.

Summary of Dietary Recommendations for Chronic Diseases

  • A holistic approach emphasizes weight control, balanced dietary patterns, and the importance of individualized nutrition plans.

Conclusion

  • Maintaining a healthy lifestyle, inclusive of balanced nutrition and regular physical activity, is vital for preventing chronic diseases and achieving overall health and well-being.