Food, Nutrition, and Disease: Study Notes for Personal Health

Task 6: Atherosclerosis and Cardiovascular Disease (CVD)

Atherosclerosis

Atherosclerosis is a chronic disease characterized by the accumulation of lipids, fibrous elements, and calcifications within large arteries. It is a leading cause of death worldwide due to its role in cardiovascular complications.

• Definition: Progressive narrowing and hardening of arteries due to plaque buildup.

• Pathogenesis: Initiated by endothelial dysfunction, followed by lipid infiltration, inflammation, and plaque formation.

• Risk Factors: High LDL cholesterol, hypertension, smoking, diabetes, and genetic predisposition.

• Complications: Can lead to heart attack, stroke, and peripheral artery disease.

• Example: Coronary artery atherosclerosis leading to myocardial infarction.

Endothelial Dysfunction

The endothelium is a thin layer of cells lining blood vessels, crucial for vascular health. Dysfunction is a key early event in atherosclerosis.

• Causes: Low shear stress, hypertension, hyperlipidemia, smoking.

• Effects: Increased permeability, leukocyte adhesion, and pro-inflammatory signaling.

Thrombosis

Thrombosis is the formation of a blood clot within a vessel, often as a complication of atherosclerosis.

• Steps:

  1. Plaque rupture exposes underlying tissue.

  2. Platelet adhesion and activation.

  3. Coagulation cascade forms fibrin mesh.

  4. Thrombus formation may occlude the vessel, causing ischemia.

• Clinical relevance: Acute events like heart attack and stroke.

Cholesterol Metabolism

Cholesterol is vital for cell membranes, hormone synthesis, and bile acid production. Its metabolism involves absorption, synthesis, transport, and excretion.

• Key Pathways: Intestinal absorption, hepatic synthesis, and lipoprotein transport.

• Regulation: Enzymes like HMG-CoA reductase control synthesis; dietary intake and genetic factors influence levels.

• Formula: $\text{Cholesterol}_{\text{total}} = \text{HDL} + \text{LDL} + \text{VLDL}$

Lipoproteins

Lipoproteins are complexes that transport lipids in plasma. They differ in size, density, and function.

• Types: Chylomicrons, VLDL, LDL, HDL.

• LDL: Major carrier of cholesterol, associated with increased risk of atherosclerosis.

• HDL: Involved in reverse cholesterol transport, protective against CVD.

Lipoprotein	Density (g/mL)	Size (nm)	Major Lipid	Major Apoproteins
Chylomicrons	<0.930	75-1200	Triglycerides	Apo B, Apo C, Apo E
VLDL	0.930-1.006	30-80	Triglycerides	Apo B, Apo C, Apo E
LDL	1.019-1.063	18-25	Cholesterol	Apo B
HDL	1.063-1.210	8-12	Cholesterol	Apo A-I, Apo A-II

Plant Stanols and Sterols

Plant stanols and sterols are compounds structurally similar to cholesterol, found in plant cell membranes. They help lower cholesterol absorption.

• Sources: Vegetable oils, nuts, seeds.

• Mechanism: Compete with cholesterol for absorption, reducing LDL levels.

• Clinical Use: Used in functional foods to manage hypercholesterolemia.

Beta-glucans

Beta-glucans are polysaccharides found in oats and barley, known for their cholesterol-lowering effects.

• Mechanism: Increase viscosity in the gut, interfering with bile acid and cholesterol reabsorption.

• Health Benefits: Lower LDL cholesterol, improve glycemic control.

Task 7: Diabetes Management

Glucose Homeostasis

Glucose homeostasis is the balance of insulin and glucagon to maintain blood glucose levels. The pancreas plays a central role.

• Insulin: Lowers blood glucose by promoting uptake into cells.

• Glucagon: Raises blood glucose by stimulating glycogen breakdown.

• Formula: $\text{Blood Glucose}_{\text{postprandial}} = \text{Blood Glucose}_{\text{fasting}} + \text{Glucose Intake} - \text{Cellular Uptake}$

Hormone	Source	Effect
Insulin	Beta cells	Lowers blood glucose
Glucagon	Alpha cells	Raises blood glucose
Somatostatin	Delta cells	Inhibits insulin and glucagon
Pancreatic polypeptide	PP cells	Regulates pancreatic secretion

Insulin Production and Release

Insulin is synthesized in pancreatic beta cells and released in response to elevated blood glucose.

• Process: Preproinsulin → Proinsulin → Insulin (via proteolytic cleavage).

• Regulation: Glucose-stimulated insulin secretion involves ATP-sensitive potassium channels and calcium influx.

Glucose Regulation in Skeletal Muscle

Skeletal muscle is the primary site for insulin-stimulated glucose uptake after meals.

• Insulin Signaling: Involves IRS, PI3K, Akt, and GLUT4 translocation.

• Insulin Resistance: Accumulation of lipid intermediates impairs signaling, reducing glucose uptake.

Glucose Regulation in Adipose Tissue

Adipose tissue regulates glucose uptake and lipid metabolism, influencing whole-body insulin sensitivity.

• Insulin Action: Suppresses lipolysis, promotes glucose uptake.

• Insulin Resistance: Leads to increased lipolysis and impaired glucose uptake.

Glucose Regulation in Liver

The liver maintains glucose stability during fasting and after meals by regulating production and storage.

• Insulin Action: Suppresses gluconeogenesis, promotes glycogen synthesis.

• Insulin Resistance: Increases hepatic glucose output, contributing to hyperglycemia.

Insulin Sensitivity and Resistance

Insulin sensitivity is the ability of tissues to respond to insulin. Insulin resistance is a reduced response, leading to hyperglycemia and metabolic syndrome.

• High Sensitivity: Efficient receptor activation, robust signaling, and proper GLUT4 translocation.

• Insulin Resistance: Triggered by inactivity, obesity, and inflammation; leads to impaired glucose uptake.

Type 2 Diabetes Mellitus (T2DM)

Type 2 diabetes is characterized by insulin resistance and relative insulin deficiency. It is the most common form of diabetes.

• Risk Factors: Obesity, aging, physical inactivity, genetic predisposition.

• Complications: Cardiovascular disease, neuropathy, nephropathy, retinopathy.

Effect of Aging

Aging increases risk for insulin resistance and T2DM due to changes in body composition, muscle mass, and mitochondrial function.

• Key Changes: Sarcopenia, reduced muscle insulin sensitivity, impaired mitochondrial function.

Effect of Physical (In)activity

Physical activity improves insulin sensitivity and glucose uptake, while inactivity increases risk for insulin resistance and T2DM.

• Mechanism: Exercise stimulates GLUT4 translocation and enhances muscle glucose uptake.

Effect of Nutrition

Dietary patterns influence glucose homeostasis and insulin sensitivity.

• Healthy Diet: High in fiber, low in saturated fat, rich in whole grains and vegetables.

• Plant Stanols/Sterols and Beta-glucans: Lower cholesterol and improve metabolic health.

Task 8: Bone Health

Bone Function and Anatomy

The skeletal system provides structure, movement, protection, and mineral storage for the human body.

• Main Functions: Support, movement, protection of organs, mineral storage, blood cell formation.

• Components: Bones, cartilage, ligaments, tendons.

Bone Remodeling and Repair

Bones undergo continuous remodeling through the actions of osteoblasts (bone formation) and osteoclasts (bone resorption).

• Remodeling: Maintains bone strength and mineral homeostasis.

• Repair: Involves inflammation, bone formation, and remodeling phases.

Osteoporosis

Osteoporosis is a disease characterized by reduced bone mass and increased fracture risk.

• Risk Factors: Aging, hormonal changes, inadequate calcium/vitamin D, inactivity.

• Prevention: Weight-bearing exercise, adequate nutrition, and lifestyle modifications.

Task 9: Muscle and Aging

Muscle Contraction and Synthesis

Muscle contraction is driven by the interaction of actin and myosin filaments, regulated by calcium ions and ATP.

• Muscle Synthesis: Involves protein synthesis pathways, notably mTOR signaling.

Sarcopenia

Sarcopenia is the age-related loss of muscle mass and function.

• Causes: Aging, inactivity, hormonal changes, poor nutrition.

• Prevention: Resistance training, adequate protein intake, and physical activity.

Nutrition and Aging-Related Muscle Loss

Proper nutrition, especially protein and micronutrients, is essential to prevent muscle loss with aging.

• Key Nutrients: Protein, vitamin D, calcium, omega-3 fatty acids.

Task 10: Exercise Physiology

Energy Metabolism

Energy metabolism refers to the biochemical processes that produce ATP for muscle contraction during exercise.

• Pathways: Aerobic (oxidative phosphorylation) and anaerobic (glycolysis) metabolism.

• Formula: $\text{ATP Production} = \text{Glycolysis} + \text{Oxidative Phosphorylation}$

Reactive Oxygen Species (ROS) and Physical Performance

ROS are byproducts of metabolism that can impair muscle function and recovery if not regulated.

• Antioxidants: Help neutralize ROS and protect muscle tissue.

Sport Supplements

Sport supplements are products used to enhance physical performance, muscle growth, and recovery.

• Common Types: Protein powders, creatine, branched-chain amino acids (BCAAs).

• Creatine: Increases ATP availability for short bursts of high-intensity exercise.

Additional info: These notes expand on the provided content with definitions, mechanisms, and clinical relevance to ensure completeness and academic quality for Personal Health students.