Comprehensive Study Guide: Vitamins, Minerals, Water Balance, and Energy Balance in Human Nutrition

Vitamins

Names, Functions, Food Sources, Toxicity, and Deficiencies

Vitamins are organic compounds essential for normal physiological function, growth, and maintenance. They are classified as either fat-soluble or water-soluble.

• Fat-Soluble Vitamins: Vitamins A, D, E, K

• Water-Soluble Vitamins: B-complex vitamins (e.g., B1, B2, B3, B6, B12, folate, biotin, pantothenic acid) and Vitamin C

• Functions: Each vitamin has specific roles, such as Vitamin A for vision, Vitamin D for calcium absorption, Vitamin C for collagen synthesis, and B vitamins for energy metabolism.

• Food Sources: Fruits, vegetables, dairy, meats, grains, and fortified foods.

• Toxicity: More common with fat-soluble vitamins due to storage in body tissues (e.g., hypervitaminosis A).

• Deficiencies: Lead to specific diseases (e.g., scurvy for Vitamin C, rickets for Vitamin D).

Example: Vitamin C deficiency causes scurvy, characterized by bleeding gums and poor wound healing.

Major Minerals

Names, Functions, Food Sources, Toxicity, and Deficiencies

Minerals are inorganic nutrients required in small amounts for various body functions. Major minerals include sodium (Na), chloride (Cl), potassium (K), calcium (Ca), phosphorus (P), iron (Fe), copper, selenium, and iodide.

Mineral	Function	Food Sources	Toxicity	Deficiency
Sodium (Na)	Fluid balance, nerve transmission	Table salt, processed foods	Hypertension	Muscle cramps
Chloride (Cl)	Fluid balance, stomach acid (HCl)	Table salt	Rare	Rare
Potassium (K)	Muscle contraction, nerve function	Fruits, vegetables	Heart arrhythmias	Weakness, paralysis
Calcium (Ca)	Bone health, muscle function	Dairy, leafy greens	Kidney stones	Osteoporosis
Phosphorus (P)	Bone health, energy metabolism	Meat, dairy	Calcification of tissues	Bone pain
Iron (Fe)	Oxygen transport (hemoglobin)	Red meat, legumes	Organ damage	Anemia
Copper	Iron metabolism, antioxidant	Shellfish, nuts	Liver damage	Anemia
Selenium	Antioxidant, thyroid function	Nuts, seafood	Hair loss	Keshan disease
Iodide	Thyroid hormone synthesis	Iodized salt, seafood	Thyroid dysfunction	Goiter

JfktAdditional info: Some toxicity and deficiency symptoms are inferred based on standard nutrition knowledge.

Bioavailability of Vitamins and Minerals

Factors Affecting Bioavailability

Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body.

• Food Matrix: Nutrient absorption can be affected by the presence of other compounds (e.g., phytates, oxalates).

• Form of Nutrient: Heme iron (animal sources) is more bioavailable than non-heme iron (plant sources).

• Nutrient-Nutrient Interactions: Vitamin C enhances iron absorption; calcium competes with iron and zinc.

• Physiological Need: Higher absorption when body stores are low.

• Health Status: Digestive disorders can reduce absorption.

Water Balance and Body Fluids

Body Fluid Locations, Percentages, and Hormonal Control

Water is distributed in intracellular and extracellular compartments. Hormones regulate water balance and blood pressure.

• Intracellular Fluid (ICF): About 2/3 of body water is inside cells.

• Extracellular Fluid (ECF): About 1/3 of body water is outside cells (includes plasma and interstitial fluid).

• Hormonal Control: Antidiuretic hormone (ADH), aldosterone, and renin-angiotensin system regulate blood volume and pressure.

Example: ADH increases water reabsorption in the kidneys, raising blood volume and pressure.

Water: Functions, Sources, and Intake

Functions, Sources, Excess, and Deficiency

Water is vital for life, serving as a solvent, temperature regulator, and medium for biochemical reactions.

• Functions: Solvent, transport, temperature regulation, waste removal, lubrication.

• Sources: Beverages, food, metabolic water.

• Excess Intake: Can cause hyponatremia (low blood sodium).

• Deficiency: Leads to dehydration, impaired function, and in severe cases, death.

Energy Balance

Definition, Imbalances, and Measurement

Energy balance is the relationship between energy intake and energy expenditure.

• Energy Balance: Energy in = energy out; maintains body weight.

• Positive Energy Balance: Intake > expenditure; leads to weight gain.

• Negative Energy Balance: Intake < expenditure; leads to weight loss.

• Components of Total Energy Expenditure (TEE):

  • Basal Metabolic Rate (BMR): Energy for basic functions at rest.

  • Thermic Effect of Food (TEF): Energy for digestion and absorption.

  • Physical Activity: Energy for movement.

• Measurement Methods: Direct and indirect calorimetry, equations (e.g., Harris-Benedict equation).

Equation:

$\text{Energy Balance} = \text{Energy Intake} - \text{Energy Expenditure}$

Body Composition Assessment

Methods to Assess Lean Body Mass and Body Fat

Several techniques are used to estimate body composition.

• Anthropometry: Skinfold thickness measurements.

• Bioelectrical Impedance Analysis (BIA): Measures resistance to electrical flow.

• Dual-Energy X-ray Absorptiometry (DEXA): Measures bone, fat, and lean tissue.

• Hydrostatic Weighing: Based on water displacement.

• Air Displacement Plethysmography (BodPod): Measures body volume and density.

Body Mass Index (BMI) and Weight Status

Definitions and Classifications

BMI is a screening tool for weight status based on height and weight.

• BMI Formula:

$\text{BMI} = \frac{\text{weight (kg)}}{\text{height (m)}^2}$

• Underweight: BMI < 18.5

• Normal weight: BMI 18.5–24.9

• Overweight: BMI 25–29.9

• Obesity: BMI ≥ 30

Hunger, Appetite, and Satiety

Definitions and Differences

These terms describe different aspects of food intake regulation.

• Hunger: Physiological need for food.

• Appetite: Psychological desire for food, influenced by environment and emotions.

• Satiety: Feeling of fullness that suppresses further eating.

Fat Cell Size Control

Regulation of Adipocyte Size

Fat cells (adipocytes) can increase in size (hypertrophy) and number (hyperplasia) in response to energy surplus.

• Weight Gain: Fat cells enlarge and may multiply.

• Weight Loss: Fat cells shrink but do not decrease in number.

Disordered Eating vs. Eating Disorders

Definitions and Distinctions

Disordered eating includes a range of irregular eating behaviors, while eating disorders are clinically diagnosed conditions.

• Disordered Eating: Irregular, unhealthy eating patterns (e.g., chronic dieting).

• Eating Disorders: Diagnosed psychiatric conditions (e.g., anorexia nervosa, bulimia nervosa, binge-eating disorder).

Types of Eating Disorders

Major Diagnosed Eating Disorders

• Anorexia Nervosa: Restriction of energy intake, intense fear of weight gain, distorted body image.

• Bulimia Nervosa: Recurrent binge eating followed by compensatory behaviors (e.g., vomiting, laxatives).

• Binge-Eating Disorder: Recurrent episodes of binge eating without compensatory behaviors.

• Other Specified Feeding or Eating Disorders (OSFED): Symptoms do not meet full criteria for above disorders.

Weight Loss Drugs and Surgical Procedures

Mechanisms of Action

• Weight Loss Drugs: May suppress appetite, reduce fat absorption, or increase satiety (e.g., orlistat, phentermine).

• Surgical Procedures: Bariatric surgeries (e.g., gastric bypass, sleeve gastrectomy) reduce stomach size or nutrient absorption.

Example: Gastric bypass surgery reroutes the digestive tract to limit food intake and absorption.

Strategies for Healthy Weight Gain

Recommended Approaches

• Increase energy intake with nutrient-dense foods.

• Eat more frequent meals and snacks.

• Include strength training to promote muscle gain.

• Choose healthy fats (e.g., nuts, avocados) and lean proteins.

Additional info: Avoid excessive intake of added sugars and saturated fats for healthy weight gain.