Nutrition

The three macronutrients supply energy and the raw materials the body needs.

• Carbohydrates are the body's main energy source (4 kcal/g); found in grains, fruits, and vegetables, they break down into glucose.
• Fats (lipids) are the most energy-dense macronutrient (9 kcal/g); they store energy, cushion organs, and help absorb fat-soluble vitamins.
• Proteins (4 kcal/g) build and repair tissue and make enzymes and hormones; they are built from amino acids.
• A balanced diet includes all three in appropriate proportions.

Micronutrients are needed in small amounts but are essential for health.

• Water-soluble vitamins (B-complex, C) are not stored and must be eaten regularly.
• Fat-soluble vitamins (A, D, E, K) are stored in body fat and can build up if overconsumed.
• Major minerals (calcium, potassium, sodium) and trace minerals (iron, zinc, iodine) support bones, nerves, and metabolism.
• Deficiencies cause specific conditions (e.g., vitamin C → scurvy, iron → anemia).

Water and electrolytes keep the body's internal environment stable.

• Water is about 60% of body weight and is needed for temperature control, transport, and reactions.
• Electrolytes (sodium, potassium, chloride) maintain fluid balance and nerve/muscle function.
• Intake should roughly match output; both dehydration and overhydration disrupt balance.
• Thirst, urine color, and skin turgor are simple hydration indicators.

Nutritional needs change at every stage of life.

• Infants need breast milk or formula; children need nutrients for steady growth.
• Adolescents have high needs for calories, calcium, and iron.
• Pregnancy and lactation increase needs for folate, iron, and protein.
• Older adults often need fewer calories but more calcium, vitamin D, and B12.

Food is broken down, absorbed, and used for energy and building.

• Digestion mechanically and chemically breaks food into nutrients along the GI tract.
• Absorption happens mainly in the small intestine, moving nutrients into the blood.
• Metabolism includes catabolism (breaking down for energy) and anabolism (building tissue).
• The liver, pancreas, and digestive enzymes play major roles.

Culture, religion, and environment shape how and what people eat.

• Food choices reflect tradition, religion, geography, and economics.
• Some cultures follow dietary laws (e.g., halal, kosher) or vegetarian diets.
• Respecting cultural food practices matters in healthcare and counseling.
• Access and cost strongly affect food habits and nutrition.

Some foods cause illness or adverse reactions.

• Foodborne illness comes from pathogens like Salmonella, E. coli, and norovirus; safe handling prevents it.
• Food intolerance (e.g., lactose intolerance) is a digestive problem, not an immune one.
• Food allergies are immune reactions (e.g., peanuts, shellfish) that can be severe (anaphylaxis).
• Reading labels and following food safety reduce the risk.

Tailored diets are used to manage or treat medical conditions.

• Diabetes: controlling carbohydrates and keeping meals consistent.
• Heart disease: limiting saturated fat and sodium.
• Kidney disease: managing protein, sodium, potassium, and phosphorus.
• Registered dietitians design and monitor these therapeutic diets.