Chapter 5: Nutrition Basics – Core Concepts for Health

Nutrition Basics

Introduction to Nutrition

Nutrition is the science of food and its relationship to health. It involves the study of nutrients in food, how the body uses them, and the relationship between diet, health, and disease.

• Nutrients are substances in food that provide energy, structure, and regulation for the body’s processes.

• There are six major classes of nutrients: carbohydrates, proteins, fats, vitamins, minerals, and water.

The Six Classes of Nutrients

Nutrient	Main Sources	Major Functions
Proteins	Meat, fish, dairy, eggs, legumes, nuts	Builds and repairs tissues, provides energy
Carbohydrates	Breads, cereals, fruits, vegetables	Primary energy source
Fats (Lipids)	Oils, butter, nuts, seeds, animal fats	Energy storage, cell structure, absorption of fat-soluble vitamins
Vitamins	Fruits, vegetables, dairy, grains	Regulate body processes, support immune function
Minerals	Fruits, vegetables, legumes, dairy	Body structure (bones, teeth), fluid balance, nerve transmission
Water	Most foods, beverages	Solvent, temperature regulation, transport of nutrients

The Human Body & Digestion

The Digestive System

The digestive system breaks down food into nutrients, which are absorbed into the bloodstream and transported to cells.

• Food energy is measured in kilocalories (kcal).

• Macronutrient energy supply:

  • Fat: 9 kcal/g

  • Protein: 4 kcal/g

  • Carbohydrate: 4 kcal/g

  • Alcohol: 7 kcal/g (not an essential nutrient)

Macronutrients

Proteins: The Basis of Structure

Proteins are made of amino acids and are essential for building and repairing tissues.

• Amino acids are the building blocks of protein.

• Essential amino acids must be obtained from the diet; non-essential amino acids can be synthesized by the body.

• Protein sources are classified as complete (all essential amino acids) or incomplete (lacking one or more essential amino acids).

• Recommended intake: about 0.8 g/kg body weight for adults.

Fats: Essential in Small Amounts

Fats are concentrated sources of energy and are necessary for the absorption of fat-soluble vitamins and cell structure.

• Types: Triglycerides (glycerol + three fatty acids), saturated, unsaturated, polyunsaturated, monounsaturated.

• Main sources: animal and plant foods.

• Polyunsaturated fats include Omega-3 and Omega-6 fatty acids.

• Most Canadians consume more Omega-6 than Omega-3 fats.

Triglyceride Structure

A triglyceride consists of a glycerol backbone attached to three fatty acid chains.

Fats and Health

• Saturated fats raise LDL (“bad cholesterol”).

• Unsaturated fats may raise HDL (“good cholesterol”).

• High intake of saturated fats is associated with increased risk of cardiovascular disease.

Carbohydrates: An Ideal Source of Energy

Carbohydrates are the body’s preferred energy source and are divided into simple and complex forms.

• Simple carbohydrates: sugars (glucose, sucrose, lactose).

• Complex carbohydrates: starches and dietary fiber.

• Glycemic index measures the effect of carbohydrates on blood glucose levels.

• Recommended intake: 45–65% of total daily calories.

Fibre: A Closer Look

• Types: Soluble fiber (slows stomach emptying, lowers cholesterol) and insoluble fiber (increases fecal bulk, prevents constipation).

• High fiber intake is associated with reduced risk of type 2 diabetes, heart disease, and colon cancer.

• Recommended intake: 38 g/day for men, 25 g/day for women.

Micronutrients

Vitamins: Organic Micronutrients

Vitamins are organic compounds required in small amounts for normal metabolism and health.

• Do not provide energy but are essential for metabolic processes.

• Fat-soluble vitamins: A, D, E, K (can be stored in the body).

• Water-soluble vitamins: B-complex, C (not stored, must be consumed regularly).

• Deficiencies are more common in developing countries.

Table: Fat-Soluble Vitamins

Vitamin	Sources	Major Functions	Deficiency
Vitamin A	Liver, dairy, carrots	Vision, immune function	Night blindness
Vitamin D	Sunlight, fish, eggs	Bone health	Rickets, osteomalacia
Vitamin E	Nuts, seeds, vegetable oils	Antioxidant	Nerve problems
Vitamin K	Leafy greens	Blood clotting	Bleeding disorders

Table: Water-Soluble Vitamins

Vitamin	Sources	Major Functions	Deficiency
Vitamin C	Citrus fruits	Antioxidant, collagen synthesis	Scurvy
Vitamin B12	Animal products	Red blood cell formation	Anemia
Folate	Leafy greens	DNA synthesis	Neural tube defects

Minerals: Inorganic Micronutrients

Minerals are inorganic elements essential for body structure and regulation.

• About 17 essential minerals, including calcium, phosphorus, potassium, sodium, chloride, sulfur, magnesium, iron, and zinc.

• Major minerals are needed in amounts >100 mg/day; trace minerals are needed in smaller amounts.

Table: Selected Minerals

Mineral	Sources	Major Functions	Deficiency
Calcium	Dairy, leafy greens	Bone health	Osteoporosis
Iron	Meat, legumes	Oxygen transport	Anemia
Potassium	Fruits, vegetables	Fluid balance	Muscle weakness
Sodium	Salt, processed foods	Fluid balance	Muscle cramps

Water: Vital but Often Ignored

Water is essential for life, making up a large proportion of body weight and involved in all bodily functions.

• Acts as a solvent, regulates temperature, and transports nutrients and waste.

• Contained in most foods; beverages are a major source.

• Recommended intake: about 3 L/day for men, 2.2 L/day for women (Health Canada).

Other Substances in Food

Foods contain other beneficial substances such as antioxidants and phytochemicals.

• Antioxidants protect the body from free radical damage (e.g., vitamins A, C, E, carotenoids).

• Phytochemicals are plant compounds that may reduce the risk of chronic diseases.

Guidelines for Healthful Eating

• Choose a variety of foods to ensure nutrient adequacy.

• Limit intake of added sugars, saturated fats, and sodium.

• Eat plenty of vegetables, fruits, whole grains, and protein foods.

• Be mindful of portion sizes and eating habits, especially when eating away from home.

Table: Nutrient Density of Selected Beverages

Different beverages provide varying amounts of nutrients and calories. Water and milk are generally more nutrient-dense compared to sugary drinks and alcohol.

Canada’s Food Guide & DRI Goals

• Fats: 20–35% of total daily calories; saturated fat <10%, cholesterol <300 mg/day.

• Two servings/week of fish (Omega-3 fatty acids) recommended.

• Limit sodium intake to about 1500 mg/day.

Types of Vegetarian Diets

• Lacto-ovo-vegetarians: include dairy and eggs.

• Lacto-vegetarians: include dairy, exclude eggs.

• Vegans: exclude all animal products.

• Vegetarian diets can be healthful but require careful planning to ensure adequate intake of protein, vitamin B12, iron, calcium, and zinc.

Reading Food Labels

• All processed foods must include standardized nutrition information.

• Labels show serving size, calories, fat, cholesterol, sodium, fiber, sugars, and protein.

Food Safety & Regulation

Protecting Yourself Against Food-Borne Illness

• Microorganisms are the main cause of food-borne illness.

• Proper food handling, cooking, and storage are essential for prevention.

• Vulnerable groups include children, pregnant women, older adults, and immunocompromised individuals.

Organic Foods

• Certified organic foods must meet strict production and processing standards.

• Organic foods are grown without synthetic pesticides or fertilizers.

• Organic foods may be better for the environment but are not necessarily more nutritious.

Additives in Foods

• Food additives are used to improve or maintain nutritional quality, freshness, and appearance.

• Some additives may cause reactions in sensitive individuals (e.g., MSG).

Genetically Modified Foods

• Genetically modified (GM) foods have altered DNA to improve yield, resistance, or nutritional content.

• GM foods are considered safe but require ongoing research and regulation.

Food Allergies and Intolerances

Food Allergies

• An allergy is an immune response to a food protein.

• Symptoms can range from mild (rash, swelling) to severe (anaphylaxis).

• Priority allergens include peanuts, tree nuts, milk, eggs, fish, shellfish, soy, wheat, sesame, and mustard.

Food Intolerances

• Food intolerances involve the metabolic system, not the immune system (e.g., lactose intolerance, gluten intolerance).

• Symptoms are often localized and less severe than allergies.

• Diagnosis is often by trial and error; consult a dietitian or physician for guidance.

Additional info: This summary expands on the provided slides with definitions, examples, and academic context to ensure completeness and clarity for exam preparation.