Understanding Nutrition

Take Home Messages

• Foods provide nutrients essential for bodily functions.
• A well-planned diet is rich in a variety of nutrients, moderate in calories, and enjoyable to consume.
• Proper eating habits include variety and moderation.
• Emphasize vegetables, fruits, whole grains, and lean proteins.
• Minimize "empty calories," added sugars, animal fats, and salt (sodium).
• Healthy eating maximizes health and minimizes disease risk.

Summary: Nutrition

• Nutrition is the act or process of nourishing or being nourished.
• Digestion breaks food down into nutrients that are small enough to be absorbed into the blood.
• Regular consumption of food and drinks determines the nutrient composition of your diet.
• Once absorbed, nutrients are metabolized.
• Excess calories are converted to fat and stored.
• Dietary choices should be made carefully.

The Six Classes of Essential Nutrients

• Proteins (4 calories/gram) form muscles, bone, blood, enzymes, cell membranes, repair tissue, regulate water and acid-base balance, help in growth, and supply energy; found in meat, fish, poultry, eggs, milk products, legumes, and nuts.
• Carbohydrates (4 calories/gram) supply energy to cells in the brain, nervous system, and blood, and to muscles during exercise; found in grains, breads and cereals, fruits, vegetables, and milk.
• Fats (9 calories/gram) supply energy, insulate, support, and cushion organs, and provide a medium for absorption of fat-soluble vitamins; found in animal foods, grains, nuts, seeds, fish, and vegetables.
• Vitamins promote or speed up specific chemical reactions within cells; abundant in fruits, vegetables, grains, meat, and dairy products.
• Minerals help regulate body functions, aid in growth and maintenance of body tissues, and act as catalysts for the release of energy; found in most food groups.
• Water makes up approximately 60% of body weight, provides a medium for chemical reactions, transports chemicals, regulates temperature, and removes waste products; found in fruits, vegetables, and liquids.
• Essential nutrients are substances that must be obtained from the diet, as the body cannot make them or cannot make them quickly enough to meet needs.

Macronutrients: Protein

• Basic framework of muscles, bones, blood, hair, and fingernails.
• Found in a combination of 20 amino acids; nine are essential (the body cannot produce them).
• Animal proteins (meat, poultry, fish) and soy are complete.
  • Complete proteins contain all nine essential amino acids.
• Grains, dry beans, and nuts are incomplete.
  • These foods lack some or all essential amino acids.
  • Incomplete proteins together can make complete protein.
• The recommended intake is 0.8 g/kg of body weight per day.
• Protein provides 4 kcal/g but is not a primary energy source.

Macronutrients: Fats (Lipids)

• Provides 9 kcal/g, a dense energy source.
• It is the main fuel source during rest and light activity.
• It carries fat-soluble vitamins (A, D, E, K).
• Fats protect organs from injury and help regulate body temperature.
• They are involved in growth and development and used to make some hormones.
• Excess calories are stored as triglycerides.
• Unsaturated fats (e.g., vegetable) are liquid at room temperature and may help to lower the risk of heart disease (CVD).
• Saturated fats (e.g., animal fats) are solid at room temperature and may be associated with an increased risk of heart disease.
• Trans fats (e.g., hydrogenated fats) are synthetic unsaturated fats that are unhealthy.
  • They are most strongly linked to CVD.
  • Minimize or eliminate from diet.

Types of Fatty Acids and Their Possible Effects on Health

• Saturated fats, found in animal fats, butter, cheese, and palm and coconut oils, raise total and LDL cholesterol levels and increase the risk of heart disease.
  • They may increase the risk of colon and prostate cancers.
• Trans fats, found in French fries, stick margarines, packaged cookies, and processed snacks, raise total and LDL cholesterol levels and lower HDL cholesterol levels.
  • They may increase the risk of heart disease and breast cancer.
• Monounsaturated fats, found in olive, canola, and safflower oils, avocados, and nuts, lower total and LDL cholesterol levels.
  • They may reduce blood pressure and triglyceride levels and may reduce the risk of heart disease, stroke, and some cancers.
• Polyunsaturated fats, including Omega-3 fatty acids, found in fatty fish, flaxseed, canola, and soybean oils, reduce blood clotting and inflammation and inhibit abnormal heart rhythms.
  • They may lower triglyceride levels and blood pressure and reduce the risk of fatal heart attack, stroke, and some cancers.
• Omega-6 fatty acids, found in corn, soybean, and cottonseed oils, lower total and LDL cholesterol levels and may reduce the risk of heart disease.
  • They may slightly increase the risk of cancer if omega-6 intake is high and omega-3 intake is low.

Macronutrients: Carbohydrates

• It is the primary source of energy for the body's cells.
• The brain can only use carbohydrates for fuel.
• Many other tissues can switch to fats if needed.
• Metabolized to simple sugars (e.g., glucose), which circulates in the body and is taken up by cells.
• Supplies 4 kcal/g of energy.
• Simple carbohydrates consist of 1 or 2 sugar units (e.g., table sugar, fruit, milk, added sweets).
  • They are more likely to produce hyperglycemia.
• Complex carbohydrates consist of longer chains of sugar units (e.g., grains, cereals, vegetables, beans).
  • They take longer to digest and are richer in fibre.
  • Help regulate blood glucose (sugar) and promote fullness.
• Animals, including humans, store some carbs as glycogen (in the liver and in muscle).
• Fibre is a complex plant carb we cannot digest.
  • It promotes regularity and heart health.
  • Fibre-rich foods include whole wheats, ryes, oats, and barley.

Micronutrients: Vitamins & Minerals

• Vitamins are organic compounds (contain carbon).
  • They help regulate body growth, maintain tissue, and release energy from foods.
  • They are involved in the manufacture of blood cells, hormones, and other compounds (e.g., A, D, E, K, thiamine, niacin, folate).
• Minerals help build bones and teeth and aid in muscle function.
  • They help the nervous system transmit messages and with enzymatic function (e.g., sodium, potassium, calcium, chloride, iron, zinc, magnesium, iodine).

Other Substances in Foods

• Antioxidants prevent harmful effects caused by oxidation in the body or exposure to environmental factors.
  • Examples include Vitamins C and E, and carotenoids.
  • Blackberries, walnuts, strawberries, cloves, and red wine are rich in antioxidants.
  • Antioxidants may help prevent some cancers and the effects of aging.
• Phytochemicals are compounds (e.g., capsaicin) found in plants that may be associated with a reduced risk of heart disease, certain cancers, Type II diabetes, and stroke.

Water

• Water's composition:
  • 85% of blood of water.
  • 70% of muscles of water.
  • 75% of brain of water.
• 2-2.5 litres of water are lost a day and must be replenished
• Functions:
  • Carries nutrients.
  • Maintains temperature.
  • Lubricates joints.
  • Aids digestions.
  • Removes waste via urine.
  • Sweat to cool the body.

Nutritional Terminology

• Dietary Reference Intake (DRI) are scientifically based reference values for the amounts of energy, nutrients, and other food components that are necessary to reduce chronic disease risk, promote general health, and minimize symptoms of deficiency.
• Recommended Dietary Allowance (RDA) is the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy individuals.
• Adequate Intake (AI) is established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy.
• Tolerable Upper Intake Level (UL) is the maximum daily intake unlikely to cause adverse health effects.
  • Not all dietary substances have a UL (e.g., sodium).

Nutrient Density

• Refers to foods being high in nutrients and relatively low in calories.
• Nutrient-dense foods contain complex carbs, lean protein, healthy fats, vitamins, and minerals.
• “Empty calories” are low in nutrients and high in sugar.
• A healthy diet emphasizes nutrient-dense foods and minimizes empty calories.

Food vs. Supplements

• Healthful foods are generally a better way to meet nutritional needs than taking supplements.
• Supplements can be helpful with:
  • Calcium to decrease the risk of osteoporosis, especially in females.
  • Iron for anemia or low iron levels, especially in females with a high menstrual flow.
  • Folate before or during pregnancy where any female capable of getting pregnant should ensure she receives sufficient folate.

Canada’s Food Guide

• Key themes of the Canadian food guide:
  • Variety: The plate has a wide range of foods in each section.
  • Accessibility: The plate features foods that are relatively inexpensive for most people.
  • Cultural relevance: There are foods that are key staples to many ethnic diets, such as rice and beans.
  • Availability: It features options that are available at times of year in different forms, either fresh, frozen, canned, or dried.
• Key messages of the Canadian food guide:
  • Have plenty of vegetables and fruit.
  • Choose whole-grain food.
  • Eat protein-rich food.
  • Be mindful of eating habits.
  • Cook more often.
  • Enjoy your food.
  • Eat meals with others.
  • Use food labels.
  • Limit foods high in sodium, sugar, and fat.
  • Be Aware of Food marketing.

Dietary Recommendations

• Eat slowly and enjoy your food and set aside a regular time to eat.
• Eat a colorful, varied diet.
  • Many Canadians typically eat few servings of fruits and vegetables which are typically inexpensive, rich in nutrients, low in fat, calories, and tasty.
• Eat breakfast for having more energy in the morning.
• Choose healthy snacks with fruits, vegetables, and grains.
• Drink mainly water.
• Pay attention to portion sizes.
• Combine physical activity with healthy eating.
• Minimize simple carbs like cakes, candies and other refined sugar products.

The Current Canadian Diet

• Generally, Canadians meet protein requirements.
• For 20-30% of the population:
  • Complex carbohydrate intake is below recommended levels.
  • Fat intake is above the recommended range.
• Most don't consume enough fiber.
• Intake of ω-6 fatty acids is too high relative to ω-3.
• Inadequate K+ intake and excessive NaCl intake.
• Prevalence of deficiency is highest for Vitamin A, Vitamin D, magnesium, and calcium.
• There may be special concerns for older adults, athletes, low-income families, and First Nations.

Vegetarian Diet Options

• Vegan includes no animal products.
• Lacto-vegetarian involves milk only.
• Lacto-ovo vegetarian includes milk and eggs.
• Semi-vegetarian includes fish only (often). Sometimes other meats (e.g., poultry), but usually excludes red meat.
• All of the above diets may have some benefits and some risks.

Food-Borne Illnesses

• Clean: Wash hands and surfaces often with warm water and soap for a minimum of 20 seconds.
• Separate: Don't cross-contaminate with different cutting boards for meat and vegetables.
• Cook to a safe temperature using a food thermometer.
• Chill: Refrigerate promptly.
  • Keep the fridge at 4°C and cool leftovers within 2 hours.

Improving Your Diet

• Know what you are consuming.
• Food labels can help consumers make food choices for good health.
• Follow current recommendations.