Nutrition
The science of food and how the body uses it in health and disease
Essential Nutrients

 Must be obtained from the diet
 Necessary for energy or for the building and maintenance of tissues
 Relied upon for the regulation of body functions
Energy-Providing Nutrients
Energy Measurements
 Energy is expressed in ‘kilocalories’
 1 kilocalorie = 1000 calories
 Kilocalorie = Calorie (note capital ‘C’)
 1 kilocalorie = heat required to raise the temperature of 1kg of water 1°C
 Average person requires approx. 2000 calories per day
Calorie Densities of Various Energy Sources
FATS
ALCOHOL
CARBOHYDRATES
PROTEINS
Proteins
 Found in every living cell
 Act as structural components for:
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 Composed of chains of amino acids
 20 commonly recognized amino acids
 Nine essential (can not be synthesized) amino acids

 Individual sources of protein are ‘complete’ if they supply all nine essential amino acids

 ‘Incomplete’ protein sources include those foods that do not contain all nine essential amino acids
 Usually from plant sources such as grains, beans, peas, and nuts
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 Foods must be combined to get all amino acids (rice and beans for example)
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 Protein consumed in excess of needs is stored as fat
 Inadequate protein consumption can lead to muscle wasting
Fats
 Also known as lipids
 Concentrated source of energy
 Fat serves to:
 Fats in food are mostly triglycerides
 Include a glycerol (an alcohol) and three fatty acid molecules
Fats can be classified as:
1.
2.
3.
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 Based on the degree of saturation or number of double bonds that exist between carbon atoms
 No double bonds = saturated
 One double bond = monounsaturated
 Two or more double bonds = polyunsaturated
Saturated Fats
 Food usually contains more than one type of fat
 The dominant fat determines the characteristics of the fat



Unsaturated Fats
 Monounsaturated and polyunsaturated fats usually come from plant sources
 liquid at room temperature (oil)
 More desirable, not linked to cardiovascular disease
 appears to lower blood cholesterol
 Also shown to reduce the risk of heart disease
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Hydrogenation
 Processed plant oils can be high in saturated fat
 Tropical oils (such as palm oil and coconut oil) used in processed foods are high in saturated fats
 Hydrogenated fats and oils are created from unsaturated fats are used to prevent spoiling and to add texture
Cholesterol
 Elevated intake of saturated fats may increase blood cholesterol levels

 Increased blood cholesterol and triglyceride levels have been implicated in the development of heart disease
Carbohydrates

 Three groups based on the number of saccharides
 Monosaccharides and disaccharides are considered sugars
 Polysaccharides are considered starches
Monosaccharides
 Simplest sugar
 Include
 Glucose makes up the blood sugar (the brain, nervous system are fueled by glucose exclusively)
 Glucose found in
 Fructose found in
Disaccharides
 Two monosaccharides
 One monosaccharide is always glucose,
 e.g., lactose = glucose + galactose
 Many ‘hidden’ sugars in food
 Primary concern related to sugar consumption is dental cavities
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Polysaccharides
 Found in vegetables, fruit, grains
 Complex carbohydrates composed of chains of many sugars
 Starches often contain many vitamins, minerals, water, protein


 Carbohydrates consumed in excess of storage capacity as glycogen are stored as fat
 An important component of the diet for athletes competing in events of long duration
Vitamins
 Serve as coenzymes in chemical reactions
 ‘Organic’ because they contain carbon atoms
 Required in small amounts
 Necessary for:
1.
 Two classifications:
 Based on the ability to dissolve in either water or fat tissue
Water-soluble Vitamins
 Not stored

 Include vitamin C and B-complex vitamins
 Dissolve quickly in water, so overcooking fruits and vegetables in water will result in the vitamins being lost to the water
Fat-soluble Vitamins

 In excess, these vitamins are stored in fat tissue
 Over-consumption of these vitamins (especially A and D) can result in toxicity
Antioxidants
 Formed from vitamins
 Aid in preserving healthy cells
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

 Include vitamins E, C, beta carotene (from vitamin A)
Minerals
 Numerous functions in the body
 ‘Inorganic’ because they do not contain carbon atoms
 Necessary for:
1.
Structural elements (teeth, hormones, muscles)
2.
Regulation of body functions (muscle contractions, blood clotting, heart function)
3.
Aid in the growth and maintenance of body tissues
4.
Catalytic action in energy release
 Approximately 17-21 identified essential minerals
 major minerals are found in relatively large amounts in the body
 Trace elements are needed in small amounts
Vitamins and Minerals
 Needed in small amounts
 Essential component to good health
 Consumption of too little/too much can have detrimental effects
 To ensure adequate intake, eat a balanced diet with variety
Water
 Large component of our bodies and food
 Important for:
 Body water is lost through:
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 Excessive water loss through:
Fibre
 Need approx. 1mL of water for every Calorie burned
 8 cups of fluid per day
 More if you are active or live in a warm climate
 Weakness or fatigue can be a sign of dehydration
 Fibre: plant substances that cannot be digested by the body
 Adds bulk to feces to facilitate elimination
 A large intake of fibre can lead to intestinal gas
 Rich sources include:
 Other sources include:
 Soluble fibre
 Insoluble fibre
Recommended Nutrient Intakes
 RNI’s
 Designed to meet the needs of virtually the entire healthy population
 RNI’s exceed the requirements of most people
 Allow for a margin of safety, taking into account individual variation
 Expressed as a daily requirement
 Should be regarded as an average recommended intake over a period of days or weeks
Recommended Daily Intakes
 RDI’s
 A reference standard for nutrition labeling purposes
 RDI’s represent the highest RNI that exists for a nutrient for a particular age group
 Expressed as the percentage of RDI of the nutrient on labels
 Two RDI’s - one for children (<2 yrs), one for adults (>2 yrs)
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Nutrition Recommendations for Canadians
 Eight recommendations made by Health and Welfare Canada
 Outline desirable characteristics of the Canadian diet
 Recommendations are intended for educators and health professionals
 User-friendly version includes 5 general statements to consider when choosing what to eat
1.
Enjoy a variety of foods
2.
Emphasize cereals, breads, other grain products, vegetables, and fruits
3.
Choose lower-fat dairy products, leaner meats, and foods prepared with
little or no fat
4.
Achieve and maintain a healthy body weight by enjoying regular
physical activity and healthy eating
5.
Limit salt, alcohol, and caffeine
Canada’s Food Guide to Healthy Eating
 Translates nutrient recommendations into a food group plan
 A guide to ensure a balanced intake of essential nutrients
 Meets the needs of all Canadians four years of age and older
 Aimed at the general population
Food Groups
Food Servings
 Amount of food needed each day from the food groups varies according to:
 A range of servings is given in order to include the energy needs of all individuals
 For example, a sedentary woman may require the lower number of servings, while an active male may choose the higher number of servings
Directional Statements within Canada’s Food Guide
 Enjoy a variety of foods from each food group every day
 Choose lower-fat foods more often
 Choose whole grain and enriched products more often
 Choose dark green and orange vegetables and orange fruit more often
 Choose lower-fat milk products more often
 Choose leaner meats, poultry and fish, as well as dried peas, beans, and lentils more often
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