Overview of Lecture 2
• Chapter 2• Definition of Healthy diet
• Food Guide and its uses
• Dietary Guidelines
• Recommended Nutrient Intakes
• Food Labeling
• Nutrient Density and the Exchange System
Chapter 2 Tools for Diet Design
• What do we need to eat to avoid diet related disease?
• A variety of foods balanced by a moderate intake of each food
• variety for all nutrients
• focus on main food groups
• stay physically active
• VARIETY, BALANCE and MODERATION
Variety
• Choose a number of different foods within any given food group
• not the same thing “day after day…”
• WHY ?
Balance
• Select from 5 food groups– four in Canada– Dairy– Vegetable / Fruit– Grains– Meats and Alternates
• fats, oils and sweets can be added for flavour and nutrients
Moderation
• Plan your day in order to juggle nutrient sources
• balance between types of foods• morning vs. evening and within
meal
• moderation of high fat and salt
• Without adopting basics of variety, balance and moderation you risk nutrition related disease
Nutritional Status
• Overall body health is determined by the sum of its nutritional status for each nutrient
• Components Include
• Anthropometry
• Biochemical measurement
• Clinical Examination
• Dietary History
Under Nutrition
• Nutrient intake does not meet body needs
• body enters state in which it can not function appropriately
• body stores can make up for short term, but become depleted
• serious problems can arise over longterm
Over Nutrition
• Prolonged over consumption of more than the body needs
• long term can lead to toxic build up and serious disease
• most common is excess energy intake– excess weight leads to serious
disease
Limits of Nutritional Assessment
• Can be a very long time between the onset of poor nutritional health and the first clinical evidence
• Often too late
• Calcium deficiency - low bone density, osteoporosis later in life ( 30 to 50 years).
• High Cholesterol - builds up in circulatory system, heart disease later in life.
Food Guide
• Rainbow in Canada, Pyramid in USA ( see appendix B)
• Nutritionists have always worked to put the science of nutrition into practical terms that could be useful to everyone
• Goal of this class is to become very familiar with the recommendations and the fundamentals that create the guidelines
Food Guide
• Estimates are based on 1200-1400 kcal intake (minimum)
• Expect an increase in caloric intake to meet energy needs
• Recent changes have increased fruit, vegetable, bread and cereal contributions to provide more calories and moderate fat
• oils and sweets used to supplement energy needs, not to replace other foods
Four Groups
• Group• Grain Products
• Vegetables and Fruit
• Milk Products
• Meat and Alternatives
• Servings• 5 - 12
• 5 - 10
• 2 - 4• Youth, and
pregnant women 3 - 4
• 2 - 3
Summary (Appendix B)• Enjoy a variety of foods
• Emphasize cereals, breads, other grain products, vegetables and fruits
• Choose low-fat dairy products, lean meats, and foods prepared with little or no fat
• Achieve and maintain a healthful body by enjoying regular physical activity and healthful eating
• limit salt, alcohol and caffeine
Menu Planning
• Utilizing the food guide as a tool
• emphasize variety as no one food is essential nor does one provide all the necessary nutrients
• Each member of food group contributes slightly different nutrients (appendix A)
Recommendations for Choices
• Low fat items from milk group
• vegetables high in protein, minerals and fiber (lentils)
• vegetables rich in Vitamin A (dark green) and fruits rich in vitamin C (oranges)
• Choose whole grain breads, cereals and pastas
• refining flour eliminates most nutrients
Sample Daily Diet
• See Table 2 - 6
• meets all requirements for 1600 - 1800 kcal
• modify for greater caloric expenditure
• if less caloric expenditure, increase physical activity
Evaluating Diet
• Most in US failed to meet theses guidelines
• Very low on Fruit and Vegetables, high on sweets, fats and oils
Dietary Guidelines
• Different method for Menu Planning
• KNOW THE DIFFERENCES AND APPLICATIONS
• Food guide designed to have nutrients met
• Main dietary problems are associated with over consumption of energy, Fat, cholesterol, alcohol and salt
• Also, under consumption of calcium, iron, B vitamins, Zinc and fiber
Dietary Guidelines• Dietary guidelines established
in light of these disease concerns
• refer to intake over a day or a week
• 1. Eat a variety of foods
• 2. Balance intake with activity• 30 min of moderate activity a day
• low fat options and nutritious snacks
• high risk with abdominal fat
• slow controlled weight loss
• habit forming changes
Dietary Guidelines
• 3. Emphasize grains, fruits and vegetables (nutrients and fiber)
• 4. Low fat, saturated fat and cholesterol (low fat options, animal products= saturated fat and cholesterol)
• 5. Moderate sugar intake
• 6. Moderate salt (sodium)
• 7. Moderate alcohol• BP, stroke, heart disease, cancer,
……
• two or fewer servings
Recommended Nutrient Intake (RNI)
• Corresponds to RDA (Recommended Dietary Allowance in US)
• Recommended intakes of nutrients that meet the needs of almost all healthy people of similar age and gender
• Used for
• large group meal planning over 3 - 7 days
• schools, hospitals, dormitories
• developing education programs and food labeling standards
• developing new foods (astronauts)
• evaluating diet survey data
RNI
• Developed by :
• estimating what average people require and individual variation
• increasing this by 30-50 % to cover all population
• increasing again to cover losses with cooking and specific needs
• incorporation of scientific judgment to create estimates without available data
RDA
• You should not expect a benefit from eating in excess of RDA
• Revised every four years
• recently focused on presentation and refinement of recommendations for age groupings
• considerations of new research such as the antioxidant effects of Vitamin C
Daily Values
• Recommendations based on daily requirements versus weekly (RNI/RDA)
• used for food labeling as they are more generic general estimates for the whole population
• Reference Daily Intakes (RDI)
• Daily Reference Values (DRV)
Nutrient Density
• Used to assess nutritional quality of individual foods
• comparison of its vitamin or mineral content to its energy provision. Higher the better.
• Fig 2 - 3, p 58
• avoid empty calorie foods.
The Human Body :A Nutrition Perspective
• Various body systems are used to aid in digestion and absorption of food products
• Digestion - breakdown of food substances
• Absorption - transport of food substances into circulatory or lymph system within body
Organization
• Cell - basic building blocks of life, each performing a specialized job, determined by selective expression of DNA
• Tissue - collection of cells designed for specific function
• Organs - groups of tissues designed to perform specific function eg. Heart
• Organism - comprised of organs acting in a coordinated manner to support life
Regulatory (Control) System
• Hormonal and Nervous systems
• hormone - compound with specific site of synthesis and release into bloodstream
• eg. Insulin, gastrin
• nervous system regulates release of acids and intestinal motility, food acquisition, preparation, choice...
Anatomy and Physiology of Digestion
• Gastrointestinal Tract (GI) - site of digestion and absorption
• hollow tube, within which food moves and mixes with digestive acids and enzymes, facilitating breakdown for absorption
• large surface area to facilitate absorption
• movement regulated by sphincters between major sections, allows full preparation
Digestive Process
• Enzyme Fig 3-7, facilitate one specific reaction repeatedly.
• Different enzymes in different sections of the GI
• Stomach• protein digestion, acid and enzymes
• stomach protected by mucous layer
• Small Intestine• Chyme - mixture of stomach
secretions and food
• entry of chyme into SI slow
• triggers release of bicarbonate and enzymes
Absorption
• Fig 3-9, p 88
• Occurs mainly in SI, 95 % of what it receives
• massive surface area, due to folding and finger like villi
• passive absorption - natural movement from high to low concentration (fats, water)
• active absorption - uses carrier and energy (glucose)
• facilitated absorption - uses carrier without energy
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