NFS284 Chapter 2 Review Notes
NFS284 Chapter 2 Review Notes

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School
University of Toronto St. George
Department
Nutritional Science
Course
NFS284H1
Professor
Tom Wolever
Semester
Fall

Description
Nutrition: Science and Applications Chapter 2 – Nutrition Guidelines 2.1 Nutrition recommendation for the Canadian Diet - Nutrient-based approach  How much of a nutrient is required to maintain health? o Recommended nutrient intakes (RNI) lasted until the 1980s o Dietary reference intake (DRI) started in the 1990s  Determined by the Institute of Medicine (IOM) - Food-based approach  Types and amounts of food to maintain health (e.g., dietary pattern) o Canada’s official food rules was established in 1942 o Now called Canada’s food guide 2.2 Dietary reference intakes (DRIs) - Nutrient requirement  Experimentally-determined requirement for a nutrient o Amount required to maintain health - Nutrient intake  Determined by the composition of the diet o Amount of nutrient consumed - Estimated average requirement (EAR)  Nutrient intake that meets the requirement of 50% of individuals in a group (e.g., sex, age) o How is it used?  To estimate the probability that an individual’s usual intake is meeting their requirement  To estimate what proportion of a group is meeting their requirement o How is it determined?  Determine a biochemical criterion that allows you to determine the intake at which individuals requirement is being met  Determine the requirement distribution from a sample of the population o Example  Consider the hypothetical Vitamin X  Vitamin X requirement is met when the level of Vitamin X in serum reaches saturation  IMPORTANT: This is not the universal criterion for all nutrients  Conduct a depletion-repletion experiment on a population of healthy adults  Create a requirement distribution o EAR is determined from the requirement distribution o EAR represents the average daily nutrient intake that meets the requirements of half the individuals  If an individual’s nutrient intake is equal to the EAR, then there is a 50% probability that the individual is meeting their requirement  If an individual’s nutrient intake is less than the EAR, then there is less probability that the individual is meeting their requirement  If an individual’s nutrient intake is greater than the EAR, then there is high probability that the individual is meeting their requirement - Recommended dietary allowance (RDA)  Nutrient intake that ensures 98% probability of meeting your requirement o How is it used?  As a goal for an individual’s usual intake because it is almost certainly adequate o How is it determined?  RDA = EAR + 2 SD - EAR cut point method  Prevalence of adequate intake within a population o How is it used?  To estimate what proportion of a group is meeting their requirements  Proportion of the population whose intake is less than the EAR  Proportion of the population that is NOT meeting its requirement o How is it determined?  Create an intake distribution from a survey of nutrient intakes  NOTE: The distribution doesn’t tail off to 0 because even the worst diets contain some level of various nutrients, but the curve is still presumed to be a normal distribution o How well a population is doing with respect to nutrient intake depends on median intake and standard deviation of the intake distribution o How is it used?  Health Canada  Considers a population to have an adequate intake if the proportion of the population whose EAR cut point ≥ 10%  Canadian Community Health Survey  Measured nutrient intake and used the EAR cut point method to determine the adequacy of nutrient intake - Adequate intake (AI) o When is it used?  When there is insufficient data to calculate EAR o How is it determined?  Based on an estimate of average nutrient intake by a healthy population o How is it used?  If your intake > AI, then intake is adequate  If your intake < AI, then your intake is may or may not be adequate - Tolerable upper intake level (UL)  The highest level of habitual nutrient intake that is unlikely to pose a risk of adverse effects o Not a recommended level of intake o No additional benefits when greater than RDA o Adverse effects are possible because of the popular use of supplements o Sometimes based only on the amount of nutrient consumed in supplement form - Energy balance o Energy content (kcal) of food consumed = Energy content expended for metabolism and exercise  Energy balance (e.g., weight is unchanged) o Energy content (kcal) of food consumed > Energy content expended for metabolism and exercise  Positive energy balance (e.g., weight gain) o Energy content (kcal) of food consumed = Energy content expended for metabolism and exercise  Negative energy balance (e.g., weight loss) - Estimated energy requirements (EER) o Variables  Age (↑ age = ↓ EER)  EER decrease with age due to the loss of muscle mass known as sarcopenia  Muscle mass is more metabolically demanding than fat  Sex (male = ↑ EER)  Men have more muscle mass  Body size, including height and weight (↑ body size = ↑ EER)  Physical activity levels (↑ physical activity level = ↑ EER)  Sedentary  Less than 30 minutes of intentional exercise per day  Low active  Walking 30 minutes at 6.5 km/h every day  Active  Walking 1 hour 45 minutes at 6.5 km/h every day  Very active  Walking 4 hours 15 minutes at 6.5 km/h every day - Acceptable macronutrient distribution ranges (AMDR)  Expressed as a % of total kcalories o Carbohydrates: 45-65% o Fat: 20-35%  Saturated fat: < 10% (Canada’s food guide) or < 7% (scientific literature)  Trans fat: < 1%  Cholesterol: 300 mg o Protein: 10-35% 2.3 Canada’s Food Guide - Regularly updated based on the most current nutritional research - The current guide was published in 2007 - The purpose of Canada’s Food Guide o To meet the nutrient needs of the individual o To reduce the ris
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