Chapter 1. An Overview of Nutrition. Chapter Objectives. Identify the six classes of nutrients and determine which are energy-yielding nutrients. List four factors that affect our food choices.
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An Overview of Nutrition
Overview of Nutrition
Science of foods and the substances they contain, their actions within the body
from plants or animal sources
Provide energy and nutrients
Used by the body for maintenance, growth, and repair
The foods one consumes.
The quality of which affects the risk of chronic diseases
We choose foods for many other reasons beyond the basic need to obtain nutrients:
We need to eat and drink to obtain:
Nutrients: chemical compounds in foods to provide fuel for energy (measured in kilocalories), growth, maintenance and to regulate body processes
Six classes: carbohydrates, fats, protein, vitamins, minerals, water
Energy: The capacity to do work. The energy in food is chemical energy, it can be converted to mechanical energy in the body.
Food energy is measured in calories
Six classes of Nutrients
Energy yielding nutrients (Macronutrients)
Calories and kilocalories
Energy density – a measure of the energy a food provides relative to the amount of food (kcal per gram)
Lower energy density
This 450-gram breakfast delivers 500 kcal, for an energy density of 1.1(500 kcal/450 g = 1.1 kcal/g)
Higher energy density
This 144-gram breakfast delivers 500 kcal, for an energy density of 3.5(500 kcal/144 g = 3.5 kcal/g)
Estimated Average Requirements -(EAR)
Recommended Dietary Allowances – (RDA)
What happens When a Person Doesn’t Get Enough or Gets Too much of a nutrient or energy?
Evaluates the many factors that influence or reflect nutritional health.
Stages in Nutrient Deficiency (example is given for iron)
Average American diet is high in:
Average American diet is low in:
Incidence of overweight and obesity is on the rise.
65% of American adults and 15% of children (ages 6 to 19) are overweight
Take in more calories than needed
Burn fewer calories due to sedentary lifestyles
Resulting in increased rate of type 2 diabetes (especially children), heart disease, cancer, and stroke
Observational Research: involves looking at factors in two or more groups of subjects to see if there is a relationship to certain health outcomes
Epidemiological research: study of populations of people
Example: Relationship of sun exposure and incidence of rickets in Norway compared with Australia
May be due to other unidentified diet or lifestyle factors
Experimental Research: involves at least two groups of subjects
Experimental group: given a specific treatment
Control group: given a placebo (“sugar pill”)
Double-blind placebo-controlled experiment is “gold standard.”
Neither scientists nor subjects know which group is receiving which treatment.
All variables held the same and controlled for both group.
Sample size – number of people in the study.
Newspaper headlines and television news items report results of a single, recent research study.
Advice from authoritative health and nutrition organizations is based on:
Consensus: the opinion of group of experts based on collection of information
Before making dietary and lifestyle changes based on media reports, read with a critical eye and ask:
Was the research finding published in a peer-reviewed journal?
Was the study done using animals or humans?
Do the study participants resemble me?
Is this the first time I’ve heard about this?
Wait until research findings are confirmed and consensus reached by reputable health organizations before making changes.
Beware of health quackery and fraud:
Registered Dietitian (RD): completed at least a bachelor’s degree at an accredited U.S. college or university and a supervised practice, passed a national exam administered by the American Dietetic Association
Public Health Nutritionist: has degree in nutrition but may not be an RD (if didn’t complete supervised practice, not eligible to take ADA exam)
Professionals holding advanced degrees in nutrition
Licensed dietitian (LD): licensed by state licensing agencies
National Institutes of Health (NIH) 10 Questions to consider when viewing a health-related website
Who runs the site?
Who pays for the site?
What is the purpose of the site?
Where does the information come from?
What is the basis of the information?
How is the information selected?
How current is the information?
How does the site choose links to other sites?
What information does the site collect about you and why?
How does the site manage interactions with visitors?
For 5 point extra credit, provide answers to the following questions:
Complete a family Health History worksheet
Bring a food label to class next time
Must be submitted next class. No exceptions.