The science of nutrition 4th edition thompson manore vaughan chapter 01

What Is Nutrition?• Food is the plants and animals we eat • Nutrition is the science that studies food: • How food nourishes our bodies • How food influences our health • Includes identi

Chapter 1 Lecture

Chapter 1:

The Science of

Nutrition: Linking Food, Function, and Health

What Is Nutrition?

• Food is the plants and animals we eat

• Nutrition is the science that studies food:

• How food nourishes our bodies

• How food influences our health

• Includes identifying how we consume, digest,

metabolize, and store nutrients

• Includes studying our eating patterns and

making recommendations

• Addresses food safety, food production, and

global food policy

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How Did Nutrition Evolve?

• Mid-1700s researchers observed an association between diet and illness

• In the 1800s, carbohydrates, lipids, proteins, and some minerals were identified

• In the early 20th century, nutrition research

focused on identifying deficiency diseases

• By WWII, nutrition research supported wellness and treating chronic diseases

• Nutrigenomics is the study that links our genes,

How Does Nutrition Contribute to Health?

• Proper nutrition supports wellness

• Wellness is more than the absence of disease

• Includes physical, emotional, social,

occupational, and spiritual health

• Is a multidimensional, lifelong process

• Two key components of wellness:

1 Nutrition

2 Physical activity

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Why Is Nutrition Important?

• Can prevent some diseases and reduce risk for others

• Healthful nutrition and regular physical exercise can increase feelings of well-being

• A poor diet, inadequate or excessive physical activity, or a combination of those, can lead to serious health problems

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ABC News Video: Two Meals a Day Could Help Diabetics Control Blood Sugar

How Does Nutrition Contribute to Health?

• Nutrition is part of the U.S national health

promotion and disease prevention plan Healthy

People (revised every 10 years)

• Healthy People is developed by experts under

the direction of the U.S Dept of Health and

Human Services

Healthy People 2020

• Four primary goals:

• Help people attain higher quality and longer

lives, free of preventable diseases, disability, injury and preventative death

• Achieve health equity, eliminate health

disparities, improve health for all

• Create social and physical environments that

promote good health

• Promote quality of life, healthy development,

and healthy behaviors across all life stages

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What Are Nutrients?

• Nutrients are chemicals found in food and are

critical for human growth and function, found in foods

• Organic nutrients contain carbon and

hydrogen, essential components of all living organisms; they include carbohydrates, lipids, proteins, vitamins

• Inorganic nutrients are those not containing

carbon and hydrogen; they include minerals and water

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What Are Nutrients? (cont.)

• Six groups of nutrients found in foods:

What Are Nutrients? (cont.)

• Macronutrients are required in relatively large

amounts to support health

• Provide energy/fuel to our bodies

• Carbohydrates, lipids, and proteins

• Alcohol = not a nutrient

• Does not support regulation of body functions

or the building or repairing of tissues

• Considered to be both a drug and a toxin

How Is Energy In Food Measured?

• Energy in food is measured in Kilocalories (kcal)

• One kcal is the amount of heat needed to raise the temperature of 1 kg water by 1 degree

Celcius

• 1 gram carbohydrates provides 4 kcal

• 1 gram protein provides 4 kcal

• 1 gram lipids provides 9 kcal

• 1 gram alcohol provides 7 kcal

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• Fiber is a type of carbohydrate

• A diverse group of substances that are largely

insoluble in water

• Composed of carbon, hydrogen, and oxygen

• Includes triglycerides, phospholipids, and sterols

• Triglycerides are most common lipid in food and

• Main energy source during rest or low- to

moderate-intensity exercise

• Stored as adipose tissue (body fat)

• In addition to carbon and hydrogen, proteins

also contain nitrogen

• Important in building new cells/tissues,

maintaining bone, repairing damage, and

regulating metabolism and fluid balance

• Not a primary source of energy

• Found in many foods, particularly meat, dairy, seeds, nuts, and legumes; small amounts in grains and vegetables

• Build and maintain healthy bones and tissues

• Support immune system and ensure healthy

vision

• Do not contain or supply energy to our bodies

• Can be destroyed by light, heat, air, etc.

Micronutrients: Minerals

• Inorganic substances required for body

processes:

• Regulate fluid and energy production

• Support bone and blood health

• Remove harmful metabolic by-products

• Exist in the simplest possible form; can't be

broken down further or destroyed by heat/light

• Two types: major and trace minerals

Macronutrient: Water

• A vital inorganic nutrient supporting all body

processes:

• Fluid balance

• Regulation of nerve impulses, body

temperature, and muscle contractions

• Nutrient transport

• Excretion of waste products

• Sources include water in its pure form, in juices, liquids and other foods like fruits and vegetables

Determining Nutrient Needs

• Dietary Reference Intakes (DRIs):

• Aim to prevent and reduce risk of chronic

disease and promote optimal health

• Expand upon RDA and set standards for

nutrients that do not have RDA values

• Establish upper level for some nutrients

• Dietary standards for healthy people only

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Determining Nutrient Needs (cont.)

• Dietary Reference Intakes (DRIs) consist of:

1 Estimated Average Requirement (EAR)

2 Recommended Dietary Allowance (RDA)

3 Adequate Intake (AI)

4 Tolerable Upper Intake Level (UL)

Determining Nutrient Needs (cont.)

• Estimated Average Requirement (EAR)

• The average daily intake level of a nutrient to

meet the needs of half of the healthy people

in a particular life stage or gender group

• Is used to define the Recommended Dietary

Allowance (RDA) of a nutrient

Determining Nutrient Needs (cont.)

• Recommended Dietary Allowance (RDA)

• The average daily nutrient intake level that

meets the needs of 97% to 98% of healthy

people in a particular life stage and gender group

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Determining Nutrient Needs (cont.)

• Adequate Intake (AI)

• Recommended average daily nutrient intake

level based on observed and experimentally determined estimates of nutrient intake by a

group of healthy people

• Used when the RDA is not available

• Many nutrients have an AI including: vitamin K,

chromium, fluoride, and some fats

Determining Nutrient Needs (cont.)

• Tolerable Upper Intake Level (UL)

• Highest average daily nutrient intake level

likely to pose no risk of adverse health effects

to most people

• Consumption of a nutrient at levels above the

UL increases the potential for toxic effects and health risks increases

• Not enough research to define the UL for all

nutrients

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Determining Nutrient Needs (cont.)

• Estimated Energy Requirement (EER)

• Average dietary energy intake to maintain

energy balance in a healthy adult

• Defined by age, gender, weight, height, and

level of physical activity

Determining Nutrient Needs (cont.)

• Acceptable Macronutrient Distribution Ranges

(AMDR)

• Ranges of energy intakes from macronutrients

that are provide adequate intakes of essential nutrients while reducing risk of chronic disease

• Nutrient intake outside of this range, has a

potential for increasing our risk for poor health

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Assessing Nutritional Status

• Nutrition professional must have a thorough

understanding of a client's current nutritional

status including:

• Weight

• Ratio of lean body tissue to body fat

• Intake of energy and nutrients

• Foundation of recommended dietary and lifestyle changes

• Baseline for evaluation

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Assessing Nutritional Status (cont.)

• Malnutrition

• Nutritional status is out of balance: with too

much or too little of a particular nutrient or energy over a significant period of time

• Undernutrition: too little energy or too few

nutrients over time, causing weight loss or a nutrient-deficiency disease

• Overnutrition: too much energy or too much

of a given nutrient over time, causing obesity,

• Nutritional imbalances may be detected by

examining hair, skin, tongue, eyes, and fingernails

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Anthropometric Assessments

• Most common measurements are height, body weight, and can include head circumference in infants, limb and waist circumferences in adults

• Require trained personnel and correct tools

• Compare standards specific for age/gender

• Repeated measurements can assess trends in nutritional status/growth

Health History Questionnaire

• Tool for cataloging history of health, illness, drug use, exercise, and diet

• Can be used to assess energy and nutrient

intakes

• Information includes:

• Age, height, weight, medications (present &

past)

• Family heath/disease history, exercise history

• Socioeconomic factors (race/ethnic

background, education level, marital status, etc.)

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Other Dietary Intake Tools

• Additional techniques to assess nutrient and energy intakes:

• Diet history

• Twenty-four-hour dietary recall

• Food frequency questionnaire

• Diet records

Nutrition Deficiencies

• Primary deficiency occurs when a person does

not consume enough of a nutrient, a direct

consequence of inadequate intake

• Secondary deficiency occurs when:

• A person cannot absorb enough of a nutrient

in his or her body

• Too much of a nutrient is excreted from the

body

• A nutrient is not utilized efficiently by the body

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Deficiency Symptoms

• Subclinical deficiency occurs in the early

stages; few or no symptoms are observed

• Covert symptoms are hidden and require

laboratory tests or other invasive procedures to detect

• Symptoms of nutrition deficiency that become

obvious are overt

2 Proposes a hypothesis (educated guess) to

explain the phenomenon

3 Develops an experimental design to test the

Scientific Method (cont.)

• If the data are rejected, an alternative hypothesis

is proposed and tested

• If the data support the original hypothesis, a

conclusion is drawn

• The experiment must be repeatable, so other

researchers can obtain similar results

Well-Designed Experiment

• The sample size (number of people being

studied) should be adequate to ensure that the results obtained are not due to chance alone

• A control group is essential for comparison

between treated and untreated individuals

• Control for other variables is applied to avoid

coincidentally influencing the results

Advancing a Theory

• A hypothesis that is consistently supported by

repeated experiments becomes a theory

• A theory represents a scientific consensus of

why a phenomenon occurs based on data from repeated experiments

• Theories can be challenged and changed as scientific knowledge evolves

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Types of Research Studies—Animal

• Is used to gather preliminary information for designing and implementing human studies

• Is used for research that cannot be done with humans

• Have advanced our understanding of many aspects of nutrition

• Drawbacks: results may not apply directly to humans; ethical implications of animal studies

Types of Research Studies—Human

• Epidemiological studies:

• Examine patterns of health and disease in

defined populations

• Indicate relationships between factors, not

cause and effect

• Observational studies:

• Involve assessing nutritional habits, disease

trends, or other health phenomena of large populations

• Determine the factors that may influence

these phenomena

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Types of Research Studies—Human

• Case control studies are more complex

observational studies with additional design

features

• Compare a group of individuals with a

particular condition to a similar group without the condition

• Clinical trials are tightly controlled experiments

• Experimental group receives an

intervention/treatment

Other Aspects of Research Studies

• Key aspects in evaluating clinical trials:

• Randomized trials: researchers randomly

assign participants to the treatment and control groups; reduces the possibility of favoritism and errors

• Single-blind experiments: participants are not

aware of which (if any) treatment is being given

• Double-blind experiments: both the

participants and the researchers are not aware of which group is getting a treatment

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Evaluating Nutrition Claims

• Conflict of interest

• Key questions to ask:

• Who paid for it?

that stands to profit from the results?

money, or perks from the research sponsor?

companies or products related to the study?

Evaluating Nutrition Claims (cont.)

• Website reliability; separating Internet fact from fiction

• Check credentials of website sponsors and/or

information suppliers

• Qualified professionals? Are financial contributors' names available? Is there expert review of content?

• Check website date

• Is it current? Is information subject to change over time? Should it be consistently updated?

• Check sources of information (for-profit or not?)

• Look for ".gov"/".edu"/".org" as reliable designations

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Evaluating Nutrition Claims (cont.)

• More ways to discern truth from fiction:

• Who is reporting the information?

• Is the report based on reputable research

studies?

• Is the report based on testimonials?

• Are the claims too good to be true?

• Quackery: promotion of an unproven product or

service—usually by an unlicensed or untrained source—for financial gain

Trustworthy Nutrition Experts

• Reliable experts have education and credentials, such as:

• Registered Dietitian/Nutritionist (RD)

• Licensed dietitian: meets state credentialing

requirements

• Professional with an advanced, related

degree: master's or doctorate degree (MA,

Government Information Sources

• Government-affiliated online sources (".gov") are considered reliable, such as:

• Centers for Disease Control and Prevention

Reliable Professional Organizations

• Academy of Nutrition and Dietetics (AND)

• American Society for Nutrition Sciences

• Society for Nutrition Education

• American College of Sports Medicine (ACSM)

• The Obesity Society (TOS)

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