Transcript The Nutritional Connection

The Nutritional Connection
Chapter 11
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Learning Objectives:

Become familiar with the anatomy and physiology of
the digestive system
 Identify the nutritional requirements and components
of a healthy diet
 Outline the official nutritional advice provided for
Canadians
 Understand the unique nutritional needs of various
populations
 Appreciate the effects of nutrition on athletic
performance
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Introduction
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Introduction
Promotion of
energy and vigor
Development of
chronic illness
and disease
NUTRITIONAL
HABITS
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Nutrition Basics

Choose foods that provide the necessary
nutrients
 Limit those foods associated with disease
 Don’t assume that a healthy diet needs to
be fat-free, low-sugar, and high-fibre all the
time
 When making food choices, consider:
• VARIETY
• BALANCE; and
• MODERATION
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The Digestive System
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The Digestive System

The role of the digestive system is to:
• Produce energy from food ingested
• To transfer energy-rich nutrients, water, and
electrolytes into your body’s internal environment

Composed of numerous structures and
organs that work together
 The digestive tract forms a continuous route
from mouth to anus
 The contents of the digestive tract are
actually part of the external environment
until absorbed through the intestinal wall
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The Gastrointestinal Tract
Digestive Tract
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
(colon)
 Rectum
 Anus
Glandular Organs
 Salivary glands
 Liver
 Gall bladder
 Pancreas
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Basic Processes of the Digestive
System
1.
2.
3.
4.
Digestion
Secretion
Absorption
Motility
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Digestion

Processes that dissolve and break down foods into
molecules that can be absorbed by the body
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Secretion



The release of substances from exocrine glands
Works closely with the digestion process
Includes many secretions, some of which are:
• Saliva by salivary glands
• Hydrochloric acid by the stomach
• Bile by the liver
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Absorption


Uptake of digested molecules across a layer of epithelial cells
lining the gastrointestinal wall
Molecules enter the blood or lymph to be distributed to body
cells
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Motility



The muscular contractions that mix and move the contents of
the digestive tract forward
Propels the contents of the digestive tract forward
Mixes food with digestive juices that promote digestion
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The Digestive System

The digestive system aims to absorb
maximally
 Waste material excreted via the
gastrointestinal tract is called ‘feces’
 Feces consist mainly of bacteria and
undigested material (including fibre)
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Functional Overview of the
Gastrointestinal Organs
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Functional Overview of GI Organs:
The Salivary Glands




Digestion begins
in the mouth
The mechanical
breakdown of food
is achieved by
chewing
Saliva produced
by the salivary
glands
Three salivary
glands in the head
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Functional Overview of GI Organs:
The Salivary Glands



Saliva contains
mucus that
moistens and
lubricates food
Saliva also
contains ‘amylase’
Amylase is an
enzyme that
catalyzes the
breakdown of
carbohydrates
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Functional Overview of GI Organs:
The Mouth and Throat

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
Voluntary swallowing is
initiated in the
oropharynx (posterior
mouth)
The bolus of food moves
to the pharynx
Involuntary swallowing
occurs in the esophagus
‘Peristalsis’ is the
involuntary contraction
of muscles and is
involved in moving food
to the stomach
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Functional Overview of GI Organs:
The Stomach

A sac-like organ
 Serves as a storage
site
 Dissolves and
partially digests food
 Prepares food for
optimal digestion
and absorption in the
small intestine
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Functional Overview of GI Organs:
The Stomach

Glands in the
stomach secrete
hydrochloric acid
(HCl)
 HCl dissolves
particulate matter in
food (except fat)
 HCl also kills some
bacteria that is
ingested with food
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Functional Overview of GI Organs:
The Stomach

The precursor
‘pepsinogen’ forms
the enzyme ‘pepsin’
 Pepsin begins
protein digestion
 Amylase (from the
salivary glands)
continues to break
down carbohydrates
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Functional Overview of GI Organs:
The Stomach

Little absorption
occurs across the
stomach wall
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Functional Overview of GI Organs:
The Small Intestine

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Site of completion of
digestion
Site where most
absorption occurs
Approximately nine feet in
length
Three segments:
• Duodenum
• Jejunum
• Ileum
Most absorption occurs in the
duodenum and jejunum
(vitamins, minerals, water)
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Hydrolytic Enzymes
Carbohydrates
Monosaccharides
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Hydrolytic Enzymes
Proteins
Amino Acids
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Hydrolytic Enzymes
Fats
Fatty Acids
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Functional Overview of GI Organs:
The Pancreas

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
Secretes digestive
enzymes
Secretes an alkaline fluid
mainly of bicarbonate ions
The alkaline fluid
counteracts the acidity of
the contents of the
stomach to protect the
small intestine
Alkaline substance also
maintains an optimal pH
range for enzymatic
functions
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Functional Overview of GI Organs:
The Liver
Secretes ‘bile’
 Bile contains
cholesterol,
bicarbonate ions, and
bile salts
 Bile salts are essential
for fat digestion and
absorption
 Bile is stored in the
gall bladder

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Absorption in the Small Intestine

Absorption within the small intestine
occurs via:
1.
2.
3.
4.
DIFFUSION (Fatty Acids)
OSMOSIS (Water)
ACTIVE TRANSPORT (Mineral Ions)
CARRIER-MEDIATED TRANSPORT
(Monosaccharides and Amino Acids)
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Functional Overview of GI Organs:
The Large Intestine


Upon reaching the large
intestine, very little
water remains, and
salts and undigested
material are left
Here, the material is
further concentrated by
further reabsorption of
salt and water
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Functional Overview of GI Organs:
The Large Intestine


When reabsorption is
complete, the feces
move to the rectum as a
result of involuntary
contractions
(peristalsis)
The coordinated
relaxation of sphincter
muscles results in
defecation
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Nutritional Requirements:
Types and Sources of Nutrients
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Nutrition
The
science of food and how
the body uses it in health
and disease
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Essential Nutrients
1.
2.
3.
4.
5.
6.
Proteins
Fats
Carbohydrates
Vitamins
Minerals
Water

In this context,
‘essential’ refers to
nutrients that the
body is unable to
manufacture (or not
in sufficient
quantities)
 They must be
obtained from the
diet
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Essential Nutrients
Necessary for energy
 Needed for the building and
maintenance of tissues
 Relied upon for the regulation of body
functions

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Energy-Providing Nutrients

Three nutrients provide
the body with energy
1.
Proteins
2.
Fats
3.
Carbohydrates
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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
 An average person requires
approximately 2000 kilocalories per day

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Calorie Densities of Various Energy Sources
FATS
9 Cal/g
ALCOHOL
7 Cal/g
CARBOHYDRATES
4 Cal/g
PROTEINS
4 Cal/g
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Proteins

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1.
2.
3.
4.
5.
6.
Found in every living cell
Act as structural components for:
Muscles
Bones
Blood
Enzymes
Some hormones
Cell membranes
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Proteins
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Composed of chains of amino acids
20 commonly recognized amino acids
Nine essential (can not be synthesized)
amino acids
1.
2.
3.
4.
5.
6.
7.
8.
9.
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
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Protein


Individual sources of protein are
‘complete’ if they supply all nine
essential amino acids
Complete protein sources include
animal products such as meat,
cheese, fish, eggs, poultry and milk
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Protein




‘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
Still good sources of amino acids
Foods must be combined to get all amino
acids (rice and beans for example)
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Protein



Protein should comprise 10-15% of total
caloric intake
Protein consumed in excess of needs is
stored as fat
Inadequate protein consumption can lead
to muscle wasting
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Fats



Also known as lipids
Concentrated source of energy
Fat serves to
1. Provide a source of energy
2. Insulate the body
3. Cushion organs
4. Aid the absorption of fat-soluble vitamins
5. Add flavour and texture to foods
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Fats

Fats in food are mostly triglycerides
 Include a glycerol (an alcohol)
 Three fatty acid molecules
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Fats

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


Fats can be classified as
1. Saturated
2. Monounsaturated
3. Polyunsaturated
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
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Saturated Fat
Monounsaturated Fat
Polyunsaturated Fat
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Saturated Fats
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Food usually contains more than one type of fat
The dominant fat determines the characteristics of the
fat
Saturated fats are solid at room temperature
Saturated fat is found predominantly in animal
products
Saturated fat has also been linked to cardiovascular
disease
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Unsaturated Fats

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
Monounsaturated and polyunsaturated fats
usually come from plant sources
Unsaturated fat is liquid at room temperature
(oil)
More desirable, not linked to cardiovascular
disease
Unsaturated fats appear 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

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Cholesterol
Elevated intake of saturated fats may
increase blood cholesterol levels
 Hydrogenation produces trans fatty
acids that may increase blood
cholesterol
 Increased blood cholesterol and
triglyceride levels have been implicated
with the development of heart disease

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Carbohydrates




Primary source of energy (60% of daily
Calories)
Three groups based on the number of
saccharides
Monosaccharides and disaccharides are
considered sugars
Polysaccharides are considered starches
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Monosaccharides


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

Simplest sugar
Include glucose, fructose, galactose
Glucose makes up the blood sugar
(the brain, nervous system are fueled
by glucose exclusively)
Glucose found in vegetables, fruit,
honey
Fructose found in fruits and berries
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Disaccharides



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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
Dietary fibre is an important complex
carbohydrate
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Carbohydrates



Liver and muscles use glucose for
carbohydrate storage in the form of
glycogen
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
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Vitamins




Serve as coenzymes in chemical
reactions
‘Organic’ because they contain carbon
atoms
Required in small amounts
Necessary for
1. Growth
2. Reproduction
3. Health Maintenance
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Vitamins


Two classifications,
1. Water-soluble vitamins; and
2. Fat-soluble vitamins
Based on the ability to dissolve in
either water or fat tissue,
respectively
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Water-soluble Vitamins




Not stored
Excess eliminated in the urine
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
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Fat-soluble Vitamins

Includes vitamins A,D,E,K
 When taken in excess, these
vitamins are stored in fat
tissue
 Over-consumption of these
vitamins (especially A and D)
can result in toxicity
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Antioxidants






Formed from vitamins
Aid in preserving healthy cells
When the body breaks down fats, or uses
oxygen, free radicals are formed
Free radicals can damage cell
membranes and mutate genes
Antioxidants react with free radicals to
decrease their negative effects
Include vitamins E, C, beta carotene
(from vitamin A)
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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
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Minerals
Approximately

17-21 identified essential minerals
Macronutrients (major
minerals) are found in
relatively large
amounts in the body
• Calcium
• Phosphorus
• Magnesium
• Sulfur
• Sodium
• Potassium

Micronutrients (trace
elements) are needed
in small amounts
• Zinc
• Iron
• Copper
• Fluoride
• Iodine
• Selenium
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Vitamins and Minerals




Needed in small amounts
Essential component to good health
Consumption of too little or too much
can have detrimental effects
To ensure adequate intake, eat a
balanced diet with variety
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Water


1.
2.
3.
4.
5.
6.
Large component of
our bodies and food
Important for:
Nutrient transport
Waste transport
Digestion &
absorption
Regulation of body
temperature
Lubrication
Chemical reactions
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Water

1.
2.
3.
4.

1.
2.
3.
4.
Body water is lost through:
Urine
Feces
Sweat
Evaporation in lungs
Excessive water loss
through:
Illness
Exercise
Hot environment
Consumption of coffee, tea,
alcohol
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Water




Need to consume approx.
1mL of water for every
Calorie burned
About 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
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Fibre



Fibre includes 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
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Fibre
 Rich sources include:
1. Fruit
2. Legumes
3. Oats
4. Barley
 Other sources include:
1. Wheat
2. Grains
3. Vegetables
4. Whole grain foods
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Fibre

Soluble fibre
 Lowers blood cholesterol
 Slows absorption of glucose

Insoluble fibre
 Facilitates feces elimination
 Can prevent constipation, lower
intestinal tract cancer
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Nutrition Guidelines and
Recommendations
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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
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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



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
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
These statements are as follows…
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Enjoy a
variety
of foods
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Emphasize cereals,
breads, other grain
products,
vegetables, and
fruits
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Choose
lower-fat
dairy
products,
leaner meats,
and foods
prepared
with little or
no fat
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Achieve and
maintain a
healthy body
weight by
enjoying
regular
physical
activity and
healthy eating
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Limit salt,
alcohol, and
caffeine
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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

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Food Groups

1.
2.
3.
4.
5.
Five food groups:
Grain Products
Vegetables and fruits
Milk products
Meat and alternatives
Other foods (such as junk food)
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Food Choices

The rainbow design of the Food Guide is a
visual representation of the relative amounts
of each food group recommended
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Food Servings

1.
2.
3.
4.
5.
6.
Amount of food needed each day from
the food groups varies according to:
Age
Body size
Gender
Activity level
If you are pregnant
If you are breast feeding
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Food Servings


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
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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
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Directional Statements within
Canada’s Food Guide
 Choose
dark green and orange
vegetables and orange fruit
more often
 Choose lower-fat milk products
more often
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Directional Statements within
Canada’s Food Guide
 Choose
leaner meats, poultry
and fish, as well as dried peas,
beans, and lentils more often
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Nutrition Questions
and Answers
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




Nutritional value of fast foods vary
Fat (especially saturated fat) and cholesterol
are major concerns for making healthy
choices
A limited variety of foods containing dietary
fibre exists
Healthy alternatives are beginning to be
offered, including salads, lower-fat meats and
milk products, and whole wheat breads
Eaten in excess, fast foods can be
detrimental to health due to high Calories, fat,
and salt
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

1.
2.
3.
4.
5.
6.

1.
2.
3.
4.
Labels are standardized presentations of the nutrient
content of food
Consists of (based on serving size):
Heading
Serving size
Values for energy
Protein
Fat
Carbohydrate
May also include:
Breakdown of fats (saturated, monounsaturated,
polyunsaturated)
Breakdown of carbohydrates (sugar, starch, fibre)
Sodium and potassium
Vitamins and minerals
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Concerns about environmental
contaminants in foods (pesticides)
 Presence of potentially dangerous
additives
 Threat of bacteria and microorganisms
causing illness
 Elderly people and children have a
higher risk of suffering severe illness as
a result of food poisoning

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



Most food-borne illness is due to bacteria and is
preventable through proper food preparation and
storage
Salmonella is common in eggs, meat, milk, and
poultry
Staphylococcus aureus is common in ham, cheese,
eggs, and seafood
More serious bacteria include Clostridium botulinum
and Escherichia coli (E-coli), which usually arise from
improperly canned foods
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
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

Various reasons cited for vegetarianism
Philosophical, health, environmental reasons
Can provide necessary nutrients
Requires planning
Children and pregnant women require special
individual guidance
Many types of vegetarianism
Potential concern in obtaining all essential
amino acids
May be difficult to get adequate intakes of
vitamin B12, calcium, iron, and zinc
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Most nutritionists agree that, given a
balanced diet, supplements are not
necessary
 Mega-doses of supplements (especially
fat-soluble vitamins) may lead to toxicity
 If you choose to supplement, consult
with a public health nutritionist, dietician,
or doctor

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The primary health concern associated
with sugar intake is cavities
 Also, calories consumed in the form of
sugar, beyond caloric requirements, is
stored as fat
 Therefore, a high sugar diet can lead to
obesity
 Obesity is a risk factor for developing
diabetes and a host of other diseases

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





Aging leads to a lower total energy requirement
as a result of less activity and a lower
metabolic rate
Leads to lower food intake among seniors
May not have adequate vitamin and mineral
intakes
Constipation may further add to a declining
interest in food
Other diseases may also affect nutrition,
including dental problems, swallowing
disorders, mood disorders, and gastrointestinal
disorders
Psychosocial issues may also negatively affect
nutrition
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Ergogenic Aids and Supplements

Canadian diet seems to be adequate to meet
protein needs of athletes
 Athletes should focus on maintaining a
balanced diet with adequate Calories rather
than supplementing
 Carbohydrate loading can increase muscle
glycogen stores for endurance-type
competition, but should be supervised by a
qualified coach
 Caffeine has been shown to enhance
endurance performance but should be
attempted on a trial basis, if at all
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Pre-Event Meals
 Meals
before an event should
be high in carbohydrates and
low in fat
 Only familiar foods should be
eaten before an event to avoid
any strange or surprising
reactions or feelings
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Hydration
The need for water is increased during
exercise because of increased losses
through the lungs and sweat
 Needs also increased in warm and
humid environments
 Drink early (prior to exercise)
 Drink often (during exercise)
 Drink after exercise
 Cool drinks increase performance by
cooling the body effectively

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Sport Books Publisher
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