Sport Books Publisher1 The Nutritional Connection Chapter 11

Sport Books Publisher 1

The Nutritional Connection

Chapter 11


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


Introduction


IntroductionPromotion of energy and vigor

Development of chronic illness and disease

NUTRITIONAL HABITS


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


The Digestive System


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


The Gastrointestinal TractDigestive Tract Mouth Pharynx Esophagus Stomach Small intestine Large intestine

(colon) Rectum AnusGlandular Organs Salivary glands Liver Gall bladder Pancreas


Basic Processes of the Digestive System

1. Digestion2. Secretion3. Absorption4. Motility


Digestion

Processes that dissolve and break down foods into molecules that can be absorbed by the body


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


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


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


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)


Functional Overview of the Gastrointestinal Organs


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


Saliva contains mucus that moistens and lubricates food

Saliva also contains ‘amylase’

Amylase is an enzyme that catalyzes the breakdown of carbohydrates

Functional Overview of GI Organs:The Salivary Glands


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

Functional Overview of GI Organs:The Mouth and Throat


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

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



The precursor ‘pepsinogen’ forms the enzyme ‘pepsin’

Pepsin begins protein digestion

Amylase (from the salivary glands) continues to break down carbohydrates



Little absorption occurs across the stomach wall



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)

Functional Overview of GI Organs:The Small Intestine


Hydrolytic Enzymes

Monosaccharides

CarbohydratesAMYLASE


Hydrolytic Enzymes

Amino Acids

Proteins PEPSIN


Hydrolytic Enzymes

Fatty Acids

Fats LIPASE


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

Functional Overview of GI Organs:The Pancreas


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

Functional Overview of GI Organs:The Liver


Absorption in the Small Intestine

Absorption within the small intestine occurs via:

1. DIFFUSION (Fatty Acids)

2. OSMOSIS (Water)

3. ACTIVE TRANSPORT (Mineral Ions)

4. CARRIER-MEDIATED TRANSPORT (Monosaccharides and Amino Acids)


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


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


Nutritional Requirements: Types and Sources of Nutrients


Nutrition

The science of food and how the body uses it in health and disease


Essential Nutrients

1. Proteins

2. Fats

3. Carbohydrates

4. Vitamins

5. Minerals

6. 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


Essential Nutrients

Necessary for energy Needed for the building and

maintenance of tissues Relied upon for the regulation of body

functions


Energy-Providing Nutrients

Three nutrients provide the body with energy

1. Proteins

2. Fats

3. Carbohydrates


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


FATS 9 Cal/g

ALCOHOL 7 Cal/g

CARBOHYDRATES 4 Cal/g

PROTEINS 4 Cal/g

Calorie Densities of Various Energy Sources


Proteins Found in every living cell Act as structural components for:

1. Muscles

2. Bones

3. Blood

4. Enzymes

5. Some hormones

6. Cell membranes


Proteins Composed of chains of amino acids 20 commonly recognized amino acids Nine essential (can not be synthesized)

amino acids1. Histidine2. Isoleucine3. Leucine4. Lysine5. Methionine6. Phenylalanine7. Threonine8. Tryptophan9. Valine


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


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)


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


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


Fats Fats in food are mostly triglycerides Include a glycerol (an alcohol) Three fatty acid molecules


Fats 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


Saturated Fat

Monounsaturated Fat

Polyunsaturated Fat


Saturated Fats 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


Unsaturated Fats 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



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


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


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


Monosaccharides 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


Disaccharides 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


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


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


Vitamins Serve as coenzymes in chemical

reactions ‘Organic’ because they contain carbon

atoms Required in small amounts Necessary for

1. Growth2. Reproduction3. Health Maintenance


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


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


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


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)


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


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

Approximately 17-21 identified essential minerals


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


Water Large component of

our bodies and food Important for:1. Nutrient transport2. Waste transport3. Digestion &

absorption4. Regulation of body

temperature5. Lubrication6. Chemical reactions


Water Body water is lost through:1. Urine2. Feces3. Sweat4. Evaporation in lungs Excessive water loss

through:1. Illness2. Exercise3. Hot environment4. Consumption of coffee, tea,

alcohol


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


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


Fibre Rich sources include:

1.Fruit2.Legumes3.Oats4.Barley

Other sources include:1.Wheat2.Grains3.Vegetables4.Whole grain foods


Fibre Soluble fibre

Lowers blood cholesterol Slows absorption of glucose

Insoluble fibre Facilitates feces elimination Can prevent constipation, lower

intestinal tract cancer


Nutrition Guidelines and Recommendations


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


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)


Nutrition Recommendations for Canadians

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…


Enjoy a variety of foods


Emphasize cereals, breads, other grain products, vegetables, and fruits


Choose lower-fat dairy products, leaner meats, and foods prepared with little or no fat


Achieve and maintain a healthy body weight by enjoying regular physical activity and healthy eating


Limit salt, alcohol, and caffeine


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



Food Groups

Five food groups:

1. Grain Products

2. Vegetables and fruits

3. Milk products

4. Meat and alternatives

5. Other foods (such as junk food)


Food Choices

The rainbow design of the Food Guide is a visual representation of the relative amounts of each food group recommended



Food Servings Amount of food needed each day from

the food groups varies according to:

1. Age

2. Body size

3. Gender

4. Activity level

5. If you are pregnant

6. If you are breast feeding


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


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



Choose dark green and orange vegetables and orange fruit more often

Choose lower-fat milk products more often



Choose leaner meats, poultry and fish, as well as dried peas, beans, and lentils more often


Nutrition Questions and Answers



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



Labels are standardized presentations of the nutrient content of food

Consists of (based on serving size):1. Heading2. Serving size3. Values for energy4. Protein5. Fat6. Carbohydrate May also include:1. Breakdown of fats (saturated, monounsaturated,

polyunsaturated)2. Breakdown of carbohydrates (sugar, starch, fibre)3. Sodium and potassium4. Vitamins and minerals



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


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



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



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



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



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



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


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


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


Documents

Sport Books Publisher1 The Nutritional Connection Chapter 11