1. 1
Asst. Prof. Theeraporn Puntheeranurak
Department of Biology, Faculty of Science
Mahidol University
Email: theeraporn.pun@mahidol.ac.th
SCBI 109 Integrated Biology
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The Only Diet You Will Ever Need
2.1 Nutrients
- Macronutrients
- Micronutrients
2.2 Enzymes and Metabolism
- Enzymes
- Calories and Metabolic Rate
2.3 Body Fat and Health
- Evaluating How Much Body Fat is Healthful
- Obesity
- Anorexia and Bulimia
SCBI 109 Integrated Biology
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• Organisms are composed of matter.
• Matter is anything that takes up space and has mass.
• Matter consists of chemical elements in pure form
and in combinations called compounds.
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Essential elements

2. 5
What are nutrients?
• Essential substances that your body
needs in order to grow and stay
healthy
• Some provide energy.
• All help build cells and tissues,
regulate bodily processes such
as breathing.
• No single food supplies all the
nutrients the body needs to
function.
 Body needs certain essential ‘nutrients’
for its well-being.
FUNCTIONS OF FOOD
1. Energy-yielding,
2. Body-building, and
3. Protective foodstuffs
according to predominant role they play in sustaining life.
Nutrients in the Human Diet
• Macronutrients
– Water
– Amino Acids and
Proteins
– Lipids
– Carbohydrates
• Micronutrients
– Vitamins
– Minerals
Six categories of nutrients:

3. Macronutrients
Function and sources of carbohydrate
Carbohydrate provides the main source of energy for the
body.
Some forms of complex carbohydrates may reduce
cholesterol which is beneficial for health.
Further classification of carbohydrate
There are different ways to classify carbohydrate.
One method is into:
1) sugar;
2) starch.
Classification of carbohydrate
Sugar
Monosaccharides are the simplest form of carbohydrate
molecules, e.g. glucose, fructose and galactose.
Disaccharides are formed when two sugar molecules join
together, e.g. sucrose (glucose and fructose), lactose
(glucose and galactose) and maltose (2 molecules of
glucose).
Starch
Polysaccharides are made up of many monosaccharide's
molecules joined together, e.g. starch, glycogen, cellulose
and pectin.

4. 13
- Monosaccharide (CH2O)n, n > 3 : simple sugars
Glucose, Fructose, Galactose, Ribose
Classification of carbohydrate
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- Oligosaccharide (with glycosidic linkage)
Maltose, Lactose, Sucrose
Classification of carbohydrate
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- Polysaccharide : starch, glycogen, cellulose, chitin
Storage polysaccharides
Structural polysaccharides
- Polysaccharide :
• complex carbohydrate
• compose of hundreds or thousands of monomer
• link by glycosidic linkage
• same monomer or different
• form of linkage can lead to different properties even
made from the same monomer
Classification of carbohydrate
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5. Another classification systems for sugars
Intrinsic can be described as sugars incorporated into the
cellular structure of food,
e.g. sugars in whole fruits and vegetables.
Extrinsic sugars can be described as not bound into cellular
structure, e.g. lactose in dairy products.
Non-milk extrinsic sugars (NMES) are sugars not bound into
cellular structure and also not found in milk,
e.g. honey, fruit juices, table sugar and confectionery
are all examples of foods containing NMES.
Excessive consumption of carbohydrate
Increased body weight
When too much carbohydrate is consumed and not used for
energy over an extended period of time, it is stored as fat.
Building up too much fat will increase body weight.
Increase dental caries
It is important that teeth are brushed twice a day and foods
high in sugar should be eaten with main meals, rather than
in between snacks to prevent dental caries.
Lack of carbohydrate
The short term effects of a lack of carbohydrates are weight
loss and lethargy (drowsiness).
Kwashiorkor (lack of protein) and Marasmus (total lack of nutrient) are
two forms of deficiency disease which can develop in
extreme conditions. These occur where energy and protein
are lacking in the diet over an extended period of time.
Protein
Protein is needed for growth, development and repair of the
body.
Excess protein can be broken down and used as a source
of energy.
Protein is made up of different combinations of amino acids.
These are the building blocks of protein.
Amino acids are compounds containing
carbon, hydrogen, oxygen, nitrogen

6. 21
20 amino acids of proteins (essential and non-essential)
The amino acids are grouped here according to the properties of their
side chains (R groups).
Protein
Indispensable or dispensable?
The human body is able to make most amino acids itself
and these are known as non-essential or dispensable amino
acids.
There are some amino acids that cannot be made by the
body. They are called indispensable amino acids (IAA) or
sometimes essential amino acids. (phenylalanine, valine,
threonine, tryptophan, isoleucine, methionine, leucine, lysine, histidine*
and arginine*, *essential for infant)
It is essential that these are provided in the diet as the body
cannot make them.
Body needs
Adults only need 8 indispensable amino acids for growth
and repair.
Children need to obtain 10 indispensable amino acids.
(phenylalanine, valine, threonine, tryptophan,
isoleucine, methionine, leucine, lysine, histidine* and
arginine*, *essential for infant)
Biological value and complementation
It is not just the amount of protein, but the quality or
biological value of the protein that needs to be considered.
If a protein contains all the indispensable amino acids it is
said to have a high biological value.
If a protein does not contain all the indispensable amino
acids it is said to have a low biological value.

7. High and low biological value
High biological value (HBV) proteins include:
meat, fish, eggs, cheese, and milk.
Low biological value (LBV) proteins include:
cereals, pulses, some nuts and vegetables.
In general, animal protein sources have a higher
biological value, than vegetable sources.
Vegetarians and vegans need to eat wisely to ensure
they are getting all the indispensable amino acids.
The body’s needs for protein
Babies and children have a high need for protein
because they are growing.
Adolescents need protein for their rapid growth spurt.
Pregnant women need more protein than other
adults because of the growing baby.
Nursing mothers also need more protein for lactation.
Protein deficiency
Protein deficiency is rare, but there is a condition called
PEM – protein energy malnutrition. This can be seen in
infants with stunted growth or thin arms and legs, and large
distended abdomens.
Marasmus (total lack of nutrient) - this condition mainly affects
infants causing them to become thin and weak. The body
adapts to the shortage of energy and nutrients. All energy
stores are depleted as it is used to supply vital organs.
Kwashiorkor (lack of protein) - this condition is known to be the
body’s adaption to shortage of energy and nutrients.
Fat
Fat performs many functions in the body including:
• providing essential fatty acids;
• providing a concentrated source of energy;
• carrying fat soluble vitamins and is important for their
absorption;
• surrounding and protecting body organs;
• forming an insulating layer keeping the body warm.
Fat is made up of
fatty acids and glycerol.
Glycerol
Fatty Acid 1
Fatty Acid 2
Fatty Acid 3

8. Essential fatty acids
The body can make most fatty acids.
Essential fatty acids (EFA) are required for important
functions in the body. These must be provided by the diet
because our bodies cannot make them.
Two EFAs are known for humans: alpha-linolenic acid (an omega-3
fatty acid) and linoleic acid (an omega-6 fatty acid).
Sources of saturated and unsaturated fats
• Saturated fat
Meat, coconut oil, palm oil, cakes and biscuits, lard.
• Unsaturated fat
* Mono unsaturated fat
Rapeseed oil, avocado and olive oil.
* Polyunsaturated fat
Oily fish, sunflower oil and pine nuts.
Over consumption of fat
Eating too much saturated fat has become a problem in our
society.
There are many health problems linked with too much
saturated fat in the diet, e.g. coronary heart disease, and
strokes.
Micronutrients

9. Micronutrients
Micronutrients are needed in much smaller amounts than
the macronutrients.
In general vitamins are needed to regulate the maintenance
and growth of the body, and to control metabolic reactions in
cells.
Most vitamins are provided to the body through the diet,
however, the body can make vitamin D, vitamin K and
niacin.
Vitamin A (retinol, carotene)
Vitamin A is fat-soluble vitamin needed for the normal
structure and functioning of the cells in the skin and body
linings, e.g. in the lungs.
This vitamin also helps with vision in dim light, as well a
keeping the immune system healthy.
It is found in two forms; retinol in foods from animal
sources and carotenoids (the most abundant of which
is the beta-carotene) from plant sources.
Vitamin A – retinol is found in liver and whole milk,
Vitamin A – carotenoids are found in dark green leafy
vegetables, carrots and orange coloured fruits.
Too much or too little?
Deficiency leads to poor vision in dim light or night
blindness. Severe deficiency can lead to total blindness.
Vitamin A is stored in the liver and too much vitamin A can
be toxic.
Consuming too much vitamin A whilst being pregnant has
been linked to birth defects.
Vitamin D (Cholecalciferol)
Vitamin D is needed for the absorption of calcium and
phosphorous from foods, to keep bones healthy.
Recent research also suggests that vitamin D enhances
immune function and improves muscle strength.
Vitamin D is found in the diet, but most of our vitamin D is
made in the body the action of ultra violet rays on the skin.
Vitamin D occurs naturally in some animal
products, including fish liver oils, oily fish,
egg yolk, and butter.
Cereals, margarine and low fat spreads are
also fortified with vitamin D.

10. Too much or too little?
Deficiency of vitamin D leads to rickets (โรคกระดูกอ่อน) and the
formation of soft bones. This causes the bones in the legs to
bend. Deficiency in adults causes Osteomalacia resulting in
pain and muscular weakness.
Vitamin D can be stored by the body. Too much vitamin D can
lead to excess levels of calcium in the blood.
Young children, housebound older adults, and people who
practice religions where their skin must be covered, may be at
risk of deficiency through lack of exposure of their skin to
sunlight.
Vitamin E (Tocopherol)
Vitamin E is a group of similar molecules with common
properties and functions.
Vitamin E acts as an antioxidant and protects cells in the
body against damage.
Vitamin E is mainly found in vegetable oils, nuts,
seeds and wheat germ.
Deficiency and excess of vitamin E
A deficiency in this vitamin is rare because it is so widely
available in the diet.
In very rare cases neurological disabilities such as lost
reflexes have developed.
Vitamin E has a low toxicity, but in very large doses may
interfere with absorption of vitamin A.
Vitamin K
Vitamin K is needed for normal clotting of blood and is
also required for normal bone structure.
Infants are given vitamin K at birth.
Vitamin K is also produced by the bacteria in the gut.
Vitamin K is found in green leafy vegetables e.g.
broccoli, lettuce, cabbage, spinach and meat and
dairy products.

11. Too much or too little?
Deficiency of vitamin K is rare in
adults, but is sometimes seen in
new born babies.
Thiamin (B1)
Thiamin is needed for the release of energy from
carbohydrate. It is also involved in the normal functioning of
the nervous system and the heart.
Thiamin is mainly found in whole grains, nuts, meat
(especially pork), fruit and vegetables and fortified
cereals.
Too much or too little?
Thiamin deficiency can lead to the development of the
disease beri-beri. Symptoms include fatigue, weakness of
the legs (ชาปลายเท้า) and anorexia (ไม่อยากอาหาร).
As the body excretes any excess thiamin, there is no
evidence of any toxic effects of high doses.
Riboflavin (B2)
Riboflavin is needed for the release of energy from
carbohydrate, protein and fat.
It is also involved in the transport and metabolism of iron in
the body and is needed for the normal structure and function
of skin and body linings.
Riboflavin is found in milk, eggs, rice, fortified
breakfast cereals, liver, legumes, mushrooms and green
vegetables.

12. Too much or too little?
There is no deficiency related disease, however, the
tongue, lips and skin become affected when the body is low
in riboflavin (ปากนกกระจอก).
As the body excretes any excess riboflavin, there is no
evidence of any toxic effects of high doses.
Niacin (B3)
Niacin is important for releasing energy from food, and is
important for the normal structure of the skin and body
linings.
Niacin is also needed for the normal functioning of the
nervous system.
Niacin can be found in meat, wheat and maize flour,
eggs, dairy products and yeast.
Too much or too little?
Deficiency of niacin can result in the disease pellagra.
Symptoms can include:
• dermatitis (คันตามผิวหนัง, ภูมิแพ้);
• dementia (โรคสมองเสื่อม);
• diarrhoea.
Problems associated with excessive intakes are rare.
Vitamin B12
Vitamin B12 is needed for the formation of red blood
cells and the normal functioning of the nervous system.
Vitamin B12 also helps to release energy from food.
Vitamin B12 is found exclusively in animal products,
plant products do not provide any vitamin B12.
It is found in meat, fish, cheese, eggs, yeasts
extract and fortified breakfast cereals.

13. Deficiency of vitamin B12
Deficiency of vitamin B12 can lead to pernicious anaemia
(โลหิตจาง).
It can also lead to some neurological problems.
Deficiency is rare, but may be a problem for people
following strict vegan or vegetarian diets.
Folate (Folic acid)
Folate is important for the formation of healthy red blood
cells.
It is also needed for the nervous system and specifically for
the development of the nervous system in unborn babies.
It can reduce the risk of neural tube defects in a fetus, e.g.
spina bifida.
Good sources of folate include green leafy
vegetables brown rice, peas, oranges, bananas and
fortified cereals.
Deficiency of folate
Deficiency of folate can lead to megaloblastic anaemia.
Symptoms can include insomnia (โรคหลับยาก), depression and
forgetfulness.
It is recommended that all women who are planning a
pregnancy take a daily supplement of folic acid. Once
pregnant, supplementation should continue for the first 12
weeks to reduce the risk of neural tube defects.
Vitamin C (Ascorbic acid)
Ascorbic acid is needed to make collagen which is required
for the normal structure and function of body tissues, such
as skin, cartilage and bones.
It also acts as an antioxidant that protects the body from
damage by free radicals.
Sources of ascorbic acid include fresh fruits, especially
citrus fruits and berries, green vegetables, peppers
and tomatoes. Ascorbic acid is also found in potatoes
(especially in new potatoes).

14. Too much or too little?
Scurvy (ลักปิดลักเปิด) can result from lack of ascorbic acid. It
tends to occur in infants and the older adults.
Scurvy leads to spots on the skin, bleeding gums and loose
or loss of teeth.
Over nutrition of ascorbic acid is rare.
Minerals
Minerals are inorganic substances needed by the body for
many different functions.
Some minerals are needed in very tiny amounts, these are
known as trace elements, such as fluoride.
Calcium (Ca)
Calcium is important for the formation and maintenance of
strong bones and teeth, as well as the normal functioning of
nervous system and muscles.
It is also involved in blood clotting.
Milk and dairy products are the most important sources
of calcium. Other sources include bread, calcium
enriched soya products, green leafy vegetables and fish
with soft edible bones.
Too much or too little?
Poor intakes of calcium can result in poor bone health which
can increase the risk of diseases such as osteoporosis later
in life.
Taking high doses of calcium supplements can cause
stomach pains and diarrhoea.

15. Iron (Fe)
Iron is needed for needed for the formation of haemoglobin
in red blood cells which transport oxygen around the body.
It is also required for energy metabolism and has an
important role in the immune system.
Haem iron is present in animal sources in the form
of haemoglobin.
Non haem iron is present in plant sources such as
beans, nuts, dried fruits, wholegrains, soya bean
flour and dark green leafy vegetables.
Too much or too little?
A lack of iron will lead to anaemia. Symptoms include:
• feeling of tiredness;
• lacking in energy;
• general weakness;
• poor concentration.
Too much iron in the diet can result in constipation,
nausea and vomiting.
Phosphorus (P)
Phosphorus is essential for the structure bones and teeth,
for the structure of cell membranes and for energy
metabolism.
Phosphorus is found in red meat, dairy products, fish,
poultry, bread, rice and oats.
Potassium (K)
Potassium is essential for water and electrolyte balance and
normal functioning of cells, including nerves.
Potassium is present in all foods, but found richly in fruit
(dried fruits, bananas, berry fruits), leafy green
vegetables (e.g. broccoli and spinach) meat, nuts,
seeds and pulses.

16. Sodium (Na)
Sodium is needed to regulate body water content and
electrolyte balance.
Sodium is also needed for the absorption of some nutrients
and water from the gut.
Sodium is present in very small amounts in raw
foods. It is often added as salt during processing,
preparation, preservation and serving.
High salt processed foods include bacon,
cheese, yeast extract and smoked fish.
Too much or too little?
Consuming too much sodium increases the risk of high
blood pressure. High blood pressure is linked with an
increased risk of heart disease and stroke.
Sodium deficiency is unlikely, but can be caused by
excessive sweating or vomiting and diarrhoea.
It is recommended that adults and children over the age of
11 years cut down on salt and consume no more than 6g
per day.
Fluoride (F)
Fluoride is needed for the formation of strong teeth and
protects against dental decay (caries).
Fluoride is a trace element, therefore only a small amount is
required for good health.
Fluoride can be found in drinking water and in small
amounts in tea and saltwater fish.
Some areas add fluoride to the drinking water.
Fluoride toothpastes are another important source.
Too much or too little?
An excessive intake of fluoride can lead to mottling or
discolouration of teeth.

17. Nutrient interactions
Some nutrients work together in the body completing
different functions.
For example:
• the vitamins A,C and E;
• calcium phosphorus and fluoride;
• calcium and vitamin D;
• iron and vitamin C;
• carbohydrates and B vitamins.
Anti-oxidants
Vitamins A, C and E are anti-oxidants and work together in
the body to protect cells against oxidative damage from free
radicals.
This damage to cells can increase the risk of developing
diseases such as heart disease and cancer.
Calcium, phosphorus and fluoride
These nutrients are involved in the mineralisation of teeth
and bones which keep them hard and strong.
Vitamin D and calcium
Vitamin D controls the amount of calcium available.
A lack of vitamin D in the body results in reduced
absorption of calcium.
Iron and ascorbic acid
Ascorbic acid aids the absorption of non haem iron (non
meat sources of iron) when eaten at the same time.
This is particularly important for people following strict vegan
or vegetarian diets.

18. Carbohydrates and Vitamins B
Riboflavin and thiamin are involved
in the release of energy from
carbohydrate.
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• A fundamental task of proteins is to act as enzymes—catalysts
that increase the rate of all the chemical reactions within cells
(over a millionfold).
• Enzymes increase the rate of chemical reactions without
themselves being consumed or permanently altered by the
reaction.
– A substrate is a molecule that is acted upon by an enzyme.
– A product is a result of the reaction between the enzyme and the
substrate.
Energy diagrams for catalyzed and uncatalyzed reactions • An enzyme converts a substrate to a higher energy state, or
transition state.
• Activation energy is the energy required to reach the transition
state, which constitutes a barrier to the progress of the
reaction.

19. • The substrate binds to a specific region of the enzyme called the
active site.
• The binding of a substrate to the active site of an enzyme is a very
specific interaction.
• Most biochemical reactions involve interactions between two or
more different substrates.
• The simplest model of enzyme-substrate interaction is the lock-and-
key model in which the substrate fits precisely into the active site.
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• mostly adds –ase at the end of substrate name eg.
maltase, lipase, protease, sucrase, cellulase, amylase
• or at the end of reaction name eg. hydrolase, isomerase,
dehydrogenase, kinase, ligase
• effects of enzyme activity
• temperature
• pH (acid-base)
• inhibitor
• etc.
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20. • Coenzymes are low-molecular-weight organic molecules that participate
in specific types of enzymatic reactions by working together with
enzymes to enhance reaction rates.
• Nicotinamide adenine dinucleotide (NAD+) is a coenzyme that functions
as a carrier of electrons in oxidation-reduction reactions.
Role of NAD+ in oxidation–reduction reactions
• Several other coenzymes also act as electron carriers, and still
others are involved in the transfer of a variety of additional chemical
groups.
• Many tasks that a cell must perform, such as movement and the
synthesis of macromolecules, require energy.
• The totality of an organism’s chemical reactions is called
metabolism (from the Greek metabole, change).
• Energy is the capacity to cause change. In everyday life, energy is
important because some forms of energy can be used to do work-
that is, to move matter against opposing forces, such as gravity and
friction.
• Calorie: a unit of energy. The calorie approximates the energy needed to
increase the temperature of 1 gram of water by 1 °C.
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Metabolic Rates and Weight
• Basal Metabolic Rate (BMR) – the amount of energy
your body uses at complete rest
• About 60–70% of calories consumed per day support
BMR

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The nutrition facts label
(also known as the nutrition
information panel) is a label
required on most packaged food
in many countries.
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Nathan’s Famous Hot Dog Eating Contest Yields
Frightening Nutrition Facts

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The glycemic load
(GL) of food is a
number that estimates
how much the food
will raise a person's
blood glucose level
after eating it.
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23. 89
BMI
• Body Mass Index
• The term BMI is often used when discussing
the obesity epidemic
• BMI is a tool for indicating
weight status.
• It is a number that shows
body weight adjusted for
height.
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• Body Mass Index (BMI) formula:
o Weight (kg) / height squared (m2) or
o Weight (lbs) x 704.5 / height (in.) / height (in.)
• 60 kg / (1.60 m x 1.60 m)
• 60 / 2.56 = 23.4 BMI
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Body Mass Index: Are You at a Healthy Weight?
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24. 93 94
Above a Healthy Weight
• If your BMI lies above the normal area,
then you may be at greater risk for
health problems such as high blood
pressure, heart disease, diabetes, and
certain cancers.
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Below a Healthy Weight
• If your BMI lies below the normal area, then
you may be at risk for health problems such
as irregular heart rhythms, depression,
anemia, and osteoporosis.
• Some people have a low BMI, but are eating
well and have lots of energy. The best advice
for people below a healthy weight is to be
aware of their health risks and maintain a
stable weight by eating well and keeping
active.
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These men have the same height, weight,
and BMI, but may have different percent
body fat.
6'3" Height 6'3"
220 lbs Weight 220 lbs
27.5 BMI 27.5
• BMI is only one of many factors used to predict risk
for disease.
• It is important to remember that weight is only one
factor related to disease.

25. 97
BMI is the not the only indicator
for health risk
Other Factors That Are Important
When Calculating Health Risk
Include:
• Diet
• Physical Activity
• Waist Circumference
• Blood Pressure
• Blood Sugar Level
• Cholesterol Level
• Family History of disease
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Obesity
Overweight and obesity are defined as abnormal or excessive fat
accumulation that presents a risk to health. A person with a BMI of 30 or
more is generally considered obese. A person with a BMI equal to or more
than 25 is considered overweight.
• Waist circumference:
– Men <40 inches (102 cm)
– Women <35 inches (88 cm)
• Waist-to-hip ratio:
– Men <1.0
– Women <0.8
Obesity
99 100
Selected Health Consequences of Overweight and Obesity

26. Portion Distortion:
Do You Know How Food Portions Have
Changed in 20 Years?
French Fries
20 Years Ago Today
210 Calories
2.4 ounces
How many calories are
in these fries?
610 calories
6.9 ounces
Calorie Difference: 400 calories
*Based on 160 pound person
How long will you have to
walk to burn* 400 calories?
How to burn* 400 calories:
Walk leisurely for 1 hr 10
Minutes
Soda
20 Years Ago Today
85 Calories
6 ½ ounces
Calorie Difference: 165 calories
How many calories are in this
soda?
250 calories
20 ounces
*Based on 160 pound person
How long would you have
to garden to burn 165 calories?.
How to burn* 165 calories:
Garden for 35 Minutes
Turkey Sandwich
20 Years Ago Today
320 calories
Calorie Difference: 500 calories
How many calories are in
this turkey sandwich?820 calories
*Based on 130 pound person
How long would you have to bike
to burn up 500 calories?
How to burn 500 calories:
Bike for 1 hour and 25 minutes

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Anorexia and Bulimia
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Anorexia nervosa is a type of eating disorder. People who
have anorexia have an intense fear of gaining weight.
They severely limit the amount of food they eat and can
become dangerously thin.
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Bulimia nervosa is an eating disorder characterized by binge
eating and purging, or consuming a large amount of food in a
short amount of time followed by an attempt to rid oneself of the
food consumed (purging), typically by vomiting, taking a
laxative or diuretic and/or excessive exercise. Bulimia nervosa
is considered to be less life threatening than anorexia; however,
the occurrence of bulimia nervosa is higher.
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