You are what you eat!
carbohydrate
fat
protein
Human
Nutrition
Part1 Diet
营养物质
Nutrition means taking in of nutrients.
Which kinds of nutrient contained
in those food?
Seven types of nutrients
1. carbohydrate 碳水化合物
2. lipid 脂肪
3. protein 蛋白质
4. vitamins 维生素
5. minerals 矿物质盐
6. water 水
7. fibre 纤维
Balanced Diet均衡饮食
A diet contains all of the nutrients in
correct amounts and proportions to
provide energy and materials for
metabolism.
• carbohydrate
• protein
• lipid
• vitamins
• minerals
• water
• fibre/ roughage
Exercise-01
Exercise-02
Energy Requirement
Why we need energy?
1. internal body process,
such as heart beating,
breathing.
2. maintain body temperature
3. other work and activities
 calorie, joules are units of energy
1 calorie= 4.1859 joules
1 Kj=1000 j
1 gram of carbohydrate → 16~17 KJ
1 gram of fat → 37KJ
We need to obtain about 12000kJ
(2867kcal) of energy each day!
Factors affecting Energy requirement
energy/ food requirements differ because:
• gender
• age
• body size/ mass
• types of activities you do
• how much exercise you do
• pregnant women
Malnutrition营养不良
Kwashiorkor disease
Malnutrition includes:
1. overnutrition: get too much food
2. undernutrition: get too little food or get wrong types
of food
overnutrition: obesity 肥胖症
undernutrition:starvation 饥饿
Undernutrition: Deficiency Disease
Disease caused by lacking of some nutrients
1. lack of vitamin C:
2. lack of vitamin D and calcium:
3. lack of iron:
4. lack of fibre:
Related Disease: Marasmus and
Kwashiorkor Disease
1. Kwashiorkor：
• lack of enough protein, less protein in blood.
• water potential of the blood higher than normal.
• fluid move from the blood into body tissue, which
causes swelling.
2. Marasmus :
• A form of severe malnutrition;
• Lead to extremely thin, fatigue and poor
resistance to infection.
Classes of Food
Carbohydrate
Fat/lipid
Protein
Vitamin
Mineral Salts
Water
Fibre
1.Carbohydrate
• Sugar appears in our diet mainly
as sucrose (refined sugar精糖)
• Glucose and fructose in many
fruits and some vegetables.
• Function: provide energy
2.Fibre
• The undigested part of
cellulose in the diet is
called fibre or roughage.
Function of Fibre
• helps move food through the gut more efficiently
• protects the intestines from cancer and other disorders
• lack of fibre can cause constipation (便秘)
Function of Fibre
• helps move food through the gut more efficiently
• protects the intestines from cancer and other disorders
• lack of fibre can cause constipation (便秘)
3.Lipid
Animal fat×
Plant oil√
saturated fat
unsaturated fat
Saturated(饱和)and Unsaturated(不饱和) lipid
 Saturated: fatty acids only consist of
single bonds.
 Unsaturated: The tails of some fatty
acids have double bonds between
neighbouring carbon atoms, like this:
–C=C–.
Benefits of Lipid
• make part of the cell membrane
• provide energy
• providing long-term storage of energy in fat
• reduce heat losses from the body (insulation)
• protect organs from mechanical damage
 Cholesterol(胆固醇) is a kind of
lipid which is an essential part of
all cells, but too much cholesterol
blocks the artery!
Harm of high-fat diet
• Too much of bad cholesterol in the blood can cause fatty
deposits to form on the inside wall of arteries, which can lead
to coronary heart disease(冠心病).
• This restricts blood flow to the heart and can lead to a heart
attack, which can be fatal.
4. Protein
1. needed for growth and repair of tissue
2. make cell membrane
3. work as enzyme to catalyse chemical
reaction
4. work as haemoglobin to transport oxygen
5.Vitamin
Vitamin C
• Vitamin C is needed in tissue repair
and important for the immune system
• Vitamin C deficiency can cause scurvy,
which lead to bleed in the gums.
Vitamin D
• the only vitamin that our body can make.
• good for our teeth and bones
• prevents rickets(佝偻病)
• helps the absorption of calcium
6.Mineral Ions/ Salts
Iron 铁
• Haemoglobin in red cell contains
iron to transport oxygen.
• Lacking of iron will cause
anaemia(贫血症), reducing the
ability of transporting oxygen
Calcium 钙
• make teeth and bones
Exercise-03
Exercise-04
Summary of Food Molecules