Food & diet - IGCSE

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FOOD AND DIET B M Subramanya Swamy M.Sc. B.Ed. CIE Co ordinator & Examination Officer Kanaan Global School Jakarta Indonesia [email protected]

Transcript of Food & diet - IGCSE

Page 1: Food & diet - IGCSE

FOOD ANDDIET

B M Subramanya Swamy M.Sc. B.Ed.

CIE Co ordinator & Examination OfficerKanaan Global School

Jakarta Indonesia

[email protected]

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FOOD ANDDIET

B M S SwamyUniversal School Jakarta

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F O O DF O O DSource of fuel for the bodyEaten in the right amount and types, it leads to good healthIt serves to :

- supply energy- promote body growth and repair of tissues- regulate body functions

Carbohydrates, fats and proteins are nutrients that provide energyVitamins, mineral salts and water are not digested. It is used to regulate body functionsDietary fibre is important in preventing constipation

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CarbohydrateCarbohydrates contain compounds of carbon, hydrogen and oxygen in the ratio of 1 : 2 : 1

Carbohydrates Types Sources Function

Monosaccharide(single/simple sugar)

Disaccharide(double/complex sugar)

Polysaccharide

GlucoseFructose Galactose

Sucrose Maltose Lactose

StarchCellulose Glycogen

Fruits and vegetables

Sugar cane, beetroot, milk

Rice, cereal, bread

• Provide energy• Converted to glycogen for storageExcess is stored as fats

Used in synthesis of DNA

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Fats_________________________ 1. Composed of carbon, hydrogen and oxygen2. Oils (fatty acids and glycerol) are liquid at room

temperature. They have a low melting point.3. Waxes are solid at room temperature.4. Fats provide twice as much energy as

carbohydrates. They are stored in the body as fats.5. There are saturated and unsaturated fats.

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Fats Sources Function

Saturated

Unsaturated

ButterAnimal fats

Fish oil Vegetable oil

Provide energy Medium for intake of

vitamin A, D, E and K

Synthesis of cell membrane

Insulation layer under skin

Protects organs from physical injury

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Proteins___________________

☺ Composed of carbon, hydrogen, oxygen and nitrogen. May contain sulphur or phosphorus.

☺ Protein molecules are composed of large numbers of amino acids linked together by peptide links.

☺ Lack of proteins lead to kwashiorkor.☺ Complete proteins come from animal sources.☺ Incomplete proteins come from plant sources.

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Proteins Sources Function

Animal/plant

Human (9 essential and 11 non-essential protein)

Lean meatFish Liver Milk Cheese Soya beans Cereals

Growth of new tissue Replacement of cell component Build up body structure like hair and nails Function of muscles, tendons and ligaments Formation of enzymes and hormones Components of antibodies

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Fibre______________________

Fibre in the diet consist of carbohydrates, mainly cellulose and ligninThey are not digested by the human body

Sources Function

Fruits, vegetables, whole meal bread and cereals

Stimulates peristalsis, moves waste along intestines Absorbs water, making wastes softer. Thus preventing constipation

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Minerals___________________ ۩ Inorganic, chemical elements۩ Regulate body processes۩ Not stored in the body (except for iron)۩ Is quickly used or lost۩ Body requires calcium, phosphorous and

magnesium more than iodine, iron and zinc

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Mineral Sources Function Deficiency Symptoms

Calcium Cheese, milk, oyster, green vegetables

• Development of strong bones and teeth• Blood clotting• Muscle contraction• Nerve/heart activity

• Soft bones• Osteoporosis (adults)• Rickets (children)• Slow blood clotting• Weakness • Wounds heal slowly

Iron Egg, lean meat, legume, green leafy vegetables

• Forms haemoglobin in RBC• Transport oxygen as oxyhaemoglobin

• Anaemia • Paleness of skin• Fatigue

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Vitamins_____________________ ♣ Organic compounds, required on small

quantities♣ Water-soluble vitamins (B and C) are not

stored in the body. Excess of these vitamins are excreted

♣ Fat-soluble vitamins (ADEK) need not be consumed everyday, it is absorbed by the body and stored in the liver

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Vitamins

Sources Function Deficiency Symptoms

A Fish liver oil, dairy products, green vegetables

• Healthy growth• Maintenance of skin tissue• Formation of visual pigment in the retina

• Poor skin• Night blindness

B1 Whole grains, egg, meat

• Promote cell respiration• Normal growth

• Lethargy • Retarded growth• Degeneration of nerves and muscles (beri – beri)

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C Fruits (esp. citrus), potatoes, green vegetables

• Healthy epithelia• Strong gums• Helps heal wounds• Aids in iron absorption

(scurvy)• Bleeding gums• Loose teeth• Bleeding under the skin• Slow healing of wounds

D Fish liver oil, dairy products

• Absorption of phosphorous and calcium• Builds and maintains bones and teeth

(rickets)• Mainly in children• Leads to bowlegs and beaded ribs

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Water________________________ 1. Makes up about 60 – 70 % of body weight 2. Lost in urine, perspiration and breathing3. If not replaced, the body gets dehydrated4. This leads to muscles cramps and weakness in

the body

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Function of water in the human bodyFunction Mode of action

Transport • Main constituent of blood and body fluid• Medium for transport of nutrients, water, hormones, etc

Reactions • Solvent for chemical reactions• Hydrolytic reactions during digestion

Lubricants • Constituent of synovial fluids in joints and mucus in alimentary canal

Homeostasis • Evaporation of water from sweating cools the body. Thus preventing overheating.

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World Food Supply

There has been a dramatic increase in world populationThere has not been an increase in natural resources to feed the increasing populationMalnutrition is a world wide problem.

It takes many forms.

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Types of Malnutrition

Malnutrition Form

Starvation • Insufficient food to supply daily requirements of the individual

Eating disorder Anorexia nervosa

Bulimia

• May be genetic or environmental• Constant dieting with rapid weight loss• Psychological condition influenced by fashion trends

Eating too much food, and then getting rid of food by vomiting or use of laxatives

Marasmus • General starvation• Both energy and protein are insufficient• Affects children less than 1 year old who have been weaned too early or given poor substitutes for mother’s milk

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Kwashiorkor • Children displaced from breast feeding after arrival of new baby• Develops protein deficiency diseases• Body is dwarfed

Obesity • Being 20% above ideal weight• May be caused by thyroid problems, or low metabolic rate

Overeating saturated fats

• Increases level of cholesterol in the blood• Is deposited on walls of arteries where they harden• May cause clots to form, leading to heart attack and high blood pressure

Constipation • Difficult bowel movement• Could be caused by lack of exercise, emotional stress, misuse of laxatives, diet low in dietary fibre• May cause vessels in rectum to produce haemorrhoids, resulting piles• Can cause pain and bleeding

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Causes of food supply shortage

Causes

Form

Population explosion

• World population on the rise• Poverty, starvation and depletion of natural resources also on the rise

Famine • Extreme shortage of food• Industrial nations have food surplus• Under-develop nations with no means to pay for the expensive food

Drought • Severe climatic change• Extreme crop damage• Destruction of farm animals

Flood • Rivers overflow their banks, monsoon rains, tidal waves etc.• Destruction of agricultural lands and crops• Lands destroyed by tidal waves not suitable for farming anymore

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Solution to world food supply shortageSolution Form

Green revolution New strain of crops to enhance food yields

Farming the sea Culturing fish, lobsters, prawn and crabs, and plants like seaweed and algae

Genetically modified food Genes altered to improve quality of foodIncrease shelf life, size, nutrient content

Distribution of food World Red Cross organizations supply food surplus to over populated third world countries

Farming technique Improve output of farmsUse machinery and fertilizers

Enriched foods Basic foods with increase in nutrients to improve quality of foodAddition of vitamins and minerals

Pest control Reduce quantity of food lost during storage or growth

Increase land under cultivation

Increase food productionUse of arid, semi – arid and desert areas with irrigation methods for farming

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Diet Balanced diet♦ Food intake and energy required varies with

sex, age and occupation♦ Good nutrition involves selecting food from

the various food groups♦ Eat grain, vegetables, fruits, dairy protein-rich food, fatty food

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Basic food group

Food group Sources Nutrients

Grain Whole grain, enriched flour

Carbohydrates, fibre, vitamin B, iron and protein

Fruits and vegetables

Dark green vegetable, deep yellow vegetable

Carbohydrates, fibre, various vitamins and minerals

Dairy Milk and milk products

Main source of calcium, protein, vitamin A, B and B2

Protein-rich Poultry, eggs, red meat, legumes

Rich in protein, vitamin B, magnesium and zinc

Fats and sweets Candy, pastry, oil, coffee

Low in nutrient value

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Energy A balanced diet supplies all the essential nutrients in the correct proportionsBasal metabolic rate (BMR) and physical activity determines the energy to maintain BMR to sustain activitiesBMR varies by sex, age and state of health of the individual

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Energy supplied by the various food types

1 g of food type Energy (kj)

Carbohydrate 2.2

Fat 8.5

Protein 7.2

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Food AdditivesAdditives substances added to foods in small quantities for a variety of reasons.

Function Examples Advantages Disadvantages

Flavorings • Monosodium Glutamate (MSG) (an amino acid)• Salt

• Chocolate flavour• Sugar

Improves taste

Improves taste

Improves taste

High doses can cause sweating and hyperactivity.

Contributes to high blood pressure.

The sugar in chocolate provides an excellent substrate for growing bacteria which produce acids which can cause tooth decay, also fattening.

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Function Examples Advantages Disadvantages

To improve nutritional quality

• Lysine is added to flours in places where diet is poor. • Vitamin D is added to white flours

Enriches poor diet

Colouring Annatto Improves appearance, by replacing colour lost in processing

Some people are allergic to annatto

Sweeteners Nutrasweet Food can taste sweet without being so fattening

Unsuitable for some people.Gives a bitter aftertaste.

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Function Examples Advantages Disadvantages

Preservatives Vinegar, salt, sugar

Reduces bacterial spoilage on ready – made meals. E.g. salad

Vitamin content of food declines with storage.

Anti-oxidant Sodium ascorbat

Stops fat spoiling and becoming rancid in pre – cooked meats

Stabilisers Carragheen Stops food textureseparating

Thickeners Guar gum Gives a thicken consistency and better sensation in the mouth.