Food and Diet

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Food and Diet

• Nutrients

2
Nutrients
Carbohydrates
Water
Fats
Minerals
Proteins
Vitamins
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Composition of Carbohydrates

• Come from plant foods
• Cheapest and most plentiful of all nutrients
• Foods which contain carbohydrates, are called
  energy foods
• All of the energy obtained from food starts with
  a single sugar unit - glucose. Some plants store
  energy for later use by combining sugars to make
  starch.

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Classification of Carbohydrates

• Sugar
• Starch
• Cellulose
• Pectin

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Carbohydrates - Sugar

• Sugars are found in honey, fruit (both fresh and
  dried) soft drinks, milk and sugar.

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Carbohydrates - Starch

• Starches are found in cereals, pasta, flour,
  bread, potatoes, root and pulse vegetables.

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Carbohydrates Cellulose / Fibre

• Cellulose or Dietary Fibre is found in
• whole cereals
• wholemeal bread
• outer skins of fruit and vegetables
• brown rice
• Oatmeal
• In refined foods the dietary fibre is removed
  during processing e.g. wholemeal flour contains
  fibre but white flour does not.

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Carbohydrates - Pectin

• Pectin is found in ripe fruit

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Functions of Carbohydrates

• Carbohydrates provides the body with heat and
  energy
• Fibre helps the movement of food through the
  intestine.
• Fibre rich and starchy foods provide a "full
  feeling
• Pectin helps jam to set

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RDA

• Nutritionists believe that the amount of sugar
  eaten in the western countries needs to be
  decreased and the amount of fibre needs to be
  increased.
• The Recommended Dietary Allowance (RDA) of fibre
  is now 30g per day. We in the western world eat
  about half the recommended amount-15g per day.

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Fats

• Fat is an important nutrient because it gives us
  energy
• The body stores energy as a layer of fat under
  the skin. This is called adipose tissue

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Composition of Fats

• Fats are made from glycerol and fatty acids
• Each glycerol is attached to three fatty acids
• Glycerol and fatty acids contain the elements
  carbon, hydrogen, and oxygen
• Fats contain a lot of carbon. This is why they
  give us so much energy.
• 1 gram of fat gives us 9 kilocalories

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Classification of Fats

• Fats are classified into two groups
• Saturated Fats
• come mainly from an animal source such as meat,
  eggs, milk and dairy produce e.g. cream and
  butter. There is a lot of saturated fat in butter
  and lard
• Unsaturated Fats
• come mainly from plant and fish sources such as
  peas, beans and lentils, whole cereals, nuts,
  cooking oil, polyunsaturated margarine and oily
  fish

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Functions of Fats

• Fat insulates the body. A layer of fat under the
  skin prevents heat loss from the body.
•  Fat protects the delicate organs such as the
  kidneys and nerves. A layer of fat surrounds
  them.
•  Fats provide the body with heat and energy.
  This helps to keep the body at the correct
  temperature (37o C).
•  Fat is a source of the fat-soluble vitamins

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RDA of Fats

• It is recommended that we eat 50 saturated fat
  and 50 unsaturated fat in our diet
• People in the western world eat too much
  saturated fat and it is recommended that we cut
  down on our intake
• We should also increase our intake of unsaturated
  fats

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To cut down on Saturated Fats

• Grill rather than fry.
• Use vegetable oil instead of hard fats for
  frying.
• Remove visible fat from meat.
• Look for hidden fats in the diet e.g. pastries
  and crisps.
• Use low fat milk, cheese, yoghurt and mayonnaise

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Protein

• Our bodies are made up of billions of cells,
  which contain protein
• Throughout our lives cells wear out and are
  replaced
• All the material for new cells comes from food
• The main nutrient involved in the building of new
  cells and replacing of worn cells is protein

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Composition of Proteins

• Proteins are made up of small units called amino
  acids
• The amino acids, which the body cannot make, are
  known as essential amino acids
• Adults need 8 and children need 10 essential
  amino acids.

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Composition of Proteins

• Proteins are broken down into amino acids in the
  digestive system
• Amino acids are smallest units of Protein. They
  can then be used to build up different proteins
  for the formation of new cells in the body
• Amino acids are made up of the elements carbon,
  hydrogen, oxygen and nitrogen

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Classification of Proteins

• Classified into two groups HBV and LBV
• High Biological Value Proteins come mainly from
  animal foods such as meat, fish, eggs, cheese and
  milk
• Low Biological Value Proteins come mainly from
  plant foods such as peas, beans and lentils,
  whole cereals and nuts. These foods also contain
  fibre and are low in fat

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Functions of Proteins

• The functions of proteins are
•  Growth of new cells such as skin hair and
  blood.
•  Repair of damaged cells.
•  Production of heat and energy.
• Manufacture of important body chemicals such as
  enzymes, hormones and antibodies.

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RDA of Proteins

• The RDA of protein depends on your body weight
• For every kilogram of body weight one gram of
  protein per day is needed, e.g. if you weigh 60
  kg you need 60 g of protein per day

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Vitamins

• The word "vitamin" comes from vita, the Latin for
  "life
• Everybody must eat a certain amount of vitamins
  to stay healthy
• Vitamins are chemicals found in very small
  amounts in many different foods. Tiny quantities
  are enough for the needs of the body
• If people live on a very limited range of foods
  they may not get their proper share of vitamins

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Classification of Vitamins

• Vitamins, of which there are 14, are classified
  into two main groups Water soluble and Fat
  soluble
• Fat soluble stored in bodies fat tissue
• A, D, E K
• Water soluble not stored in the body
• B vitamins, folic acid vitamin C

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Vitamins

• Fat soluble
• Vitamin A - needed for healthy vision, bone
  growth, reproduction and the immune system
• found in dark green, orange and yellow
  vegetables, such as spinach, carrots, broccoli,
  mangos, apricots, vegetable soup and tomato
  juice.It is also found in meat and dairy
  products such as liver, beef, chicken, whole milk
  and eggs.

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Vitamins

• Fat soluble
• Vitamin D - controls the absorption of calcium
  and phosphorus, which are essential for bone
  growth and development
• sardines and tuna, liver, egg yolks, some
  breakfast cereals and vitamin D-fortified milk.
  Vitamin D can also be made when the skin is
  exposed to sunlight

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Vitamins

• Water soluble
• Vitamin C - helps to maintain skin integrity,
  absorb iron from the gut and heal wounds, and is
  important in immune functions
• Vitamin C is found in citrus fruit and juices,
  tomatoes, spinach, potatoes, berries, green and
  red peppers, and broccoli

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Vitamins

• Water soluble
• Folate (folic acid), also called vitamin B9 is
  essential for the normal formation of the red
  blood cells, protein metabolism, growth and cell
  division
• Food sources include liver, citrus juices and
  fruits, beans, nuts, seeds, liver, dark green
  leafy vegetables.

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Minerals

• The human body requires about 20 mineral elements
• Each has a specific function and is found in
  certain foods
• A good varied diet should supply all essential
  minerals
• Some minerals are described as trace elements
  because the are required in smaller amounts
• Minerals are lost into the water during cooking

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Macrominerals

• Calcium - for muscle and digestive system health,
  builds bone, neutralizes acidity, clears toxins,
  helps blood stream
• Found in milk, cheese, green leafy vegetables
• Potassium for growth of lean tissue
• Found in bananas
• Sodium regulation of water balance in the blood
• Found in table salt, bacon, snack foods
• Sulfur
• Magnesium
• Phosphorus

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Trace Minerals

• Iodine Needed for the formation of thyroxine, a
  hormone in the thyroid gland which controls
  metabolism
• Found in vegetables and sea fish
• Iron Needed to make red blood cells
• Found in red meat, liver cabbage
• Manganese Processing of oxygen
• Zinc
• Cobalt
• Copper

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Water

• Water is absolutely essential to life. Over 70
  of the human body is made up of water. It is
  found in
• Muscles
• Saliva
• Blood
• Digestive Juices
• Mucus
• Sweat

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Composition of Water

• Water contains the elements hydrogen and oxygen
• They are present in the ratio 21, two parts
  hydrogen to one part oxygen
• Pure water freezes at 0C and boils at 100C

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Sources of Water

• The main sources of water are drinking water and
  beverages like tea, coffee and alcoholic drinks
• Water is also present in many other foods like
  meat and fish
• Fruits and green vegetables are high in water.
  Almost all foods contain water, except those with
  a high fat content (butter), and dry foods (sugar
  and flour)

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Functions of Water

• It is the chief component of all body fluids.
• It helps dissolve foods and aids digestion.
• It helps remove waste material from the body.
• It regulates body temperature by perspiration.
• It is a source of dissolved minerals such as
  flourine and calcium.
• It keeps the body fluids liquid so that they may
  flow easily.

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RDA of Water

• As 2-2.5 litres of water are lost daily by
  excretion, and perspiration, an equal amount is
  required daily by the body to avoid dehydration
• 1.5 litres of water is obtained from beverages
  and 0.8 from food.