Macronutrients

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Macronutrients
Extension
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Learning objectives

• To understand macronutrients are needed by the
  body.
• To know the sources and functions of
  carbohydrate, protein and fat.
• To understand the consequences of malnutrition of
  carbohydrate, protein and fat.

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Macronutrients

• The macronutrients are
• Carbohydrate
• Protein
• Fat.

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Function and sources of carbohydrates

• Carbohydrate provides the main source of energy
  for the body.

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Further classification of carbohydrate

• There are different ways to classify
  carbohydrate.
• One method is into
• sugar
• carbohydrate.

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Classification of carbohydrates

• Sugars
• 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)
• Starches
• Polysaccharides are made up of many
  monosacharides molecules joined together, e.g.
  starch, glycogen, cellulose and pectin.

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Another classification systems for sugars

• Intrinsic can be described as sugars
  incorporated into the cellular structure of
  foods.
• 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 obviously
  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.

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Excessive consumption of carbohydrates

• Decrease cholesterol levels
• A positive effect is where some forms of complex
  carbohydrates may reduce cholesterol which is
  beneficial for health.
• 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 sugary foods should be eaten with main
  meals, rather than in between snacks to prevent
  dental caries.

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Lack of carbohydrates

• The short term effects of a lack of
  carbohydrates are weight loss and lethargy.
• Kwashiorkor and Marasmus 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.

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Protein

• Protein is needed for growth 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 and, in some
  cases, sulphur.

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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 indispensible amino acids (IAA)
  or sometimes essential amino acids.
• It is essential that these are provided in the
  diet as the body cannot make them.

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Body needs

• Adults only need 8 indispensible amino acids for
  growth and repair.
• Children need to obtain 10 indispensible amino
  acids.

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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 indispensible
  amino acids it is said to have a high biological
  value.
• If a protein does not contain all the
  indispensible amino acids it is said to have a
  low biological value.
• The amino acid that is in the shortest supply in
  relation to need is termed the limiting amino
  acid.

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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 indispensible amino
  acids.

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Protein complementation

• Complementation of low biological value (LBV)
• protein sources ensures that all essential amino
  acids
• are consumed.
• Amino acids of one protein source can compensate
• for the limitations of the other, resulting in a
• combination to create a high biological value
  meal.

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An example of protein complementation

• Two foods providing vegetable protein are eaten
  at a meal e.g. a cereal (bread) and a pulse
  (baked beans).
• The amino acids of one protein compensates for
  the limitations of the other.
• This results in a combination of higher
  biological value.

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The bodys 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 normal
• adults because of the growing baby.
• Nursing mothers also need more protein for
  lactation.

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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 - 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 - this condition is known to be the
  bodys
• adaption to shortage of energy and nutrients.

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Fat

• Fat performs many functions in the body.
• A concentrated source of energy.
• Surrounds and protects body organs.
• Forms an insulating layer keeping us warm.
• Provides fat soluble vitamins.
• Fat is made up of
• fatty acids and glycerol.

Fatty Acid 1
Fatty Acid 2
Fatty Acid 3
Glycerol
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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.
• Foods which provide fat contain a mixture of
  fatty acids but usually one type of a fatty acid.

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Sources of saturated and unsaturated fats

• Saturated fat
• Meat, coconut oil, palm oil, cakes and biscuits,
  lard.
• Unsaturated fat
• Mono unsaturated fat
• Rapeseed oil, and olive oil.
• Polyunsaturated fat
• Oily fish, sunflower oil and avocado.

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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.

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Review of the learning objectives

• To understand macronutrients are needed by the
  body.
• To know the sources and functions of
  carbohydrate, protein and fat.
• To understand the consequences of malnutrition of
  carbohydrate, protein and fat.

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