Macronutrients

• Protein

  • Proteins are made up of long chains of amino acids held together by chemical bonds
  • Amino acid chains then fold to form proteins with specific structures and functions

  A) Amino acids

  B) protein

  
• Protein functions for the body

  • cell growth and cell division
  • repair and maintenance of tissues
  • an energy reserve; proteins can be broken down to release energy when the body has used up other energy stores
  • produce enzymes, red blood cells and hormones
• What are some sources of protein

  • meat
  • poultry
  • fish
  • dairy
  • eggs
  • cereal grains, e.g. wheat
  • Quorn
  • soya
• Protein deficiency:

  • reduced growth
  • brittle hair and nails
  • weakened immune system
  • poor digestion
  • kwashiorkor, which has symptoms such as swelling of the feet, hands, abdomen and face, as well as an enlarged liver, often found in developing countries
• Excess of protein:

  • digestive issues and nausea
  • dehydration
  • headaches
  • damage to the kidneys and liver
  • cardiovascular disease
• Why do some groups require different amounts of protein?

  • growing children need a lot of protein for muscle and tissue growth and repair
  • active individuals are likely to need more protein to maintain muscle
  • pregnancy and breastfeeding increases the demand for protein to help develop the baby's skin, hair, fingernails and muscles
• What are high biological value (HBV) proteins?

  Proteins with all essential amino acids and are often found in animal products such as meat, fish and eggs.

  However, soya is also considered an HBV protein.
• What are low biological value (LBV) proteins?

  Proteins that contain some but not all essential amino acids and are often found in plant products such as beans, nuts and pulses
• What is protein complementation?

  combining different LBV protein foods in order to gain all essential amino acids which then makes it HBV.

  For example, beans on toast.

  • This can be particularly useful for vegetarian or vegan diets which contain fewer HBV proteins
• What are some protein alternatives?

  • soya beans
  • Soya beans contain HBV proteins
  • processed for a range of products, e.g. soya milk and tofu
  • tofu is coagulated protein from soya milk, producing a solid curd
  • Tofu can be soft or firm
  • textured vegetable protein (TVP) is mostly made from soya protein but can contain other ingredients like wheat and oats
  • TVP can have a similar texture to meat so its often used in dishes, such as burgers or bolognese sauce
  • mycoprotein - fungi grown in large vats, processed into food
  • Quorn is a popular brand that produces vegetarian meat-like products using mycoprotein
• Fat functions

  • Fats can be present in food in the form of solid fats and liquid oils
  • a concentrated energy store
  • production of cell membranes
  • insulating the body to reduce heat loss
  • protecting internal organs against impact damage
  • allowing the absorption of fat soluble vitamins, ADEK
• sources of fats

  • Sources of animal fats include:
  • meat, e.g. bacon and pork belly contain visible fat
  • dairy, e.g. butter and cheese
  • fish
  • eggs
  • Sources of plant fats include:
  • plant oils, e.g. olive oil and sunflower oil
  • avocados
  • olives
  • nuts and seeds
• fat deficiency:

  • the body breaking down protein in order to release energy, which can lead to muscle loss and physical weakness
  • an inability to absorb fat-soluble vitamins, such as A, D, and E, resulting in vitamin deficiencies
  • omega-3 deficiency increases the risk of heart disease
  • increased heat loss
• excess of dietary fat:

  • weight gain and obesity
  • Obesity increases the risk of other associated conditions, such as type 2 diabetes
  • an increased risk of cardiovascular disease, e.g. high blood pressure, coronary heart disease and stroke
• • Fatty acid chains are hydrocarbons, made up of carbon atoms joined together with hydrogen atoms

  A) Fatty acid chain

  B) Glycerol

  
• Saturated fats:

  • only single bonds between carbon atoms; they are 'full', or saturated, with hydrogen atoms
  • Saturated fats are more likely to be solid at room temperature, e.g. in:
  • meat
  • butter
  • lard
  • coconut oil
  • Saturated fats are associated with increased blood cholesterol and are thought to increase the risk of heart disease
  • Increasing the ratio of unsaturated fats to saturated fats in the diet is thought to reduce the risk of heart disease
• Unsaturated fats:

  • Unsaturated fats contain at least one double bond between carbon atoms; they are not saturated with hydrogen atoms
  • These fats are more likely to be liquid at room temperature, e.g. in:
  • plant oils
  • oily fish, e.g. salmon
  • Monounsaturated fatty acids contain a single double bond, e.g. avocado and peanut oil
  • Polyunsaturated fatty acids contain more than one double bond, e.g. soybeans and sunflower oil
• Carbohydrates functions

  • Carbohydrates are a collection of biological molecules that include simple sugars, starches, and fibre
  • The main function of carbohydrates in the body is to act as an energy source
  • Carbohydrates contain glucose, which is released during digestion and used in respiration
  • Glucose is the preferred energy source for body cells, so consuming carbohydrates reduces the need to break down and use other energy sources, like protein
• Sources of Carbohydrates

  • Carbohydrates are present in foods that are high in sugar, starch or fibre, e.g.
  • fruit
  • cake
  • bread
  • potatoes
  • rice
  • cereals
• Carbohydrate deficiency:

  • symptoms of low blood sugar, e.g. fatigue, hunger and dizziness
  • needing to break down protein in the muscles to release glucose for respiration
  • This can lead to muscle wastage, even in people who consume protein in their diet
  • a lack of dietary fibre that increases the risk of bowel issues like constipation, and also increases the risk of bowel cancer
• Excess of carbohydrates:

  • Consuming a diet high in sugar can lead to weight gain and obesity
  • Being obese increases the risk of heart disease
  • Sugar can cause blood sugar levels to fluctuate, leading to conditions such as type 2 diabetes
  • Tooth decay is linked to a diet high in sugar
  • Consuming too much fibre can reduce the ability of the digestive system to absorb iron and calcium, resulting in mineral deficiencies
• What are sugary carbohydrates

  Sugars, or simple carbohydrates break down quickly and gives quick-release energy. They can be in the form of monosaccharides and disaccharides
• Monosaccharides

  • Monosaccharides are single sugar molecules
  • These sugars do not need to be broken down in the digestive system and are absorbed quickly into the blood
  • Examples include:
  • glucose
  • fructose

  
• Disaccharides

  • Disaccharides are double sugar molecules that are made up of two monosaccharides joined together
  • Double sugar molecules must be broken down into monosaccharides during digestion before being absorbed into the blood
  • Examples include:
  • sucrose, found in caster, granulated, demerara and icing sugar
  • lactose, found in milk
  • maltose, found in cereals
• Problem of sugars

  • Sugars can be absorbed easily into the blood and so can cause blood sugar levels to spike
  • While this can be useful in some situations, e.g. during sport, repeatedly fluctuating blood sugar levels can lead to health problems
• Sources of dietry sugar

  • fruit and fruit juices
  • cereals
  • confectionary, e.g. biscuits and chocolate
  • jam
  • soft drinks
  • sauces, e.g. ketchup
  • soups
• Starchy carbohydrates

  • Starches are known as polysaccharides because they are made up of long chains of glucose joined together by chemical bonds
  • These chemical bonds must be broken down during digestion and therefore it takes more time to release the glucose into the blood
  • Starch is described as a slow-release carbohydrate for this reason

  
• sources of dietry starch

  • potatoes
  • bread
  • pasta
  • cereals
  • lentils and beans
• dietary fibre

  • Dietary fibre is a polysaccharide found in the cell walls of plants
  • This polysaccharide is known as cellulose
  • Fibre cannot be digested by the human digestive system, meaning that it provides benefits such as:
  • slowing digestion and increasing feelings of fullness, so reducing snacking between meals
  • absorbing water and aiding the movement of digested food through the intestines; this reduces constipation
  • reducing the risk of bowel cancer
• sources of fibre

  • wholegrain foods such as bran cereal and wholegrain bread
  • fruits and vegetables
  • brown rice
  • oats
  • nuts