02SFoodHlth: Basic Nutrition

Food Health is the science of food and nutrient and how we use those nutrients. Macro Nutrients – we need large amounts. Micro nutrients – we need in tiny amounts.

There are 7 classes of nutrients.

Macro carbohydrates > gives energy
proteins > gives energy
fats > gives energy
fibre good for intestinal health
water (7-8 glasses of fluid daily) good for intestinal health
Micro minerals


carbo – relates to the element carbon; hydrate – meaning water.

glucose is a typical carb.

  • – made up of carbon, and oxygen and hydrogen
  • – is a ring molecule
  • carbon has 4 available bonds
  • oxygen has 2 available bonds
  • hydrogen has 1 available bonds.
Carbohydrate molecule

Carbohydrate molecule


are monosaccharides.

mono meaning 1 carbon ring; saccharide meaning sugar.

disaccharides have two carbon rings; polysaccharides have many carbon rings.

Complex carbs have many carbon rings and takes the body longer to break it down, giving a steadier release of nutrients. These are Low GI carbs.

Simple sugars spike blood sugar levels.


  • the star of the nutrients
  • very complex molecule
  • made up of carbon, oxygen, hydrogen and nitrogen (nitrogen has 3 available bonds)
  • made of subunits called amino acids

there are 22 amino acids – our body can make 20 but the other two are essential amino acids, meaning we must take them supplementally to get these nutrients. When you join the amino acids into a chain, you make protein.

Amino Acids

Amino Acids

A protein chain is made up of lots of amino acids and called peptide.

Essential Amino Acids

  • Phenylalanine
  • Valine
  • Threonine
  • Tryptophan
  • Isoleucine
  • Methionine
  • Leucine
  • Lysine
  • Histidine

and for babies

  • Cysteine
  • Tyrosine
  • Arginine

Albumin contains 585 amino acids (egg white)!


  • essential for brain function
  • made up of long chains
  • there are two essential fatty acids we can’t make from inside our own body – alpha-linolenic acid and linolenic acid.

Fats are divided into saturated and unsaturated. For a healthy diet, we prefer to eat unsaturated fats, except transfats.

Saturated fats are animal fats. Unsaturated fats are plant fats. Transfats are very bad, synthetically made unsaturated fats.

Fibre & Water

Dietary fibre is the indigestible component of vegetables and plants. Fibre can be soluble and insoluble.


The body needs these in small amounts – trace elements

Fat soluble Vitamins: A D E K can be stored in the body for long periods.

Water soluble vitamins: some B group and Vitamin C cannot be stored for long in the body and the excess is excreted away.

Toxin vs Poison

  • Toxin – made by a living organism
  • Poison – an inorganic thing.

Digestive Tract

At the top of the digestive tract is the oral cavity and the oesophagus.

The digestive tract is used for

  • ingestion – taking in of food
  • secretion – various enzymes that break down the food (like saliva)
  • digestion – breaking down of complex food (via chewing)
  • absorption – absorbing nutrients into the body
  • egestion – excretion of waste.

Amylase is an enzyme that breaks down starch in the oral cavity which is released when we chew food.

The oesophagus is extra cellular – outside of the body. It is a muscular tube with 2 layers of muscle.

The wall of the stomach has 3 layers. It is lined by mucus secretary layer that secretes into the lumen and secretes HCL (hydrochloric acid). It also secretes pepsin and mucus (like snot). A peptic ulcer is caused when part of the stomach wall is digested away.

Food stays in the stomach from 20 mins to 2 hours. It uses chemical digestion and churns to break down food. Food is broken down into a gruel like soup. The stomach doesn’t absorb nutrients at all, but can absorb toxins like alcohol.

Next is the duodenum. It is 12 inches long and comes from the latin meaning 10 plus two inches. It is attached to the stomach via a valve and is the first part of the small intestine on the other end.

The pancreas is a glandular organ that secretes into the duodenum. It secretes bicarbonate ions which are alkaline to offset the HCL from the stomach. The bicarbonate ions along with the amylase and other enzymes like liposes which break down fat. It also secretes hormones including insulin.

The liver is a massive organ and weighs around 1.5kg. It secretes bile.

The gall bladder stores the bile that the liver secretes which helps to break down fat.

Small intestine

The small intestine is 7 – 8 metres long. The first half of the small intestine is called the Jejunum and the last part is called the Ileum. Food is digested by the Jejunum and the nutrients are absorbed.

The intestinal walls are made up of circular folds. Finger-like projections called Villi sit on top of these folds. Micro-villi grow on top of the villi. This increases the surface area which allows for greater absorption of nutrients.

Large Intestine

The large intestine is 1.5m long and contains all our faecal material. It connects to the small intestine on one end and the rectum and anus on the other. The terminal part of the ileum called the ileocaecal valve at the end of the small intestine joins to the large intestine.

The appendix dangles off the bottom of the caecum and has nests of immune cells.

Food spends 16 – 20 hours in the large intestine. The large intestine contains billions of flora bacteria; Vitamin K and some B group vitamins are made by this flora. The lower intestine absorbs water, electrolytes and some vitamins.

The more fibre and water we have, the better poo we have.


Macro Nutrients

  • Give Energy
    • Proteins
    • Carbs
    • Fats
  • Aid Digestion
    • Fibre
    • Water


  • Minerals
  • Vitamins

Digestive Tract

  • Oral Cavity
  • Oesophagus
  • Stomach
  • Small Intestine
    • Duodenum
      • Pancreas
      • Liver
    • Jejunum
    • Ileum
  • Large Intestine
    • Caecum
    • Colon
    • Rectum
    • Anus



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