Lipids

• chemical structure fat is made up of

  carbon, hydrogen and oxygen
• function 


  -protects vital organs

  -keeps body insulated

  -used for energy

  -helps absorb A,D,E,K vitamins
• sources - saturated


  are usually animal sources: butter, bacon, cream, beef and coconut oil
• sources - unsaturated 


  mono unsaturated - olive oil and avocado

  poly unsaturated - vegetable oil and fish like sardines and salmon
• deficiency of lipids

  -cold as lacking fat which is stored in the adipose tissue so don't have any insulation.

  -vital organs may be damaged as not fat stored in adipose tissue.

  -malabsorption of fat soluble vitamins. for example vitamin A can lead to poor eyesight
• excess of lipids:


  -hyperlipidemia causes high cholesterol and clogs arteries with fatty deposits which can lead to CHD and other heart related diseases like heart attack or stroke.

  -too much fat stored in adipose tissue which leads to mobility issues.

  -eating too much energy dense foods like fast food and chocolate.
• saturated fats:


  -solid at room temperature

  -no double bonds between carbon atoms

  -carbon bonds are surrounded by hydrogen atoms

  -higher melting point

  -they are stable and have a linear structure
• unsaturated fats:


  -liquid at room temperature

  -unstable, react easily (can oxidise quickly)

  -flexible structure (curved and bent)

  -low melting point, shorter chains

  -cis form: bent molecules - changed by hydrogenation

  -trans form: straight molecules - hydrogen atom is on opposite side of double bond.
• Hydrogenation:

  hydrogen atoms are added to unsaturated fatty acid.

  to improve shelf life and more stable so less chance of oxidation.
• essential fatty acids: omega-3

  -sources: soya beans, rape seed oil, walnut and green leafy veg.

  -body can't produce omega in body so must get t from the body.

  -Omega-3 converted to help proper nerve function and helps reduce arthritis.

  -helps development of nervous system in foetus

  -helps body metabolise
• Essential fatty acids - omega-6

  -sources: soya, sunflower, corn oil

  -helps body produces hormones and regulates body temperature.

  -regulates metabolism
• triglyceride 


  consists of one glycerol and three fatty acids
• Trans fats are bad:


  -increases likeihood of CHD and obesity.

  -body enzymes find it hard to break down trans fats and has been shown to stay longer in the blood stream increasing fatty deposits in arteries.

  -have affect on liver activity.
• Digestion of fat:

  -bile emulsifies fats. the lipase breaks fat into glycerol and fatty acids.

  -Glycerol and fatty acids absorbed into lymphatic.

  -Fat broken down further into lipase in small intestine.
• to lower cholesterol:


  have HDL foods which are high density lipo proteins.

  having foods containing sterols lowers cholesterol and naturally found in plants and added to foods like yogurt and butter.
• LDL - low density lipo-proteins 


  -are bad and raised by eating saturated fats and trans fats.

  -where cholesterol and other fats are carried along the bloodstream.