The role of fats in a Healthy Diet

What is Fat ?

• In their most simple form fats are • 1 molecule of Glycerol + 3 molecules of fatty

acid + 3 molecules of water

What are fatty acids?

• Fatty acids determine whether the fat is saturated, mono-unsaturated or poly-unsaturated.

• The saturated-ness of a fat is down to the presence of double bonds in the molecule

• Saturated fats have none, Mono-unsaturated fats have one in the middle, and Poly-unsaturated fats have 2 or more

Fatty acids are represented like this

• Saturated fat:

• Mono-unsaturated:

• Poly-unsaturated:

What about Omega 3 ?

• Omega 3 is a type of poly-unsaturated fat • The Omega 3 part of the name refers to the

location of the last double bond in relation to the left hand part of the molecule.

Enough Biochemistry• So why do we need fat in our diet?• Fat contains fatty acids – some fatty acids are

essential• Essential means the body cannot make

something itself and you have to eat it to get it. (You also get essential amino acids from protein)

• Fatty acids are used across the body for lots of different things

• Lipid – is just another name for fat – the terms are often used interchangeably

What do fatty acids do?

• They are in the membrane of every cell

• Fats are used to make hormones:

Also used• Fats are used to make Prostaglandins which:• Regulate the production of hormones• Inhibition/Stimulation of platelet aggregation –

for healing – via Thromboxane A2 and Prostacyclin

• Regulation of nerve transmission• Mediation of inflammatory response• Inhibition of gastric secretions• Stimulation of smooth muscles (the gastro-

intestinal-tract)

50% of your brain is fat

Fat cushions and insulates

• There is supposed to be some fat around your joints to act as a shock absorber, and your internal organs to maintain your body temperature

Fat Soluble Vitamins

Vitamin A• Vitamin A is essential for: Night vision, growth, cell

differentiation, embryogenesis, immune response. • Deficiency results in: night blindness, increased

susceptibility to infectious diseases – particularly diarrhoea and respiratory infections.

• As well as acne, dry hair, fatigue, growth impairment, insomnia, hyperkeratosis (thickening and roughness of skin),

• And can contribute to nutritional deficiency anaemia (lethargy, palpitations, heartburn, shortness of breath, restless legs)

Vitamin E

• Anti-oxidant: protects cell membranes and lipoproteins from damage.

• Maintenance of cell membrane integrity• Regulation of prostaglandin synthesis• DNA synthesis• Deficiency results in: reduced tendon reflexes, loss of

touch sensation, unsteady gait, loss of co-ordination, impaired eye movement

Vitamin K

• Essential for blood coagulation• Essential for bone protein synthesis• Deficiency can result in, increased bleeding

times due to poor blood clotting• Reduced bone integrity

Vitamin D• Essential for bone mineralisation, immune function,

inhibition of cell proliferation• Deficiency: rickets in children: in adults – bone pain and

muscle weakness, burning sensation in mouth, diarrhoea, insomnia, myopia, nervousness,

• Increased susceptibility to bone fracture osteomalacia, osteoporosis

• Actually 2 forms – the most efficient form, Cholecalciferol, is manufactured by the body in reaction to sunlight.

• Cholecalciferol is built from cholesterol – which is made from fat

I thought Cholesterol was bad?• Most people think it is• Cholesterol is actually the building block for a vast

number of molecules in your body • Cholesterol is used as the basic building block of over a

quarter of your brain, all hormones, Vitamin D, bile salts essential for fat absorption, and regulates the fluidity of cell membranes

• Most of the cholesterol in your body is made by the liver• Dietary intake of cholesterol has very little effect on

levels

Cholesterol has a lot of uses

If cholesterol is used so much why is there a problem with high levels?

• High levels of cholesterol are a problem because cholesterol can literally stick to the walls of your blood vessels

• It is normal for some to stick and over time a small amount of build up will happen – it may even be protective – the problem is with high amounts.

• Lots of cholesterol being left behind narrows the vessels and can cause blood clots to form – which can then block the vessel narrowed by cholesterol deposits.

In Summary• Fat has a lot of uses in the body• The body needs fat to survive so in its absence• 1st the body uses body fat stores – including fat used to

insulate and protect organs (you feel cold)• 2nd hormone production is impaired – first the sex hormones

(periods stop in women)• With impaired hormone production and low stores all other

body systems are impaired and work very inefficiently ( e.g. difficulty in concentrating, co-ordinating, low mood, constipation, diarrhoea, dry skin and hair, repeated infections, tiredness, sweats)

• Every system and function of the body is affected

Healthy Eating includes fat

• Most of the western world consumes far too much fat, especially saturated fat

• This does not mean that the fat is bad – just that people eating more than their body was designed to handle is …

• Around 30% of our energy from fat ensures we get all the Vitamins and fat we need for health … of which <10% should be saturated.

• We don’t need a lot … but we do need some!

Which has the most saturated fat?

• Lard• Butter• Coconut oil

• Which has the least• Olive • Rapeseed• Sunflower

Any Questions?

Sources of fat ?

What about trans-fats• trans- refers to the shape of the fat molecule. • Why are they considered bad?• Trans fats are metabolised the same as saturated

fat – except they are stickier when being transported and hence more likely to stick to blood vessels

• Trans fats increase the amount of total cholesterol circulating

• We are not entirely sure what else happens to trans-fats when they are metabolised ….

Heard of HDL, LDL, VLDL?

• These terms are used a lot: they refer to the molecules which transport fat round the body in the blood stream:

• VLDL's carry lipids synthesized by the liver to body cells

• LDL's carry cholesterol around the body• HDL's carry cholesterol from the body back to the

liver for breakdown and excretion.

A very simplified diagram of glucose and fat energy metabolism!