Revision document on Lipids

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  • Created by: Stephen
  • Created on: 02-05-13 20:00

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Fat (lipids)
Contains elements Carbon, Hydrogen and Oxygen
Chemistry of Fats:
98% of fats in foods are described as TRIGLYCERIDES. This is where one molecule of
GLYCOGEN is linked with 3 FATTY ACIDS
If the fatty acids are identical then the resulting triglyceride is a simple one
If it contains 2 or 3 different fatty acids it is called a Mixed Triglyceride
Types of Fat:
All fats contain both saturated and unsaturated fatty acids but are usually called
saturated or unsaturated according to the proportions of the fatty acids present.
1. Saturated Fats
Full fat dairy products
Functions (apply to fat as a whole):
Concentrated source of energy
Important for structure of cell membranes
Fat soluble vitamins (A,D,E and K)
Digested slowly- keep hunger pangs at bay
Protection (heart, liver and kidneys)
Risk Factor: Can raise blood cholesterol (LDL cholesterol) ­a major risk factor in heart
disease and stroke.

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Government Recommendations:
Total Fat= 35% of calorie intake
Saturated= 10% of this 35%
2. Unsaturated fat:
2a) Polyunsaturated (essential fatty acids PUFA's)
Required by the body in small quantities for the functioning of the body (cannot be
synthesised within the body). Therefore they must be supplied by diet.
Some PUFA's can be hardened (hydrogenated) and therefore become harmful to the
body (e.g.…read more

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DHA* is vital for the babies brain and eye development/growth. Important for
development of the nervous system in young adults.
Anti-inflammatory e.g. cod liver oil used to ease stiff joints
*DHA is normally found in breast milk of mothers who eat a healthy balanced diet but
may be inadequate in bottle fed babies. Some milk is now being formulated with omega
Government recommendations:
Omega 3 should provide 0.2% of total energy per day or 1.…read more

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The relative proportions of n-6 and n-3 acids in the Western diet have changed for a
number of reasons:
There has been an increase in consumption of vegetable oils (e.g. corn and
sunflower) as a result of healthy eating initiatives, to replace the traditional
consumption of butter and other animal fats.
Total intakes of meat from ruminant animals (which are a source of omega 3)
have fallen.…read more

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Tran's fats raise blood cholesterol and are found in hydrogenated margarines and
shortenings as well as products made from them e.g.…read more

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Transportation and absorption
Fat is a vehicle for other nutrients (fat soluble vitamins and fatty acids)
Absorption of fat soluble vitamins depends on digestion/absorption of fats
People with low fat diets may have a deficiency in these vitamins (ADEK)
Functions of Fat:
1. A concentrated source of energy:
Fat is broken down by a process called oxidation to release energy
Fat is an energy dense fuel
2. Formation of adipose tissue
Excess fat which is not immediately required for energy is stored in adipose tissue.…read more

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Carriers fat soluble vitamins
6. Sensory appeal
7.…read more

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LDL cholesterol can:
Block arteries
Lead to heart attacks and stokes
LDL can be partially controlled by diet low in saturated fat, Tran's fats and oxidised
polyunsaturated fat as well as a diet high in monounsaturated, omega 3, DHA, EPA, fruit
and vegetables and soluble fibre
Benecol foods contain plat sterol ester which works with body
to lower blood cholesterol when eaten as part of a healthy
diet.…read more

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There may be a relationship between a high fat intake and an increased risk of certain
types of cancer (colorectal). There is moderate evidence linking a high fat diet with
increased breast cancer in women.
Fat and obesity
Fat is a concentrated source of energy and foods that are high in fat provide a lot of
energy.…read more


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