Transcript Dietary Fats We can`t live without them

Dietary Fats
Can’t live with them
Can’t live without them!
What are Fats and Oils?
- Fats are macronutrients that provide the most
concentrated energy source for our bodies. They
provide 37kJ (Kilojoules) per gram.
-Also known as Lipids
called Oils when Liquid
Fats when solid
(at room temperature)
- Fats are composed of Carbon, Hydrogen and Oxygen
Why do we need fats?
Here are a few functions:
 It is the most concentrated energy source
 It acts as a fuel reserve as fats are stored in almost every part
of the body
 It creates an insulator for the body by forming a layer under the
skin to prevent the loss of heat
 It creates a protective layer around organs such as the heart,
kidney and nerves
 It provides the body with extra nutrients. Vitamins A, D, E an K
are carried to the intestines by fats and oils
 It slows digestion and so, prevents hunger
 It provides flavour to our food.
 55% of energy from Breast milk comes from fat as it promotes
rapid growth, and brain and nervous system development
Fats explained......
• FATS are formed when three fatty
acids and glycerol combine –
called triglycerides
• During digestion, all fats are
broken down into fatty acids and
glycerol ready for use by the body
• The foods which contain fat can
carry a mixture of saturated,
polyunsaturated and monounsaturated fatty acids
Saturated Fats – BAD fats!!!!
• Fats are composed of carbon, hydrogen and oxygen
• Saturated fats occur when every carbon atom in the
molecule has its full quota of hydrogen atoms
• It is called saturated because it cannot hold anymore
hydrogen
• These fats are hard at room temperature and are usually
from animal sources
• Eg. Lard, dripping, butter
Unsaturated Fats – a better choice
• These fats occur when the carbon chains in the fatty acid molecules
contain less than the maximum amount of hydrogen
• Usually soft at room temperature and found mainly in plant foods
• Eg. Vegetable oils, fish oils
Mono-unsaturated – only one double bond between the carbon atoms
Polyunsaturated – two or more double bonds between the carbon
atoms
Unsaturated Fats cont....
• Some Polyunsaturated fatty acids are essential for the
efficient functioning of the body – they are needed for the
building of cell membranes
• These Polyunsaturated fatty acids cannot be made by
the body and are called Essential Fatty Acids
- Omega 3
- Omega 6
Omega 3 Family of Fatty Acids
Sources:
Fish
Dark green vegetables
Flaxseed
Walnuts
Canola
Soy
You need your omega 3s, dear.
Omega 6 Fatty Acid
Plentiful in our diets; perhaps too plentiful.
Sources:
Safflower oil
Sunflower oil
Corn oil
Soybean oil
- helps lower cholesterol; thereby lowering our risk of
heart disease
- helps make our blood "sticky" so it is able to clot
- support skin health
Introducing: THE ENEMY
Many of the foods that we have grown to love!
What are Trans-Fats?
• An unsaturated fatty acid that is
bombarded with hydrogen atoms
• They are used commercially in
foods in order to extend the shelf
life of a food and to add texture
(Hydrogenation) – used to solidify
liquid vegetable oils to make
products such as margarine and
shortening
• Can be found naturally in meat and
milk from certain animals
• They raise bad cholesterol and
lower good cholesterol contributing
to heart disease
What Fats should we consume?
Dietary fat should make up no more than 30% of
our total daily Kilo joule intake.
For all of us:
- Most fat should be from poly or mono-unsaturated
sources of fat (such as fish, nuts and vegetable oils)
- Limit our intake of fats and oils high in saturated
and/or trans fatty acid
Too much
Weight gain
Not enough
•Starvation
•Eczema
•Skin lesions
•Failure to grow
Cholesterol
• Cholesterol is a fatty substance produced by all animals
(including humans)
• It is made in the liver and intestines
• It is only present in foods of animal origin
Functions of Cholesterol
- It is part of the structure of all cell membranes
- It is required for the manufacture of vitamin D and
horomones
- Used by the liver to make bile acids which help in the
digestion of fats
What’s the problem?
• Too much cholesterol can block arteries and result in heart
attacks – the more cholesterol carried in the blood, the greater
the chance of heart disease
• Cholesterol is carried in the blood by carriers called
‘lipoproteins’
HDL (High Density Lipoproteins) – good cholesterol as they
can remove cholesterol from the arteries and take it back to
the liver – helps protect against heart disease
LDL (Low Density Lipoproteins) – bad cholesterol as they
result in deposits on the artery walls – helps promote heart
disease
• To avoid cholesterol and heart disease – reduce the intake of
SATURATED fats.......
Changing our Diets!
We can change our diet to be more healthy just by thinking
about the kind of fats we consume. See page 64 in the
textbook to read about changes that you can make to
recipes.
Certain foods claim to be able to lower our cholesterol
levels and therefore offer a healthier lifestyle.
Prac lesson next Tuesday is to cook a ‘fat modified’
recipe
If the recipe says.......
Sour Cream
Cream
Milk
Mayonnaise
Cream Cheese
Butter / margarine / oil
Sauteeing or browning
Meat casseroles, soups etc
Pastry
Grated cheddar cheese to brown in oven
Oil, salad dressing
Gravy
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Possible modifications
Low fat Yoghurt/Buttermilk
Evaporated skim milk/buttermilk
skim milk and ricotta cheese mixed together
Skim milk
Low fat natural yoghurt
Cottage and low fat ricotta cheese mixed together
Continental bakers cheese
Reduce the amount if possible
Substitute saturated fats with unsaturated (polyunsaturated,
mono-unsaturated)
Use lean meat, trimmed of visible fat
Sautee in polyunsaturated/olive/canola oil
Use non-stick pan instead of oil
Chill overnight in refrigerator to set the fat which can then be
removed
Trim meat before cooking
Reduce the meat content and add legumes
Use Filo instead of Puff pastry
Do not brush EVERY layer with oil or margarine
Replace oil with eggwhite or skim milk
Halve the cheese required
Use low fat cheese
Mix cheese with rolled oats/breadcrumbs/wheatgerm to extend
Use lemon juice, orange juice or vinegar and herb dressings
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Use apple sauce (with pork)
Mint sauce with lamb
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