Higher Diloma in Hospitality Nutrition

Diploma in Hospitality Management

Nutrition Lecture Six

Lipids

What are Lipids?

Fat

Triglycerides

composed of three fatty acids attached to a cental cor of 3 carbon glycerine:

This example has three 8 Carbons per fatty acid (in red) chain most fat have longer fatty acid chains usually 18 or 16

Solid fat or liquid fat (edible oils)

depending on type of fatty acids included

Phospholipids

Similar to triglycerides but: replace one fatty acid with a Phosphoric acid

Steroids

30 carbon cyclic compounds many of which are important hormones and are all made in the body from cholesterol;

Testosterone

Oestradiol

Aldosterone

Progesterone

Corticosterone

Vitamin D

Steroids may be not attached to any other molecules when they are called Free Cholesterol (FC) or it may be attached to fatty acids. Then it is called cholesterol esters (CE)
The body is able to make all it’s own cholesterol and dietary cholesterol has little influence over the amounts the occur in the blood. A diet high in saturated fats however increases the amount the body makes and can cause excess levels of blood cholesterol.
Blood cholesterol has to be carried in lipoproteins like other lipids. Cholesterol carried in VLDLP is on it’s way to the bodies tissues and can increase cholesterol in blood vessels. Cholesterol carried in HDLP is being returned to the liver and is in the process of reducing cholesterol in the tissues.
VLDLP and LDLP cholesterol is some times called bad cholesterol while HDLP cholesterol is referred to as good cholesterol.
It is nor enough to just measure the total amount of cholesterol in the blood. It is the LDLP cholesterol that must be determined

Why does the body need Lipids?

Primary store of energy

main sauce of energy for muscles

Protection for organs (cushioning)

Insulation against cold

Fat smooths body shape

Women more than men

Body can make most of what it needs from carbohydrates and protein

Needed supply essential fatty acids

Needed to supply fat soluble vitamins

Essential Fatty Acids

The body cannot make unsaturated fatty acids with double bonds before the 7th C

We need fatty acids with double bond between carbon 6 and 7

These are called w 6 fatty acids
They are all poly unsaturated fatty acids

having more than just the w 6 double bond

w 3 fatty acids have w 6 as well as other double bonds total three or four

Essential fatty acids are needed to manufacture prostaglandins

Prostaglandins are hormone like compounds that are needed for many activities in the body
Many are need to allow other hormones to act.

Cis and Trans double bonds

Cis double bonds are the only one that occur in natural fatty acids

Trans double bonds are produced when fats are processed such as in making margarine

Digestion and Absorption of Lipids

Digestion

Transport of Lipids in Blood

Lipids are insoluble in water and body fluids

must be carried with proteins called Lipoproteins

These include:

Chylomicra

carry fat from Intestine to tissue

VLDLP (very low density lipoprotein)

carry lipids from Liver to tissues
VLDLP loose fatty acids to tissues they get denser and become IDLP and eventually LDLP

remnant LDLP and chylomicra return to liver

HDLP

carry cholesterol from tissues to liver

sometimes called Revers transport

Danger of Excess Dietary Fat

Colon Cancer

Undigested fatty acids reaching the colon can act as a mitogen
fatty acids make soap that wash of cells lining the gut

This acts as a MITOGEN ie stimulates cell growth

Cancer needs two stages to develop:

Mutagen

The change in genetic information that causes it to be cancerous
and then a mitogen to start it growing

Increases cholesterol production

inbalance of carbohydrate and fat metabolism

Excessive fat catabolism results in a build up of intermediates that are used to make cholesterol.
Excess cholesterol can be deposited in the arteries causing arteriosclerosis
Reducing blood flow and increasing the chance of a heart attack or stroke.

Obesity

Obesity increases the chance of maturity onset (type two) diabetes
Obesity increases the chance of hypertension

Increased Blood cholesterol

High blood cholesterol can lead to deposits or plaques in the arterial walls restricting the flow of blood.

This can cause cramp in the heart called angina
Lack of blood to the legs can result in toes dieing
Narrowing of the arteries make it easier for blood clots to plug the artery completely stopping blood flow and causing tissue death

Heart attacks and Strokes

How to Reduce Lipid Intake

Eat more fibre
Modern "functional foods" are replacing fat with new forms of fibre and still keeping organoleptic quality
Fat Replacements

Fruit fibres
Olean

Fatty Acid Metabolism

The End

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