Lipids

Functions of lipids

1. Energy
2. Protection (protects body from mechanical stress)
3. Insulation (for body and axons)
4. Carries and stores fat soluble vitamins (ADEK) and essential fatty acids
5. Conversion to other molecules needed by the body
6. Makes up the lipid bilayer in cell
7. Adds taste, texture and smell to food and aids in satiety (in mouth and stomach)

What are lipoproteins?

any of a group of soluble proteins that combine with and transport fat or other lipids in the blood plasma.

How much energy is in each gram of fat?

9kcal/g; takes less energy to store and holds less water than carbohydrate

What is chylomicron?

type of lipoprotein formed in enterocytes to transport lipids away from the GI tract

Basic building blocks of lipids

glycerol and fatty acids

saturated lipids

all single bonds, solid at room temp.,ex: butter, wax,blubber

unsaturated fatty acid

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.

monounsaturated fats

category of unsaturated fatty acids with one double bond; sources include canola oil and olive oil

polyunsaturated fats

category of unsaturated fatty acids with 2 or more double bonds; sources include corn oil and soybean oil

Naming Fatty Acids (Omega System)

Count C at the omega end (not the acid end) til you get to the first double bond eg.omega 3 and omega 6 fatty acid in picture

short chain fatty acids

less than 6 carbons

medium chain fatty acids

6-12 C; not naturally occuring in foods (except coconut); can be made synthetically; helpful for lipid malabsorption; helps fast abosorption for athletes or those with GI diseases.

long chain fatty acids

12 or more carbons

Very long chain fatty acids

22 or more carbons

Structure of lipids

They are long fatty acids attached together to make long chains.

saturated dietary fat

Saturated, solid (at room temperature)(can "stick" to artery walls)
•Found mostly in animal products
•Generally LESS healthy
•REASERACH update

unsaturated dietary fats

Unsaturated, liquid (at room temperature), think "flow" right through...eg. less tendency to oxidize on artery walls
•Found mostly in plant foods
•Generally MORE healthy

trans fatty acids

a kind of fat formed when hydrogen is added to vegetable oil during processing
Increases shelf life and improves consistency of foods but increases health risks

Pros and cons of butter

Pros: All natural, right from the cow, maybe salt added
•Tastes great!
•CLAs (conjugated linoleic acid; naturally occurring trans fats found in dairy products and help prevent cancer)
•Cons: Animal fat; saturated

Pros and cons of margarine

Cons: Hydrogenated; trans fats! (don't buy these ones!)
•Pros: Non-hydrogenated; mostly veg. oil with a bit of saturated fat added; beta carotene added for colour
•Plant fat; unsaturated
•Choose ones made with plant oils with more

linolenic fatty acid

-Omega 3
-•makes hormones involved in heart and immune system functioning
•part of cells of cerebral cortex and retina
•found in canola, soybean, flax and walnut oils, human milk, cold water fatty fish and fortified foods

linoleic acid

omega 6
play a role in cell membrane formation
•found in nuts, seeds, whole grains, vegetable oils\***, leafy greens
•\*** eg. sunflower, safflower, corn oils
•in processed foods
•too much fosters systemic inflammation and increased health

What is VLDL?

Very-low density lipoprotein made up of liver cells to transport lipids to various tissues in the body, composed of triglycerides

What is LDL?

low density lipoprotein (bad cholesterol)

What is HDL?

high density lipoprotein (good cholesterol)

essential fatty acids

fats needed by the body that must be consumed in the diet because the human body cannot manufacture them

Conjugated Linoleic Acid (CLA)

a polyunsaturated fatty acid in which the position of the double bonds has moved so that a single bond alternates with two double bonds

What makes a saturated fat so stable?

High heat capability
More solid because of ability of molecules to lay closely together.

ALA fatty acid

Omega 3 family Alphalinolenic acid vegetable oils, can be converted to EPA and DHA in the body (*essential* fatty acid)

DHA fatty acid

Omega 3 family
Docosahexaenoic acid
harder to get in diet but are the best kind as they are readily usable by the body

EPA fatty acid

Omega 3 family
Eicosapentaenoic acid
harder to get in diet but are the best kind as they are readily usable by the body

Fish oil supplements

\[high] concentrations of omega-3 fatty acids, lower triglycerides by decreasing production of VLDL and apolipoprotein B
Very high in vitamin A- can become toxic
And can impact calcium

What should your Omega 3 to Omega 6 ratio be?

What is the function of Omega 3?

The function of omega 3 is to reduce inflammation, dilate blood vessels, helps prevent the formation of blood clots and lowers blood pressure

Triglycerides

The most common type of fat in foods and stored in the body
•3 fatty acids + 1 glycerol
•Trigycerides are made from excess carbohydrates, fats and/or protein
Triglycerides are stored in fat tissue
•High tri levels in blood are a health risk

Eicosanoids

biologically active compounds that regulate body functions
Made from essential fatty acids derived from C20 unsaturated FA
•Act like hormones
•Make prostaglandins and leukotrinesfor immune function
•Play a role in cell membranes
•Increase vascular permeability

Sterols

A sterol molecule of C rings with side chains of C, H, O
•Part of every cell membrane (cholseterol)
•Component of myelin sheath
•Precursor to Vit. D (calcitrol), sex hormones (eg.estrogen etc.), cortisol (eg. stress response)
•Component of bile
Found in eggs, liver, animal foods only

Cholesterol

A type of fat made by the body from saturated fat; a minor part of fat in foods.
NOT ESSENTIAL
We absorb only about 50% of cholesterol we eat
•Contributes to 40% or less of body's total cholesterol
•We make cholesterol (endogenous) in liver
•This accounts to 60% or more of total
Part of arterial plaques leading to CVD, high BP

Phospholipids

•Fatty acids plus a phosphate group

•Lipid bilayer in cell membranes

Lipoprotein

•Lipoproteins are
lipid molecules
containing proteins
•Important as a
transport molecule
in blood
•More details in
Metabolism

Metabolism of Lipids

When we eat fats, it is broken down into FA by enzymes and bile (bile acts as an emulsifier to mix fat and watery liquids eg.digestive enzymes)
•Short & med. chain FA absorbed into blood
•Long chain fatty acids incorporated into a lipoprotein and absorbed into lymph first
•Lipids used for energy, made into other molecules, and excess form into triglycerides and stored in adipose tissue

What are plant sterols?

phytosterols

How can plant sterols be used to reduce cholesterol?

What is AMDR?

What are trans fats and how are they made?

What are some examples of fat substitutes?

What are the side effects of fat substitutes?

What are the cholesterol recommendations?

What general practice should you follow when choosing oils and dietary fats?

Why should we make these choices?

What are the health benefits of chocolate?

What are the health benefits of carob?

What is steric acid?

What benefits does steric acid have?

What is the path of long chain fatty acids through the body?

The molecules are too big to be absorbed directly into the blood so they are
•put into a lipoprotein (a chylomicron specifically)to be carried in the lymph and then into the bloodstream, then delivered to body cells