Nutrition McGraw hill Chapter 6

True or False: Fat is unhealthy and we should consume as little as possible

False

True or False: Fat is an important fuel of source during rest and exercise

True

True or False: Dietary cholesterol is essential because our body cannot make all the cholesterol it needs.

False

True or False: Certain fats play a role in protection against heart disease.

True

What are lipids?

hydrophobic molecules

What are the three categories of lipids?

triglycerides, phospholipids, sterols

What is the difference between a fat and an oil?

A fat is solid, while an oil is liquid at room temperature.

Triglycerides structure

glycerol + 3 fatty acids

Esterfication

The formation of an ester in the reaction of a carboxylic acid and an alcohol

De-esterification

Process of removing a fatty acid from a glycerol molecule

diglyceride

glycerol + 2 fatty acids

monoglyceride

a glycerol molecule with one fatty acid attached

long chain fatty acids

-12 or more carbons

-Beef, pork, lamb, most plant oils

- Goes through lymphatic system

medium chain fatty acids

6-10 carbons

coconut and palm oil

Can go through Portal vein

short chain fatty acids

Less than 6 carbons.

Milk fat.

Can go through Portal Vein

the carboxyl end of a fatty acid

polar, hydrophilic (alpha- first)

The Methyl end of a fatty acid

hydrophobic; (omega- Last)

saturated fats

adds hydrogen to remove double bonds

Why are saturated fats solid at room temperature?

There are no double bonds in the fatty acid tails, allowing them to pack more tightly together.

monounsaturated fats are liquid at room temp because...

of the kink that is formed from the double bond

polyunstaurated fats are liquid at room temp because...

of the double bonds

Cis Fatty Acids

Two covalent single C-C bonds angle in the same direction adjacent to the C=C double bond

trans fatty acids

fatty acids with hydrogens on opposite sides of the double bond

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen

Why is hydrogenation important?

Preserves or purifies many products

Why are trans fats bad?

They raise LDL's and lower HDL's

Essential fatty acids (EFA)

must be obtained from the diet and necessary for health. (All others can be made by the body.)

Eicosanoids

biologically active compounds that regulate body functions

linoleic acid

an essential polyunsaturated fatty acid of the omega-6 family

sources of linoleic acid

safflower oil, soybean oil, corn oil, sunflower seeds, pecans, pine nuts, Brazil nuts

Alpha-linoleic acid (ALA)

essential fatty acid Omega 3

Sources of Alpha-linolenic acid (omega 3)

green leafy vegetables, flaxseed, fish & fish oils

Visible fats are

Fats we add to foods; butter, cream, and mayo

Hidden Fats

fats that are not apparent, or "hidden" in foods, such as the fats found in baked goods, regular-fat dairy products, marbling in meat, and fried foods

Fat replacements

-Water

-Protein

-Carbohydrates- starch derivatives, fiber and gums

-Engineered fats- Olestra, Salatrim

Fats to include in diet

- Fish

- Plant source: avocados, walnuts, soy, canola, flax seeds, olive oil

-low fat versions of food

Fat soluble vitamins

Vitamins A, D, E, K

DHA (Docosahexaenoic Acid, Omega-3)

The Brain's preferred structural Fatty Acid

Eicosanoids function

- >100 actions

- Bp regulation, clotting

- Body Temp

- Inflammation and hypersensitivity

Structure of a phospholipid

made of 1 glycerol, 2 fatty acids and 1 phosphate

phosphate forms a hydrophillic head, fatty acids form hydrophobic tails

forms a phospholipid bilayer, basic structure of membranes

Function of phospholipids

major component of cell membranes

Emulsifiers are used to:

- forms a shell to allow fat and water to mix

- Essential for fat digestion and transportation

- Bile and lecithin

Lecithin

A phospholipid manufactured by the liver and also found in many foods; a major constituent of cell membranes.

food sources of phospholipids

egg yolks, liver, soybeans, peanuts

sterols (cholesterol)

Multi-ring structure

Only found in animal products

Contains hydroxyl group (-OH)

Cholesterol is the starting material for

-Bile acids

-Sex hormones

-Adrenal hormones

-Vit D

Food source of sterols

Animal origin: meat, eggs, and dairy

AMDR for fat intake

20-35%

Daily cholesterol intake should be less then

300 mg/day

Saturated fat should be

less than 10%

EFA's (essential fatty acids)

omega 3 and omega 6

Mediterranean diet

Typical diet of people around the Mediterranean region, focusing on olive oil, red wine, fish, grains, legumes, vegetables, and fruits, with limited amounts of red meat, fish, milk, and cheese.

North American Diet

-excess calories

-too much animal protein (saturated fat and cholesterol)

-too many processed foods (too much sugar and salt, too little fiber)

-too few fruits and veggies

Lingual lipase breaks down

lipids

Gastric lipase

enzyme to digest fat

CCK (cholecystokinin)

released by small intestine- stimulates gallbladder, pancreatic juices

bile emulsifies

fat

liver produces

bile

Gallbladder function

Store & concentrate bile produced by the liver until it is needed in the small intestine

pancreas function

secretes digestive enzymes to SI

Micelles

tiny spherical complexes of emulsified fat that arise during digestion; most contain bile salts and the products of lipid digestion, including fatty acids, monoglycerides, and cholesterol

Lipoproteins

clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood

Chylomicron

a type of lipoprotein that carries digested fat and other lipids through the lymph system into the blood

short and medium chain fatty acids

travel as a water-soluble molecule through the portal vein to the liver

Lipids are transported in the blood as

lipoproteins

Why are lipoproteins necessary?

they are necessary because lipids are not soluble in the blood and need to be accompanied by proteins

composition of lipoproteins

the outer layer consists of micelle like membrane apolipoproteins (phospholipids, and cholesterol)

center is composed of hydrophobic components of fatty acids, cholesterol esters, triglycerides, and fat soluble vitamins (ADEK)

classes of lipoproteins

chylomicrons, VLDL, LDL, HDL

Chylomicrons

- After a meal

- Mostly triglyceride

- From lacteal (SI) to subclavian vein

- Transport to body tissue

- Release by by LPL

- remnants return to liver

How long does it take for chylomicrons to clear?

12- 14 hours after meal

Relevance of chylomicrons to blood lipid panel

You need them cleared out before you do the panel

VLDLs function

-Transport of endogenous lipids

-Stored or made by liver

VLDL (very low density lipoprotein)

carries fats packaged or made by the liver to various tissues in the body

LDLs are referred to as "bad cholesterol" because

they are the blood serum particle with the highest concentration of cholesterol.

HDLs (high density lipoproteins)

compounds that are composed of equal amounts of protein and fat that seem to carry excess cholesterol from the cells back to the liver for reformation or disposal; called "good cholesterol" because high levels of HDL's in the blood are associated with a decreased risk of CVD

HDLs are produced in:

liver