Chapter 5 Flashcards
Lipids
A group of organic molecules, most of which do not dissolve in water. They include fatty acids, triglycerides, phospholipids and sterols
- contain 9 calories per gram
- contribute texture, taste, flavour and aroma
- little in whole grains, lots in meat, lots in oils
What is the AMDR for fat
20-35% kcalories
Unsaturated fat examples
Fish, nuts, soybean, canola, flaxseed, and olive oils
Triglycerides (TG)
The major form of lipid in food and in the body. They consist of 3 fatty acids attached to a glycerol molecule
- utilized for immediate energy
- stored for later use
Fatty acids
Organic molecules made up of a chain of carbons linked to hydrogen atoms with an acidic group at one end and a methyl or omega end on the other.
- classified as: short chain (<6 carbons), medium chain (6-10 carbons), long chain (>12 carbons)
- chain length determines absorption and function
Phospholipids
Types of lipids containing phosphorous. The most common are the phosphoglycerides, which are composed of a glycerol backbone with two fatty acids and a phosphate group attached
- allow for transport in the blood (water based environment)
- EMULSIFIERS
- important to cellular membrane lipid bilayer. Controls what comes in and out of the cell
- phosphates head towards water and fatty acid end towards other lipids
Sterols
Types of lipids with a structure composed of multiple chemical rings.
Types: phytosterol and cholesterol
-cholesterol is made in liver
- do not dissolve well in water
- found in plants and animals
Saturated fatty acids
A fatty acid in which the carbon atoms are bound to as many hydrogens as possible, which, therefore, contains no carbon-carbon double bonds. Found in both plants and animals.
- solid at room temperature!!
- long chains
- butter, lard, animal fats, coconut oil
Tropical oils
A term in the popular media to refer to the saturated oils-coconut, palm and kernel oil-that are derived from plants grown in tropical regions
(Saturated fatty acids)
Unsaturated fatty acids
Contain some carbons that are no saturated with hydrogens. The carbons within the chain that are bound to only 1 hydrogen form carbon-carbon double bonds. If it contains 1 double bond it is a monounsaturated fatty acid. More than one double bond is a polyunsaturated fatty acid.
(One or more double binds in carbon chain)
- Liquid at room temperature
- squiggly looking at carb bonds
- plant oils and seafood
Monounsaturated fatty acid
Polyunsaturated fatty acid
A fatty acid that contains 1 carbon-carbon double bond. (Olive oils and beef)
A fatty acid that contains 2 or more carbon-carbon double bonds. (Corn, soybean oil)
Omega-3 (w-3) fatty acid
A fatty acid containing a carbon-carbon double bond between the third and fourth carbons from the same mega end.
(Unsaturated fatty acid and polyunsaturated fatty acid)
-fish oils
Alpha linolenic acid can become EPA (eicosanoids suppressing inflammation and blood clotting) or DHA (normal brain development)
Omega-6 (w-6) fatty acid
A fatty acid containing a carbon-carbon double bond between the 6th and 7th carbons from the omega end.
-corn and safflower oils, and oils in meat and fish.
Unsaturated fatty acids
Polyunsaturated fatty acids
Linoleic acid can become arachidonic acid for brain development or eicosanoids (promote inflammation and blood clotting)
Trans fatty acid
An unsaturated fatty acid in which the hydrogen atoms are on opposite sides of the double bonds
- has a higher melting point than fatty acids in the cis configuration
- come from a hydrogenation process
- used by the food industry
- turns unsaturated fatty acid into the behaviour of a saturated fatty acid (stiff at room temp-liquid to solid)
- BAD FOR YOU-increase risk of heart disease
Hydrogenation
The process whereby hydrogen atoms are added to the carbon-carbon double bonds of unsaturated fatty acids, making them more saturated.
- most of the trans fat in food supply before prohibited in Canada came from the partial hydrogenation of vegetable oils
- increasing melting point to secure shelf life
Phosphoglycerides
A class of phospholipid consisting of a glycerol molecule, two fatty acids and a phosphate group
- fatty acid end is soluble in fat
- phosphate end is water soluble
Can mix in both water and fat and makes them emulsifiers
Emulsifiers
Substances that allow water and fat to mix by breaking large fat globules into smaller ones
Lipid bilayer
Two layers of phosphoglyceride molecules oriented so that the fat-soluble fatty acid tails are sandwiched between the water-soluble phosphate-containing heads
Lecithin
A phsophoglyeride composed of a glyercol backbone, two fatty acids, a phosphate group and a molecule of choline
- major component of cell membranes
- made in liver
Cholesterol
A lipid that consists of multiple chemical rings and is made only by animal cells
- liver manufactures it so not needed in diet
- found in cell membranes
- found in myelin (coating of nerve cells)
- testosterone and estrogen component
- when it circulates in blood at higher levels it may increase the risk of heart disease
- cell membrane integrity
- precursor for other compounds: vitamin D, Bile acids, sex hormones
Most digestion of dietary fat takes place in …..
Small intestine-lipases
Bile from gallbladder helps break down fat into smaller globules and then lipases from pancreas digest them into fatty acids and monoglycerides. These form micelles which allow for absorption. Inside mucosal cells, fatty acids are reassembled into triglycerides and incorporated into lipid transport particles which enter the lymph
Micelles
Particles formed in the small intestine when the products of fat digestion are surrounded by bile acids. They facilitate the absorption of fat into mucosal cells of small intestine
Lipoproteins
Particles containing a core of triglycerides and cholesterol surrounded by a shell of protein, phospholipids, and cholesterol that transport lipids in blood and lymph
- classified based on density:
- Chylomicron, VLDL, LDL, HDL
Post-prandial state
The time following a meal when nutrients from the meal are being absorbed
Chylomicrons
- LARGEST Lipoprotein
- least dense
- mostly TG
- intestinal cells to liver
- made in small intestine
- carry large dietary lipids such as long-chain fatty acid, cholesterol and fat soluble vitamins through the lymphatic system and eventually enter blood stream then deliver the lipids to various cells of the body. -heart, muscle, mammary and adipose tissue
Lipoprotein lipase
An enzyme that breaks down triglycerides into fatty acids and glycerol; starched to the cell membranes of cells that like the blood vessels.
What is the major lipid producing organ in the body
Liver
Very-low density lipoproteins
Lipoproteins assembled by the liver that carry lipids from the liver and deliver triglycerides to body cells
- as they circulate in the blood stream, they shrink
- some left-over particles circulate back to the liver;others become LDL
- 2nd largest
- less TG
- less dense
- liver to tissues
Low-density lipoproteins
- derivatives of VLDL
- 3rd largest
- mostly cholesterol
- less dense
- transfer from liver to tissues
- deliver cholesterol to tissues via the blood
Referred to as bad cholesterol
-they deliver cholesterol to the tissues and having high levels of LDL in the blood is associated with an increase risk of heart disease.