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How many kcalories per gram of fat?
9 kcalories / 1 g of fat
What are fatty acids?
Molecules made up of a hydrocarbon chain ( hydgogen bound to carbon ) with an acid at one end ( carbon bound to two oxygen and a hydrogen ( COOH)).
What is glycerol?
3 carbons, 8 hydrogens, and 3 oxygens C3H8O3
Up to three fatty acids can attach to it.
What is a triglyceride?
A glyceride with 3 fatty acids attached to it.
What is a phospholipid, phosphoglyceride?
Phospholipids are molecules that have two fatty acids attached to a phosphorous group. The phosphorus group is attracted to water and mixes with it and the lipid group is a fatty acid that mixes with fat.
- Physphoglycerides are:
- 2 fatty acids+glycerol+phosphate+polar molecule
What is an emulsifier?
Emulsifiers are substances that allow water and fat / oil to mix by breaking down fat globules into smaller fat globules.
Chocolate has emulsifiers in it so that the fats in the chocolate mix nicely instead of allowing big globs of fat to form.
What is a lipid bilayer?
Lipid bilayer is made up of phosphoglycerides and is what makes up the outer shell of the cells in your body. It is two layers of phosphoglycerides with the water-hating fatty acid "tails" pointing towards each other and the water-loving phosphorous "heads" pointing towards outside and inside the cell.
This provides a barrier around the cell that allows only certain things to go in or out of the cell.
What is lecithin?
Lecithin is a phospholipid / phosphoglyceride that is:
2 fatty acids+glycerol+phsphate group+choline molecule
The body can use it to make acetylcholine which helps brain function.
Food industry also uses it as an emulsifier in chocolate and other stuff.
What are sterols?
Lipids made up of chemical rings.
Cholesterol is a sterol.
Cholesterols is made by the liver ( and only exists in animals that have livers ) and is necesarry for the body but too much of it can raise the risk of heart disease.
Egg yolks have a lot of cholesterol, organ meats ( hearts, livers, skin ) have a lot of cholesterol. - 300mg / 3 ounces
Lean meats like chicken ( without the skin ) have less cholesterol - 90mg / 3 ounces.
Fish has even less - 50mg / 3 ounces.
Your liver will make it's own cholesterol from plant sterols you eat, you don't have to get them from other animal foods.
At room temperature short chain fatty acids are...
At room temperature long chain fatty acids are...
What is a saturated fatty acid?
The carbon atoms in a fatty acid can be attached to just each other or to each other and also hydrogen.
When every C atom in a fatty acid has H attached to it ( except at the acid COOH end ) it is saturated. Like, saturated with hydrogen.
What is an unsaturated fatty acid?
A fatty acid in which some of the carbons in the carbon chain are double bonded to each other and thus have fewer hydrogen atoms attached.
Monounsaturated means two of the C atoms are attached to each other ( double bond ) instead of to other H atoms.Polyunsaturated means more than one pair of C atoms forms a double bond.
Polyunsaturated is a fatty acid that has more than one pair of carbon atoms bonded to each other.
What are omega6 and omega3 fatty acids?
Fatty acids have an acid ( or alpha end ) and an omega end. The COOH end is the acid / alpha end, the omega end is simply the other end of the fatty acid.
If a fatty acid has a double bond in it ( unsaturated ) then cound from the C at the omega ( non-acid ) end towards the first C of the first double bond.
What's the difference between cis and trans bonds in a fatty acid, what is trans-fat?
At a a double bond in a fatty acid the shape of the molecule can either kink to one side ( cis ) or remain straight ( trans ).
What is hydrogenation, how does it affect fatty acids?
Hydrogenation is a process which adds hydrogen atoms to unsaturated fatty acids ( unsaturated fatty acids have C=C double bonds and fewer H atoms ). Doing this makes the oil made from fatty acid more solid at room temperature and makes it last longer / not go bad as fast.
It also changes the shape of the fatty acid from a crooked cis to a straight trans. Trans fats can raise the risk of heart disease.
( I think this is because the straight shape of the fatty acid allows them to stack up and stick together really easily which is not good in or around your heart. )
How does the body digest fat?
Mouth - A very small amount of digestion happens here due to lipases ( lip=fat, ase=enzyme ) in saliva.
Stomach - A small amount of digestion happens here due to lipases from mouth and lipases in stomach.
- SI - Most fat digestion happens here.
- Liver makes bile and sends it to gall bladder >
- CCK in duodenum signals gall bladder to send bile to SI - bile breaks down fat into glycerol and fatty acids
- CCK also signals pancreas to send pancreatic enzyme lipase to SI - lipase breaks fat down into glycerol, fatty acids, monoglycerides >
monoglycerides ( and choloesterol and fat-soluble vitamins ) mix with bile to form micelles ( globs of fat and bile ) which are absorbed by the lining of the SI.
What are micelles?
Globs of monoglycerides and bile that are absorbed by the lining of the SI.
What are lipoproteins?
Lipoproteins are kind of like bubbles made of phospholipids, proteins, and regular lipids.
Long chain fatty acids can't travel through the bloodstream as just big globs of fat. So lipoproteins are formed as kind of a bubble made of phospholipids with their water-loving heads poking outside the bubble and the water-hating tails poking inside the bubble.
Fat is held nicely on the inside of the bubble while the water-loving heads on the outside of the bubble allow the lipoprotein to move through the bloodstream.
How are long-chain and short-chain fatty acids moved from SI to other parts of the body?
Short and medium chain fatty acids can go straight from the SI to the bloodstream to different parts of the body.
Long-chain fatty acids are not water soluble so they are contained inside special lipoproteins called chylomicrons. The chylomicrons then take the long-chain fatty acids , form them into triglycerides, and thake them to the lymphatic system.
From there they diffuse into the blood stream where lipoprotein lipase present in cells that line blood vessels break the triglycerides back down into fatty acids and glycerol. The fatty acids and glycerol are absorbed into the bloodstream and remnants of the chylomicrons are sent to the liver.
Chylomicrons have lots of fatty acids, small amount of protein, and small amount of cholesterol.
What are VLDLs?
Very Low Density Lipoproteins - VLDLs are a kind of lipoprotein manufactured in the liver. VLDLs can transport cholesterol and lipids to different parts of the body. Lipoprotein lipase enzyme in the cells lining blood vessels break down VLDLs, take some of the lipids for the cells, and leave behind IDLs.
They have more protein, more cholesterol, and less fatty acid than chylomicrons.
What are IDLs?
Intermidiate density lipoproteins - The lipoprotein left over after VLDLs are broken down by lipoprotein lipases.
It is a smaller, denser lipoprotein than VLDL.
2/3 of them go back to the liver and 1/3 of them are broken down into LDLs.
What are LDLs?
Low density lipoproteins - What is left over after IDLs are broken down by lipoprotein lipases.
Smaller and denser than IDLs they have less fatty acids, more proteins, and lots more cholesterol than IDLs or VLDS.
LDLs have a protein called "apo B" on their surface that cells can recognize, grab hold of, and be used by the cell. If there is more LDL in the blood than the body's cells need or if there are too few receptors for LDL it can lead to an overabundance of LDL in the system which can increase the risk of heart disease. Of the lipoproteins in your body, LDL has the most cholesterol.
It is "bad cholesterol".
What are HDLs?
High density lipoproteins - HDLs go around the body picking up spare cholesterol and taking it back to the liver where the liver where the cholesterol is disposed of ( don't know process for this ). Having lots of HDL in your body helps prevent cholesterol from sticking to the inside of your arteries.
HDL is smaller and more dense than LDL, it has more protein and less cholesterol than LDL. It is "good cholesterol".
What is adipose tissue?
Fat. It's the layers of fat in your body, just under the skin. It can cushion your body, help keep you warm, and provide a source of energy for organs.
What are essential fatty acids? Which acids are essential fatty acids?
Essential fatty acids are fatty acids that our bodies cannot make on their own and must be consumed in food.
Omega6 fatty acid ( linoleic acid ) is an essential fatty acid. It's good for your skin integrity, fertility, red blood cell structure.
Omega3 fatty acid ( alpha-linoleic acid ) are important for cell membranes in the eye and for the central nervous system.
What are eicosanoids?
Regulatory molecules which regulate things like blood clotting, blood pressure, immune function. Eicosanoids are made from omega6 and omega3 fatty acids.
Eicosanoids made from omega6 increase blood clotting.
Eicosanoids made from omega3 decrease blood clotting.
How does omega3 fatty acid reduce the risk of heart disease?
Inflamation plays a role in the progression of heart disease, eicosanoids made from omega3 fatty acids help reduce inflamation.
What is beta-oxidation?
The first step in the process of creating ATP and thus energy for cells, where the carbon chain of a triglyceride is broken down into 2-carbon bits, releaseing high energy electrons in the process. The freed electrons can be used to manufacture ATP.
What is hormone-sensitive lipase?
An enzyme inside fat cells in adipose tissue that can receive a hormonal signal telling the cell to turn stored triglycerides into glycerol and fatty acids which can be used as a source of energy for the body.
What is essential fatty acid deficiency?
Not having enough fatty acids in your diet. It can result in dry flaky skin, poor hearing and sight, poor healing of wounds. Essential fatty acid deficiency is pretty rare, you need to be reeeeally deficient in fatty acids for it to affect you.
What is athereosclerosis?
A type of cardiovascular disease that involves the buildup of fatty material in the artery walls.
What is an artherosclerotic plaque?
A plaque that can develop in an artery that is made up of cholesterol, smoothe muscle tissue, fibrous tissue, and calcium.
How are artherosclerotic plaques formed?
When something injures the inside of an artery it becomes more permeable to LDL particles ( remember LDL has loads of cholesterol ), which migrate into the arterial wall.
The LDL oxidises and becomes oxidized LDL which is harmful to the body, so, immune system cells go to the site of injury / oxidized LDL. WBCs at the site become macrophages and "consume" the LDL. As they consume more and more LDL they eventually burst, laying out a nice, thick layer of cholesterol / fat. Smooth muscle begins to form over the fat streak, blood cells begin to clot around the area which causes the artery to narrow, decreasing blood flow. This pocket of WBCs, cholesterol / fat, it's smooth muscle covering can burst, sending a blood clot through the artery which can block blood flow to the heart or brain... which is bad.
What is a good cholesterol level for adults?
<200mg cholesterol per 100mL of blood.
For healthy adults it should be <100mg / 100mL blood.
For people with high risk or heart attack they should have <70mg / 100mL blood.
How do different dietary lipids affect health?
Dietary cholesterol - For some people the more cholesterol they consume, the less their liver manufactures. For others, regardless of how much cholesterol they consume, their liver will keep making the same amount. So, it could be that when you eat more cholesterol your body is not going to compensate by making less.
Saturate fat - More saturated fat in the diet increases LDL production goes up while LDL receptor activity in the liver decreases so that LDL is not removed from the system very well.
Trans fat - trans fat increases LDL levels and can lower HDL.
How do dietary lipids help protect agains heart disease?
Omega6 fatty acids - decrease LDL in the system, but can also decrease HDL as well.
Omega3 fatty acids - decreases LDL and does not affect HDL at all.
Monounsaturated fats - Lowers LDL, makes LDL less suseptible to oxidation.
Other things that affect heart disease.
Plant foods - fruits and vegetables, whole grains, legumes - reduce cholesterol levels.
B vitamins -
Alcohol - reduces stress levels.
Recomondations for dietary intakes for fatty acids, fat intake.
AI for linoleic acid for men: 17g / day, for women: 12g / day- which is about 1/2 cup of walnuts.
For alpha-linoleic acid for men: 1.6g / day, 1.1g / day for women.
AI ratio of linoleic acid to alpha-linoleic acid is between 5:1 and 10:1
DRI for fat intake for adult...
20% - 35% of daily intake of kcalories
Fat free means...
< .5g of fat per serving
Low fat means...
3g of fat or less per serving.
Reduced fat means...
at least 25% less fat per serving than regular or reference product.
Cholesterol free means...
< 2mg cholesterol and 2g or less of saturated fat per serving.
Less than 10g of fat, 4.5g or less of saturated fat, less than 95mg cholesterol per serving and per 100g