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Name 3 main types of lipids and what they are.
Triglycerides: fatty acids
Phospholipids: Lecithin, bile
Sterols: cholesterol, estrogens, testosterone
Triglycerides: a lipid (basics)
*Most abundent lipid in all foods.
Consists of glycerol and 3 fatty acids
Diglyceride (2): loss of one fatty acid (2 remaining fatty acids)
Monoglyceride (1): loss of two fatty acids (contains only 1 fatty acid)
In triglycerides (lipids), what is esterification, de-esterification (lipolysis, triglyceride hydrolysis), and re-esterificatiopn?
- esterification: Joining 3 fatty acids to a glycerol unit via ester bonds (C-O-C).
- de-esterification: release of fatty acids.
re-esterification: reattaching a fatty acid.
Carbon chain length of fatty acid. What are the chains and how many carbons does each contain?
Short chain fatty acid: less than 6.
Medium chain fatty acid: 6-10 C.
Long chain fatty acid: 12 or more C
Saturation of fatty acids. What are they and how many bods does each consist of?
Saturated: NO double bonds.
Monoun: 1 double bond.
Polyun: Many double bonds.
Shape (isomerization) of fatty acids
CLS fatty acid: bent carbon chain; most fatty acids.
Trans fatty acids: Straight carbon chain; hydrogenated oils & fats from ruminants.
Hydrogenation: adding hydrogen to make an unsaturated fat more saturated and can yield trans fatty acids.
What are some factors that make a chain more solid?
1) longer chain length
2) more saturation
3) more trans bonds
Naming fatty acids. What are the two systems that are commonly used?
Based on: # of C atoms & location of double bonds in a fatty acid's carbon chain.
Position of double bond (C=C) closest to omega (methyl) end.
Ex: 18:2 w6 (18:2 n6) This means that linoleic acid has 18 Cs in its carbon chain & 2 double bonds, and the first double bond starts at the 6th carbon from the omega end (orange box area).
Essential fatty acids (we can't make them). What are they and what are they used to make?
Linoleic (C18:2): Omega-6 fatty acid. Used to make longer chain omega-6 fatty acids.
Alpha-linolenic (C18:3): Omega-3 fatty acid, used to make longer chain omega-3 fatty acids (e.g. eicosapentanenoic acid: EPA, and DHA)
*Both are used to make eicosanoids; hormone-like compounds that serve a variety of functions in signaling.
Fat replacements. What are some fat replacements and are engineered fats digested/absorbed?
What is the problem w/ Olestra and Salatrim?
Water, protein or carbs used in some products.
Engineered fats are NOT digested/absorbed
Problem w/ Olestra & Salatrim: Can reduce fat-soluble vitamin absorption.
*If fat is removed from products, s/th must be added-commonly, sugars.
Functions of Triglycerides in our body
*Most TAG stored in adipose tissue
1) Provide energy storage
4) Aid in fat soluable vitamins absorption, transport/storage
Phospholipids: hydrophobic & hydrophilic ends, define them and their functions & sources.
Hydrophobic: hates water
Hydrophilic: loves water
Functions: Component of cell membranes; emulsifier (brings water & fat together)
Sources: synthesized by the body.
Food: egg yolks, wheat germ & peanuts are good sources.
Sterols (e.g. cholesterol). What are they? What are there functions and sources?
Ring structure - does not contain fatty acids.
- Functions: steroid hormones, bile, cell membranes, chylomicrons.
- Sources: Synthesized by the body.
Food: animal origin.
Fat digestion. Where it begins and ends (6 steps)
1) Mouth: lipase secreted. Little or no fat is digested.
2) Stomach: Gastric lipase is secreted. Little fat is digested.
3) Liver: Produces bile, which is stored & released by the gallbladder into bile duct, which empties into the small intestine. Bile emulsifies fat.
4) Pancreas: Secretes pancreatic lipase. cholesterol esterase into the bile duct, which empties into the small intestine. Pancreatic lipase digests triglycerides. Phospholipase digests phospholipids. Cholesterol esterase digests cholesterol.
5) Small intestine: Fat is digested & absorbed in the duodenum & jejunum. Bile is reabsorbed in the ileum.
6) Large intestine: Less than 5% of fat passes thru the large intestine & is excreted.
Transporting fat. Fat is transported in the blood as what?
Lipoproteins: mixture of lipids & proteins.
Allows hydrophobic fats to be transport in hydrophilic blood.
*Shell composed of protein, phopholipids & cholesterol.
Major Lipoproteins in the blood.
Define them, their dietary component, and key role.
HDL: protein; helps remove cholesterol from cells and, in turn, excretion of cholesterol from the body (known as "good" cholesterol).
LDL: cholesterol, carries cholesterol made by the liver and from other sources to cells.
Pathways for cholesterol uptake. LDL is taken from blood by cells with what LDL receptor & scavengers?
- via receptors: LDL receptor (B-100).
- -Inside the cell LDL is broken down to free cholesterol and protein.
(white blood cells): oxidized LDL is engulfed & digested by scavenger cell embedded in blood vessels.
Oxideized LDL increases the risk for what diseases?
Cardiovascular disease (heart disease); #1 cause of death in America.
High amounts of LDL speed this development because over a period of time, cholesterol builds up in white blood cells. Cholesterol builds up on the inner blood vessel walls which clogs the arteries w/ plaque. Diets rich in saturated, trans fat, & cholesterol encourage this process.
Fat intake in America & the omega 3 & 6. Important information.
What has happened to fat intake in americans over the last century?
Fat intake has doubled over the last century mostly due to eating more.
Omega 6: intakes are plentiful (soybean oil, corn oil, etc.)
Omega 3: inakes are usually low. Low intake of fatty fish (also flax, walnuts, etc.)
How do omega 3's decrease the risk of cardiovascular disease and heart attacks?
Omega 3's reduce blood clotting in arteries.
Lowering blood triglycerides.
Health Concerns. What are some health concerns regarding the omegas (6,3), rancid (bad) fats, and diets high in total fat?
Too high of omega 6: omega 3 ratio may be bad esp. for inflammation.
Intake of rancid fats: oxidation of unsaturated fats, inhibit by antioxidents.
Diets high in total fat may increase risk for cancer, Type II Diabetes, etc.
Two kinds of trans fats: Naturally & manufactured. Where are they from?
Natural fats: meat, milk & other dairy products.
Manufactured fats: altered so it acts like a saturated fat.
*Hydrogenation: converts unsaturated fats to saturated.
*Trans fatty acids extend shelf life.
Trans fat in the news. What has happened in Denmark and NY? How much can we decrease the rate of CVD and T2D if we eliminate trans fats from our diets?
Denmark: banned trans fats in 2003.
NY: As a reult, banned it in restaurants in '05.
*FDA requires trans fat content to be listed on food labels.
*It would decrease CVD by 20%, and T2D by 40%.
CVD: what are the risk factors?
Age, gender, race, and genetics.
Blood triglyceride, LDL, cholesterol, hypertension, smoking, physical inactivity, obesity, T2D and other diseases.
How can we prevent CVD?
Low trans fats
Majority of fat monounsaturated or polyunsaturated.
Omega 3's 2x/week
Keep body weight at a healthy level
Increase physical activity
Statin drugs: most widely prescribed in the world.
What is the Mediterranean Diet? What is it high in?
Associated w/ lower risk of chronic disease.
Diet is high in: olive oil, fruits & veggies, whole grains, beans, nuts & seeds, red wine consumption.
*Limit eggs & red meat.