NTR 301 - Exam 3: Lipids
18. Explain what a lipoprotein is and explain the primary functions functions of the 4 lipoproteins discussed.
The lipoprotein has a single phospholipid bilayer that makes traveling through the vessels of the body easier for lipids
27. Give examples of components of the *Mediterranean diet* that may to reduce CVD risk
"Healthful" Components: - *poly and monounsaturated fatty acids:* olive, nut & seed oil - *omega-3 fatty acids:* fish - *plant sterols:* fruits, vegetables, & legumes - *soluble fiber:* legumes
24. List the *DRI* and/or *Daily Value* recommendations for saturated and trans fat ad the Daily Value for cholesterol.
*DRI for saturated and trans fat* = keep to a minimum *Daily Values:* -saturated = 10% or less or 20g -no DV for trans fat -dietary cholesterol = < 300 mg/day
14. cont. - II. Phospholipids
A. Form the basic structure of all cell membranes
8. Define the term *hydrogenation,* explain why food manufacturers hydrogenate oils and give an example of a food in which you may find an hydrogenated oil and why
*hydrogentation*: making unsaturated fatty acids more saturated by adding hydrogens in place of the double bond *Why use it?* 1) turn liquid oils into solids for spreadable products and baked goods 2) increase shelf life of commercial baked products and frying oils *ex.* spreadable products, baked goods, commercially fried foods
11. Describe the structure and characteristics of *mono* and *diglycerides* and identify their sources
*monoglyceride:* 1 fatty acid + glycerol back bone *diglycerides:* 2 fatty acids + glycerol back bone *Dietary sources:* not naturally found in the diet but are used as food additives because they can function as emulsifiers
12. Describe the structure and characteristics of *phospholipids* and identify specific types found in animal and plant sources
*phospholipids:* glycerol + 2 fatty acids + lecithin (phosphorus containing group). Phospholipids have *hydrophobic heads* and *hydrophilic tails* *Dietary sources:* -as a food additive because they can function as an emulsifier -naturally occurs in soy and egg yolk
9. Describe the structure and characteristics of *trans fatty acids* and identify their potential dietary sources.
*trans fatty acids* are unsaturated fatty acids produced during hydrogenation while H's add to opposite side of the double bond *ex. stick margarine*
19. Determine what lipoprotein is being described by its *components* and/or its *origins* .
- *Chylomicron:* made in the intestinal cells; contain dietary lipid → composed of TGs (triglycerides) that *came from the diet* - *VLDL:* made in the liver; composed primarily of TGs that were *made in the liver* - *LDL:* made from the remains of VLDL; composed primarily of cholesterol - *HDL:* originates in the liver; primary constituent is cholesterol
22. Explain how each type of *dietary fatty acid* may affect LDL and HDL levels and make recommendations to someone regarding the type of fat or oil to use in cooking.
- saturated fat is associated with *higher LDL* levels -trans fat is associated with *higher LDL* levels and *lower HDL* levels -both monounsaturated and polyunsaturated fat are associated with *lower LDL* and possibly *higher HDL* levs *For cooking:* Most desirable) *monounsaturated* → olive, canola, avocado oils and nuts & seats 2) polyunsaturated 3) saturated Least desirable) *trans*
25. Match other dietary components with their CVD risk-reducing effects
-*dietary plant sterols* (beta-sitosterol) can slightly *lower serum cholesterol levels* - *soluble fiber may* reduce total serum cholesterol levels; foods rich in soluble fiber like oats and legumes may help *decrease cholesterol levels* -diets *lower in carbohydrates* may reduce *serum triglyceride levels* -some hormone-like eicosanoids made from *omega(n)-3 fatty acids may reduce blood pressure, blood clotting and inflammation*
6. Predict how the degree of fatty acid saturation affects the *physical characteristics* of dietary triglycerides in which they're found
-*more double bonds* = more *unsaturated* fatty acids = more likely to be *LIQUID* at room temp. -*no or less double bonds* = more *saturated* fatty acids = more likely to be *SOLID* at room temp.
4. Describe what it means for a fatty acid to be *saturated*, *monounsaturated*, and *polyunsaturated*.
-*saturated*: all carbons have hydrogens -*monounsaturated*: 1 double bond replaces 2 hydrogens -*polyunsaturated*: 2 or more double bonds replace 2 or more hydrogens
28. Explain the limitation associated with most food additives used as *fat substitutes.*
-can be heated to high temps -indigestible -may cause indigestion -may cause loss of fat-soluble vitamins; must be fortified with vitamins A,D,E, and K -may cause loss of other fat-soluble phytonutrients
16. List the reasons why there is a need for dietary triglyceride and how much is considered the minimum amount necessary v. the DRI and explain the reasoning behind the DRI level.
1) Aid in the absorption of the fat-soluble vitamins = vitamin A,D,E,K -Triglycerides help to carry the vitamins into the body 2) Provide the two *essential fatty acids* -Linoleic acid (18C, n-6) → arachidonic (20C, n-6) ∙ sources include safflower, corn, soybean, cottonseed oils -Linolenic acid (18C, n-3) → EPA (20C, n-3) ∙ sources include flax seed, soybean, canola, wheat germ, walnut oils *To accomplish the above:* -minimum necessary fat intake should be at least 10% of total calories -however, the DRI recommends 20-35% of total calories *This is the DRI level because it is attainable and associated with lowered risk for cardiovascular disease*
15. Explain why we store most of our energy as fat vs. carbohydrate
1. Because fat (triglycerides) are a more *concentrated* energy source (9 cal/g for fats vs. 4 cal/g for carbohydrates). So *it would take over twice as much carbohydrates to equal the same amount of energy* 2. *Also because there is very little water stored with fat.* For every gram of glucose stored as glycogen there are 2.6 grams of water stored along with it, adding to body weight
3. Describe the *3* ways in which *fatty acids* can differ from each other
1. number of carbon atoms (4-22) 2. number of double bonds or degree of "saturation" (0-6) 3. the position of the first double bond in polyunsaturates (omega-6 v. omega 3)
2. Describe the basic structure of a *triglyceride*
3 fatty acids, one to each of the glycerol backbone's carbon atoms
14. cont. - III. Cholesterol
A. Serves as the starting material for: 1. Bile 2. Vitamin D 3. Steroid hormones - *sex hormones* (testosterone, estrogen) and *adrenal hormones* (cortisol, aldosterone) B. Is a component of all cell membranes -multiring structure provides rigidity for more fluid fatty acids "tails" of the phospholipid bilayes -the cholesterol that you are eating when you are eating an animal product comes from the cholesterol in the membranes of all the animal cells → doesn't matter what type of animal product, all will contain some amount of cholesterol
10. Describe the current *alternatives* to trans fatty acids and identify their potential dietary sources
Alternatives to trans fat containing items: For solid products at room temp: naturally harder fats like *palm oil* with canola and olive oils (*less polyunsaturated oils*) For commercial frying and other cooking applications: -partial hydrogenation (doesn't produce trans fatty acids) -full hydrogenation (doesn't produce trans fatty acids) -blends of oils with higher monounsaturated oils like *canola and soybean oils* and less polyunsaturates (such as safflower oil) = *fewer total double bonds* -new varieties of seed oils that have higher levels of monounsaturated fatty acids (oleic acid) and lower levels of polyunsaturated acids (e.g. high oleic acid canola and sunflower seed oil)
14. cont for Triglycerides
B. Provide body with insulation and protection for internal organs C. Help to maintain the integrity of skin and hair
14. cont for Phospholipids
B. Provide insulation for nerve fibers C. Acts as *emulsifiers along* with bile in the small intestine
21. Explain how LDL cholesterol contributes to the development of *atherosclerosis.*
Cardio/Cerebrovascular Disease (CVD) results from a years-long process called atherosclerosis or "hardening" of the arteries. LDL contributes to plaque formation if it get *oxidized* -Oxidized LDLs are taken up into the build up of plaque as it is forming and contribute their cholesterol to its growth, causing plaque to build up int he blood vessel walls causing *atherosclerosis*
18. Explain the primary functions functions of the 4 lipoproteins discussed. - chylomicron
Chylomicrons bring TGs (triglycerides) from the diet to fat cells for storage or other cells (e.g. muscle cells) to be used for energy
14. cont. - Individual fatty acids
Essential Fatty Acids 18-carbon fatty acids can be elongated to make 20-carbon fatty acids: -Linoleic acid (18C, n-6) → arachidonic (20C, n-6) -Linolenic acid (18C, n-3) → EPA (20C, n-3) These 20-carbon fatty acids can be used to make a group of compounds called *eicosanoids* *Eicosanoids are hormone like compounds that: -If make from *arachidonic (n-6) tend to: ↑ blood pressure ↑ blood clotting ↑ inflammation -If made from *EPA* (n-3) tend to: ↓ blood pressure ↓ blood clotting ↓ inflammation
18. Explain the primary functions functions of the 4 lipoproteins discussed. - HDL
High Density Lipoproteins → *GOOD* (H = Happy) -pick up excess cholesterol from the bloodstream and get it back to the liver for removal
14. List the functions that each type of lipid ( *triglycerides, phospholipids, cholesterol, and individual fatty acids* ) serves in the body
I. Triglycerides A. Provide energy (9 cal/g) from fatty acids for: -daily use -storage as body fat (adipose tissue)
17. Describe how dietary lipids are digested and absorbed.
Lipids are digested and absorbed with the help of lipoproteins (they act as taxi cabs) A lipoprotein has a single phospholipid layer (the hydrophilic phosphorus head points *outwards* ; the hydrophobic fatty acid tails point *inward* )
18. Explain the primary functions functions of the 4 lipoproteins discussed. - LDL
Low Density Lipoproteins → *BAD* (composed primarily of cholesterol) -deliver its cholesterol to all cells that need it
23. Explain whether most people need to limit their *dietary cholesterol* intake.
Most people do not need to limit dietary cholesterol, dietary saturated and trans fats have a greater impact on serum cholesterol levels
26. Describe some other potential health benefits of *omega-fatty acids* and the type of omega-3's that are most closely associated with their benefits more generally
Some hormone-like eicosanoids made from *omega(n)-3 fatty acids may reduce blood pressure, blood clotting and inflammation* The 20 (or 22) carbon EPA in fish or as a supplement to get a significant beneficial effect
13. Describe the basic structure of *sterols* and identify specific types found in animal and plant sources
Sterols *DO NOT* have a glycerol backbone; they have *multi-rind structures* *animal sources:* cholesterol (found in meat, dairy, fish) *plant sources:* other plant sterols (i.e. beta sitosterol)
20. Explain why there is no *"good'* or *"bad"* cholesterol in the *diet* .
There is only ONE type of cholesterol in the DIET -- it comes from the cell membranes of the animal products we consume. "Good" and "Bad" cholesterol are found in the *blood* and we are not consuming lipoproteins!
18. Explain the primary functions functions of the 4 lipoproteins discussed. - VLDL
Very Low Density Lipoprotein -deliver its triglycerides to fat cells for storage or other cells (e.g., muscle cells) for energy
7. Explain what it means for a dietary triglyceride to be saturated, monounsaturated, and polyunsaturated, give examples of each type, and provide the technical difference between a *"fat"* and an *"oil"*
dietary triglycerides are classified as saturated, monounsaturated, and polyunsaturated based on which fatty acid dominates in the mixture. -*fats are solid at room temp.* while *oils are liquid at room temp*
5. Identify the structural ways in which the fatty acids in *fish oil* and *breast milk* are different from those in other food sources
fatty acids in fish oil and breast milk are *highly unsaturated* (20-22 carbons, 5-6 double bonds, and omega 3)
1. Define the term *lipid*
lipids are soluble in organic (carbon-containing) solvents and typically insoluble in water (inorganic)