1. Lecture 4
Ch. 5 Lipids

2. Lipids Overview Variety of compounds that do not dissolve in water
Fats - solid at room temperature
saturated fats - animal
Oils - liquid at room temp.
unsaturated fats - plants
Triglycerides - storage form
Phospholipids - polar and non-polar, form cell membranes
Lipoproteins - carriers for fats in blood

3. Fatty Acids Fig. 5-1, common to most lipids
long chains of carbon (C) and hydrogen (H) linked together
large variety of fatty acids
most fats are a mixture
Saturated
all carbons full of Hydrogen
animal fats, solid at room temp.
Unsaturated
missing some H, has double bonds
many d. bonds, polyunsaturated

4. Triglycerides Main form of fats in body
3 carbon glycerol with three fatty acids attached
diglyceride - two F acids
monoglyceride - one F acid
fats become mono before absorption into SI, then reform triglycerides

5. Other Fats Phospholipids (lecithin) Sterols
built on glycerol within body
FA is replaced by phosphorous and nitrogen compounds
becomes bipolar - can interact with fat and water - emulsification
component of cell membranes
Sterols
multi ringed structure
cholesterol - made in liver
forms hormones, bile, cell membranes

6. High Fat Foods Salad oils, butter, margarine, mayonnaise
Avocados, bologna, bacon, cheese, peanut butter
Animal fats
very high in saturated fat
only source of cholesterol
tropical oils
higher in saturated fats
Fat reduction not calorie reduction

7. Functions of Lipids Very diverse functions only some required in diet
Essential Fatty Acids - humans can not make these
Omega 3 - alpha linolenic acid
Omega 6 - linoleic acid
1 tbls of veg oil, fish twice a week
Moderation

8. Other roles of Lipids
Energy storage - Adipose tissue very high density, limitless, low water content (light)
energy - rest and light exercise 50%
insulation - subcutaneous
transport of vitamins - ADEK
Satiety - needed for feeling of fullness (calorie reduced diet)

9. Other roles of Lipids
Phospholipids - required in many components of body cells
can be manufactured in body
emulsifiers (lecithins)
allow water and fat to mix, due to both water and fat soluble ends
Cholesterol -components of hormones - estrogen, testosterone, vitamin D
bile acids - fat digestion
manufactured in liver - 100mg
intake mg (1/2 absorbed)

10. Hydrogenation For some baking, solid fat is more appropriate
Polyunsaturated vegetable oils require hydrogenation to become more solid
(similar to saturation)
addition of hydrogen to double bonds
also creates trans-fatty acids
raises blood cholesterol (LDL)
avoid deep fried foods, non-dairy creamers, veg. Shortening

11. Recommendations
No RDA, 4 % of calories from plant oils and fish twice a week
upper limit of 30 % of caloric intake 10 : 10 : 10
Table 5-2
polyunsaturated - LDL oxidation
reducing saturated - clears LDL
recommendations easily reached - fires - 30g of fat (mostly trans)
Fig 5-4
recommendations do not apply to children under 2 years

12. Fat Digestion Initiated in stomach, primarily in small intestine
TG broken into mono and di
bile aids in emulsification
formation of small micelle
improves digestion and absorption by increasing surface area
Enterohepatic circulation
98 % of bile re-circulated
soluble fiber

13. Fat Absorption Passively absorbed into SI cells
short chain FA (< 12) into portal circulation
long chain (>14) into lymph circulation
bind with cholesterol, phospholipids and protein coat to make lipoproteins

14. Fats in the Blood Must be lipoproteins to float in blood
TG broken down into FA and glycerol by enzymes on wall of blood vessels
absorbed into muscle and adipose cells
burned or reform TG

15. Transport of Fats
Liver produces fat and cholesterol from dietary intake
coats cholesterol and TG in protein and phospholipids
VLDL - very low density lipoprotein
circulate and TG are broken down and absorbed by cells
density increases, forming LDL which is mainly cholesterol

16. Low Density Lipoprotein
LDL absorbed by liver and broken down to make bile ...
process is inhibited by high saturated fat and cholesterol in diet
If LDL is not taken up by liver, scavenger cells will oxidize fat (take an electron), fat builds up on inner walls of blood vessels,
form plaques which lead to atherosclerosis
antioxidant - donates electrons - fruits and veg - reduce damage of oxidizing compounds

17. High Density Lipoprotein
High protein content (increases density)
picks up cholesterol in blood stream
transport back to liver, may prevent oxidation of LDL
good versus bad cholesterol is dependant on carrier
HDL versus LDL

18. Cardiovascular Disease
Major killer in America
symptoms develop slowly over many years - beginning in childhood
associated with inadequate circulation to heart or brain (stroke)
myocardial infarction - death of part of the heart
fig 5-2
disruption of plaque leads to clot formation and blockage
plaque builds with cholesterol, protein, smooth muscle and calcium

19. Risk Factors High cholesterol - over 200mg/dl
(dl = 100ml)
high LDL mg/dl
low HDL - under 35 mg/dl
Age - men over 45 women over 55
family history
smoking
High blood pressure
diabetes
lack of physical activity and obesity
several factors compound risk

20. What you can do Diet changes for LDL Blood triglycerides Raise HDL
reduce sat fats and cholesterol
inc mono and polyunsaturated
inc dietary fiber (soluble)
Blood triglycerides
do not overeat, limit alcohol and sugar, spread out meals
Raise HDL
increase activity
BP, TG,