Chapter 6 Lipids
Objectives:
•
Describe the lipids of major biological importance; their basic structure and
function
•
Understand how lipids are digested and absorbed by the GI tract; how they are
transported and stored in various locations
•
Understand how lipids are packaged into various types of lipoproteins; how
these lipoproteins can be distinguished from one another, and how they are
related to cardiovascular disease.
•
Learn how the major lipids are metabolized via b oxidation, how ketones are
formed, and how we regulate the manufacture and breakdown of cholesterol
•
Understand how lipid metabolism is regulated, and how diet and
pharmaceutical aids target this regulation
•
Learn how some fats are “good” for you and can potentially prevent disease
•
Learn about the thermogenic capacity of brown fat and how it differs from
yellow fat
• By 2020 about one in five health care dollars spent on people ages 50-69
could be consumed by obesity-related medical problems -- up about 50
percent from 2000.
• The proportion of health care expenditures associated with treating the
consequences of obesity would increase from 14 percent in 2000 to 21 percent
in 2020 for 50-69 year-old men, and from 13 percent to 20 percent for women
in the same age group.
• Many of the improvements in health achieved by middle-aged and older
Americans in recent decades as a result of medical advances could largely be
erased over the next two decades if population weight continues to increase.
BMI
(kg/m2)
19
20
21
22
23
24
Height
(in.)
25
26
27
28
29
30
35
40
Weight (lb.)
58
91
96
100
105
110
115
119
124
129
134
138
143
167
191
59
94
99
104
109
114
119
124
128
133
138
143
148
173
198
60
97
102
107
112
118
123
128
133
138
143
148
153
179
204
61
100
106
111
116
122
127
132
137
143
148
153
158
185
211
62
104
109
115
120
126
131
136
142
147
153
158
164
191
218
63
107
113
118
124
130
135
141
146
152
158
163
169
197
225
64
110
116
122
128
134
140
145
151
157
163
169
174
204
232
65
114
120
126
132
138
144
150
156
162
168
174
180
210
240
66
118
124
130
136
142
148
155
161
167
173
179
186
216
247
67
121
127
134
140
146
153
159
166
172
178
185
191
223
255
68
125
131
138
144
151
158
164
171
177
184
190
197
230
262
69
128
135
142
149
155
162
169
176
182
189
196
203
236
270
70
132
139
146
153
160
167
174
181
188
195
202
207
243
278
71
136
143
150
157
165
172
179
186
193
200
208
215
250
286
72
140
147
154
162
169
177
184
191
199
206
213
221
258
294
73
144
151
159
166
174
182
189
197
204
212
219
227
265
302
74
148
155
163
171
179
186
194
202
210
218
225
233
272
311
White Adipose
06CO, p. 128
Fats with Structural or Biological Importance
Fatty Acids
•SFA
•MUFA
•PUFA
•Essential fatty acids
•N-3 fatty acids (w-3 FA)
SATURATED
(SFA)
MONOUNSATURATED
(MUFA)
CIS VS. TRANS
Fig. 6-1, p. 130
Partially hydrogenated
Deep fat frying
Essential Fatty Acids
Linoleic
alinolenic
Δ12 and Δ15 desaturases
Fig. 6-2, p. 130
N-3 fatty acids or Omega-3-fatty acids
(EPA – eicoapentaenoic acid, and DHA – docosahexaenoic acid)
Hypolipidemic effects
Antithrombotic effects
Table 6-1, p. 131
Triglycerides
medium chain triglycerides
- weight gain
- athletic performance
Fig. 6-3, p. 132
Sterols
Fig. 6-7, p. 133
Fig. 6-8, p. 134
Fatty Acid and Cholesterol Composition of Some Common Fats
Saturated
g/Tbsp
Monounsaturated
g/Tbsp
Polyunsaturated
g/Tbsp
Cholesterol
mg/Tbsp
Canola Oil
1.0
8.2
4.1
0
Safflower Oil
1.2
1.6
10.1
0
Sunflower Oil
1.4
2.7
8.9
0
Corn Oil
1.l7
3.3
8.0
0
Olive Oil
1.8
9.9
1.1
0
Sesame Oil
1.9
5.4
5.7
0
Soybean Oil
2.0
3.2
7.9
0
Peanut Oil
2.3
6.2
4.3
0
Vegetable Shortening
3.2
5.7
3.3
0
Chicken Fat
3.8
5.7
2.7
11
Lard
5.0
5.8
1.4
12
Beef Tallow
6.4
5.3
0.5
14
Butter
7.1
3.4
0.6
31
Coconut Oil
11.8
0.8
0.2
0
Phospholipids (two types)
1. Glycerophosphatides
phosphatidylcholine (lecithin)
-protection from alcoholic cirrhosis
-synthesis of eicosanoids
phosphatidylserine (rice & GLVs)
-”brain booster” (beware viruses)
- athletic performance
phosphatidylinositol (whole, unprocessed
grains, citrus fruits cantaloupe, brewer’s
yeast, unrefined molasses, and liver. It is
also available in wheat germ, lima beans,
raisins, peanuts, cabbage, and some nuts)
-anchoring membrane proteins
-synthesis of eicosanoids
Fig. 6-11, p. 135
Virgin Olive Oil vs. Lite Olive Oil vs. Extra Virgin Olive Oil
•All virgin olive oils are extracted mechanically from the olives. No processing or
other processes other than filtering have been done to the oil.
•Virgin vs. Extra Virgin refers to the concentration of oleic acid present in the oil.
The oleic acid lowers the pH. The lower the pH, the less “taste” of the olive is
present.
•Olive oil is monounsaturated and has to be heated to very high temperatures to
be converted to its trans form. This is highly likely in industrial fryers, but
relatively unlikely to happen on the cooking stove in a home.
PGH2 synthases = Cox1 and Cox 2
Table 6-5, p. 160
2.Sphingolipids
- Sphingomyelins
Fig. 6-9, p. 134
Intestinal mucosal cell
Endoplasmic reticulum
Glycerol
Glucose
Cholesterol
Micellar
particles
Apoprotein
a-GP
CHOL
CE
FA-CoA
Free fatty
acids
Monoacylglycerols
Lysophosphatidylcholine
(direct absorption)
Lymphatics
MG
TG
LYSPC
PC
HDL
CHYLO
Short-chain
FFA
Albumin
Lipid Transport and Storage
FA-albumin
Portal
circulation
Fig. 6-16, p. 139
Peripheral apoprotein
(e.g., apoC)
Phospholipid
Free
cholesterol
Cholesteryl
ester
Triacylglycerol
Core of mainly
nonpolar lipids
Integral
apoprotein
(e.g., apoB)
Monolayer of mainly
polar lipids
Fig. 6-17, p. 140
Table 6-3, p. 140
LCAT = lecithin:cholesterol acyltransferase
Table 6-4, p. 141
Fig. 6-18, p. 142
Fig. 6-19, p. 143
Fig. 6-20, p. 144
Metabolism of Circulating Lipoproteins
Things to remember:
• LDLs are the major carrier of cholesterol to tissues,
where it may be used for membrane construction or
converted into other metabolites.
• HDLs remove cholesterol from cells and other
lipoproteins and return it to the liver for excretion in the
bile.
How cells know whether to take or give away cholesterol
(b)
(a)
1.pHMG CoA
reductase
LDL receptor
(coated pit)
2.qACAT
LDL
Cholesteryl
oleate
Cholesteryl Protein
Linoleate
Cholesterol
3.pLDL receptors
Lysosome
Amino acids
LDL binding
Internalization
Lysosomal
hydrolysis
Regulatory
actions
Fig. 6-21, p. 145
Macrophage
[N]LDL
Arterial lumen
MC
Platelets
Endothelium
EI
[O]LDL
[O]LDL
PDGF
Macrophage
Intima
Foam
cells
Smooth muscle cells
p. 166
Major Metabolic Pathways for Fat Metabolism
Catabolism
Fatty Acids
•Catabolism via b oxidation in mitochondrial matrix
•Formation of ketone bodies
Cholesterol
•Esterification and bile acid synthesis
Synthesis
Fatty Acids
Cholesterol
Triglycerides
Fig. 6-23, p. 151
Fig. 6-34, p. 161
Fig. 6-35, p. 163