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 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 25 26 27 28 29 30 35 40

Height(in.)

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

06CO, p. 128

White Adipose

Fats with Structural or Biological Importance

Fatty Acids

•SFA

•MUFA

•PUFA

•Essential fatty acids

•N-3 fatty acids (FA)

Fig. 6-1, p. 130

SATURATED

(SFA)

MONOUNSATURATED

(MUFA)

CIS VS. TRANS

Partially hydrogenated

Deep fat frying

Fig. 6-2, p. 130

Δ12 and Δ15 desaturases

Essential Fatty Acids

Linoleic

linolenic

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

Fig. 6-3, p. 132

Triglycerides

medium chain triglycerides

- weight gain

- athletic performance

Fig. 6-7, p. 133

Sterols

Fig. 6-8, p. 134

Fatty Acid and Cholesterol Composition of Some Common Fats

 Saturatedg/Tbsp

Monounsaturatedg/Tbsp

Polyunsaturatedg/Tbsp

Cholesterolmg/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

Fig. 6-11, p. 135

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

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

Fig. 6-9, p. 134

2.Sphingolipids

- Sphingomyelins

Intestinal mucosal cell

Endoplasmic reticulum

HDL

Lymphatics

FA-albumin

Lysophosphatidylcholine

(direct absorption)

Monoacylglycerols

Free fatty acids

Glucose

Glycerol

Micellarparticles

Cholesterol

LYSPCCHYLO

Apoprotein

FA-CoACE

Short-chain FFA

PC

TG

Albumin

MG

CHOL

a-GP

Portalcirculation

Fig. 6-16, p. 139Lipid Transport and Storage

Peripheral apoprotein (e.g., apoC)

Phospholipid

Cholesterylester

Triacylglycerol

Core of mainly nonpolar lipids

Monolayer of mainly polar lipids

Integral apoprotein(e.g., apoB)

Free cholesterol

Fig. 6-17, p. 140

Table 6-3, p. 140

Table 6-4, p. 141LCAT = lecithin:cholesterol acyltransferase

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.

LDL receptor(coated pit)

CholesterylLinoleate

Protein

(b)(a)

LDL

LDL binding

Lysosome

Internalization Lysosomal hydrolysis

Amino acids

Cholesterol

Cholesteryloleate

3.pLDL receptors

2.qACAT

1.pHMG CoAreductase

Regulatory actions

Fig. 6-21, p. 145

How cells know whether to take or give away cholesterol

[N]LDL

Platelets

Foamcells

Smooth muscle cells

[O]LDL

EI

MC

[O]LDL

Arterial lumen

Endothelium

Intima

Macrophage

Macrophage

PDGF

p. 166

Major Metabolic Pathways for Fat Metabolism

Catabolism

Fatty Acids

•Catabolism via 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