Lipids

Question 1

Fatty acids

Answer 1

basic unit of lipid

Question 2

Triglycerides

Answer 2

3 fatty acids attached

to a glycerol backbone

Question 3

Phospholipids

Answer 3

2 fatty acids and a phosphate head attached to a glycerol backbone

Question 4

Sterols

Answer 4

multi-ring structures, soluble in lipids

Question 5

Bile

Answer 5

emulsification

– 98% reabsorbed unless use Rx, plant sterols/stannols, soluble fiber

Question 6

Lipase

Answer 6

separates triglycerides into individual fatty acids

Question 7

chylomicrons

Answer 7

Fatty acids absorbed by small intestine cells, packaged into chylomicrons, released into the lymphatic system

Question 8

Fat as Fuel

Answer 8

 9 kcal/gram
 Preferred storage form in the body
(adipose tissue)
– Can increase 50 times in weight
 1⁄2 of energy used at rest or with light activity is from fat
 Need adequate CHO intake to completely metabolize fat


Question 9

Fat for Insulation/Protection

Answer 9

 Insulating layer beneath skin
 Protecting layer around organs
 Females with anorexia nervosa who lose more than 25% of body weight and become virtually fat-free  become amenorrheic, bone loss, grow lanugo, at risk for internal organ damage


Question 10

Fat for Transporting/Storing Vitamins

Answer 10

 Fat-soluble vitamins (A, D, E, K) are absorbed into the lymphatic system with lipid
 Fat-soluble vitamins are stored in adipose tissue
 Diseases affecting lipid absorption also hinder fat-soluble vitamin absorption

Question 11

Recommendations

Answer 11

 30% or less of total kcal intake
– 1/3 (or 10%) from each of the three
classes of fatty acids
 Less fat if trying to lose or maintain body weight
 More if trying to gain weight

Question 12

Classes of Fatty Acids-form

Answer 12

 Based on number of carbon-carbon double bonds in the hydrocarbon chain
 Related to health benefits or risk  Only 2 are essential

Question 13

Three classes

Answer 13

– Saturated fatty acids
 No double bonds, chain is completely “saturated” with hydrogen instead
– Monounsaturated fatty acids (MUFA)  One double bond
– Polyunsaturated fatty acids (PUFA)  Two or more double bonds

Question 14

Saturated Fatty Acids

Answer 14

 Food source: primarily animal – Also found in coconut, palm oils
 Health consequence:
– Increases “bad” cholesterol
 Recommendation:
– Less than 10% of total Calorie intake


Question 15

MUFAs

Answer 15

Food source: primarily plant
– Canola, olive and peanut oils, avocados
 Health consequence:
– Decrease “bad” cholesterol, increase
“good” cholesterol
 Recommendation:
– 10% or more of total Calorie intake (no more than 30% if other fats not eaten)


Question 16

PUFAs

Answer 16

Food source: primarily plant
– Corn, soybean, sunflower, safflower oils
 Health consequence:
– Decrease “bad” and “good” cholesterol
 Recommendation:
– 10% of total Calorie intake
 Essential fatty acids:
– Alpha-linolenic acid (an omega-3) and linoleic acid (an omega-6)


Question 17

Which of the 3 classes of fatty acids is considered “bad fat” or is the most unhealthy for the cardiovascular system?

Answer 17

PUFA’s hydrogenated to trans fatty acids, after that the saturated fats are most ‘dangerous’ to the cardiovascular system.

Question 18

Which of the 3 classes of fatty acids provides the 2 essential fatty acids?

Answer 18

PUFA

Question 19

Which of the 3 classes of fatty acids should we consume most?

Answer 19

PUFA

Question 20

Hydrogenation

Answer 20

PUFAs can be hydrogenated to produce a more shelf-stable, solid product
 By-product = trans fatty acids  Increase “bad” cholesterol


Question 21

Cholesterol

Answer 21

– Not fat
– Not an essential nutrient
– Normal functions in the body:  Precursor for bile acids/salts
 Cell membrane component
 Hormones: testosterone, progesterone, estrogen, vitamin D


Question 22

Long-chain Omega-3

Answer 22

Omega-3 FA (fish, canola oil, walnuts, flax seed, enriched foods) derivatives:
– Decrease blood clotting
– Decrease inflammation
– Vasodilation
– LowerTGs
– Calm smooth muscle
– Decrease pain w/ rheumatoid arthritis
– May help w/ some behavioral disorders and depression

Question 23

Omega-6

Answer 23

Omega-6 FA derivatives:
– Increase blood clotting
– Increase inflammation
– Vasoconstriction
– Excite contractions in smooth muscle

Question 24

Heart Disease and Lipids

Answer 24

Lipoproteins, “Good” vs. “Bad” Cholesterol, Atherosclerosis

Question 25

three types of lipoproteins

Answer 25

VLDL, HDL, LDL

Question 26

Chylomicron

Answer 26

Chylomicron – lipoP carrier for dietary fat, cholesterol, and fat-soluble vitamins
– Absorbed in the lymphatic system, dumps into the circulatory system
– Lipoprotein lipase enzyme on inside wall of blood vessels causes chylomicrons (and other lipoproteins) to release TGs and fatty acids for cells to absorb and use/store

Question 27

VLDL

Answer 27

Similar to chylomicrons but consist of lipids and cholesterol packaged by the liver during the fasted state
– Become depleted of TGs and fatty acids because of lipoP lipase  LDL

Question 28

LDL

Answer 28

– Primarily cholesterol core
– Attaches to LDL receptors on cells, taken into cells, phospholipids and proteins recycled, cholesterol used to make bile, hormones, etc…….UNLESS…….
Oxidative damage of LDL by free radicals    heart disease
 If LDL continues to circulate, is susceptible to oxidative damage
 “Consumed” by special white blood cell phages (scavenger cells)  become large and sluggish  attach to and bury into artery walls  tissue damage  inflammation, clotting, calcium cap = atherosclerosis
 Atherosclerotic plaque build-up increases risk of occluding arteries  decreased oxygen flow  heart attack, stroke, pulmonary embolism, deep vein thrombosis

Question 29

Antioxidants

Answer 29

May protect LDL from oxidative damage by free radicals by “quenching” them
 Fruits, vegetables  Vitamins C, E, A  Caution with iron

Question 30

HDL

Answer 30

– Mostly protein by weight
– Produced by liver
– Picks up cholesterol from dead and dying cells  takes to liver to be turned into bile
 Factors affecting HDL levels: – Gender
– MUFA intake – Exercise

Question 31

Factors that decrease LDL

Answer 31

Low saturated fat intake
 Increased soluble fiber intake  Plant sterols/stannols
 MUFA/PUFA