Lipids Flashcards
Fatty acids
basic unit of lipid
Triglycerides
3 fatty acids attached
to a glycerol backbone
Phospholipids
2 fatty acids and a phosphate head attached to a glycerol backbone
Sterols
multi-ring structures, soluble in lipids
Bile
emulsification
– 98% reabsorbed unless use Rx, plant sterols/stannols, soluble fiber
Lipase
separates triglycerides into individual fatty acids
chylomicrons
Fatty acids absorbed by small intestine cells, packaged into chylomicrons, released into the lymphatic system
Fat as Fuel
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

Fat for Insulation/Protection
 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

Fat for Transporting/Storing Vitamins
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
Recommendations
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
Classes of Fatty Acids-form
Based on number of carbon-carbon double bonds in the hydrocarbon chain
Related to health benefits or risk Only 2 are essential
Three classes
– 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
Saturated Fatty Acids
Food source: primarily animal – Also found in coconut, palm oils Health consequence: – Increases “bad” cholesterol Recommendation: – Less than 10% of total Calorie intake 
MUFAs
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) 
PUFAs
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) 
Which of the 3 classes of fatty acids is considered “bad fat” or is the most unhealthy for the cardiovascular system?
PUFA’s hydrogenated to trans fatty acids, after that the saturated fats are most ‘dangerous’ to the cardiovascular system.
Which of the 3 classes of fatty acids provides the 2 essential fatty acids?
PUFA
Which of the 3 classes of fatty acids should we consume most?
PUFA
Hydrogenation
PUFAs can be hydrogenated to produce a more shelf-stable, solid product
By-product = trans fatty acids Increase “bad” cholesterol

Cholesterol
– 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

Long-chain Omega-3
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
Omega-6
Omega-6 FA derivatives: – Increase blood clotting – Increase inflammation – Vasoconstriction – Excite contractions in smooth muscle
Heart Disease and Lipids
Lipoproteins, “Good” vs. “Bad” Cholesterol, Atherosclerosis
three types of lipoproteins
VLDL, HDL, LDL
Chylomicron
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
VLDL
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
LDL
– 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
Antioxidants
May protect LDL from oxidative damage by free radicals by “quenching” them
Fruits, vegetables Vitamins C, E, A Caution with iron
HDL
– 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
Factors that decrease LDL
Low saturated fat intake
Increased soluble fiber intake Plant sterols/stannols
MUFA/PUFA

