Lipids

Lipids

Triglycerides, Phospholipids, and Sterols

I Lipids aka: fats
A. organic compounds, insoluble in water
B. Building blocks: fatty acids
C. Include:
1. fats and oils
2. phospholipids
3. sterols
D. functions of fat
1. provides a concentrated source of energy
a. 9 kcal/g
2. provides the essential fatty acids
a. linoleic
b. linolenic
3. carries fat-soluble vitamins (A, D, E, K and photochemicals)
4. provides insulation
5. serves as a shock absorber
6. serves as a component of cell membranes
a. provides flexibility to cell membranes
7. increases flavor and palatability of food
E. composed of:
1. carbon
2. hydrogen
3. oxygen
II Types of fat: Triglycerides
A. triglycerides
1. 3 fatty acids + 1 glycerol base
2. 98% of our fat intake is in this form
3. most of the body fat stores are triglycerides
4. transport form of fat
5. used for energy and tissue maintenance
B. saturated fats
1. hard by nature
2. animal product
3. tropical oils: palm, coconut
4. hydrogenated
5. raises blood cholesterol
C. polyunsaturated fat
1. liquid
2. vegetable product
3. more than one double bond
4. lowers total blood cholesterol
D. monounsaturated fat
1. liquid
2. vegetable product
3. 1 double bond
4. lowers bad cholesterol
III Hydrogenation
A. the addition of hydrogen to unsaturated fatty acids
1. necessary to make liquid fats solid
B. Benefits:
1. improves shelf life, taste, cooking properties
C. disadvantages:
1. increase in amount of saturated fats
2. increase in amount of trans fats
D. cis and trans fatty acids
1. cis fats are the most common, naturally occurring fatty acids
2. trans fats occur when cis fats are changed during hydrogenation
3. trans fats increase blood cholesterol and heart disease risk
IV Fatty acids in fish oils
A. Omega 3
B. omega 6
C. provides protection against
1. heart disease, stroke
2. certain types of cancer
3. arthritis
D. over-consumption may lead to;
1. GI upsets
2. vitamins A and D toxicity
3. easy bruising and increased bleeding
4. mercury poisoning
E. fatty acid deficiency
1. Essential fatty acids: linoleic and linolenic
2. deficiency:
a. dry, scaly skin
b. poor growth in infants
c. impaired vision and hearing (infants)
d. liver abnormalities
e. poor healing of wounds
V Types of Fats: Phospholipids
A. phospholipids in foods
1. contain glycerol, two fatty acids and a phosphate group with a molecule of choline
2. used as emulsifiers in food industry
3. a well known phospholipid is lecithin
4. food sources of lecithin include eggs, liver, soybeans, wheat germ, and peanuts
B. functions of phospholipids
1. enable transport of lipids across cell membranes
2. emusifiers
3. lechithin is made by the liver
4. supplementes increase energy intake and can cause GI upset
VI Types of Fats: Sterols
A. Sterols in foods
1. found in plant and animal foods
2. cholesterol is found ONLY in animal foods. (meat, eggs, fish, poultry, dairy. Exogenous)
B. Cholesterol: a well known sterol
1. not an essential nutrient, but essential to the body
2. structural component of all cells
3. necessary for the formation of many hormones
a. estrogen
b. testosterone
4. necessary for the formation of Vit D
5. major component of bile
6. major component of nerves and brain
7. does not contribute to kcalories (same family as fat, but no kcal)
8. made in the liver
a. liver produces 800-1500mg/day (endogenous)
9. stored in the liver
10. transported in the body as lipoproteins
11. Low Density Lipoproteins (LDL) aka bad cholesterol
a. carries much cholesterol for body storage
b. increases risk of heart disease. increased by:
i. inactivity and obesity
ii. smoking
iii. high saturated fat, high cholesterol diet
12. High Density Lipoproteins (HDL) aka good cholesterol
a. provides protection from heart disease. Increased by:
i. regular exercise
ii. weight (fat) reduction
iii. smoking cessation
iv. saturated fats reduction
v. moderate alcohol intake (<2 drinks/day)
VII Cardiovascular disease
A. Coronary heart disease
1. #1 cause of death in US
2. Risk factors
a. diet and physical activity are modifiable risk factors
b. age, gender, and family history
i. cannot change these factors
ii. men higher risk than women
iii. men older than 45 years of age
iv. women older than 55 years of age
v. immediate family history of premature heart disease
c. obesity and physical inactivity
d. body mass index:
i. desirable: 18.5 – 24.9
ii. borderline: 15 – 29.9
iii. high: >30
e. weight loss and regular physical activity are protective
f. cholesterol (see below)
3. Cigarette smoking
a. powerful increase risk
b. increases blood pressure and the workload of the heart
4. atherogenic diet
a. a diet high in saturated fats, trans fats, and cholesterol an low in fruits and vegetables elevates LDL cholesterol.
b. antioxidants and omega 3 fatty acids lower the risk of CHD
5. Metabolic syndrome
a. aka syndrome x or insulin resistance syndrome
b. insulin resistance is a risk factor
c. Any three of the following factors = syndrome X
(3 aspects of this syndrome: high BP, High blood sugar, high cholesterol)
i. abdominal obesity
men waist > 40”
women waist >35”
ii. triglycerides: >150 mg/dL
iii. HDL: <40mg/dL in men, <50 mg/dL in women
iv. blood pressure: >130/85
v. fasting glucose: >100mg/dL
6. Recommendation for reducing CHD
a. cholesterol screening
b. lifestyle changes
i. low fat, low cholesterol diet
ii. limit sodium and sugar intake
iii. exercise
iv. moderate alcohol intake
v. avoid tobacco smoke
B. Atherosclerosis
1. formation of plaques in the arteries
2. How developed:
a. blood pressure and atherosclerosis
i. arteries are narrowed due to plaque, clots,or both
ii. the heart must generate more pressure to deliver blood to the tissues.
iii. higher blood pressure results in further damages.
3. the result
a. angina: pain or pressure feeling around the area of the heart
b. heart attack: restricted blood flow to the heart
c. transient ischemic attack or stroke (mini stroke): restricted blood flow to the brain
C. hypertension
1. elevated blood pressure >120/80
2. essential hypertension
a. develops without identifiable cause
b. affects more than 60 million
c. major risk factor in CHD
d. the silent killer
3. risk factors
a. age: risk increases with age
b. genetics: family history, African American, hisp, Ameri. Indi, Pacific islanders
c. obesity: 60% of those with hypertension are obese
d. salt sensitivity (genetic)
e. alcohol may raise bp and is associated w/strokes
4. treatment
a. weight control is one of the most effective treatments
b. physical activity will help. Moderate aerobic for 30-60 minutes most days
c. the DASH diet. Dietary approaches to stop hypertension
i. grains: 6-8 oz
ii. vegs: 2 -2 ½ cups
iii. fruits: same
iv: milk (low fat or fat free): 2-3 cups
v. meat (lean): 6 oz or less
vi. nut, seed, legumes: 4-5 oz per week
vii. 2000 kcal
d. drug therapy
i. diuretics and antihypertensive agents
ii. watch potassium
D. Risks for cardiovascular disease (coronary heart disease)
1.Cholesterol
a. total levels:
i. desirable <200mg/dL
ii. borderline: 200-239
iii. high: >240 mg/dL
c. HDL cholesterol
i. desirable >60 mg/dL
ii. borderline: 59-40 mg/dL
iii. high: < 40 mg/dL
d. LDL
i. desirable <100 mg/dL
ii. above optimum level : 100-129
iii. borderline: 130-159
iv. high: 160-189
v. very high: 190
VIII Lipids in the body
A. the triglycerides have important roles in the body (transport and store fat)
1. energy reserve when stored
2. use carbs and protein efficiently
3. insulation
4. shock protection
B. essential fatty acids also play important roles
C. The body can store unlimited amounts of fat when fat is consumed in excess
D. the liver can also convert excess carbohydrate and protein to fat (after glycogen stores filled)
E. fat needs carbohydrate to break down efficiently
F. inefficient breakdown of fat forms ketone bodies
IX Guidelines to groceries
A. fat replacers
1. ingredients derived from carb, protein or fat
2. replace fat in foods
3. artificial fats offer sensory and cooking qualities but no kcals
4. decreases the absorption of fat-soluble vitamins and may cause digestive distress
B. read food labels
1. provide info on fat grams and % DV
2. % DV are not the same as % of kcal from fat