Advanced Nutrition Fat Exam

Are lipids water soluble or insoluble?

Water insoluble

What are lipids soluble in?

Organic solvents (ex acetone or benzene)

Are lipids a concentrated form of energy or not?

Yes, they are a concentrated form of energy

What are the functions of fat?

Energy source, satiety, blood clotting, thermal insulation, cell membrane structure, fat-soluble vitamins, sex hormones, organ protection, and acts as a signaling molecule

What is a simple lipid?

A fat containing carbon, hydrogen, and oxygen only

What are examples of simple lipids?

Fatty acids and triglycerides

What are compound lipids?

Lipids containing carbon, hydrogen, oxygen, and 1 or more of another element

Examples of compound lipids?

Phospholipids, cholesterol, and lipoprotiens

What is the structure of fatty acids?

A hydrocarbon chain terminating with a carboxyl group (COOH)

Is is more common to have an even or odd amount of carbons on a fatty acid?

Even amount (4 to 24 carbons)

What amount of carbons are most abundant in fatty acids?

16c, 18c, and 20c

What is a saturated fatty acid?

Saturated fatty acids are fatty acids where all the carbon atoms in the chain are bound to the maximum number of hydrogen atoms

Are saturated fats typically solid or liquid at room temperature?

Typically solid at room temperature

Do saturated fats increase or decrease LDL?

Increase LDL

How many kcal should come from saturated fats?

Recommendations are at 10%, but 7% is ideal

What are common sources of saturated fats?

Animal products: bacon, cheese, milk, etc.

What is unsaturated fat?

Unsaturated fats have a "kink" or bend in their structure due to the presence of double bonds between carbon atoms in the fatty acid chain

What is monounsaturated fat?

One double bond (ex. oleic acid)

What is a polyunsaturated fat?

Two or more double bonds present (ex. oils)

Is unsaturated fat typically solid or liquid at room temperature?

Typically liquid at room temperature

What are recommendations surrounding unsaturated fat intake?

Replace saturated fat intake with unsaturated fat to decrease cholesterol

What are common sources of unsaturated fats?

Olive oil, canola oil, safflower oil, corn oil, sunflower oil, and soybean oil

What is the delta (Δ) system?

Counts the double bonds from the carboxyl end

(# of carbons) : (# of double bonds) Δ ^{(double bond location)}

What is an example of using the delta (Δ) system?

18 : 3 Δ^9,12,15

What is the omega (w or n) system?

Counts double bonds from the methyl end

(# of carbons) : (# of double bonds) w/n - (first double bond location)

What is an example of using the omega (w or n) system?

18 : 3 w - 3 OR 18 : 3 n - 3

What are essential fatty acids?

Fatty acids that cannot be synthesized by the body

How many essential fatty acids are there?

Two: alpha-linolenic acid and linolenic acid

What are descriptors of alpha-linolenic acid?

• 18 : 3 Δ ^9,12,15

• Considered an omega-3 fatty acid

What are examples of foods that contain alpha-linolenic acid?

Linseed, soybeans, and other seed oils

What are descriptors of linolenic acid?

• 18 : 2 Δ ^9,12

• Considered an omega-6 fatty acid

What are examples of food that contain linolenic acid?

Corn, safflower, soybeans, etc.

What are omega-3 fatty acids?

A group of essential polyunsaturated fats that play crucial roles in overall health

What are fatty acids that are considered omega-3s?

• alpha-linolenic acid (vegetarian)

• Eicosatetraenoic acid, EPA, (20 : 5 Δ^5,8,11,14,17)

• Docosahexaenoic acid, DHA, (22 : 6 Δ^{4,7,10,13,16,19})

What are the dietary guidelines for omega-3s?

0.6 to 1.2 % of total kcal/d

What do omega-3s help to make in the body?

• Prostaglandins (dilation/constriction of blood vessels)

• Leukotrienes (smooth muscle contraction)

• Thromboxane (vasoconstriction)

Benefits of increasing omega-3 intake?

• Adults: decreased heart related conditions, increased mental health, and decreased risk of cancer

• Infants: increase in neural and eye development

How to calculate the correlation of increase in w-3 in RBC?

EPA + DHA / total fatty acids , 8% is considered adequate

How much alpha-linolenic acid is converted to EPA and DHA?

• EPA: 0.2%

• DHA: 0.1%

What are symptoms of omega-3 deficiencies?

• Dermatitis

• Cracked fingernails

• Impaired vision

• Memory disabilities

What are possible concerns with omega-3 supplementation?

• Increased bleeding

• Decreased wound healing

• Increased methyl-mercury contamination

• High amounts of vitamins A and D

What are omega-6 fatty acids?

A group of essential polyunsaturated fats that play crucial roles in overall health

Where can omega-6 fatty acids be found?

• Linolenic acid (18 : 2 Δ^9,12)

• Arachidonic acid (20 : 4 Δ^5,8,11,14)

What are the dietary guidelines for omega-6s?

5 to 10% of total kcal/d

What are eicosanoids?

A group of lipid-based signaling molecules derived from 20-carbon polyunsaturated fatty acids that play a crucial role in regulating inflammation, pain, and other physiological processes

What are prostaglandins?

Prostaglandins are hormone-like substances that play a vital role in various bodily functions. They are produced in the body from arachidonic acid.

What are different types of prostaglandins?

All aid with coagulation:c

• PGI₂ : anti-aggregating

• PGE₂ : vasodilation

• PGF₂ : vasoconstriction

What are some descriptors of lipoproteins?

• Droplets of lipids

• Transport lipids

• Can vary in size, density, and composition

What is chylomicron’s apoprotein counterpart?

Apo B-48

What is VLDL’s apoprotein counterpart?

Apo B-100

What is IDL’s apoprotein counterpart?

Apo B-100

What is LDL’s apoprotein counterpart?

Apo B-100

What is HDL’s apoprotein counterpart?

Apo A-1

Where are chylomicrons assembled?

In the intestine

What is apoprotein c-II’s role in chylomicrons?

They activate LP lipase to hydrolyze triacylglycerol

What is apoprotein c-III’s role with chylomicrons?

Activating cholesterolase

What is apoprotein e’s role with chylomicrons?

Bind to hepatic receptors for the uptake of chylomicron remnants

Where is VLDL made?

Assembled in the liver

What contents make up VLDL?

Newly synthesized TG, cholesterol, cholesteryl esters, phospholipids, and lipids from CM remnants

Where are they released and what happens during this process?

Released from the liver into circulation where they are taken by mainly adipose tissue, the cell surface has LP lipase, phospholipase, and cholesterol esterase

What happens to VLDL when triacylglycerol is removed?

The VLDL becomes IDL

Where is LDL formed?

LDL is formed in circulation and can be taken up by the liver via LDL receptors

What happens to oxidized LDL?

Oxidized LDL is not recognized by the LDL receptors and is taken up by macrophages. This causes them to turn into foam cells which then creates plaque in arteries (CVD).

Where is HDL is secreted?

HDL is secreted by the liver as an empty protein shell

What is HDL’s function?

Picks up cholesterol from peripheral cells and converts them to cholesterol esters to initiate exchange with other LPs to receive TG

What are fat cells?

Excess fat stored in lipocytes which can expand until the fat is used for fuel

How does the body respond to the postprandial state?

Takes up extra glucose which is converted to TG. This stimulates increase in insulin.

How does the body respond to the fasting state?

Fat is hydrolyzed (a release of fatty acids used for energy) which is stimulated by hormone sensitive lipase

What causes increased lipolysis?

• Thyroid hormones

• Glucagon

• Epinephrine/norepinephrine

• Caffeine

• Cortisol

• Growth hormone

What causes decreased lipolysis?

• Insulin

• Increased phosphodiesterase activity (insulin)

• Nicotinic acid

• Beta blockers

What are the steps to LCFA beta-oxidation?

1. Dehydrogenation catalyzed by acyl-CoA dehydrogenase, which removes two hydrogens between carbons 2 and 3.

2. Hydration catalyzed by enoyl-CoA hydratase, which adds water across the double bond.

3. Dehydrogenation catalyzed by 3-hydroxyacyl-CoA dehydrogenase, which generates NADH.

4. Thiolytic cleavage catalyzed beta-ketothiolase, which cleaves the terminal acetyl-CoA group and forms a new acyl-CoA which is two carbons shorter than the previous one.

What is lipogenesis?

Excess dietary CHO and PRO is converted to fat in the liver

What are the steps when a diet is rich in CHO?

1. Glucose

2. Acetyl CoA

3. Free fatty acid

4. TG

What are the steps when a diet is rich in PRO?

1. Amino acids

2. Acetyl CoA (or pyruvate)

3. Free fatty acid

4. TG

Where does fatty acid synthesis take place?

In the cytosol in the cells