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Nutritional Biochem 2 > Final Exam (Omega-3 Fatty Acids) > Flashcards

Final Exam (Omega-3 Fatty Acids) Flashcards

1
Q

Alpha-Linolenic (ALA)…

A

18:3

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2
Q

Eicosapentaenoic (EPA)…

A

20:5

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3
Q

Docosahexaenoic (DHA)…

A

22:6

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4
Q

What living thing makes ALA?

A

Plants

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5
Q

*The most widely available sources of EPA and DHA are cold water fish, what are these fish?

A 
SMASH-T
Salmon
Mackerel
Anchovies
Sardines
Herring
Tuna
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6
Q

*DHA concentrations are highest where? EPA concentrations are highest where?

A
  • DHA - Retina/Cerebral cortex

- EPA - TRICK QUESTION, LOW EVERYWHERE

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7
Q

The conversion of ALA to EPA/DHA occurs where? What is unique about this conversion?

A
  • Occurs in the SER

- The FINAL step (B-ox) occurs in the peroxisome

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8
Q
  • Delta-5 desaturase… AKA…

* Delta-6 desaturase… AKA…

A
  • FADS1 (Fatty acid desaturase)

- FADS2 (fatty acid desaturase)

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9
Q

*ALA –> D6-desaturase –> elongase –> D5 desaturase =

A

EPA

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10
Q

*EPA –> Elongase –> Elongase –> D6 desaturase –> B-oxidation =

A

DHA

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11
Q

The level of EPA/DHA in where is an indicator of Omega-3 FA intake?

A

RBC membrane!

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12
Q

*What is the rate limiting step in ALA conversion to EPA and DHA?

A

D6-Desaturase (very inefficient)

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13
Q

*Since conversion of ALA to DHA is so poor, what would one explanation for this be?

A
  • ALA is the most rapidly oxidized unsaturated FA, a large portion of ingested ALA is then B-oxidized to Acetyl-CoA
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14
Q

*What will inhibit D6 and D5 desaturase and reduce EPA and DHA concentrations in the body?

A
  • ALCOHOL
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15
Q

What are the two elongase enzymes that help convert EPA –> DHA?

A
  • Elovl2

- Elovl5

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16
Q

*What is the most rapidly oxidized unsaturated FA, and less of this gets converted to DHA…

A
  • ALA
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17
Q

Which FA competes with ALA for D6-desaturase?

A

Linoleic Acid

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18
Q

Does DHA or EPA supplementation raise EPA levels?

A

DHA raises EPA levels through Retro-conversion

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19
Q

*What confounds efforts to establish cause and effect relationships between dietary EPA and DHA?

A

Retro-conversion

DHA –> EPA thru Beta-ox

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20
Q

T/F: Increased seafood consumption outweighs the risk of mercury? (SMASHT)

A

TRUE

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21
Q

*If someone takes >3g/day of Omega-3 FA, what can result?

A
  • Moderate GI upset
  • Likely fishy aftertaste in the mouth
  • Moderate level of worsening Glycemia
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22
Q

Is there a regional variation in mercury concentration depending where you are? Which body of water has the most ppm of mercury, and which has the least…

A
  • YES
  • Gulf of mexico (1.45ppm)
  • North Atlantic (0.05ppm)
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23
Q

This is a neurotoxin and can impair normal neurological development in a fetus or child….

A

Methylmercury

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24
Q

What are the 3 reasons fish oil supplements do not contain as high of levels of mercury than a serving of fish?

A
  1. smaller fish -low in mercury
  2. mercury binds to protein (fish meat, not oil)
  3. mercury may be removed in the making of oil (distilled)
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25
*Which type of salmon have lower concentration s of mercury than wild ocean-caught salmon?
- Farm-raised
26
*Farm-raised salmon have high levels of what 3 things? Who should avoid this?
- Dioxins - Polychlorinated biphenyls (PCB) - Chlordane - young children, pregnant/nursing women
27
*High enough concentrations of what is considered a carcinogen?
- PCB (polychlorinated biphenyls (PCB)
28
*What 2 things are more susceptible to lipid oxidation than other fatty acids? and why?
- EPA/DHA | - Due to them having more double bonds (5, 6)
29
*Why are polyunsaturated fatty acids easily oxidized?
- Because they have an electron which can be easily scavenged - Free radicals easily grab this electron due to the ease of the sp2 hybridized p-p (pi) bond that can separate...
30
*Why do many companies put Vitamin E in their Fish oil supplements?
- Vit E is a preservative that keeps the fish oil from going rancid - If there is no vitamin E or other preservative in the capsule the oil can go bad, and you are putting OXIDIZED fish oil in your body = BAD!
31
Omega-3 FA in fish oil are thought to be beneficial in treating...
Hypertriglyceridemia, Heart disease, insulin resistance, cancer, neurodegenerative diseases (depression, anxiety), RA, Osteoporosis, IBD, asthma
32
*EPA/DHA both will do what to NFkB (nuclear factor kappa B)?
- Down-regulate
33
*EPA/DHA will bind to activate what substance that will then inhibit the activation of NFkB --> limits inflammatory actions...
- PPARy (PPAR-gamma)
34
*(COX-PGH2) --> _______
- Prostacyclin (vasodilation, inhibit platelet aggregation)
35
*(COX-PGH2) --> _______
- Thromboxane (vasoconstriction, promote platelet aggregation)
36
*Arachidonic acid --> Cyclooxygenase --> ______
- PGE2 = vasodilation, increase vascular permeability
37
*Arachidonic acid --> Lipoxygenase --> ______
- Leukotrienes (B4) = vasoconstriction, bronchospasm (all leukotrines are involved with ASTHMA)
38
*Arachadonic undergoes hydrolysis at what position?
- Sn-2 position
39
*Healthy ratios of Omega-6: Omega-3 should be what?
1:1, 4:1
40
EPA or DHA will compete and replace what at which position of the glycerophospholopids?
- Arachidonic acid - Sn-2 position - Therefore, this will decrease arachadonic acid and decrease all inflammatory eicosanoid production!
41
* EPA inhibits release of arachidonic acid via competitive inhibition of what? * EPA reduces eicosanoid production by competitively inhibiting what?
- Phospholipase A2 | - COX and 5-LOX
42
EPA/DHA produce novel anti-inflammatory and inflammation resolving mediators called...
- Resolvins
43
*What 3 resolvins are produced through COX-2 and 5-LOX enzymes?
- Resolvin E1 (RvE1) - Resolvin D1 (RvD1) - Neuroprotectin D1 (NPD1)
44
What is the primary action of resolvins?
- Shut off ongoing inflammatory process to limit tissue damage
45
*Resolvin E1, D1, Neuroprotectin E1 all serve to inhibit what two things?
- IL-1 | - TNF
46
*Resolvin E1, D1, Neuroprotectin E1 all inhibit neutrophil infiltration at the sites of inflammation by reducing what two things?
- E-selectin | - ICAM-1
47
*NFkB turns on what?
- Pro-inflammatory genes! - EPA and DHA downregulate this! - EPA/DHA activate PPARy --> inhibits NFkB
48
*PGE2 at high concentrations activates what?
- RANKL receptors of preogenitor osteoclasts which then activates bone resorption. At mild levels it supports bone formation. - A high Omega6:3 ratio means there is an excess of arachidonic acid which will produce more PGE2
49
*Omega-3 vs Cancer...
Anti-inflammatory, pro-apoptotic, antiproliferative, antiangiogenic, estrogen antagonist, activator of PPARy (tumor supressor gene)
50
*Omega-3 vs CVD...
- Decrease trigs, increase blood viscosity, vasodilator, decrease inflammation, increase mitochondrial function, decrease BP, decrease platelet adhesion and organ damage, antiarrhythmic, vasoprotective - Anti-thrombotic, Anti-atherogenic, anti-arrythmic, vasoprotective
51
*Is DHA or EPA better for reducing triglycerides?
- DHA | - This will increase LDL's more though, as opposed to EPA
52
*>3g/day of fish oil will increase what?
- Bleeding | - Can increase the risk of Hemorrhagic stroke
53
EPA and DHA are precursors to what?
- Resolvins E1 and D1 | - Neuroprotectin E1
54
*Omega-3's may prevent overload of this nutrient? How is this done?
- Calcium - Omega-3's do this by inhibiting the activity of L-type Ca channels during period of stress and increase the activity of cardiac Ca/Mg ATPase active transports that move calcium back into the SR - Basically, this mechanism works to prevent excess Ca from accumulating in the cardiac cell's cytoplasm and therefore may prevent the development of arrhythmias
55
*Activation of PPARy will activate what to inhibit TAG synthesis and increase FFA Beta-ox...
- Adiponectine
56
*Activation of PPAR-alpha will increase hepatic beta-ox via what mechanism to reduce triglyceride substrates and decrease lipogenesis (decrease FA synthesis)
- Lipoprotein lipase
57
*Omega-3's promote insulin sensitivity which in turn does what?
- Protects the body against insulin resistance
58
What are some markers of oxidative stress?
- MDA - oxLDL - 8-oxoguanine - Reduced Vit C - Reduced Vit E - Increased glutathione peroxidase and catalase
59
Lipid membrane peroxidation is involved in 2 different diseases, what are they?
- Atherosclerosis | - DNA damage
60
*What are the 3 conditions where Omega-3 supplements are most effective?
- Hypertriglyceridemia - Hypertension - Prevention of Secondary CVD

Nutritional Biochem 2 (6 decks)

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