Dietary fat Flashcards by Caroline Sandberg

Name a few food sources of dietary fats?

Fatty fish
Margarine
Dairy products
Vegetable oils
Avocado
Chocolate

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Is cholesterol present in food the same as cholesterol present in the blood?

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According to Riksmaten 2010/2011

How much dietary fats are consumed in E%?

34 E%

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According to Riksmaten 2010/2011

How much saturated fat and which fatty acid was highest?

13 E%

Palmitic acid C16H32O2

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According to Riksmaten 2010/2011

How much monounsaturated fat and which fatty acid was highest?

13 E%
Oleic acid
C18H34O2
omega-9 fatty acid

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According to Riksmaten 2010/2011

How much polyunsaturated fat and which fatty acid was highest?

5.6 E%
Linoleic acid
C18H32O2
omega-6 fatty acid one of two essential fatty acids - must obtain it through diet

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NNR 2012

Recommend what energy percentage of fat?

25-40 E%

Fat quality more important than quantity

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NNR 2012

Recommended intake of saturated fat, polyunsaturated fat and monounsaturated fat?

<10 E% saturated fat
5-10 E% polyunsaturated fat (>1 E% should come from omega-3 fatty acids)
10-20 E% monounsaturated fat

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How are dietary fats built?

A triglyceride (triacylglycerol) with a glycerol backbone and 3 esterified fatty acids

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Which two fatty acids are essential?

Linoleic acid (n-6) and Alfa-linolenic acid (n-3)

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Dietary sources of linoleic acid (n-6)?

Flaxseeds and flaxseed oil.
Canola (rapeseed) oil.
Soybeans and soybean oil.
Pumpkin seeds and pumpkin seed oil.
Perilla seed oil.
Tofu.
Walnuts and walnut oil.

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Dietary sources of Alfa-linolenic acid (n-3)?

Alpha-linolenic acid is a type of omega-3 fatty acid found in plants. It is found in flaxseed oil, and in canola, soy, perilla, and walnut oils. Alpha-linolenic acid is similar to the omega-3 fatty acids that are in fish oil, called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

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What determines if omega 3 or 6?

the position of the first double bond from the methyl-group

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Ex. of saturated fatty acids

butter, red meat, cocunut oil, palm oil, milk and chocolate

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Ex. monounsaturated fatty acids

Olive oil, red meat, rapeseed oil and avocado

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Ex. polyunsaturated fatty acids

sunflower oil, fatty fish, nuts and seeds

How does Linoleic acid get converted to Arachidonic acid?

Through desaturation by D6D
18:2n-6 --> 18:3n-6
then elongation by Elongase 
18:3n-6 --> 20:3n-6
Desaturation by D5D
--> 20:4n-6 (Arachidonic acid)

Explain the digestion of triglycerides

Triglycerides are broken down by bile salts + lipases in the digestive tract to monoglycerides + fatty acids + glycerol

What is Arachidonic acid and what is the connection to inflammation?

Arachidonic acid is a polyunsaturated fatty acid covalently bound in esterified form in the cell membranes of most body cells. Following irritation or injury, arachidonic acid is released and oxygenated by enzyme systems leading to the formation of an important group of inflammatory mediators, the eicosanoids.

How are triglycerides, cholesterol and phospholipids transported?

By lipoproteins

How are short- and medium chain fatty acids absorbed?

They are absorbed into blood, bound to albumin

What are chylomicrons and what do they do?

lipoprotein particles that consist of triglycerides (85–92%), phospholipids (6–12%), cholesterol (1–3%), and proteins (1–2%). Chylomicrons transport lipids absorbed from the intestine to adipose, cardiac, and skeletal muscle tissue, where their triglyceride components are hydrolyzed by the activity of the lipoprotein lipase, allowing the released free fatty acids to be absorbed by the tissues. When a large portion of the triacylglycerol core have been hydrolyzed, chylomicron remnants are formed and are taken up by the liver, thereby also transferring dietary fat to the liver.

What happens after the glycerol and fatty acids have been absorbed into the small intestine?

They are packed in Enterocytes where they are repacked as triglycerides then these new triglycerides are packed into chylomicrons (which is then transported into the blood

What happens to Chylomicron remnants?

Goes to liver (provide some TG) and then new particles are formed, VLDL-particles (a lot of triglycerides in the particle) leave the liver

What are VLDL-particles

Particles with alot of triglycerides - produced in liver

What is the difference between VLDL and LDL?

VLDL contain proportionally mostly TAG but when that is left it contains mostly cholesterol and then called LDL (rich in cholesterol)

Why can LDL-particles be harmful?

LDL are small and can therefore damage your arteries that carry blood from your heart to the rest of your body. Then once the damage has started, LDL keeps on penetrating and building up in the artery walls

What can LDL do?

Leave cholesterol to muscles or be transported back to liver

What is the role of HDL?

To transport the excess of cholesterol from tissues to the liver where it is broken down

Why can saturated fats be dangerous?

Saturated fatty acids inhibit the receptor on the liver – LDL-particles cannot be taken up by the liver – increase the risk of cardiovascular disease since there are more LDL that can get stuck in capillary

Beskriv de 4 stegen i Beta-oxidation av fettsyror

FAD tar upp två väteatomer så att en dubbelbindning bildas mellan fettsyrans α- och β-kolatom. FADH2 bildas. En vattenmolekyl adderas till α-β-dubbelbindningen. OH-gruppen binds till β-kolatomen. NAD+ oxiderar β-kolatomen (därav namnet beta-oxidation). NADH + H+ bildas. Acetyl-CoA avspjälkas samtidigt som ett nytt koenzym A kopplas på. Acetyl-CoA och fettsyra-CoA bildas. Det som är kvar av fettsyran går in i ett nytt varv i cykelns andra steg. Detta upprepas tills fettsyran har brutits ner till acetylgrupper.

What is the synthesis of new fatty acids called?

de novo lipogenesis (DNL) | occurs predominantly in the liver and adipose tissue

Short explanation of DNL

Sugar + amino acids goes into the liver and makes Acetyl-CoA which eventually makes Palmitic acid. Being TG for storage and put in VLDL-particles

Some important functions of dietary fats

- Two fatty acids are essential (linoleic acid, alfa-linolenic acid) - Energy (9kcal/g) → tool to increase/decrease energy density - Increase palatability of food - Important for absorption of fat-soluble vitamins (A, D, E, K) - Precursors for eicosanoids (blood pressure, inflammation)

What can happen if fat starts to accumulate in the liver?

less efficient – deteriorate So it might impact blood glucose control and can be a riskfactor for type two diabetes – high sugar in blood

Do saturated fat and PUFA result in different amount of body fat?

Saturated fats accumulate to a higher degree in the liver. | Also difference in fat mass, visceral fat mass and fat free mass.