Lipids Flashcards
Is there any recommendation concerning cholesterol consumption, type of fat,etc.?
There is evidence to restrict cholesterol consumption to healthy people. However, there is one for people with cardiovascular diseases. CFG states that we should consume less saturated fat and eat more MUFAs and PUFAs
More omega 3 and less omega 6 ( the ratio should be 1:8, now 1:15)
Why low fat diet is not efficient?
Because our body can produce cholesterol on itself and also usually people balance lack of fats with more CHOs. As the result, consuming more calories, more obese
Name three types of lipids
1) triacylglycerol
2) phospholipids
2) sterols
How phospolipids and triacylglycerols related?
Phospholipids are the same as triacylglycerols, but one fatty acid substituted with phosphocholine
What property does phospholipids have?
Amphipathic compounds
Why plant products that claims no cholesterol on the package are not fair?
Cholesterol comes only from animal based products
Plants have phytocholesterol that we do not digest
What changes can be done to reduce fat in the diet?
To lower the milk fat percentage gradually
To trim the steak from fat, for example
In what products lecithin is found?
Eggs, mustard
What are functions of lipids in foods?
- 2 essential fatty acids
- concentrated energy
- carry fat soluble vitamins
- flavor,aroma,texture
- satiety
- emulsification
What are metabolic functions of fat in our diet?
- Adipose tissue is a concentrated energy store
- Cell membranes (phospholipid bilayer)
- Nerve impulse transmission
- Eicosanoid synthesis
What type of lipids is 99% of our diet?
Triacylglycerols
How the bond between glycerol and fatty acid is formed?
Ester bond with elimination of water( similar to glycemic bonds)
How can we use glycerol in our body (except triacylglycerols)?
To synthesize glucose
What is the reactive end and its polarity?
Carboxylic end. It is polar
What is the non-polar group in fatty acids?
Methyl end
Give the example of saturated fatty acids family and its short abbreviation
Stearic acid. 18:0
The example of MUFAs with the short name. Where can we find this fatty acid?
Oleic acid. 18:1.Omega-9 In the olive oil
What does Omega 9 mean in the naming of the fatty acid?
The position of the first double is located 9 carbons away from the methyl end.
Name 2 representatives of PUFAs class
Linolenic acid C 18:3 omega 3
Linoleic acid C 18:2 omega 6
Do we know the other positions of double bonds in linolenic acid?
Yes, as it is omega 3 and it has 3 double bonds, so the places are 3,6 and 9
For linoleic acid omega 6, so the other bond is at position 9
How do double bonds effect physical properties of lipids?
More double bonds, more liquid the fat at cooler temperatures
Why people hydrogenated fats?
For preservation
What happens to fats with double bonds on the sunlight?
Double bonds are very susceptible to oxidation( light, heat). As they are exposed to the light or heat, they turn to free radicals. These free radicals will cause other fatty acid to convert to free radicals as well. Eventually, can cause oxidative stress in the body and damage DNA, cause cancer
Hydrogenation is
Making double bonds into single bonds
What is margarine?
Hydrolyzed vegetable oil
What are the most naturally occurring fats?
Cis fats
What is the difference between trans fats and cis fats in the structure
Trans fats are more linear than cis fats
How fats can become trans fats?
Partial hydrogenation of unsaturated fats. Cis changes to trans during the reaction.
What is the consequence of different configurations of fats?
They are handled differently in the body
Why trans-fats are dangerous for humans?
In the body, trans fats are converted to peroxides. Peroxides lead to oxidation. Oxidation leads to DNA damage,cancer, cardiovascular disease
The classification of fatty acids according to the chain length
Short 2-6C
Medium 8-12(14)
Long >16
How does the solubility changes with the length of fatty acid chain?
Short fatty acids are pretty soluble
As the length increases, the solubility decreases
The classification of fatty acids, according to the double bonds (number,position,stereochemistry)
Number( saturated, MUFAs,PUFAs)
Position (omega3,omega6,omega9)
Stereochemistry (cis,trans)
What oils and fats are mostly saturated fat?
Animal fats and tropical oils (coconut,palm)
What are the best choices for oils and why ( a hint: expensive)
Flaxseed oil
Walnut oil
Because they have a lot of MUFAs and a good ratio of omega 3 to omega 6
What are the best healthy options for budget?
Canola oil for cooking
Olive oil for other purposes
A lot of MUFAs and a good ratio of n=3 to n=6
Why peanut oil is not a healthy choice?
-A lot of omega 6, no omega 3
The sources of linoleic and alpha-linolenic acids in oils
Linoleic- corn,peanut,safflower
Alpha-linoleic - canola,flax,soy
Why linoleic and alpha-linolenic acids are so-called essential?
Because when removed from the diet, there is pathology of the skin (deficiency of essential fatty acids), corrected when put back. Can not be produced form other fatty acids in our body
What is the requirement for linoleic and alpha-linolenic acids?
1 gram(linoleic) and 8 gram(alpha)
Why the consumption of these two acids are not a concern for clinical nutrition?
Because everybody on every diet does not have fatty acid deficiency
Name four families of fatty acids with the examples and short names
Saturated(stearic, 18:0)
MUFA n-9 (Oleic, 18:1)
PUFA n-6 (Linoleic, 18:2)
PUFA n-3 (Alpha-linolenic, 18:3)
Why saturated and MUFAs are not essential in our diet?
Excess of glucose will be converted to stearic FA. We have the enzyme to insert a double bond into n-9, but into 3 or n-6. That is why we can get oleic, but not linoleic or alpha-linolenic. The enzyme is called- desaturase
Why it is important to have both linoleic and alpha linolenic acids in the diet?
Both of the families use desaturase and elongase. As they are the same, one class can out-compete the other. But we need the products from two families.
At what part of the molecule does the elongaze insert carbons?
At the reactive end
What fatty acid does peanut have?
Arachidonic acid
Describe the pathway of linoleic acid
Linoleic( c18:2 n-6)->(desaturase) c 18:3 n-6 ->(elongase) c 20:3 n-6-> (desaturase) Arachidonic C20:4 n-6-> ( multiple steps-> eicosanoids n-6
What do eicosanoids do in our body?
Metabolic regulators