Class 8- Lipids pt 1

Chapter 5

what do lipids include

triglycerides, phospholipids, sterols

why are fats important?

• Building blocks for cell membranes

• Padding protects your organs

• Insulation for extreme temps

• Fat reserve for energy in case of starvation situation

• Essential Fatty Acids (omega-3 and omega-6)

• Raw material for important compounds (hormones and neurons)

• Carrier of fat-soluble vitamins (A, D, E and K)

• In foods: satiety, taste, energy dense

where are the 3 lipids found/

1. Triglycerides (or triacylglycerols)

▫ ~95% of all lipids found in food

and the human body

2. Phospholipids

▫ In cell membranes and lecithin

3. Sterols

▫ Cholesterol, phytosterols

What is triglyceride made out of, how many types of fatty acids

1 glycerol + 3 fatty acids

there are : Saturated, unsaturated, monounsaturated, polyunsaturated FATTY ACIDS

what is the run for forming a triglyceride?

3 fatty acids attach to glycerol in condensation rxn

what is form of Fatty Acids (FA)

• org, acids

• chains of C and H 

• carboxylic acid @ one end, methyl (CH3) @ other end

what are different lengths of carbon chains in FA? where are they found?

Very long-chain (20–24 C) —> fatty fish

Long-chain (14–18 C) —> most abundant, meat,

fish, vegetable oils

Medium-chain (6–12 C) —> dairy products

Short-chain (4 C or fewer) —> dairy products

Do triglycerides have 3 identical

FA’s or could they have FA’s of

varying length?

Could all be identical or could be varying

 Chain lengths most often tend to vary

 A long chain triglyceride might have 16C and 18 C and 20C

why do carbon chains tend to have even # of C atoms

 Natural fatty acids found in plants and animals

are typically composed of only even numbers of

carbon atoms

 BUT Bacteria can synthesize odd-numbered chains

which FA are produced by microbiota and how?

Short-chain fatty acids (SCFAs) such as butyric

acid/butyrate are the main metabolites produced

by the microbiota in the large intestine through the

anaerobic fermentation of indigestible

polysaccharides such as dietary fiber and resistant

starch.

saturated fats are …

unsaturated fats are…

what are the three ways FA can differ?

1. Length (from 4 to 22 carbon atoms)

2. Degree of saturation of carbon atoms

3. Location of double bond between carbon atom

• saturated

• monounsaturated (1 DB)

• polyunsaturated ( 2+ DBs)

what are the 4 18-Carbon FA?

• steric acid (sat), oleic acid (monounsat), linoleic acid (polyunsat), linolenic acid (polyunsat)

what are the 2 essential FA?

1. Linoleic acid (LA) —> omega 6

2. alpha-linolenic acid (ALA) —> omega 3

essential bc they can’t be synthesized by body

what are some functions of essential FA

Both LINOLEIC and LINOLENIC can:

• Provide raw material for eicosanoids.
  Serve as structural and functional parts of cell membranes.

• Contribute lipids to the brain and nerves.

• Promote normal growth and vision.

• Assist in gene regulation.

• Maintain outer structures of the skin, thus protecting against water loss.

• Help regulate genetic activities affecting metabolism.

• Support immune cell functions.

what are the two families of essential FA?

omega 3 and omega 6

what are the two important acids coming from omega 6 pathway vs omega 3 pathway?

omega 6:

• LINOLEIC (LA)

• ARANCHIDONIC (AA)

omega 3:

• EICOSAPENTAENOIC (EPA)

• DOCOSAHEXANOIC (DHA)

why is it recommended to consume foods rich in EPA and DHA?

eicosapentaenoic acid (EPA)

and docosahexaenoic acid (DHA) CAN be synthesized from ALA, but due to low conversion efficiency eating enough/supplementation is recommended

what are omega 3 eicosanoids cardiovascular benefits , how many grams of fish per week is recommended?

 Anti-inflammatory

 Lower blood pressure through vaso-dilation

(vessels are more relaxed and wider—> better blood flow)

 Reduce or prevent unwanted blood clot formation

 Protect against irregular heartbeat

 Reduce inflammation in small vessels and

capillaries

• 350-425 g /fish per week

what are risks of fish oil supplements?

Often made from fish skins & liver and may

have accumulated toxic conc. of:

 Pesticides

 Heavy metals, such as mercury

 Other industrial contaminants

why is it recommended to eat mono/poly unsaturated fat?

Unsaturated fats:

• may lower the “bad” LDL

cholesterol and reduce risk of cardiovascular

disease

• keep “good” HDL cholesterol high

what were the healthy dietary fats provided in the mediterranean diet study?

 In the Prevención con Dieta Mediterránea

(PREDIMED) trial, 7447 ppl consumed Mediterranean diet supplemented with

extra-virgin olive oil (56 ml/day), a Mediterranean

diet supplemented with mixed nuts (30 g/day; 15gof walnuts and 7.5 g of almonds and 7.5 g of

hazelnuts) or a control diet reduced in dietary fat.

 RESULTS= after 4.8 years, consumption of

a Mediterranean diet supplemented with either

extra-virgin olive oil or nuts resulted in a 30%

reduction in risk of myocardial infarction, stroke, or death.

why are nuts so healthy?

 Fibre, protein

 Phytochemicals that act as antioxidants

 Plant sterols

milk contains sat. fat. why is it still deemed good? 

• dairy is Source of Short chain FA’s and medium chain FA’swhich are beneficial.

• due to the complex nature of dairy

fats, the presence of beneficial nutrients like

calcium, potassium and conjugated linoleic acid

(CLA) is good

difference between cis/trans fats

• cis= H on same plan, usually unsat. fats comes from plants and contain cis unsaturated fatty acids

• the cis DB causes kink which prevents FA from packing tightly —> causing liquid @ room temp 

• trans= H on app sides at a certain point on chain, used to improve shelf life and texture

why are trans fats banned? why was hydrogenation even a thing?

 Mainly found in highly processed foods

 Pose risks to heart health: Raise “bad” LDL cholesterol and Lower “good” HDL cholesterol :(

 Produces inflammation in the body

• hydrogenation adds H to unsaturated fats, makes liquid more solid @ room temp, increases shelf life

what FA have lowest oxidative stability (and what does this mean?)

• PUFA bc of DBs, saturated fats are most stable

• all fats will spoil when exposed to O2 

• oxidation = process of combining with oxygen and losing e-

what does ‘refined’ vs ‘unrefined’ mean. what is EVOO?

• after extraction, oils can be either packaged right away or refines/processed

Extra virgin” olive oil (EVOO): most natural

version from first press of olive, cold-pressed (not

heated)

what are phospholipids? are they essential ?

• a glycerol + 2 FA + Phosphorus contains molecule

• form cell membranes 

• are considered non-essential 

phospholipid vs triglyceride form 

phospholipids are similar to a triglyceride BUT contains only two fatty acids.Third position is occupied by a phosphate group and sometimes a functional group attached to the phosphate 

what are sterols? what are some functions?

large lipid consisting of interconnected rings of

carbon atoms, + side chains of carbon, hydrogen and oxygen 

Functions= 

• Naturally found in plants (phytosterols) and animal based products (cholesterol)

• Subgroup of steroids -Sex hormones (estrogen,

testosterone)

what is cholesterol? what 3 common synthesis pathways is it involved with?

• structural component of cell membrane 

• precursor for:

 1.making bile in gallbladder

2. steroid hormone biosynthesis (test, estrogen, progesterone)

3. vit. d syntheis