Lipids, Fats, and Oils
Do we need fats? Why? RDA
Yes, they are a source of energy. 9 kcal/gram
What happens to excess calories?
Converted to or stored as fat. Efficient energy store. Very easy to mobilize/metabolize when energy is needed.
Yes from Palmitate (16-carbon fat that the body makes. 40 ATP/CoA x 8
Until age 50, why do women need more fat that men?
for reproductive success and necessary energy to support breast-feeding the offspring (evolution).
Is below 5% of body fat healthy?
No, may result in amenarche in women due to low estrogen release from adipose tissue.
What other problems may result form low adipose-derived estrogen to support healthy bone meatolism?
Loss of bone may also result from low adipose-derived estrogen to support healthy bone meatolism
What is an essential fatty acid?
Linoleic acid (structural role, used to make arachidonic acid.
What is the requirement of Linolecic Acid?
At least 1% of calories; below this level the symptoms of deficiency will eventually develop.
Optimum Linolec acid?
About 4% of calories; above this level there may be a consequence. As americans, we currently consum3e 6-10 % of calories as linoleic acid.
Deficiencies of Linoleic acid?
Were typical in the past until it was established that there was a critical fat in oils that needed to be included in the diet.
Why we have an essential fatty acid to make arachidonic acid leading to the prostaglandins and leukotrienes.
Problems associated with excess?!
Excess eicosanoid synthesis can have detrimental effects including: decrease in the immune system function. An increase in predisoposition to cancer, and an increase in cardiovascular disease.
n (or W)? vs Delta?
N counts for methyl (-Ch3) end of the molecule
Delta- counts for the carboxy (-COOH) end of the molecule
Where is Linoleic acid found (essential fatty acid)
18:2n6 found in plants
Polyunsaturated fatty acid (PUFA) (essential fatty acid)
because it possesses two or more double (=) bonds.
Saturated fatty acid (essential fatty acid)
has two H's on all C's except methyl end (above left end), which has three H's or COOH (right end) which has none.
Essential fatty acid deficiency n-6 fatty acids.
Decreased growth and growth rate - metabolites may/are involved in growth hormone release.
Dermatitis: maintains skin integrity, are the more flexivle/fluid of the fatty acids, in the male first shows up on the scrotum.
Increased watter loss through skin: loss of skin integrity and flexibility, Increased cracking and fluid loss.
decreased immune system function: low levels of prostagladin E2 (PGE2) the immune system will not be turned on
Reproductive failure: Metabolites of the eicosanoids are necessary for oocyte maturation and follicle rupture and release of the egg for fertilization.
Poor sperm development: may be irreversible if prolonged, related to eicosanoids.
n-3 fatty acids. ex?
Docosahexaenoic acid (DHA) is high in the brain retina, and male reproductive tissues. May be essential for the development of these tissues in the fetus
Eicosapentenoic acid promotes what?
Immune system function by reducing immune suppressive agents.
the formation of platelet aggregating factor and promotes the formation of an antiaggregatory factory. Thus reduces stroke.
Recommendation of N-3 fatty acids?
650 mg can be all, as alpha-LNA is probably way off. What is probably better is 2.2 g with 650 mg as alpha-LNA, remainder as DHA/EPA
Uses of fat?
Necessary to absorb and carry fat-soluble vitamins.
Do fats trigger bile release? If so, why is this necessary.
yes, necessary for fat and fat-soluble vitamin absorption.
Other uses for fat?
Component for building body materials- cell membrnaces-- as a component for phospholipids.
Two types: hydrophiloic and hydrophobic.
How do hydrophilic and hydrophobic work together?
They work together to create a membrane bilayer that prefers water on the sides, expodsed to the inside and outside of a cell with the fat layer sandwiched between.
Other functions of fat?
Palatability and mouth feel. Satiety or feeling fuller longer. Fat floats to the top. Does not mean that you should eat fat to fill up and not eat as much food.
Fats also did what for 1. Ancestors? 2. Bones? 3. Organs 4. Insulation?
1. allowed them to go longer periods of time without eating. 2. rounds the sharp planes of bones in body, prevent cutting with another bone like shoulder blade. 3 cushions vital organs. 4. Insulation (maintains body temp.
What is one of the main reasons why need to reduce excess stored fat?
Reduce cardiovascular disease.
Total consumption is up since 1900. Why?
Fat related substances. What are they?
1. Sterols: Cholesterol, vitamin D, steroids (testosterone, progesterone, estrogen).
2. Phosopholipids: Lecithin, sphingomyelin, etc. Structural role in cell membranes.
Chemical makeup and linkage of Lipids
C, H, O - same as carbohydrates whereas amino acids have other components such as N and S.
Fatty acid lenngth?
short < 8 C, meidum 8-12 C, Long is >12 C. Most fatty acids in the body are 16-24 carbons in length.
What does saturated mean?
Carbon saturated with H's, no double bonds.
One double bond, lacking two hydrogen
More than one double bond
What is the typical US diet?
37% Sat, 41% mono, 12% poly, about 10% other.
What would we like to see the Average American diet at?
33%, 33%, 33% with cholesterol below 300 miligrams/day (mg/d), according to American Medical Association (AMA) recommendations. some say lowere than 150/day, but our body will make all that we need
More saturated, the ___ solid at room temp?
Where is saturated fat from?
from meat animals and tropical oils
vegetables and fish
How do we get vegetable oils solid and animal fats soft at room temp?
Hydrogenation - add H2, PUFA more saturated,knocks out some double bonds, results in "cis-trans" isomerization.
Whipping - whip air and/or water into animal fats to soften, You pay extra for added water and air. Nuaturally occuring fatty acids are mostly cis.
cis -> hydrogenation -> trans (cancer inducer)
Physical properties of Lipids?
Insoluble in water, need carrier in body (in blood carried lipoporteins) thus impossible to excrete, have to burn or reduce caloric intake.
Do lipids float?
Yes, that is why we use underwater weighing for percent body fat. They digest slower, rise to the top in stomach as with milk. Remains in stomach longer, promotes longer feeling of satiety.
Are they toxic? From what? What are the most toxic?
Toxicity of excess fat soluble vitamins due to inablility to excrete or burn. Most toxic are vitamins A and D).
What to antioxidants and fatty acid oxidation prevent?
Prevents PUFA from being oxidized at double bonds by being preferentially oxidized instead, BAT and butylated hydroxytolune (BHT) but will also protect vitamens A and E as well.
Is dietary fat invisible?
Most is. It's already present in foods or is added by the cooking method.
Are cholesterol adds misleading?
Yes, any animal or fish or anything coming from these sources will have cholesterol unless it is specifically removed. Foods of plant origion will not.
Food labeling problmes?
Deception and the presence of water, Based on perweight not calories. You pay more for items, because most is considered water.
In the fluid component of the blood, soluble ____ increasse the solubility of insoluble cholesterol, long chain FA, PL, and TG.
Where do Chylomicrons come from and what are they made of?
From intestine and made up mostly of triglycerides.
Where do Chylomicrons travel?
To the left sublavian vein via the lacteals.
Function of Chylomicrons?
They carry dietary fat to the rest of the body, including storage in adipose tissue.
What happens to Chylomicrons as TG are lost.
It is converted to a chylomicron remnant which may be an important particle in the promotion of heart disease. Remnant can be deposited in the wall of the artery.
Typically, what happens to the chylomicron remnant?
It is taken up and repackaged by the liver and sent back out in the form of a VLDL (very low density lipoprotein.
What can be said about VLDL
Mostly from liver, some can be synthesized in intestine.
Mostly TG that was delivered from an excess of CHO or protein calories.
Also made up of fat returned to the liver from a VLDL remnant particle knwon as an: Intermediate Density Liproprotein
What can be said about Intermediate Density Lipoprotein (IDL).
Not seen unless there is a defect in metabolism.
Very rapidly cleared by the liver (95%)
By continuing to lose fat, those that remain in circulation are metabolized to a (LDL)
Low Density Lipoprotein (LDL)
Come from a VLDL via an IDL that has lost the majority of its TG and thus is high in cholesterl.
Take cholesterol and TG to tissue.
The problem lipoproteins as they are deposited in the lining of our arteries and result in CVD.
What is a transporter to the Liver?
High Density Lipoproteins (HDL)
What are HDLS
Sent out by the liver to return cholesterol to the liver--Is referred to as Reverse cholesterol transport.
HDLs? Initial studies suggest?
That they are synthesized in the intestine. However, data indicates that they are dynamic particles and are always in ta state of flux, as are other lipoproteins.
What is the protein component of the lipoprotein?
Apoproteins, and these are exchanged with other particles to give the appearance that they are derived from the intestine.
4 alternative forms of "isoforms"?
1. Disc shaped: comes from liver with TG and cholesterol to be returned.
2. Sphere shaped: filled w/ TG and cholesterol to be returned to the liver
3. Egg or ellipse shaped: an intermediate between 1 and 2
4: egg or ellipse shaped - the result of when 2 has released contents similar to 3.
HDLs transport cholesterol, PL, and lipids to where?
In blood: water soluble lipids are ______?
Not truly free or soluble. they are associated with a carrier.
In blood, free-short and medium-chain fatty acidss are ______ than long chain fatty acids
Ferformed PL and FFA...
Both usually carried conjugated to ALBUMIN
back to the liver, used in glucose synthesis (gluconeogenisis). Is often the goal molecule, as in the case with diabetes, and fats may either be a side effect or a problem.
Distribution of Fat?
White adipose tissue and adipocytes
Where is subcutaneous fat more unsaturated?
near the skin
Deep fat is more saturated. What keeps it soft?
Brwon fat is known as what? It is involved with ______ but may only be found during _____. Location>
Brown adipose tissue (BAT). thermoregulation; infancy. Scapular location.
White adipose tissue that is metabolically active. ONly increased by exercise.
Rancidity of food is often a result of what?
Bacterially induced oxixdation of PUFA> For this reason, it is important to add antioxidants.
High temperature cooking in olis. Do they breakdown with repeated use at a fast food join tin the fryer?
Doesn't promote oxidation
Trans Fatty Acids? Problem?
Yes, Hydrogenation of PUFA and the creation of abnormal fatty acids -- is carcinogenic and atherogenic. They block blood vessels.
Coronary Heart disease?
Look at page 91 for statistics.
Recommendations for fat?
Reduce fat to 25-30% of calories with sat and trans fat combined at <10% of calories.
Increase PUFA to 33% of fat, 10% of calories
Increase complex CHO intake, including fibers.
Continued Recommendations for fat.
15-20% of calories as protein.
No more than 150 mg cholesterol/day or 300 mg/day according to AMA.
To get 150 mg cholesterol?
three-fourths of an egg
less than five cups of milk
2 1/2 ounces butter
5 ounces cheddar cheese (1/3 lb)
Decrease trans fatty acid intake - high trans fatty acids can increase LDL and lower HDL. to do so, decrease partially hydrogenated vegetable oil intake. Also, increase fish consumption to two times/week :can lower plasma TG and lower platelet aggregation, decrease likelihood of stroke.
Other examples of how to lower cholesterol.
Different locations of fatty streak or plaque development?
Brain: Occluded artery -> stroke
Heart: Occluded vessels -> myocardial infraction
Rest of Body: CVD or peripheral vascular disease.
Is lowering cholestero the sole answer?
Ways to increase HDL and lower LDL
Exercise, decrease sat and trans fat consumption, loose wiehgt, increase fiber and fish intake, reasonable coffee intake, medication, regular/balanced meals, avoid smoking, increase alcohol (small), increase CHO intake, estrogen in women, Drugs:
Fat and Cancer?
Second highest US killer.
close to $100 billion /year
excess calories from fat with trans being the workst.
Cancer types that may be induced by fat or excess fat intake?
breast, prostate, uterus, colon, rectum, pancreas, liver
how many people die from breast cancer each year? Reducing fat calories from ___ to _____ would reduce deaths by _____?
41% (38 is current); 25%; 25%
Inducers or promoters of cancer?
Sat and trans fat.
promoters of immune supression?
excessive n6 PUFA--to follow in the Eicosanoids- specifically PGE2)
Does fiber reduce cancer?
Yes in all cases it somewhat does.
n3 PUFA intake is potentially the most effective means of reducing the incidence of cancers, although many minerals and some vitamens may be more as importnat.
n3 Pufa induce their benefit through emlimanation or reductions in the immunosupressive agents mentioned in item 6.
Is Dietary cholesterol necessary?
what is the #1 oil for ingestion? #2? #3?
Olive oil, canola oil, peanut oil.
Read over page 99
read over page 99
What are Eicosanoids?
Hormone-like compounds that play many regulatory roles in the body including the formation of blood clots, altering blood pressure and blood lipids, immune responses, and the inflammatory response to injury and infection.
made by the cyclooxygenase pathway. THis enzyme is inhibited by aspirin and is what you are attempting to do when you take aspirin for a headache, athritis, to decrease the possiblity of a stroke or disorder.
Made via the Lipoxygenase pathway-no inhibitors, but can be inhibited in lab. Process occurs as an agonist induces membrane to release AA or EPA bound on phospholipid. AA or EPa then goes to one of the pathways depending on type of stimulus.
Read over page 103
Read over page 103
Balance n3 and n6 PUFA in diet to get a "balanced" production of eicosanoids.