chapter 5 - lipids Flashcards
what are fats
lipids
greasy substances that arents soluble in water
solbue in some solvents like ether, benzene, chloroform
provide concentrated source of energy (9 cal per gram)
fat-rich foods are more expensive
composed of C, H, O w substantially less O
function of fats
functioning and structure of body tissues
cnecessaryt part of cell membranes (cell walls)
contain essential fatty acids and carriers for fat-solbuel vitmains A,D, E, and K
provides energy when one cant eat
adipose tissue protects organs and bones from injury by serving as protective padding and support
body fat also = insulations
fats = satiety after meal bc flavor and slow rate of digest ion
what are food sources for fats
animal foods: red meats, higher fat poultry cuts w skin like thigh and wing, whole, low-fat and reduced fat milk, cream, butter, cheeses made with cream, egg yolks, fatty fish like tuna and salmon (sat fat can raise cholesterol)
plant foods: cooking oil from olives, sunflowers, safflower, seasme seeds, corn, peanuts, canola oil, soubygeans, margarine, salad dressing, or mayo, nuts, seeds, avocadoes, coconuts, and cocoa butter
deficiency of fat signs
eczema
weight loss
retarded growth
visible fats
fats that are purhcased and used as fats, such as butter, margarine, lard, and coking oils
invisible fats
found in other foods like meats, cream, whole milk, cheese, egg yoke, fried foods, pastries, avocadoes, and nuts
what percent of lipids in body are triglycerides
95
what are the lipids found in food and human body
triglycerides
phospholipids
sterols
what are triglycerides
three fatty acids attached to glycerol
glycerol s iwater-soluble carb - alcohol that has three carbon atoms
what are fatty acids
organic componds of carbon atoms to which hydrogen atoms are attached
essentail fatty acids
necessary fats humans cant synthesized
must be obtained through diets
long chained poly unsaturated fatty acids derived from linoleic acid and linolenic acid
typo families of EFAs
omega 3
omega 6hat
what about omega 9 fatty acids?
necessary but nonessential bc body can product modest amount of EFAs r present
what are another method of classification of fatty acids is by degree of situation w hydrogen atoms
saturated
monounsaturated
polyunsaturated
what are saturated fats
each fatty acid carbon atom carries all hydrogen atoms possible
animal foods have more saturated fatty acids than unsaturated
plant food chocolate, coconut, palm oil , and palm kernel oils have more saturated fatty acids
solid at room temp
no more than 10% of total daily cal should be unsaturated
AHA said less than 7% w 5-6% if lipids are high nd risk for heart disease
what are monounsaturated fats
one place among carbon where fewer hydrogen atoms
ex: olive oil, peanut oil, canola oil, avocadoes, cashew nuts
lower amount of LDL if replacing saturated fats
20% of tail cal should be monounsaturated fats
what are polyunsaturated fats
two or more places among carbon atoms w fewer hydrogen atoms then in saturated fats
point at which carbon-carbon double bonds occur in polyunsaturated fatty acid determine how body metabolizes it
two major fatty acids denote placement of double bonds are omega 3 and omega 6 fatty acids
usually soft or oil
less than 10% of total daily cal
what is omega 3
reported to lower risk of heart disease
found in fish oils so inc of fatty fish intake
what is omega 6
linoleic acid
cholesterol-lowering effect
use of supplements isn’t recommended
foods containing polyunsaturated fats
cooking oils made from sunflower safflower or seasem seeds or from corn or soybeans, for margarines whose major ingredient is liquid veg oil and fisdh
what are transfatty acids
produced when hydrogen atoms added to monounsaturated or polyunsaturated fats to produce semi-solid product like margarine and shortening
likely to contain high amt of TFA if partially hydrogenated vegetable oil is listed in first three ingredients on label
major source of TFAs are baked goods and foods eaten in restrauttnats
required to be on food label since 2006
inc LDLs and dec HDLs
inc risk of developing heart disease, stroke, and T2D
what are hydrogenated fats
polyunsaturated veg oil to which h has been added commercially to make them solid at room temp
called hydrogenation: turn polyunsaturated veg oils into sat fats (margarine; soft margarine has less sat fat then firm margarine)
what is cholesterol
sterol
not true fat byt fat-like substance in animal foods and body cells (doesn’t exist in plant foods
essential to synthesize bile, sex hormones, cortisone, vitamin D and thus necessary for every cell
body makes 800-1000 mg daily in liber
thought to be contributing factor in heart disease bc hypercholesterolemia is common in pt w atherosclerosis
blood levels shouldn’t be more than 200 mg/dL
Where is cholesterol found
egg yolk, fatty meats, shellfish, butter, cream, cheese, whole milk, organ meats
how to reduce serum cholesterol levels
reduce amt of total fat, sat fat, cholesterol and inc amt of monounsaturated fats, wt loss, and exercise
solble dietary fiber bc cholesterol binds to fiber and is eliminated, preventing absorption in small intestines
medication
____ of ingested fats are digest
95%
where does chemical digestion of fats occur
in small intestine where bile emulsified fats and pancreatic lipase reduce them to fatty acids and glycerol
not in mouth, slightly in stomach through gastric lipase acting on emulsified fats (like in cream and egg yolk)
what are lipoproteins
bile joins products of fat digestions and protein combines w final products of fat digestion to form lipoproteins which carry fat to body cells by way of the blood
classifications of lipoproteins
chylomicrons
very low desntiy lipoproteins (VLDLs)
LDLs
HDLs
what are chylomicrons
first lipoprotein identified after eating
largest and lightest
80-90% triglycerides
lipoprotein lipase breaks down triglycerides into free fatty acids and glycerol
The protein
and phospholipid exterior of a chylomicron enables the fat housed in the core of the chylomicron to travel in the water-based blood
what are very low density liporproteins
made primarily by liver cels and are 55-65% triglycerides
carry triglycerides and other lipids to all cells
as VLDLs lose triglycerides they pick up cholesterol from other lipoproteins and become LDLs - become more dense
what are LDLs
approx 45% cholesterol w few triglycerides
most of blood cholesterol from liver to cells
> 130 mg/dL of LDL contribute to atherosclerosis
bad cholesterol
what are HDLs
carry cholesterol from cell to liver for excretion
<40 mg/dL is dangerous
> 60 mg/dL is protective against heart disease
good cholesterol
inc w exercise, wt maintenance, and giving up smoking
liver role in fat metablism
hydrolyzes triglycerides and form new ones as needed
metabolism of fat occurs in cells (fatty acids r broken down to CO2 and water, releasing energy)
portion of fat not needed immediately stored as adipose tissue
CO2 and water are byproducts that are removed from body
how to determine if item is necessaty for health
not included in Recommended Dietary Allowance (RDA), Dietary reference intakes (DRIs), or Adequate Intake (AI)
what is lectin
fatty substance classified as phospholipid
found in both plant and animal foods
synthesized in liver
natural emulsifier that transports fat in bl;oodstream
used commercially to make food products smooth
while some health food salespersons promote lecithin can prevent CV disease this hasn’t been scientifically proven
olestra
olestra - made form sugar and fatty acids
approved by FDA for snack foods (potatoes chips, tortiall chips, and crackers)
gov require food labels indicate olestra inhibits absorption of some vitamin and other nutrients
fat-solbule vitamins A,D,E, and K have been added to foods containing olestra
has no cal but cause cramps and diarrhea
what is simplesse
fat alternative made from egg white or milk protein and contains 1.3 kcal/g
used only in cool foods like icre cream bc it becomes thick or gels when heated
not available for home use
what is oatrim
carb based and derived from oat fiber
heat stable and used in baking but not frying
manufactures have used carb based compounds for years as thickeners
provides cal but significantly less fat
concern among nutritionists about fat alternatives
used in place of nutritious foods that provide vitmains, minerals, proteins and carb
min amout of fat
no specific dietary requirements for fats is included in RDA and DRIS but deficiency symptoms if less than 10%
fat deficiency in infants and IV feedings
in inftants fed formula lacking essential fatty acid linoleic acid and in people on IV feedings lacking linoleic acid can develop eczema, growth retardation, and wt loss
what does excess fat lead to
obesity
heart diease
assocated w colon, breast, uterus, and prostate cancer
Food and Nutrition Board’s Committee on Diet and Health rec how much fat
30% of total cal
what does AHA rec about fat
7% sat fat
10% polyunsaturated fats
20% monounsaturated fats
according to mayo clinic what percent of cal in us dieet derived from solid fats and sugar
35%
Fatty acids can be saturated or unsaturated. Saturated fatty acids have no double bonds in their chemical structure. They have a full load of hydrogen atoms. An unsaturated fatty acid has at least one double bond between two carbon atoms in each molecule. If a double bond is broken, two hydrogen atoms can be added to the molecule. The number of double bonds and hydrogen atoms in the fatty acid chain determine the degree of saturation. A monounsaturated fatty acid has only one double bond between carbon atoms. A polyunsaturated fatty acid has two or more dou-ble bonds (Figure 7.2).
Hydrogenation
process of
breaking the double carbon bonds in an unsaturated fatty acid and adding hydro-gen
break liquid oils to solid fat
creates trans fat
rancid
describes a food oil in which the fatty acid molecules have combined with oxygen. This causes them to break down, and the oil spoils. Rancid oils have an unpleasant smell and taste.
Lecithin
is a phospholipid that is made by the liver, so it is not essential to the diet. Lecithin is also found in many foods of animal origin, including egg yolks. Lecithin, like other phospholipids, is an emulsifier. An emulsifier is a substance
that can mix with both water and fat. For example, egg yolk acts as an emulsifier in mayonnaise to prevent the oil and vinegar from separating. The lecithin in the egg yolk keeps the oil particles suspended in the watery vinegar. In the body, lecithin is part of cell membranes.
Phytosterols
compounds from plants that are similar in structure to cholesterol
include plant sterols and stanols
can only be obtained through dietary sources. They are naturally present in small quanti-ties in many fruits, vegetables, nuts, seeds, cereals, legumes, vegetable oils, and other plant sources
help lower LDL cholesterol levels and the risk for heart disease
About____ of adipose tissue is just under your skin.
half
The brain is nearly____ percent fat
60
ruminants
Trans fats occur naturally in food from ruminants (animals that chew cud) such as cows, sheep, and goats
