Chapter 6: Fats

Question 1

Fat

Answer 1

nutrition: fats are energy-containing nutrients found in food
medicine: fats are known as lipids, large fat-containing components in the blood
physiology: a fat is a long chain of carbon molecules
adipose tissue: the body’s long-term storage site for fats

Question 2

Importance of fat

Answer 2

important energy source at rest and during exercise
fat from diet provides the essential fatty acids that the body cannot manufacture and is needed for the absorption of the fat-soluble vitamins (A, D, E, K)
fats in foods helps satisfy hunger
most concentrated form of energy
containing 9 kcal/g
fat intake needs to be relative to CHO and protein intakes

Question 3

Different types of fats

Answer 3

fats vary in their chemical composition
lipids include 3 different classes of fat
1) triglycerides: three fatty acids attached to a glycerol molecule (95T% of fat in body)
2) sterols
3) phospholipids: phosphate containing fats; found in food and in the body

Question 4

Differences in fatty acids

Answer 4

due to chemical composition
saturated fatty acids, unsaturated fatty acids

Question 5

Saturated fatty acids

Answer 5

fat that is solid at room temperature
no double bonds between carbon atoms
saturated with hydrogen atoms
mainly found in animal foods
a few plant foods such as coconut, coconut oil, palm oil, and palm kernel oil

Question 6

Unsaturated fatty acids

Answer 6

fat that is liquid at room temperature
have one or more double bonds between carbon atoms
monounsaturated (one double bonds) - olive, peanut, and canola oils, avocados, almonds, hazelnuts, and pecans, pumpkin, and sesame seeds
polyunsaturated (multiple double bonds) - sunflower, corn, soybean, and flaxseed oils, walnuts, flaxseeds, fish, canola oil
hydrogenated fats
omega 3, 6, 9

Question 7

Hydrogenated fats

Answer 7

are made through a process to make liquid oils more solid and to increase shelf life of the product
produces trans fat
trans fat associated with an increased risk for cardiovascular disease and type 2 diabetes, increases bad cholesterol (LDL) and reduced good cholesterol, increases in insulin resistance
there are some naturally occurring trans fat found in beef, lamb, dairy products that may have some healthy benefits

Question 8

Trans vs cis formation

Answer 8

trans formation of atoms results in atoms being on opposite sides of the double bond which allows for the trans fats to stack on top of each other and can build up into plaque in blood vessels
cis formation of atoms results in atoms being on same side of double bond allowing the fatty acid to bend and no stacking occurs

Question 9

Omega 3, 6, 9

Answer 9

polyunsaturated fatty acids that have double bond between carbons at certain locations

Question 10

Formation of fats in foods

Answer 10

in form of triglycerides
nearly 95% of all fat consumed in the diet
triglyceride is composed of four parts (3 fatty acids attached to a glycerol
individual fatty acids that make up a triglyceride influence the temperature at which fat will melt
foods are grouped based on the predominant fatty acids

Question 11

Two essential fatty acids

Answer 11

widely found in food
linoleic = omega 6 fatty acids is in many vegetable oils such as corn, soy, safflower, and sunflower oils
alpha-linoleic = omega 3 family found in soy, canola, and flaxseed as well as leafy green vegetables, fatty fish, and fish oils
important because body cannot make them
omega 3 fatty acids = positive effects on immune and inflammation responses
omega 6 fatty acids = opposite effects
ratio between omega 6 to omega 3 fatty acids ration should be about 4:1 or less (western diet is 15:1)

Question 12

Omega 3 fatty acids and recovery from strenuous exercise

Answer 12

1.5 hours or more of moderate to high intensity exercise (55-75% of VO2 max)
experience an increase in many of the compounds associated with inflammation - normal response to skeletal muscle injury and acute inflammation that occurs with exercise; increase in body’s anti-inflammatory compounds
goal for athlete is to have proper balance between inflammatory and anti-inflammatory compounds
trained athletes may not benefit from omega 3 supplementation because their anti-inflammatory responses may already be enhanced sufficiently as a natural response to their training
greatest benefit may be to those who have certain diseases or those who are untrained

Question 13

Sterols and phospholipids

Answer 13

5% of fat found in foods
most common sterol found in food is cholesterol
cholesterol found only in animal foods such as meat, egg yolks in which the fat has not been removed
important component of cell membranes
phospholipids are structural component of all living tissues

Question 14

Healthy fats

Answer 14

lower risk of CV disease
unsaturated fatty acids and omega 3 fatty acids

Question 15

Unhealthy fats

Answer 15

saturated fatty acids
limit to less than 10% of the diet

Question 16

Fat intake for athletes

Answer 16

appropriate amount will depends on overall energy need and macronutrient balance

Question 17

What is the challenge of fat digestion and absorption?

Answer 17

relatively large molecules
do not mix well with water which means transport in blood requires most fat to be bound to protein

Question 18

Digestion

Answer 18

begins in the mouth and continues in stomach, but most occurs in small intestine
undigested fat in the stomach delays the emptying of the stomach contents and results in a feeling of fullness
athletes may limit their fat intake temporarily in certain situations when they do not want gastric emptying delayed
athletes may include fat containing foods when they want to avoid feeling hungry for several hours
fats are exposed to bile salts and digestive enzymes before they cross the membranes of the intestinal cells (because don’t mix well with water)
triglycerides are broken down by enzymes to diglycerides, monoglycerides, and free fatty acids; digestion reduces the size of the fat particles and readies them for absorption by the mucosal cells of the intestine
digestion of phospholipids is similar process as triglycerides but with different enzymes
sterols are not broken down at this point

Question 19

Bile salts

Answer 19

part of bile
emulsifier to help breakdown fats

Question 20

Pancreatic lipase

Answer 20

secreted by pancreas into the small intestine and helps break down the large fatty acids into smaller components
is used once the bile salts breakdown the fat molecule into many smaller molecules

Question 21

Absorption

Answer 21

once in mucosal cells, monglycerides are resynthesized into triglycerides
become part of chylomicron which is a lipoprotein (triglycerides, cholesterol and phospholipids become part of chylomicron)
lipoproteins transport fat throughout the body
chylomicrons are transported out of the mucosal cells of the intestine into the lymph system

Question 22

Transportation

Answer 22

body’s main transport fluids are blood and lymph
chylomicrons released slowly into lympathetic vessels
blood lipid levels are usually highest about 3 hours after fat consumption, but may take as long as 6 hours for the dietary fat to be transported into the blood (because too big to go into the bloodstream directly)
some fatty acids in mucosal cells are not incorporated into chylomicrons and are released right into the blood via portal veins, where each will be bound to plasma protein (albumin)
chylomicrons circulate through all the tissues
triglyceride portion of the chylomicron can be absorbed by adipose and muscle cells by lipoprotein lipase stimulating the release of the fatty acids from the triglyceride which are then rapidly absorbed by the fat and muscle cells (occurs when pass near muscle/adipose cell)
absorption into muscle cells occurs if needed in the muscle for energy
in the liver, triglyceride portion of chylomicron is broken down and becomes part of the fatty acid pool
cholesterol portion of the chylomicron remains and is transported to the liver to be processed

Question 23

Difference between blood and lymph

Answer 23

blood consists of water, red and white blood cells, and many other constituents like oxygen and nutrients
some components of blood are filtered out of the capillaries into the spaces of the tissue known as interstitial fluid
most this fluid is returned to capillaries but the amount that is not returned is referred to as lymph
lymph consists of white blood cells, proteins, fats, and other compounds and it moves through its own set of vessels that are separate from capillaries
eventually lymph and blood vessels are joined near the heart

Question 24

Storage

Answer 24

stored in body largely in the form of triglycerides in adipose tissue, liver, muscle, and small amount in the blood
chylomicron flows through blood stream after they go through lympathetic vessels
capillaries near fat cells have lipoprotein lipase in their walls
when activated the triglycerides in the chylomicron are broken into monoglycerol and fatty acids
monoglycerides and fatty acids pass into the fat cells and then are reformed into triglycerides
activity of LPL and the process of triglyceride formation are primarily stimulated by insulin
pancreas secretes insulin in response to food consumption - in hours after a meal, the body has the hormonal environment and the substrates that favour triglyceride formation and fat storage
muscle can also store fate (intramuscular triglycerides) - occurs primarily in muscle that is highly aerobic; same process with adipocytes
fats are very energy dense vs CHO or proteins - every gram of glycogen stores 2g of water (increases weight without increasing energy content

Question 25

Metabolism

Answer 25

in order to metabolized, fats must be removed from storage, transported to cells, and taken up into mitochondria to be oxidized

Question 26

Esterification

Answer 26

process of triglyceride formation