Lecture 4 Flashcards
1
Q
What are the fat soluble vitamins?
A
A, D, E and K
2
Q
What is fat made up of, as are carbohydrates and protein?
A
C, H, and O
3
Q
Define lipids
A
A family of organic compounds that are not soluble in water.
4
Q
What are the three categories of lipids?
A
Triglycerides (fats and oils)
Phospholipids (e.g., lecithin)
Sterols (e.g., cholesterol)
5
Q
Which category makes up 95% of all lipids in foods & the human body?
A
Triglycerides
6
Q
Triglycerides are made up of fats and oils. Define these two
A
Fats: lipids that are solid at room temperature
Oils: lipids that are liquid at room temperature
7
Q
What are the functions of fat?
A
- Body’s chief storage form for excess food energy (glycogen is very bulky – way too much water, whereas fat is very energy-dense, so in a small weight can store lots of energy)
- Provides much of the energy needed for the body’s work (energy when a person becomes ill & stops eating)
8
Q
Only limited fat storage is possible for most body cells. But, what are the cells specialized for fat storage called?
A
Adipose cells
9
Q
How is adipose tissue active?
A
Secretes hormones and produces enzymes that influence food intake & affect the body’s use of nutrients
10
Q
What are some other functions of fat?
A
- Shock absorbers (pads of fat surround vital internal organs)
- Thermoregulation (fat pads under the skin insulate the body from temperature extremes)
- Cell membranes (lipids are a component of cell membranes)
11
Q
Fat-soluble vitamins are found mainly in what types of foods?
A
Foods that contain fat
12
Q
Why do people naturally like high-fat foods?
A
- Fats carry many compounds that give foods pleasant aromas and flavours
- Fat makes meat and baked good tender
13
Q
Fat contributes to satiety. What is that?
A
Feeling of fullness or satisfaction that people experience after meals.
The fat in the food triggers a series of physiological events that slow the emptying of the stomach & promote satiety.
14
Q
How does fat contribute to the feeling of fullness and satisfaction?
A
Fat in the small intestine signals release of CCK (aids in digestion and reduces appetite)
15
Q
What are triglycerides made up of?
A
3 fatty acids + glycerol
16
Q
What are fatty acids?
A
Organic acids composed of carbon chains of various lengths. Each has an acid end & hydrogens attached to all of the carbon atoms of the chain. Differ on the basis of length & degree of saturation.
17
Q
What is the backbone for triglycerides?
A
Glycerol
18
Q
How does the degree of saturation relate to a food’s solidity?
A
Affects melting temperature:
- The more saturated, the more solid at room temperature
- The more unsaturated, the more liquid at room temperature
19
Q
Fatty acid chains of what length are most common in the diet? And where are they found?
A
Long chain fatty acids (12 to 24 carbons)
Found in meat , seafood, and vegetable oils
20
Q
Medium chain fatty acids are of what length? Where are they found mainly?
A
6 to 10 carbons
Short (less than 6)
Found in mainly dairy products
21
Q
How is the length of carbon chains associated with the firmness of fats?
A
Lower carbon chain length leads to lower firmness
22
Q
What are the health recommendations related to firmness of fats?
A
Limit saturated fats and limit/avoid trans fats
Using monounsaturated fats or polyunsaturated fats instead
23
Q
Where do you find fats that are rich in polyunsaturated fatty acids?
A
Safflower, sunflower, corn oil
24
Q
OIive oil is rich in what?
A
Polyunsaturated fatty acids
25
Which types of fats are generally the most saturated?
Animal fats and tropical fats
Fatty meats: Over 1/3 of the fat in most meats is saturated
Whole-milk products: Over 1/2 of the fat in whole milk & other high-fat dairy products, is saturated
Coconut & palm oils: Mostly used in commercially prepared foods
26
Evidence from Mediterranean regions suggests olive oil offers what?
A degree of protection against heart disease when it is used in place of other fats
Dark-coloured olive oils deliver more phytochemicals
27
What can be said about canola oil?
It is rich in both monounsaturated & polyunsaturated fatty acids
It is lowest in saturated fat
28
What is hydrogenation?
A chemical process by which hydrogens are added to monounsaturated or polyunsaturated fatty acids to reduce the number of double bonds, making the fats more saturated (solid) and more resistant to oxidation
29
How are trans fats formed?
A polyunsaturated fat is rarely hydrogenated completely during processing. Fat is generally partially hydrogenated, so double bonds remain
These double bonds change from the cis to the trans formation
No longer allowed to add partially hydrogenated food to our diets in Canada due to the negative effects on health
30
A small amount of trans fats are found naturally in what?
Milk and meat products
31
What are the advantages of hydrogenation (3)?
- Protects against oxidation by making polyunsaturated fats more saturated. Commerical benefit: longer shelf life
- Alters the texture of food by making liquid vegetable oils more solid. Commercial benefit: improved food texture (shortening -- flaky pie crust, spreadable margarine, creamy pudding)
- Hydrogenated oil has a higher smoke point -- more stable in high cooking temperatures
32
What are phospholipids made up of? And what can be said about its solubility?
2 fatty acids + glycerol + a phosphorus-containing molecule.
Fatty acid is soluble in fat and phosphorus is soluble in water
33
Phospholipids are emulsifiers. What does that mean?
It is a substance that mixes with both fat & water & disperses the fat in the water, forming an emulsion
34
What key roles do phospholipids play?
- In the structure of cell membranes
- Phospholipids help fats travel back & forth across the lipid-containing membranes of cells into the watery fluids on both sides.
35
What is a common phospholipid and where can you find it?
Lecithin
Eggs & peanuts
36
What are sterols made of?
Large molecules consisting of interconnected rings of carbon atoms with side chains of carbon, hydrogen & oxygen
37
Sterols are present in foods derived from both plants and animals. What are the two categories of sterols?
Cholesterol (only food derived from anumals contain significant amounts of cholesterol)
Phytosterols (plant sterols that have structural similarities to cholesterol, lower blood cholesterol by competing with cholesterol for absorption).
38
Cholesterol (a sterol) serves as the precursor for making what?
Bile, which is an emulsifier made by the liver & stored in the gallbladder.
39
Does bile digest fats?
No. Enzymes do. It emulsified fats allowing contact with enzymes in watery fluids to split the fatty acids from the glycerol backbone for absorption.
40
What else are sterols?
Vitamin D and sex hormones (e.g., estrogen and progesterone)
41
What are some characteristics of cholesterol?
- Component of cell membranes
- Can be made by the body (not essential, manufactured in the liver, the body generally makes more cholesterol than what is eaten)
- Forms a major part of the plaques that narrow arteries in atherosclerosis
42
How does cholesterol lead to plaque which is often the cause of heart attacks and strokes?
Either narrow it down until they completely block off the artery, or for a stroke, a piece of this plaque may break off and travel throughout the blood vessels until it reaches a small blood vessel in the brain & blocks it off
43
How are fats digested in the mouth?
Lingual lipase produced by the tongue acts on triglycerides with short and medium chain fatty acids (plays a major role in infants, little importance to digestion in adults)
44
How are fats digested in the stomach?
Strong and muscular -- mix fat with other stomach contents.
Churning grinds the solid pieces into finer particles, and disperses the fat into small droplets
Gastric lipase begins to break down triglycerides. Works best in the acidic environment of the stomach.
45
How are fats digested in the small intestine?
When fat enters the small intestine, bile is secreted (in response to CCK)
Bile emulsifies fat particles -- mixing them with watery fluid for contact with enzymes for digestion
Then the emulsified fat particles are acted on by fat-digesting enzymes secreted by the pancreas.
46
What happens if someone's gallbladder has been removed?
Liver still produces bile -- small continuous amount in small intestine
They can no longer store bile & release it at mealtime
47
What is a diet recommendation for those whose gallbladder has been removed?
Follow a low-fat diet to start. Then, instead of having a large amount of bile that the gallbladder can release at once, the liver delivers a trickle. Generally, the body does react.
Otherwise, they will have fatty diarrhea — fats undigested because the body cannot digest them w the enzymes in the bile.
48
What do the enzymes do to the fat particles in the small intestine?
Triglycerides are split into monoglycerides, free fatty acids and sometimes glycerol.
These cling together in spheres surrounded by bile
49
How do the cells extract the lipids?
Bile shuttles the lipids across the mucus layer to the absorptive cells of the intestinal villi.
The bile may be absorbed and reused or exit with the feces
50
How much of the triglycerides from a meal are absorbed? (percentage)
Up to 98%
51
What happens to glycerol, short and medium chain fatty acids after the small intestine?
Pass directly through the cells of the intestinal lining into the bloodstream and onto the liver
52
What happens to the larger products of lipid digestion after the small intestine?
Inside the intestinal cells, monoglycerides and long-chain fatty acids are reformed into triglycerides and clustered together with proteins & phospholipids
53
These larger products of lipid digestion are formed into what?
Chylomicrons (a type of lipoprotein -- largest and least dense of the lipoproteins)
They travel in the lymph to the bloodstream. Then, body tissues take triglycerides from the chylomicrons in the bloodstream.
54
What are lipoproteins and what is their function?
Clusters of lipids associated with protein.
Serve as transport vehicles for lipids in lymph and blood (without a mechanism to keep it dispersed, large lipid globules would separate out of the watery blood & disrupt the blood's normal function
55
What are the major lipoproteins?
- Chylomicrons
- Very low-density lipoproteins (VLDL)
- Low-density lipoproteins (LDL)
- High-density lipoproteins (HDL)
56
What are VLDLs/what is their function?
Carry triglycerides and other lipids made in the liver to body cells for their use
Not even typically measured (usually turn into LDLs)
57
What are LDLs/what is their function?
"Bad cholesterol" -- really talking about the vehicle that contains cholesterol. Want it to be LOW.
Transport cholesterol & other lipids from the liver to body tissues
Made from VLDL after they have donated many of their triglycerides to body cells
Elevated LDL cholesterol is associated with increased heart disease risk
58
What are HDLs/what is their role?
"Good cholesterol"
Want it to be HIGH
Carry cholesterol from body cells to the liver for disposal.
Really referring to a transport vehicle. This one is going around the blood vessels, picking up the cholesterol, and taking it back to the liver for disposal.
59
High intakes of certain dietary fats are associated with disease. What are these?
Diets high in trans and saturated fats are associated with increased risk of heart disease (CVD) & sometimes cancer.
High energy density foods may increase likelihood of exceeding energy needs, and obesity carries serious risks to health.
60
Describe the structure of LDL and HDL
LDL: larger, lighter & richer in cholesterol than HDL
HDL: smaller, denser & packaged in more protein than LDL
61
What is an important differentiation to make when discussing heart disease risk and cholesterol?
Heart disease risk is related to the proportions of lipids the lipoproteins contain & the tasks they perform, NOT the type of cholesterol they carry (cholesterol is cholesterol)
61
What are some risk factors that cannot be controlled for heart disease risk?
Increasing age
Being male
Family history of premature heart disease
62
What are some risk factors that a person can often control?
High blood LDL; low blood HDL
High blood pressure
Diabetes
Obesity
Physical inactivity
Cigarette smoking
Atherogenic diet – increased trans fats, low in veg and fruit etc.
63
Which raises blood LDL cholesterol more? Cholesterol in food, or something else?
Most saturated food fats & trans fats raise blood LDL cholesterol more than food cholesterol does.
64
What are some foods with high sources of cholesterol?
Eggs, liver, and shellfish
Have other benefits, though, so eat in moderation.
65
How can one lower LDL cholesterol?
Reduce trans fats and saturated fats (replace with mon and polyunsaturated fat; trim fat off foods to reduce sat fat; etc.)
Weight loss
Addition of soluble fibre
66
LDL is susceptible to damage by oxidation. What is that and why is that bad?
Interaction of a compound with oxygen
Evidence indicates that oxidation of the lipid part of the LDL can be damaging to the arteries of the heart
67
What can slow LDL oxidation?
Dietary antioxidants like vitamins C & E, selenium, antioxidant phytochemicals
68
How can you raise HDL cholesterol?
Dietary measures are generally ineffective but trans fat can lower HDL and saturated fat can raise HDL
Physical activity can raise HDL
Quitting smoking can raise HDL
69
What can be said about the link between phytosterols and cholesterol?
"Help reduce cholesterol" is allowed on food labels in Canada as it can lower cholesterol levels by up to 15%
Maximum effects are observed at phytosterol intakes of approx. 2 grams per day
70
How can body fat be used up for energy?
Decreasing intake of food energy
Increasing the body's expenditure of energy
71
What are the only fatty acids that cannot be synthesized by the body, are essential nutrients, and are polyunsaturated fatty acids and used by the body to make eicosanoids.
Linoleic acid and linolenic acid
72
What are eicosanoids?
Biologically active compounds that regulate body functions like:
- Muscle relaxation and contraction
- Blood vessel dilation & constriction
- Blood clot formation, blood lipids
- Response to injury & infection
73
What other functions do linoleic acid and linolenic acid have?
Structural and functional parts of cell membranes
Contribute lipids to brain and nerves
Promote normal growth and vision
Support immune cell functions
74
What are the symptoms of a fatty acid deficiency?
Rare in NA -- usually occurring only in infants fed fat-free milk or following a very low-fat diet
- Growth delay
- Reproductive failure
- Skin lesions
- Kidney and liver disorders
- Neurological and vision problems
75
Name a major omega-6 fatty acid and describe what that means.
Linoleic
It is a polyunsaturated fatty acid with its first double bond 6 carbons from the end
76
Linoleic acid can be used to produce other omega-6 fatty acids. What is the starting material from which a number of eicosanoids are made?
Arachidonic acid
77
Foods high in omega-6 fatty acids should be consumed in moderation. What are some of these foods?
Most vegetable oils (ex. corn, sunflower, safflower, soybean)
78
Name a major omega-3 fatty acid and describe what that means.
Linolenic acid
A polyunsaturated fatty acid with its double bond 3 carbons from the end.
79
What are some sources of linolenic acid?
Flaxseed oil. Canola oil and walnut oil contain less but are still good sources.
80
The body makes limited amounts of EPA and DHA. How can we get enough of them?
Abundant in fish oils, cold water fish
A diet that includes 2 meals of fatty fish each week can reduce deaths & illness from heart disease.
81
Excessive amounts of either omega-3 or omega-6 fatty acids can interfere with normal functions that depend on a proper balance between the two. Why?
Making the other members of the omega-3 family is in competition with the omega-6, since if there is more 6, they monopolize the enzymes (similar structure) and the 3s cannot build.
82
What are the recommendations to maintain the omega 3 and 6 balance?
Consume sources of Omega-6 in moderation and try increase sources of Omega-3 (ie fatty fish 2 or 3 meals/week)
Consume a variety of fish
- Minimizes exposure to any particular toxin that may accumulate in a particular fish species
- High-mercury fish include tilefish, swordfish, king mackerel, marlin, shark & fresh tuna
- Pregnant women & children are most sensitive to the side effects of mercury
83
What are some sources of fat in the diet?
Meat
Dairy products contain fat which is often removed to various degrees (%m.f.)
Grains sometimes contain fat
Most unprocessed vegetables and fruits are fat-free, except avocados and olives (rich in monunsaturated fat)
84
What are some invisible fats in the diet?
Marbling of meat
Fat ground into lunch meats & hamburger
Fats blended into sauces of mixed dishes
Fats in avocados, biscuits, cheese, coconuts, other nuts, olives & fried foods.
85
What can be said about fats in coconut oil?
Coconut oil are higher in saturated fatty acids than the butterfat in fatty dairy products
86
Should one consume butter or margarine?
Hardened margarines & shortenings are made largely from hydrogenated fats
are saturated & contain substantial trans fatty acids
Soft margarines – “non-hydrogenated”
Are less likely to elevate blood cholesterol than the saturated fats of butter
Some margarines contain an added phytosterols- compete with cholesterol for absorption
Some saturated fat in the diet is ok - some people more comfortable with butter
Bottom line: No answer in isolation — really is about the overall picture — how much mf is consumed from other sources (meat, cheese, milk fat, etc.)
87
What can fat replacers include?
- Carbohydrates: fruit purees or strachers. Sugars: provide calories but fewer than real fats
- Fibres: viscous fibres may provide texture similar to real fat
- Proteins: microparticulated protein or fermented whey. Provide calories, but fewer than real fats.
88
What is artificial fat?
Zero energy fat replacers that are chemically synthesized to mimic the sensory and cooking qualities of natural fats but are totally or partially resistant to digestion.
89
One should focus on total fat reduction since this would also reduce saturated fat. What are some problems that can accompany low-fat diets?
- Difficult to maintain
- Not necessarily low-calorie diets
- Diets high in carbohydrates, especially refined sugars, but low in fibre, cause blood triglycerides to rise
- May exclude nutritious foods that provide the essential fatty acids, phytochemicals, vitamins & minerals (Fatty fish, nuts, seeds, vegetable oil)
90
Who are the most vulnerable to foodborne illnesses?
Pregnant women, infants and children under 5, individuals 60 and over and those with a weakened immune system
91
What are the most common symptoms for foodborne illnesses?
- Stomach cramps
- Nausea
- Vomiting
- Diarrhea
- Fever
- Death in severe cases
92
How long can things be at room temperature?
2 hours
93
How high should cooking temperature be for beef?
74
94
How should food be stored in the fridge?
Vegetables above meat
95
How should items be cooled in the fridge?
Never in the whole pot -- takes too long for middle to get out of danger zone
96
What is the important information to know for Hepatitis A?
Infection
Food sources: undercooked or raw shellfish, contaminated produce, contaminated water and ice. Eating foods prepared by an infected person
Symptoms: after 2-4 weeks, up to 7 weeks. Fever and jaundice
If contracted by pregnant women in their 2nd or 3rd trimester there is an increased risk of preterm labour and other pregnancy complications.
Prevention: cook food thoroughly, avoid untreated water and ice cubes, avoid non-peelable fruits and vegetables
97
What two main ways can microbes cause foodborne illness?
Foodborne infection (caused by eating foods contaminated with infectious microbes)
Food intoxications (caused by eating foods containing natural toxins, or microbes that produce toxins)
98
What is the important information to know for Listeriosis?
Infection
Illness from bacteria that live in the intestines of animals and humans as well as soil, vegetation and water
Food sources: unpasteurized milk, fresh soft cheeses, luncheon meat/hot dogs/pâté, raw/undercooked meat
Symptoms: 3 to 70 days. Flu. Blood poisoning and can spread to nervous system; can cause miscarriages and illness or death of newborns
Prevention: use sanitary food handling methods, cook foods thoroughly, use pasteurized milk
99
What is the important information to know for Salmonellosis?
Infection
Food sources: raw or undercooked eggs, raw or undercooked meat (especially poultry), unpasteurized dairy products, raw produce (sprouts and cantaloupe)
Symptoms: 1-3 days
Prevention: use sanitary food handling methods, cook foods thoroughly
100
What is the important information to know for E Coli?
Infection
A bacteria found in human and animal intestines
Food sources: undercooked ground beef, unpasteurized milk and milk products, contaminated water, and person-to-person contact
Symptoms: 1 to 10 days. Bloody diarrhea, acute kidney failure. Can be fatal
Prevention: Cook ground beef thoroughly (71C), avoid unpasteurized milk and milk products, use sanitary food handling methods, wash hands after contact with animals
101
What is botulism?
Intoxication
Clostridium botulinum bacterium produces the botulinum toxin called botulin.
Food sources: improperly prepared low-acid, home-canned foods (like asparagus, beets, green beans, mushrooms, peppers), improperly smoked fish, improperly canned meats, non-refrigerated storage of low-acid fruit juices (carrot juice), Honey - infants
Symptoms: 12 to 72 hours. Nervous system symptoms include double vision, inability to swallow, speech difficulty, progressive paralysis of the respiratory system, often leaves prolonged symptoms in survivors
Prevention: proper canning methods for low acid foods, refrigerate homemade garlic and herb oils, avoid bent; broken or bulging cans.
102
What is the important information to know for Staphylococcal food poisoning?
Most common food intoxication
Commonly found on the skin and nasal passages. Concentrated in skin wounds, acne and boils. Can become contaminated from moisture drops expelled (breathing, sneezing or coughing) or touching blemishes then foods or touching foods with cut hands.
Symptoms: 1-8 hours
Food sources: toxin produced in improperly refrigerated meat, poultry, egg products, tuna and macaroni salads, cream filled pastries
Prevention: use sanitary food handling methods, cook food thoroughly, refrigerate foods promptly and properly
103
What is the important information to know about vibrosis?
Infection
Symptoms: 24 hours. Moderate illness (vibrio parahaemolyticus) or a bit more severe (vibrio vulnificus)
Raw oysters
Don’t need to know the difference between the two bacteria, just need to know the general idea. An illness that tends to come from improperly cooked seafood — associated with oysters right now.
Prevention: cooking shellfish, especially oysters thoroughly before eating, keeping raw and cooked shellfish separate, keeping all seafood, both raw and cooked, refrigerated
104
What are the 4 keys to preventing foodborne illness?
Clean
Separate
Chill
Cook
105
What does clean entail?
Handwashing
Sanitizing (boards, discarding worn ones)
Washing (raw fruits and vegetables, lunch boxes, grocery bags)
106
What does chill entail?
Keep bacteria out of danger zone (4-60C); refrigeration slows bacterial growth (0-4C); freezing at or below -18C can stop bacterial growth but it does not kill it.
Thaw in fridge or microwave, never at room temperature. If thawing in water, replace cold water every 30 minuutes
Refrigerate or freeze foods within 2 hours
Marinate meat and fish in the fridge, not on the counter
107
What does separate entail?
Bacteria can be carried in raw meat juice, so store meat on bottom shelf of the fridge, use clean utensils for cooked/ready-to-eat food, keep raw food away from ready-to-eat food while shopping, storing, and preparing foods.
108
What does cook entail?
Cook foods to a safe internal temperature
Use a digital food thermometer to check
Keep hot food hot
109
How should one store leftovers?
Refrigerate immediately (within 2 hours)
Hot items: stir frequently to accelerate cooling, refrigerate when steaming stops, refrigerate or freeze leftovers in uncovered or loosely wrapped, shallow containers for faster cooling -- cover once cooled
Debone large pieces of meat or poultry and divide them into smaller portions before storing
Do not overcrowd refrigerator (circulation of cold air)
Date leftovers -- eat within 2-3 days
Always put leftovers in clean containers and never mix them with fresh food
110
How should one reheat leftovers?
Solid leftovers to at least 74C
Bring gravies, soups, and sauces to a full, rolling boil and stir during the process
Discard uneaten leftovers after they have been reheated
111
Which of the following is a source of omega 3?
- flaxseed oil
- walnut oil
- canola oil
- fish oil
- all of the above
all of the above
112
Which of the following is the largest and least dense of the lipoproteins and travels through the lymphatic system?
- Chylomicrons
- VLDL
- LDL
- HDL
- MDL (made up)
Chylomicrons
Long chain fatty acids & monoglycerides — when they enter intestinal cells, they cannot pass into the bloodstream. They are then joined to the chylomicrons and carried through the lymphatic system, due to their triglyceride content
113
Which of the following is true?
- Amino acids are joined together in a protein by condensation reactions
- Fish oils good source of omega 3s
- Olive oil is rich in monounsaturated fatty acids.
- a and c
- a, b, and c
a, b and c
114
Review quiz questions
