KIN 346 Module 2 Flashcards
Why are lipids important?
cell membranes, bile acids, vitamin D, eicosanoids, hormones, source of energy, temperature regulation, transport of fat soluble vitamins, lipoproteins, protection of internal organs, taste (moist and crumbly), good smells, energy
What are lipids composed of?
C, H, and O. High proportion of C and H compated to O = more energy dense than CHOs
What are the types of lipids?
fatty acids (mono, polunsaturated, saturated), triglycerides, phospholipids, sterols
Fatty acid?
AN organic acis that is a chain of C atoms with H atoms attached with an acid group (COOH) at one end and a methyl group (CH3) at the other
FAs are differentiated by?
Length of the C chain, degree of saturation, location of the double bonds
Most naturally occurring FAs contain…
even numbers of Cs in their chains (up to 24 Cs)
Long chain FAs?
12-24 Cs…most abundant in the diet from meats, fish, and vegetable oils
Medium chain FAs?
6-10 Cs and short chains (<6Cs)…less abdunant in diet and from dairy products
What are the most common FAs in the diet?
18 C, with stearic acid being the most common from meat
A saturated FAs carries the maximum number of…
H atoms (no double bonds)
Formula for stearic acid and where it is mostly found?
18:0, mostly in animal fats
A unsaturated acid includes…
a point of unsaturation (double bond) between >2Cs and less Hs
Notation for oleic acid and where it is mostly found?
18:1 n-9. Olive and canola oils
Notation for linoleic acid, and where it is found?
18:2 n-6. Sunflower, safflower, corn and soybean oils
What is the omega number?
Describes the location of the doulbe bond(s) from the omega/methyl end
Notaiton for linolenic acid, and where it is found?
18:3 n-3. Soybean and canola oils, flaxseed, walnuts
Are FFAs usually found in the diet or the body?
no…majority are incorporated into triglycerides
What are triglycerides?
Lipids composed of 3 FAs attached to a molecule of glycerol
How does FA structure affect the foods we eat?
Chain length, degree of saturation, and location of double bond(s) can all impact the qualitites of the fats and oils found in the food supply
What qualities of food are affected based on FA structure?
Firmness at room temp (vegetable oils versus tropical oils vs animal fats). Susceptibility to oxidation/rancidity (natural nut butters versus butter)
What type of FAs are most likely to oxidize? Least?
Most = PUFAs (bonds are less stable) Least = saturated (bonds are more stable)
What is hydrogenation?
A process used by manufacturers to enhance the shelf life of fat containing products. Some or all the points of unsaturation are saturated by adding H molecules.
Adcantages to hydrogenation?
improves shelf life, protects against oxidation (natural vs hydrogenated nut butters), alters textures of foods (vegetable oils versus margarine)
Disadvantages to hydrogenation?
Creation of trains fatty acids
What are trans fatty acids?
A FA with its hydrogens on the opposite sides of the double bond, making them act more like saturated fats in the body
Trans Fat Task Force recommendations?
- Limit the trans fat content of vegetable oils and soft margarines to 2% total fat 2. Limit the trans fat content of all other foods to 5% total fat, including restaurant foods. 3. Encourage to replace trans fat with MUFAs and PUFAs (not saturated fats)
What sector presents the greatest challenge to reducing trans fat?
Cafeterias in schools and institutions because they don’t have the funding
For the most part, are most sectors under the limits under the trans fat amount?
Yes
What trans fat doesn’t need to appear on labels?
Conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNs) are found naturally in the meat and milk of ruminant animals (2-5% total fat) and do not fallt in CFIA’s trans definition…actually have health benefits
Total trans fat on the label can be rounded to zero when per serving…
- the food contains less than 0.2g trans fat 2. The food contains less than or equal to 2g saturated and trans fat combines 3. The food provides less than or equal to 15% energy from the sum of saturated and trans fats
Is the majority of trans fat labelling accurate?
Yes
Phospholipids?
Similar to TGs but have a phosphate group and choline in place of one of the FAs…used in the food industry as emulsifiers.
WHere are phospholipids naturally occurring?
Eggs, liver, soybeans, wheat germ, and peanuts
What is lecithin?
one of the phospholipids. Both nature and the food industry use lecithin as an emulsifer to conbine water-soluble and fat-soluble ingredients that do not ordinarily mix, such as water and oil
What makes phospholipids emulsifiers?
Contain a hydrophilic part (methioine part…the choline), and a hydrophpbic part (2 fatty acids)
Phospholipids in the body?
Major constituents of cell membranes. Help fat-soluble substances (vitamins and hormones) pass in out and cells, keeps fat suspended in the blood and body fluids, and major components of lipoproteins
Are lecithin supplements needed?
NO…your liver makes all the lecithin you need. It is not an essential nutrient. Too much can cause weight gain, GI distress, sweating, and loss of appetite
Percentage of Canadians that are regualr users of dietary supplements?
40-70%
What are sterols?
Lipids with multiple ring structures
Where are sterols found?
In both plants and animals, but only animal food contain cholesterol.
What do sterols in plants do?
Interfere with choelsterol absorption, lowering blood cholesterol levels
Where sterols found in the body?
Bile acids, sex hormones, adrenal hormones, vitamin D, components of cell membranes
How much cholesterol does the liver manufacture per day?
800-1500 mg per day…>90% resides in the cells
Examples of sterols in the body?
Cholesterol and Vitamin D3
How many TGs do we consume per day?
50-100g
How man phospholipids do we consume per day?
4-8g
How much cholesterol do we consume per day?
200-350mg
What is the biggest problem when digesting fats?
They are hydrophobic and the enzymes that digest them are hydrophilic
What are lipids broken down into?
Monoglycerdies, fatty acids, glycerol
Can the body absorb triglycerides?
NO
How are triglycerides digested?
Hydrolysis
What happens with lipid digestion in the mouth?
Hard fats begin to melt as they reach body temperature, salivary glands at the base of the tongue release linguinal lipase (plays a minor role in fat digestion in adults but better at digesting short and medium chain FAs in milk for babies), end products of digestions are diglycerides and fatty acids
Lipid digestion in the stomach?
Strong muscle contraction of the stomach churn and propel its contents toward the pyloric sphincter. The churning action is important because it grinds solid pieces into finer particles, mixes the chyme, and disperses the fat into small droplets. Little digestion occurs, mostly juts exposes fat for attack by gastric lipase
What triggers the release of cholecystokinin (CCK)? from the gallbladder?
Fat in the SI
What do bile acids do in the SI?
Act as emulsifiers, drawing fat molecules into the surrounding watery fluid
What are the major fat digesting enzymes?
Pancreatic lipases…remove TGs’ outer FAs, leaving a monoglyceride (can be absorbed), occasionally, all FAs are removed, leaving glycerol
How are phospholipids digested?
In a similar way to TGs, with 2 FFAs and the choline part being the end products
How are sterols digested?
Most are absorbed as is
What are bile acids made of?
Cholesterol (hydrophobic) and amino acid (hydrophilic)
Where is bile made? Stored?
Liver, gall bladder
What is the goal of emulsification of fats?
Increase the surface area –> enhanced efficiency of digestion
Circulation of bile?
Made in liver –> stored in gall bladder –> enters SI through common bile duct in response to CCK –> recycled back to liver OR bound by soluble fibres and excreted in the feces
What are the problems caused by pancreatic insufficiency to make lipases, or decreased amount being released into the SI?
Fat malabsorption and fat-soluble vitamin malabsorbtion
What lipids diffuse easily into intestinal cells?
Small molecules of digested triglycerides (glycerol and short and medium chain FAs)
How are larger molecules (monoglycerides and long chain FAs) absorbed?
Merge into spherical complexes known as micells…emulsified fat droplets formed by molecules of bile surrounding monoglycerides and FAs –? soluble in intestinal fluids, transport to intestinal cells
Inside intestinal cells, what happend to monoglycerides and long-chain FAs?
Reassembled into new triglycerides
How are lipids transported from cells to the bloodstream?
- Newly made trigylcerides and other lipids (cholesterol, phospholipids, vitamisn) are packed with protein into lipoprotein transport vehicles called chylomicrons 2. Via pinocytosis, chylomicrons are released from intestinal cells to the lymphatic system –> entry into bloodstream via the thoracic duct –? blood carries the lipids to the rest of the body for immediate use or storage
4 lipoproteins from least dense to most dense?
Chylomicrons –> VLDL –> LDL –> HDL
What is the relationship between size, density, and lipid content?
Bigger the lipoprotein, the less dense it is and the the more TGs/lipids it contains
What are the largest and least dense lipoproteins?
Chylomicrons…lots of TGs
What do chylomicrons do?
Transport diet-derived lipids from small intestine to the rest of body
What happens to chylomicrons over time?
Body cells remove triglycerides, leaving chlyomicron remnants. Most TGs have been depleted 14 h after absorption leaving only a few remnants of protein, cholesterol, and phospholipid. Protein receptors on the liver recognize the remnants and remove them from the blood –? dismantling for use or recycling
What is VLDL?
Lipids made in the liver and those collected from chylomicrons remnants are packaged with proteins as VLDL and shipped to other parts of the body. VLDL travels through the body, TGs are removed and it shrinks/loses density –> shift in the proportion of lipids to become LDL
What does HDL do?
removes cholesterol from the cells and carry it back to the liver to be recycled or disposed
What is “bad” choelsterol?
Ldl…primarily choesterol…linked to heart disease…High LDL is not desirable
What is “good” cholesterol?
HDL…primary protein…carries cholesterol back from the rest of the body to the liver for breakdown.excretion…anti-inflammatory properties…high HDL is associated with a protective effect (desirable)
Factors that lower LDL and increase HDL?
weight control, MUFAs/PUFAs instead of saturated fat, soluble fibre, phytochemicals like sterols, moderate alcohol consumption, physical activity
Can HDL and LDL cholesterol be consumed?
NO, body makes it
Is the cholesterol from HDL different than that of LDL?
No, both same type of cholesterol, but it the proportion and composition of lipoprotein that make it different
Role of triglycerides?
Provide energy…>2x that of CHOs and proteins. Efficient storage form of energy. Body’s fat stores have virtually unlimited capacity; the fat cells of adipose tissue readily take up and store TGs
What are adipokines?
Adipose tissue secreted proteins that help regulate energy balance and influence several body dunctions
Examples of adipokines?
Leptin, adiponectin, resistin, visfatin
What are the 2 essential FAs?
Linoleic and linolenic acid
Why are linoleic and linolenic acid considered essentiaL?
Must be supplied by the diet because cells cannot convert omega-6 to omega-3 and vice versa
Why should EPA and DHA be taken in the diet, even thought the body can make them from linolenic acid?
Desaturation and elongation are possible to make longer FAs of the same family, but the process is very inefficient
What is linoleic acid?
18:2n-6. Important component of membrane phospholipids and primary member of the omega-6 family. Can be converted to arachidonic acid. In times of dietary inadequcy, arachadonic acid and all other omega-6s derived from linoleic acid become essential
WHat is linolenic acid?
18:3n-3. Primary member of omega-3 family. Important component of membrane phospholipids. Limited amounts of eicosapentaenoic acid (EPA, 20C) and docasahexaenoic acid (DHA, 22C) can be made.
What are EPA and DHA important for?
Found in eyes and brains. Essential for growth and cognitive development. Prevention and treatment of heart disease.
What are eicosanoids made from?
EPA and arachidonic acid
What type of eicosanoids have greater health benefits?
Those from EPA exude greater health effects –> lower BP, reduce blood clot formation, protect against irregular heart beats, reduce inflammation
Eicosanoids are described as “hormone like,” but how are they different from hormones?
Affect only cells in which they are made or nerby cells in the same localized environment and different effects on different cells and actions of various eicosanoids oppose each other
General recommendations for lipids and health?
Choose a diet that is low in saturated fat and trans fat and cholesterol and moderate in fate
Desirable level for total cholesterol?
Less the 5.2 mmol/L
Desirable level for LDL cholesteroL?
Less that 2.5 mmol/L
Desirable level for HDL cholesterol?
Greater than 1.5 mmol/L
Desirable level for TGs?
less than 1.7mmol/L
What type of fats raise LDL cholesterol?
Saturated fats…some raise it more than others
What type of saturated fats raise LDL the most?
tropical fats…lauric acid, myristic, and palmitic acids (12,14,16 C)
Does stearic acid raise LDL?
NOPE
How does sat. fat contribute to heart disease?
Promote blood clotting…atherosclerotic
Main sources of saturated fat?
Animal products (meat and milk), vegetable fats (coconut and palm), hydrogenated fats
Relationship between dietary trans fats and heart disease?
Trans fats raise LDL and lower HDL
Average daily intake of trans fat in Canada?
~3.4g/day (1.4% total energy) mostly from hydrogenated products
Why have trans fat intakes decreased over the past decades?
Trans Fat Task Force and people are more aware of it
What to look for on labels when wondering about trans fat?
Partially hydrogenated oil and shortening
What raises blood cholesterol more, dietary cholesterol or saturated and trans fat?
Saturated and trans fat do
How can cholesterol intake be lowered?
Consuming minimal animal products in moderation and avoiding especially high sources (also high in saturated fats)
Most effective dietary method for preventing heart disease?
Substituting MUFAs and PUFAs in the place of saturated and trans fat
Some major sources of MUFAs?
olive oil, canole oil, peanut oil, avocados, flax seed oil, walnuts
Major sources of PUFAs?
safflower oil, sesame oil, soy oil, corn oil, sunflowe oil, nuts, seeds
What is canola/rapeseed oil?
Low in saturated fats, higher in oleic acid(61%), linoelic acid(21%), and alpha-linoleic acid(11%), plant sterols, an tocopherols (vit. E/anti-oxidant) –> cardioprotecitve effects
What does regular cinsumption of omega-3s do?
Helps prevent blood clots, protects against irregualr heartbeats, lowers BP, especially in people with hypertension or atherosclerosis, anti-inflammatory properties, and improves immunity
Sources of linoleic acid?
vegetable oils (corn, sunflower, safflower, soybeanm cottonseed), poutry fat, nuts, seeds
What is arachidonic acid made from?
Linoleic acid
Sources of arachidonic acid?
Meats, poultry, egggs
Examples of linolenic acid?
oils (flaxseed, canola, walnut, wheat germ, soybean), nuts and seeds (butternut, flaxm walnuts, soybea kernels), soybeans
What are EPA and DHA made from?
linolenic acid
What are sources of EPA and DHA?
Human milk, Pacific oysters, and fatty fish
What are the best sources of EPA and DHA?
fatty fish…char, herring, mackerel, trout, sardines, and salmon
Fish high in mercury?
tilefish, swordfish, king mackerel, shark
Fish low in mercury>
cod, haddock, pollock, salmon, sole tilapia, most shellfish
What is more important to increase in your diet more…omega 3 or 6?
omega 3
AMDR for lipid intake?
20-35% for 19-30 years old
AI for omega-3 for males?
1.6 g
AI for omega-3 for females?
1.1 g
AI for omega-6 for males?
17 g
AI for omega-6 for females?
12 g
Suggested DV of fat based on a 2000 kcall diet?
65 g
DV for saturated fat?
20 g or 10%