Chapter 6: Lipids Flashcards
define: lipids
lipids: molecules that are partly or entirely hydrophobic
What are the different types of lipids (4)?
Types of lipids: triglycerides, fatty acids (fats), sterols, and phospholipids
define: triglycerides
Triglycerides: main dietary lipid; consist of a glycerol backbone with 3 fatty acids attached to it
define: saturated fatty acids
Saturated fatty acids: no double bonds and saturated with h bonds
define: unsaturated fatty acids
Unsaturated fatty acids: 1 or more double bonds (mono/poly)
fill in the blank ____ fats are solid at room temperature and ____ fats are liquid at room temperature
saturated; unsaturated
What foods have saturated fats?
animal products
What risk does saturated fatty acids come with?
Longer chains of saturated fatty acids are more common in animal foods and increase CVD risk → increases LDLs
What type of saturated fats may promote weight loss. Why?
Medium chains of saturated fatty acids are found in tropical oils and easier to digest/absorb; They go directly into the blood, bypassing lymph and peripheral tissues, less likely to be deposited as body fat.
What foods have unsaturated fats?
plant based foods
Define: monounsaturated fats;
Monounsaturated fats: one double bond
Define: polyunsaturated fats
Polyunsaturated fats: 2+ double bonds
Define: essential fatty acids
Essential fatty acids: polyunsaturated fatty acid with a double bond before the 9th position
What are 2 essential fatty acids?
omega-3 and omega-6
Examples of foods with omega-3
- alpha-linolenic acid: chia and flax seeds
- DHA and EPA example: milk, fish, beef, lamb
Fill in the blank: alpha-linolenic acid can be used to synthesize 2 other omega-3 fatty acidS: ____ and ___
DHA and EPA
Sources of omega-6
soybeans, corn, vegetable oils
fill in the blank: Linoleic acid can be used to synthesize another omega-6 fatty acid called _____
arachidonic acid
Functions of essential fatty acids (3)
- Important for formation of phospholipid bilayer of cell membrane (and therefore important for growth, skin integrity, fertility, red blood cell structure)
- Arachidonic acid and DHA are essential for normal brain development in infants and young children
- Longer chain omega-6s and omega-3s help form eicosanoids
Fill in the blank: Both omega-6 and omega-3 fatty acids can be used to synthesize _____
eicosanoids
define: eicosanoids
Eicosanoids: signalling molecules (hormone-like)
What are eicosanoids associated with?
overall: decreased risk of heart disease
- Reduced inflammation
- Vasodilation
- Inhibition of blood clotting
- Lower blood cholesterol
What are some signs of essential fatty acid deficiency (5)
- Dry scaly skin
- Liver abnormalities
- Poor healing
- Impaired vision
- Growth failure in infants
Sources of fatty acids by length
- long
- medium
- short
- Long chains are found in a variety of animal products and some plants
- Medium chain fatty acids are found in tropical oils
- Short chain fatty acids are made by bacteria when they ferment indigestible carbs in our large intestine
define: trans fatty acids
Trans fatty acids: made artificially through the process of hydrogenation
Risks with trans fats?
significantly increase risk of CVD by increasing LDL levels
Give examples of trans fatty acids
Examples: margarines, shortening, cooking oil
Trans fatty acid structure
Hydrogens are on the same side of the double bond and there is a kink in the chain
define: cis fatty acids
Hydrogens are on different sides of the double bond and the chain stays straight
phospholipid structure
Hydrophilic heads and hydrophobic tails
phospholipid functions
- Act as an emulsifier
- Can carry other lipids around the body (example: phospholipids)
What can travel through the phospholipid bilayer? How?
Water and nonpolar substances can travel through the bilayer ; everything else needs a protein transporter to pass through
define: sterol
sterol: subgroup of steroids that have a hydrocarbon chain arranged in a ring formation; Hydrophobic
What are sources of sterols?
- Plant derived sterols: found in unrefined vegetable oils, nuts, seeds, and fruits and may limit the absorption of animal derived sterols
- animal derived sterols: cholesterol
What is the most common sterol?
cholesterol
Cholesterol functions (3)
- Important for cell membrane structure
- Precursor for vitamin D
- Precursor for estrogen and testosterone
Is cholesterol essential?
Not essential; can be synthesized by the liver and other body structures
What are sources of cholesterol?
the only dietary source are animal sources
Fill in the blank: triglycerides must first be digested into _____ and _______
glycerol and fatty acids
What does bile do for lipid digestion?
Bile emulsifies lipids and lingual, gastric, pancreatic lipase digest them
What does the drug Orlistat do to lipid digestion?
Orlistat: drug marketed for weight management that blocks the active site of gastric lipase and pancreatic lipase. Lipids that cannot be digested cannot be absorbed and will pass through the system. Promotes digestive discomfort. Decreases fat absorption by 30%
Define: micelle
Micelle: Bile surrounds fat droplet. Bile helps emulsifies fat, breaking it up to be easily transported by micelles (phospholipids) to be transported easily, especially to intestinal walls and villi
What happens during lipid absorption to a micelle?
Micelle is broken down and its lipid contents are absorbed into the small intestine cells through passive diffusion. Lipids get wrapped in phospholipids as they exit the small intestine cell and enter the centre of the villus. The resulting lipoprotein structure is called a chylomicron.
Why do lipids enter the lymphatic system first?
Chylomicrons are too large to enter the blood and instead enter lacteals
What transports lipids around the body?
Lipoproteins: lipid transporters that carry them around the body (chylomicron, VDL, LDL, HDL)
How much energy does 1 gram of lipid have?
9 kcal
What happens to lipids if there is adequate carbohydrate intake? What if theres inadequate intake?
- If adequate carbohydrate intake: triglycerides are metabolized and their products enter the citric acid cycle and the electron transport chain to yield ATP
- Inadequate carbohydrate intake: ketones are formed
What happens to excess dietary lipids?
Energy surplus: excess dietary lipids is packaged into chylomicrons, transported, and stored as lipid in adipose tissue
What happens to excess dietary carbohydrates and proteins?
Excess dietary carbohydrates and proteins are converted into fatty acids and packaged into VLDL by the liver then deposited into adipose tissue
What fat-soluble vitamins do lipids transport and store? What type of lipid is required?
Vitamin A, D, E, K; lipoproteins
What key molecules does cholesterol synthesize?
Cholesterol-derived molecules include: steroid hormones, estrogen, testosterone, bile salts, Vitamin D
What key molecules does essential fatty acids synthesize?
Essential fatty acid derived molecules include: eicosanoids, endocannabinoids
How does cardiovascular disease hurt the cardiovascular system?
inhibits the systems ability to:
- Deliver cellular needs
- Remove wastes
define: atherosclerosis
Atherosclerosis: build-up of fatty materials in artery walls, type of CVD that causes heart attack and some strokes
Trans Fatty acids and CVD
Known to increase:
- LDL:HDL ratio
- Risk of CVD
- Risk of CVD mortality
How to reduce and eliminate trans fatty acid consumption?
minimize consumption of processed and ultra-processed foods, especially those that are hydrogenated
What are the protective effects of omega-3 and omega-6 on the brain?
Studied for potential to improve brain health, reduce risk of Alzheimers, etc
How many people are cholesterol hyper responders? What does this mean?
25-30% of people are cholesterol hyper-responders; their LDL increases with more dietary cholesterol
What is the nutritional information of an egg?
- 75kcal in each egg
High in protein, fat, vitamins, and minerals - Can be high in omega-3 fatty acids if chickens are fed flaxseeds because a chicken can convert alpha-linolenic acid to DHA
- Eggs are high in cholesterol (225 mg/egg)
Why do plant sterols reduce LDL levels?
Reduced LDL levels by competing with cholesterol for absorption and altering cholesterol metabolism
The AMDR recommends what percent of calories comes from lipids? What about children aged 1-3?
- AMDR recommends 20-35% of calories come from lipids
- AMDR for children aged 1-3: 30-40% of calories from lipids
