Macro #5 & #6: Lipids and Health Implications Flashcards
3 Reasons we need lipids
- Energy
- Essential fatty acids for fatty acid synthesis
- Absorption of essential fat-soluble vitamins
General recommendations for lipids
- No RDA
- Diets should not have more than 35% fat
- Avoid trans fatty acids
Distinguishing feature of fats/lipids
Don’t dissolve well in water
3 classifications of dietary fats/lipids
- Triglycerides
- Sterols
- Phospholipids
Triglycerides
Primary dietary lipid and source of energy
How are triglycerides composed?
1 glycerol + 3 fatty acids
Esterification
Bonding of fatty acid to glycerol
Where does esterification occur?
Primarily in the liver, enterocytes, and adipocytes
Fatty Acid Lengths
Short: <6 carbons
Medium: 6-12 carbons
Long: >14
Chain length determines the method of digestion and absorption
Two types of fatty acids
- Saturated
- Unsaturated
Saturated Fatty Acids
Carbons are saturated with Hydrogen, no double bonds and solid at room temp
Unsaturated Fatty Acids
One or more double bond between C and H. Liquid at room temperature
Monounsaturated fatty acid (MUFA)
Type of unsaturated fatty acid where there is only one double bond between carbons
Polyunsaturated fatty acid (PUFA)
two or more double bonds between carbons
Alpha-Linolenic acid
Omega-3 fatty acid: the double bond is on the third carbon
Anti-inflammatory effect
Linoleic Acid
Omega-6 fatty acid: the first double bond is on the sixth carbon
Excess consumption = pro-inflammatory effect
Trans fatty acids
Artificial trans fats are created in a process that adds hydrogen to liquid vegetable oils to make them more solid
Where are trans fatty acids seen the most?
Used primarily in
1. processed foods
2. to increase shelf-life
3. improve taste and texture
4. Used for frying foods
What are trans fatty acids listed as on food labels
(Partially) hydrogenated oil
Why are trans fatty acids bad?
They raise LDL cholesterol (bad cholesterol) and lower HDL cholesterol (good cholesterol)
What is the loophole for food companies when putting trans fatty acids on the label
If there is <0.5g, the company can put “zero trans fat” on the label but still have to put it on the label
Did the FDA ban trans fat usage in foods?
Yes. They banned it in 2015 but postponed the implementation from 2018 to 2020/2021
Sterols
Lipids that hold together the phospholipid bilayer.
Includes nuts, peanuts, legumes, soybeans, flour etc
Cholesterol
Nonessential nutrient that is part of a Sterol group
Where is cholesterol synthesized?
The liver
3 Purposes of Sterol in the body
- Components of all cell membranes
- Produces testosterone, estrogen, adrenal hormones, and vitamin D
- Produces bile to digest fat
Phospholipids
2 fatty acids attached to a phosphate group which create a phospholipid bilayer
Purposes of phospholipids in the body
- Create cell membranes
- Supply fatty acids for cellular metabolism
- Are incorporated into the outer surface of lipoprotiens
Lipid Digestion
- In the mouth via salivary lingual lipase
- Put into the small intestine where bile from the gallbladder breaks it down
- Pancreatic lipase can now breakdown the new clumps of fat into monoglycerides and fatty acids
Lipid Absorption
- Monomers absorbed into the enterocytes occurs via passive diffusion
- Once in the enterocytes, monoglycerides and fatty acids are esterified (put back together) into triglycerides in the ER of the enterocyte
- Triglycerides added to cholesterol and delivered to lymphatic system through a type of lipoprotein called a chylomicrons
Chylomicrons
large triglyceride-rich lipoproteins produced in enterocytes from dietary lipids. Short-lived, metabolized a few hours after a meal
Lipoprotien
Particles of protein and fats that carry cholesterol through your bloodstream
Apolipoprotein
Protein that binds triglycerides and cholesterol together to create the chylomicron AND THEN facilitates the MOVEMENT of the chylomicron
Where do chylomicrons go?
Leave the enterocyte and enter the lymphatic system then drain into the venous system (final step of absorption
Difference between chylomicrons and lipoproteins
Chylomicrons are lipoproteins that contain the MOST amount of triglycerides possible
Overall summary
- Monomers from breakdown enter epethilial cells due to enterocytes
- Monomors are esterified into TG in the endoplasmic recticulum
- TG combine with choleterol and form chylomicrons due to the apolipoprotein
- Chylomicrons take contents out of the cell and into the lymphatic system
- Chylomicrons are drained into the blood from the lymphatic system
Chylomicrons in the blood
Chylomicrons come in contact with lipoprotein lipase
Lipoprotein lipase
An enzyme that stimulates lipolysis (breakdown of TG into fatty acids and glycerol so they can enter the cell)
What happens to the chylomicron after it deposits triglycerides and cholesterol into blood
Chylomicron is sent back to the liver
4 types of lipoproteins
- Chylomicron
- Very low-density lipoproteins (VLDL)
- Low-density lipoproteins (LDL)
- High-density lipoproteins (HDL)
Very low-density lipoprotiens (VLDL)
Synthesized in the liver. Transports endogenous fats
If you eat too many CHO, they are converted into fatty acids and then triglycerides and packaged as VLDL in the liver
Low-density lipoproteins (LDL)
Synthesized in the liver and transports cholesterol. High levels of LDL can increase risk of cardiovascular disease. Labeled “bad” cholesterol
High-density lipoproteins (HDL)
Synthesized in the liver and removes cholesterol. High levels of HDL decreases risk of cardiovascular disease. Labeled “good” cholesterol
Heart Disease
Leading cause of death
cardiovascular disease (CVD)
General term for conditions affecting the heart or blood vessels
Examples of CVD
- Blood Vessel Disease
- Congenital heart defects
- Heart valve diseases
- Heart infections
Health implications of excessive dietary fat intake
Coronary artery disease (heart disease)
Obesity
Forms of cancer
Atherosclerosis
Disease where plaque accumulates in arterial walls. Blocks the flow of blood through the vessel
Heart (coronary arteries)
Brain (carotid arteries)
Symptoms of atherosclerosis
Chest pain, plaque rupturing leading to a blood clot, blood clots may dislodge, stroke of the heart or brain
4 main coronary arteries
- Right coronary artery
- Left coronary artery
- Left anterior descending artery
- Left circumflex artery
What do coronary arteries do?
Supply blood and oxygen to the muscles of the heart
Symptoms of Coronary Artery Disease
shortness of breath
chest pain
fatigue
dizziness
How to help your coronary artery disease (CAD)
- Avoid trans fats
- <10% of calories should be from saturated fats
- Maintain healthy weight
- Avoid smoking
- Exercise
Dyslipidemia
The imbalance of lipids like high LDL cholesterol, low HDL cholesterol, high TG, high total cholesterol
How to improve blood lipids?
Aerobic exercise
Dietary modification
Medications
Dietary Modifications to improve blood lipids (lower LDL, raise HDL, lower TG)
- Fiber-rich diet
- Reduce saturated fat intake
- Avoid trans fats
- Consume fatty fish/fish oil supplements (omega-3)
- Moderate alcohol consumption
Foods high in saturated fat
Increase LDL but ALSO increases HDL!!
Pork, lamb, cream, butter, cheese, yogurt
Foods high in monosaturated FA
nuts/seeds, olive oil, avocado, canola oil, peanut oil, sesame oil
Foods high in omega-3 polysaturated FA
Brussel sprouts, spinach, flaxseeds, salmon, halibut, seabass, oysters
Health benefits of MARINE omega-3 PUFA
- Lower TG
- Increase HDL
- Prevents clotting
- Lowers blood pressure
- Anti-inflammatory
