Unit 3 - Lipids Flashcards
What are lipids soluble in?
Organic solvents
What is the body’s chief storage place for excess food energy?
Fat
What is the typical fuel mix at rest for the liver and muscles?
50/50 carbohydrate/lipid
The body has limited stores of ____ but unlimited stores of ____
- Glycogen
- Fat
Why does the body have unlimited capacity to store fat?
Because of the fat-storing cells of the adipose tissue
What do fat cells secrete?
Hormones that help to regulate the appetite and influence other body functions
Is fat a good source of glucose?
Nope
What are 4 functions of fat besides energy?
1) Provide oil for skin and scalp
2) Insulate the body from temp. extremes
3) Hard fat protects kidneys
4) Cell membrane constituents that help maintain structure and health of all cells
What are the 3 types of lipids?
1) Triglycerides
2) Phospholipids
3) Sterols
What is the major form of lipid found in the body and in foods?
Triglycerides
What are triglycerides made up of?
3 fatty acids and a glycerol backbone
What is the most important phospholipid?
Lecithin
What are sources of lecithin?
- Eggs
- Liver
- Soybeans
- Wheat germ
- Peanuts
What are phospholipids made of and what does each part do for the molecule?
- Glycerol backbone
- 2 fatty acids that make the phospholipid fat soluble
- 1 phosphate group that enables the phospholipid to dissolve in water
What do phospholipids act as in the body and what does this mean?
Emulsifiers, which keep fats in solution in the watery blood and body fluids
What are sterols?
Large molecules consisting of interconnecting rings of carbon atoms, w/ side chains of C, H, and O
What is the best known sterol?
Cholesterol
Is cholesterol an essential nutrient?
No, it can be made by the body
What are other sterols besides cholesterol?
- Bile
- Vitamin D
- Sex hormones
What are plant sterols?
Phytochemicals that interfere w/ cholesterol absorption in the intestinal tract, therefore lowering blood cholesterol levels
What are sources of sterols?
- Meats
- Eggs
- Poultry
- Dairy products
Where are sterols naturally found (other than cholesterol)?
Plants
How are fatty acids classified?
By chain length and saturation
What are the 3 classifications of fatty acids?
- Saturated
- Monounsaturated
- Polyunsaturated
What does saturation of a fatty acid effect?
Firmness at room temp. and stability
How can you increase the stability of a fatty acid and make it firmer at room temp.?
Hydrogenation
What is the downside to hydrogenation?
Can create trans-fatty acids
What is hydrogenation?
Adding hydrogens to saturate some or all points of unsaturation
Which fatty acids are softer at room temp. and melt easier?
Fats that contain a shorter chain or the more unsaturated fatty acids
What are the 2 essential fatty acids and where are they found?
1) Linoleic acid
2) Linolenic acid
- Found in plant oils
Is it likely to have a deficiency in the essential fatty acids?
No, because the body readily stores them
What are the main sources of saturated fatty acids?
- Fatty meats
- Whole-milk products
- Tropical oils
- Products containing any of these foods
Which fatty acid type has the strongest effect on blood cholesterol levels?
Saturated
Nuts contain mostly ____ fat
Monounsaturated (w/ some polyunsaturated)
What are trans fatty acids?
Fatty acids that after hydrogenation have changed the double bond from cis to trans
Trans fats behave like _____ fats by ____
- Saturated
- By increasing blood cholesterol and the risk of heart disease
What are sources of trans fats?
- Avocados
- Olives
- Products made w/ partially hydrogenated vegetable oils
What is the main goal of fat digestion?
To breakdown triglycerides into monoglycerides, fatty acids, and glycerol
How do the mouth and salivary glands aid in fat digestion?
- Some hard fats begin to melt
- Salivary gland secretes lingual lipase which has a large effect on milk fats
How does the stomach aid in fat digestion?
- Churning action mixes fat w/ water and acid
- Gastric lipase hydrolyzes a very small amount of fat
How do the small intestine and pancreas aid in fat digestion?
- Cholecystokinin signals gallbladder to release bile
- Bile converts fat to emulsified fat
- Pancreatic lipase flows in from pancreas & converts emulsified fat to monoglycerides, glycerol, and fatty acids
How does the large intestine aid in fat digestion?
Some fat and cholesterol trapped in fibre is excreted in feces
What does high LDL do?
Increases the risk for heart disease because LDL promotes the uptake of cholesterol in the blood vessel walls
What are the main dietary factors associated w/ elevated blood LDL cholesterol?
High saturated fat and high trans fat intakes
What foods/ingredients provide abundant saturated and trans fat and cholesterol?
Solid fats (shortening in cakes or pies)
What do commercially derived trans fats do to blood cholesterol levels?
Raise LDL levels and lower HDL cholesterol
What is the recommended dietary cholesterol?
- Less than 300 mg per day for healthy individuals
- Less than 200 mg for people w/ or at high risk of heart disease
Does dietary cholesterol affect LDL cholesterol levels?
Not really
What are the main contributors of cholesterol in the US?
- Eggs!
- Chicken
- Beef
- Cheese
How can someone increase HDL?
- Maintaining a healthy body weight
- Engaging in regular physical activity
- Quit smoking
How can someone lower LDL?
- Increase intake of soluble fibre
- Replace saturated and trans fats w/ monounsaturated and polyunsaturated fatty acids
How can someone lower their saturated fat intake?
Limit the amount of solid fats in the diet
What is the recommended intake for trans fat?
As low as possible
What are the 3 omega-3 fatty acids?
1) Eicosapentaenoic acid (EPA)
2) Alpha-linolenic acid (ALA)
3) Docosahexaenoic acid (DHA)
Where are omega-3 fatty acids found?
Oils of certain fish and in human milk
What can ALA be changed into in the body?
EPA and DHA
What are the health benefits of DHA and EPA?
- Brain, nerve, and eye development in infants
- Help prevent and treat heart disease
- May help reduce symptoms of rheumatoid arthritis
- May help prevent dementia
How do DHA and EPA help prevent and treat heart disease?
- Lower blood triglycerides
- Prevent blood clots
- Lower blood pressure
How can someone increase their intake of omega-3 fatty acids?
- Best to get them from foods and not supplements
- ALA - flaxseeds, canola and soybean oil, soy products, walnuts, non-hydrogenated margarine
- DHA and EPA - eat at least 2 servings of fish/week
What is metabolic syndrome?
A group of conditions that occur together and increase a person’s risk for other health problems (mostly heart disease, stroke, and type 2 diabetes)
How is metabolic syndrome diagnosed?
When at least 3 of the following disorders are present:
- hyperglycemia
- abdominal obesity
- hypertriglyceridemia
- reduced HDL
- hypertension
What causes metabolic syndrome?
Both genetic and environmental factors
What are common treatments for metabolic syndrome?
- Weight loss
- Increasing physical activity
What is hypertriglyeridemia?
Elevated blood triglycerides
What are some treatments for hypertriglyceridemia?
- Healthy body weight
- Regular physical activity
- Restricting alcohol intake
- Limiting intake of refined carbs and simple sugars
Which omega-3 fatty acids will lower triglycerides?
DHA and EPA
What is the DRI for fats?
- 20-35% of energy from dietary fat, less than 10% energy from saturated fat
- 5-10% energy from linoleic acid (omega-6)
- 0.6-1.2% energy from linolenic acid (omega-3)
What is the DRI for cholesterol?
Minimize intake w/in context of healthy diet
What are fat replacers?
Ingredients that replace some or all of the function of fat; may or may not provide calories
What is an example of a fat replacer?
Olestra
What are draw-backs to Olestra?
- Cannot be broken down by GI enzymes, so it passes through the system unabsorbed
- Binds to fat-soluble vitamins A, D, E, and K and carries them out of the body, so manufacturers must fortify Olestra w/ these vitamins
Is total fat consumption to blame for higher rates of heart disease?
No, the type of fat consumed is
Why do people in the Mediterranean region have lower rates of heart disease?
B/c of their liberal use of olive oil
