Lipids
category of compounds containing, carbon, hydrogen, and oxygen that are hydrophobic
Fat
the common name for just one type of lipid, known as a triglyceride
Fats serve mutiple functions in foods:
1. give flaky texture to baked goods
2. make meats tender
3. provide flavor and aromas
4. contribute to satiety
Fats and other lipds perform important functions in the body:
1. energy storage
2. insulation
3. transport of proteins in blood
4. cell membrane structure
Three types of lipids found in foods and in your body:
1. Triglycerides (fats), phospholipids, and sterols
Fatty Acids
chain of carbon and hydrogen atoms with acid group (COOH) which is the Basic unit of triglycerides and phospholipids.
How many fatty acids are there and how do they vary?
over 20 diff. fatty acids that can vary by:
1. length of chain
2. whether carbons have double or single bonds between them
3. total number of double bonds
Saturated fatty acid
Stearic acid - singly straight line
monosaturated fatty acid
Oleic acid - double bond in carbon chain creates a bend
Polyunsaturated, omega-6 fatty acid
Linoleic acid - 2 dbl bonds create 2 bends
Polyunsaturated, omega-3 fatty acid
alpha-linolenic acid - 3 dbl bonds create 3 bends
Saturated fatty acids
all carbons bonded to hydrogen
eg. stearic acid (18 carbons) solid at room temperature.
Unsaturated fatty acids
one or more double bond between carbons (less saturated with hydrogen)
More liquid at room temperature
Monounsaturated fatty acids
one double bond
eg. Oleic acid, 18 carbons (olive oil)
Polyunsaturated fatty acids
more than one double bond
eg. essential fatty acids linoleic and alpha-linolenic acids (soybean oil)
What is the major visual difference between sat. and unsat. fatty acids
chains are bent due to double bonds between carbons
Triglyceride:
three fatty acids connected to glycerol "backbone."
Most common lipid found in foods and body
referred to as fats. Sat. fats have mostly saturated fatty acids whereas unsat. fats have mostly unsaturated fatty acids
Structure of a triglyceride (looks like a tadpole with 3 flagella)
Glycerol backbone is the oval. 3 fatty acids make up the tails eg. palmitic acid, oleic acid, stearic acid.
Phospholipids
have glycerol backbones but two fatty acids and a phosphorous group at the head which is hydrophyllic. The fatty acid tail is hydrophobic. Cell membranes made of phospholipid bilayer.
Lecithin
Major phospholipid in cell membrane which is emulsifier in foods such as salad dressings to keep oils and water mixed together
Sterols
Comprised mainly of four connecting rings of carbon and hydrogen. unique looking.
Cholesterol
A sterol that is
1. important role in cell membrane structure
2. Precursor of important compounds in body
3. Not required in diet since body makes all cholesterol that is needed
What happens to fat you eat
1. mouth
2. stomach
3. small intestine
1. chewing mechanically breaks down food. Lingual lipase secreted here to act in stomache.
2. Fat digestion continues in the stomach with gastric lipase
3. bile acids in bile secreted from gallbladder help emulsify fat into smaller globules. Pancreatic li
Lipoproteins and types and where they take fat
transport fat through the lymph and blood
1. chylomicrons - digested fat through lymph into bloodstream
2. very low-density lipoproteins (VLDL) deliver fat made in liver to cells
3. Low-density lipoproteins (LDL, "good" cholesterol): deposit cholesterol o
High-density lipoproteins
remove cholesterol from body cells and deliver to liver for excretion
chylomicron is made of
phospholipid membrane with protein extending from triglycerides in center through membrane. cholesterol also extends from fat droplet center past phospholipid membrane.
What types of lipoproteins are the majority composed of triglycerides
chylomicron and VLDL
what types of lipoproteins are the majority composed of cholesterol
LDL
Wht types of lipoproteins are the majority composed of protein
HDL
An energy-dense source of fuel whose release is simulated by glucagon to fuel heart, liver and muscle
fat with 9cal/grm
Fat is needed for absorption of
vitamins A,D,E,K and carotenoids
Two polyunsaturated fatty acids that are essential and why
1. Linoleic acid (omega-6)
Alpha-linolenic (omega-3)
2. supply eicosanoids, help maintain healthy skin cells, nerves, and cell membranes, supply eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
Eicosanoids
hormone-like substances involved in inflammation, blood clotting, blood pressure that is derived from omega-3 or omega-6
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
two omega-3 fatty acids that are heart healthy
Important roles of cholesterol
part of cell membranes
precursor for vitamin D, bile acids, sex hormones
What percentage of calories from fat should your diet be acording to AMDR of DRI?
what about from sat. fats?
20-35%
>10%
percent from linoleic acid daily?
percent from alpha-linoleic acid
5-10%
0.6-1.2%
what types of fats should you minimize and which of the two are worse?
sat. fats and trans fats (created by food manufacturers through hydrogenation) trans fats are worse for your heart.
Creating trans fatty acids
cis
hydrogens are initially on the same side of the double bond
trans
hydrogens are on opposite sides of the double bond
Your body makes all the cholesterol you need. so healthy individuals over the age of 2 are advised to limit to...
>300mg daily
trans fats most prevalent in
1. baking products, animal products, margarine, fries
unsaturated fats are better for you because:
they aren't as bad for your heart plus they often contain essential fatty acids
Because they have more then double the cal. per gram, fat substitutes have potential to reduce calories from fat by more than 50%. what type of food base can they use?
all three, carbohydrate-, protein-, or fat-based
what is the most common base for fat substitutes?
carbohydrate-based, often plant polysaccharides
what are the carb-based fat substitutes
1. fibers from grain (Getatrim)
2. fibers, cellulose (Cellulose Gel)
3. Gums
4. Polydextrose (Litesse)
5. Modified food starch (Sta Slim)
What are the Protein-based fat substitutes?
1. Microparticulated protein (simplesse) can't be cooked because it willl denature so it's used in dairy, salad dressings, and spreads
what are the fat-based fat substitutes
1. Mono- or diglycerides (Dur-Lo)
2. Short-chain fatty acids (Salatrim)
3. Olestra (Olean)
Atherosclerosis
marks early stage of heart disease, it is the narrowing of arteries due to buildup of plaque (hardened debris of cholesterol-laden foam cells, platelets, calcium, cellular waste products). It's thought to begin with injury to lining of arteries (from hi B
Risk factors of heart disease you can control
1. High blood pressure
2. High LDL levels
3. Low HDL levels
4. Type 2 diabetes mellitus
5. smoking
6. Excess body weight
7. physical inactivity
Other potential risk factors
1. high levels of:
a. homocysteine
b. Lp(a) protein
c. C-reactive protein (sign of inflammation)
2. presence of Clamydia pneumoniae
3. Syndrome X: group of risk factors, including insulin resistance, that increase the risk of heart disease.
Methylmercury
toxic chemical especially harmful to nervous systems of unborn children. it accumulates in larger fish with a longer life span (swordfish, shark, king mackerel, tilefish)
FDA recommendations for young children and women of childbearing age in relation to methylmercury and fish consumption
1. that they avoid the four types of fish (swordfish, shark, king mackerel, and tilefish)
2. pregnant women/women of childbearing age only eat up to 12 oz of other fish (variety) weekly with a 6oz/week limit for canned albacore tuna