2.6 KiB
2.6 KiB
- Lipids are a class of nutrients that do not dissolve in water.
- They will dissolve in organic solvents
- Oil is less dense than water, so it will rise to the top of a solution
- Major functions of lipids in the body include
- Providing and storing energy
- forming and maintaining cell membranes
- producing steroid hormones
- insulating the body
- cushioning the body against bumps and blows
- forming body contours
- absorbing fat soluble vitamins and phytochemicals
Fatty Acids
A fatty acid is a hydrocarbon chain found in lipids; one end of the chain forms a carboxylic acid, and one end forms a methyl group.
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Short chain fatty acids have 2 to 4 carbons
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Medium chain fatty acids have 6 to 12 acids
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Long chan acids have 14 to 24 carbons
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Fatty acids are identified by:
- The number of carbon atoms
- The type of bond between carbon atoms
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Saturated fatty acid (SFA) Every single carbon atom is filled with hydrogen atoms
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Unsaturated fatty acid is a fatty acid that is missing hydrogen atoms and has one or more double bonds within the carbon chain
- Monounsaturated (MUFA)
- Has one double bond within the carbon chain
- Sources include:
- Canola oil
- Olive oil
- Avacados
- Nuts
- Seeds
- Peanut butter
- Polyunsaturated (PUFA)
- Fatty acid that has two or more bonds within the carbon chain
- Sources include:
- Soybean oil
- Fatty fish
- Flax seed
- Walnuts
- Corn oil
- Sunflower oil
- Monounsaturated (MUFA)
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Most naturally occurring fatty acids are cis fatty acids
- Hydrogen atoms of the double bonded carbon are on the same side of the hydrocarbon atom
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Trans fats are unsaturated fatty acids that have a trans double bond.
- Hydrogen atoms of the double bonded carbons are on the opposite side of the hydrocarbon chain
- Hydrogenation is the food manufacturing process that adds hydrogen atoms to liquid vegetable oil, forming trans fats.
- Can be stored for longer periods because they are less likely to undergo oxidation
- Raise "bad" cholesterol levels in the blood
- Increases risk of heart disease
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Essential fatty acids are fatty acids that must be supplied by the diet
- Linoleic acid - 18 carbon omega-6 fatty acid found in vegetable oils
- Alpha-linolenic acid - 18 carbon omega-3 fatty acid, found in flaxseed, walnuts
- Precursor for
- Eicosapentaonoic acid (EPA) - 20 carbons
- Docosahexaenoic acid (DHA): 22 carbons
- Both acids are found mainly in fatty fish
- Essential fatty acids are needed for growth and healthy cell membranes, especially in the brain.