Lipid Basics
What is the common property shared by lipids that distinguishes them from many other nutrients?
They do not readily dissolve in water.
A fatty acid containing only single bonds between its carbon atoms is called what?
A saturated fatty acid.
What enzyme breaks triglycerides into glycerol and fatty acids?
Lipase
What is a lipoprotein?
A transport vehicle for lipids in the bloodstream, consisting of a lipid core surrounded by a shell containing protein, phospholipids, and cholesterol.
What percentage of total daily calories does the Acceptable Macronutrient Distribution Range recommend coming from fat?
20–35% of total calories.
How many kilocalories does fat provide per gram?
9 kcal per gram.
What is the difference between a monounsaturated and polyunsaturated fatty acid?
A monounsaturated fatty acid has one double bond, while a polyunsaturated fatty acid has more than one double bond.
Approximately what percentage of dietary fat is absorbed?
Approximately 95%.
Which lipoprotein carries dietary fat from the small intestine to cells?
Chylomicrons
According to the Dietary Guidelines, saturated fat should be limited to less than what percentage of total calories?
Less than 10% of total calories.
Name the three major types of lipids discussed in this chapter.
Triglycerides, phospholipids, and sterols.
Name the two essential fatty acids that must be supplied by the diet.
Linoleic acid (omega-6) and alpha-linolenic acid (omega-3).
Where are short- and medium-chain fatty acids absorbed after digestion?
Into the hepatic portal vein.
Which lipoprotein carries cholesterol to body cells and is commonly called "bad" cholesterol?
LDL — low-density lipoprotein.
What two essential fatty acids are associated with omega-6 and omega-3 fatty acids?
Linoleic acid = omega-6
Alpha-linolenic acid = omega-3
A triglyceride is made of what three components?
One glycerol molecule and three fatty acids.
A student wants to increase dietary alpha-linolenic acid. Name two foods from the chapter that could provide it.
Any two of the following: flaxseeds, walnuts, perilla seed oil, chia seed oil, canola oil, or soybean oil.
Most dietary fats contain long-chain fatty acids. After absorption, where are these fatty acids transported first?
Into the lymphatic system.
Which lipoprotein helps remove cholesterol from cells and contributes to its excretion from the body?
HDL — high-density lipoprotein.
What are two important functions of essential fatty acids?
They form body structures, support the immune and nervous systems, and help produce regulatory compounds such as eicosanoids and hormones.
A phospholipid contains glycerol, two fatty acids, and what additional component?
A phosphorus-containing compound.
Why are polyunsaturated fatty acids particularly susceptible to rancidity?
Their double bonds can break down when exposed to oxygen or UV light, producing unpleasant odors and flavors.
Why are bile acids and phospholipids important during fat digestion?
They act as emulsifiers, helping suspend lipids in water and break large fat droplets into smaller droplets so digestive enzymes can act on them.
Put these lipoproteins in the correct order based on their roles in transporting dietary fat and liver-produced lipids: chylomicrons, VLDL, LDL, HDL.
Explain how oxidized LDL contributes to the development of atherosclerosis.
Oxidized LDL particles are taken up by white blood cells, which contribute to the formation of atherosclerotic plaques in blood vessels. As plaque builds up, vessels become narrower and less flexible, increasing cardiovascular risk