Module 5: Lipids Answer the following

Question 1

Identify healthy blood lipid profile ranges.

Answer 1

Total Cholesterol- Less than 200

LDL Cholesterol- 100-less than 100

HDL Cholesterol- 60 or higher (considered protective)

Question 2

Describe the structure of triglycerides, saturated fats, monounsaturated fats, and trans fats.

Answer 2

Tryglycerides- To form a triacylglycerol, a glycerol molecule is joined by three fatty acid chains. Glycerol is a 3-carbon alcohol that is the backbone of a triacylglycerol; various fatty acids attach to the glycerol backbone.

Saturated fats- Fatty acid chains are held together by carbon atoms that attach to each other and to hydrogen atoms. The term saturation refers to whether or not a fatty acid chain is filled (or “saturated”) to capacity with hydrogen atoms. If each available carbon bond holds a hydrogen atom it’s a saturated fatty acid chain. All of the carbon atoms in a saturated fatty acid chain are bonded through single bonds. The structure created by single bonds means saturated fatty acids can pack tightly together and are solid at room temperature. Examples of foods high in saturated fatty acids include animal fats, butter, and lard.

Monounsaturated fats-Any fatty acid that has only one double bond is a monounsaturated fatty acid, an example of which is olive oil (75 percent of its fat is monounsaturated). Monounsaturated fats help regulate blood cholesterol levels, thereby reducing the risk for heart disease and stroke. A polyunsaturated fatty acid is a fatty acid with two or more double bonds or two or more points of unsaturation. Soybean oil contains high amounts of polyunsaturated fatty acids. Both monounsaturated fats and polyunsaturated fats provide nutrition that is essential for normal cell development.

Trans fats- In a trans fatty acid, the hydrogen atoms are attached on opposite sides of the carbon chain. Unlike cis fatty acids, most trans fatty acids are not found naturally in foods, but are a result of a process called hydrogenation. Hydrogenation is the process of adding hydrogen atoms to an unsaturated fat (the hydrogen atoms are added where there are double bonds), thus making the fatty acid saturated (or less unsaturated, in the case of partial hydrogenation).

Question 3

What makes lipids solid or liquid at room temperature?

Answer 3

Foods that have a high percentage of saturated fatty acids tend to be solid at room temperature. Examples of foods high in saturated fats include chocolate and meat. Foods rich in unsaturated fatty acids, such as olive oil, tend to be liquid at room temperature.

Question 4

What makes lipids solid or liquid at room temperature?

Answer 4

All of the carbon atoms in a saturated fatty acid chain are bonded through single bonds. The structure created by single bonds means saturated fatty acids can pack tightly together and are solid at room temperature. Examples of foods high in saturated fatty acids include animal fats, b

Question 5

Discuss how the level of saturation of a fatty acid affects its shape and the form it takes.

Answer 5

In a saturated fat the chain has no double bond or bend in the shape.
The introduction of a carbon double bond in a carbon chain, as in an unsaturated fatty acid, can result in different structures for the same fatty acid composition. When the hydrogen atoms are bonded to the same side of the carbon chain, it is called a cis fatty acid. Because the hydrogen atoms are on the same side, the carbon chain has a bent structure. Naturally occurring fatty acids usually have a cis configuration.
In a trans fatty acid, the hydrogen atoms are attached on opposite sides of the carbon chain Unlike cis fatty acids, most trans fatty acids are not found naturally in foods, but are a result of a process called hydrogenation.

Question 6

Understand the function of the following in digestion of fat: stomach, gallbladder, liver, pancreas, bile, small intestine, pancreatic enzymes.

Answer 6

Stomach-
Fat is separated from other food substances. In the stomach, gastric lipase starts to break down triacylglycerols into diglycerides and fatty acids.Within two to four hours after eating a meal, roughly 30 percent of the triacylglycerols are converted to diglycerides and fatty acids. The stomach’s churning and contractions help to disperse the fat molecules, while the diglycerides derived in this process act as further emulsifiers. However, even amid all of this activity, very little fat digestion occurs in the stomach.

Gallbladder-Bile is produced by the liver and stored in the gallbladder; when needed bile is secreted from the gallbladder into the small intestine. Bile contains bile salts, lecithin, and substances derived from cholesterol so it acts as an emulsifier. It attracts and holds on to fat while it is simultaneously attracted to and held on to by water. Emulsification increases the surface area of lipids making them more accessible to the digestive enzymes

Liver-Bile is produced by the liver and stored in the gallbladder; when needed bile is secreted from the gallbladder into the small intestine. Bile contains bile salts, lecithin, and substances derived from cholesterol so it acts as an emulsifier. It attracts and holds on to fat while it is simultaneously attracted to and held on to by water. Emulsification increases the surface area of lipids making them more accessible to the digestive enzymes.

Pancreas- Produces digestive enzymes that help the small intestine digest lipids. The enzymes break down fats which are not easily digested and are not water soluble

Bile- Bile is produced by the liver and stored in the gallbladder; when needed bile is secreted from the gallbladder into the small intestine. Bile contains bile salts, lecithin, and substances derived from cholesterol so it acts as an emulsifier. It attracts and holds on to fat while it is simultaneously attracted to and held on to by water. Emulsification increases the surface area of lipids making them more accessible to the digestive enzymes.

Small intestine-In the small intestines bile emulsifies fats while enzymes digest them. The intestinal cells absorb the fats.The majority of lipid digestion takes place in the small intestine.Micelles transport the end products of lipid digestion (free fatty acids and monoglycerides) to the digestive tract lining for absorption. As stomach contents enter the small intestine, the digestive system sets out to manage a small hurdle, namely, to combine the separated fats with its own watery fluids.

Pancreatic enzymes- Digestive enzymes that help the small intestine digest lipids. The enzymes break down fats which are not easily digested and are not water soluble

Question 7

Identify the tissue where fat/triglycerides are stored for later use.

Answer 7

Muscles, breasts, external layers under the skin, and internal fat layers of the abdomen, thighs, and buttocks where they are stored by the body in adipose tissue for future use.

Question 8

Explain the lymph system’s role in fat transport.

Answer 8

Long-chain fatty acids form a large lipoprotein structure called a chylomicron that transports fats through the lymph system.
Chylomicrons are formed in the intestinal cells and carry lipids from the digestive tract into circulation.

Question 9

Describe functions of lipids in the body and in food.

Answer 9

Functions of Lipids in the Body:
-Energy Storage

-Regulating and Signaling

-Insulating and Protecting

-Transporting

Role of Lipids in Food:

-High Energy Source

-Smell, Taste, Texture, and Satiety

Question 10

Fat provides _____ kilocalories per gram.

Answer 10

9

Question 11

What is the AMDR for total fat?

Answer 11

AMDR- 20-35 (Percent of total calories)

Question 12

What is the recommendation for saturated fat intake?

Answer 12

AMDR-<10 (Percentage total Calories)

Question 13

Identify foods that are high in each of the following: saturated fat, polyunsaturated fat, monounsaturated fat, omega 3 fatty acids, trans fats, cholesterol.

Answer 13

Saturated Fat-animal products, dairy products, palm and coconut oils, and cocoa butter

Polyunsaturated Fat-nuts (walnuts, hazelnuts, pecans, almonds, and peanuts), soybean oil, corn oil, safflower oil, flaxseed oil, canola oil, and fish (trout, herring, and salmon)

Monounsaturated Fat-nuts (almonds, cashews, pecans, peanuts, and walnuts) and nut products, avocados, extra virgin olive oil, sesame oil, high oleic safflower oil, sunflower oil, and canola oil

Omega 3 fatty acids- canola oil, flaxseed oil, soybean oil, olive oil, nuts, seeds, whole grains, legumes, green leafy vegetables, cod liver oil, and fatty fish (tuna, herring, mackerel, salmon, and trout)

Trans fats- animal products, dairy products, palm and coconut oils, and cocoa butter

Cholesterol- animal products, liver, eggs, dairy products

Question 14

What would you look for in the ingredients list on a food label if you were looking for trans fatty acids?

Answer 14

AMDR- Acceptable Macronutrient Distribution Range

Less than 1 percent

Question 15

What food groups contain cholesterol?

Answer 15

Animal products, liver, eggs, dairy products

Question 16

Which type of dietary fat is known to elevate blood cholesterol levels?

Answer 16

LDL-Low Density Lipoprotein

Question 17

What are diets high in trans fatty acids associated with?

Answer 17

Heart disease

Question 18

Describe the roles of VLDL, LDL, and HDL in the body.

Answer 18

VLDLs. Very low-density lipoproteins are made in the liver from remnants of chylomicrons and transport triacylglycerols from the liver to various tissues in the body. As the VLDLs travel through the circulatory system, lipoprotein lipase strips the VLDL of triacylglycerols. As triacylglycerol removal persists, the VLDLs become intermediate-density lipoproteins.
IDLs. Intermediate-density lipoproteins transport a variety of fats and cholesterol in the bloodstream and are a little under half triacylglycerol in composition. While traveling in the bloodstream, cholesterol is gained from other lipoproteins while circulating enzymes strip its phospholipid component. When IDLs return to the liver, they are transformed into low-density lipoprotein.

LDLs. Low-density lipoproteins are commonly known as “bad cholesterol”. LDLs carry cholesterol and other lipids from the liver to tissues throughout the body. LDLs are comprised of very small amounts of triacylglycerols, and contain over 50% cholesterol and cholesterol esters. As the LDLs deliver cholesterol and other lipids to the cells, each cell’s surface has receptor systems specifically designed to bind with LDLs. Circulating LDLs in the bloodstream bind to these LDL receptors and are brought into the cell. Once inside the cell, the LDL is taken apart and its cholesterol is released. A deficiency of these LDL receptors will leave a high quantity of cholesterol traveling in the bloodstream, which can lead to heart disease or atherosclerosis. Diets rich in saturated fats limit the number of LDL receptors and thus leave cholesterol in the bloodstream that could be deposited in arteries and block blood flow.

HDLs. High-density lipoproteins are responsible for carrying cholesterol out of the bloodstream and into the liver, where it is either reused or removed from the body with bile. HDLs have a very large protein composition coupled with low cholesterol content compared to the other lipoproteins. Hence, these high-density lipoproteins are commonly called “good cholesterol.”