Lipids

Which of these blood levels is associated with a reduced risk for cardiovascular disease?

> A high level of high-density lipoprotein (HDL) cholesterol A high level of high-density lipoprotein (HDL) cholesterol in the blood is associated with a reduced risk for cardiovascular disease. HDL is often referred to as the "good" cholesterol carrier, as it helps remove cholesterol from the arteries and deliver it to the liver, where it is used to create bile and/or is excreted from the body. Low-density lipoprotein (LDL) cholesterol delivers cholesterol to the cells and is often referred to as the "bad" cholesterol carrier because it deposits cholesterol in the walls of the arteries, where it can contribute to atherosclerosis. For a reduced risk for cardiovascular disease, both the total cholesterol level and the LDL cholesterol level should be low.

Which of the following statements about atherosclerosis is true? (Atheroslcerosis is a narrowing of arteries due to build-up of plaque.) (Smoking increases the risk for atherosclerosis.) (High blood pressure can accelerate the development of atherosclerosis.)

> All options are correct. All options are correct. Atherosclerosis is a condition in which the arteries become narrowed and sometimes entirely blocked by hardened deposits of plaque consisting of cholesterol, calcium, and cellular wastes. Smoking increases the risk for atherosclerosis, causing inflammation and damage to artery walls. The force of blood pounding at high pressure against artery walls can accelerate the development of atherosclerosis.

Which of the following foods are good sources of monounsaturated fatty acids? (cashew nuts and almonds) (olives and olive oil) (canola oil)

> All options are correct. All options are correct. Cashew nuts and almonds, olives and olive oil, and canola oil are good sources of monounsaturated fatty acids. Foods that contain unsaturated fats (both monounsaturated and polyunsaturated fats) are more healthful than foods high in saturated fat, cholesterol, and/or trans fat. Vegetable oils, such as soybean, corn, and canola oils, as well as soybeans, walnuts, peanut butter, flaxseed, and wheat germ are all good sources of unsaturated fats.

Which of the following is a function of fat in the body? (insulate the body and regulate body temperature) (cushion the bones, organs, and nerves) (Enable the absorption of fat-soluble vitamins)

> All options are correct. All options are correct. Fat provides energy (9 kilocalories per gram); it enables the absorption of certain nutrients, including the fat-soluble vitamins A, D, E, and K; it insulates the body and regulates core body temperature; and it surrounds the organs, bones, and nerves to provide protection.

Fatty acids are classified by ________. (whether the carbons are connected by single or double bonds) (the total number of double bonds) (the length of the fatty acid chain)

> All options are correct. All options are correct. Fatty acids are classified by whether the carbons are connected by single or double bonds, the total number of double bonds, and the length of the fatty acid chain. For example, a saturated fatty acid has all of its carbons bound with hydrogen. When a double bond occurs between carbon molecules at just one point in the chain, the molecule is called a monounsaturated fatty acid. A polyunsaturated fatty acid contains more than one double bond and is even less saturated with hydrogen than a monounsaturated fatty acid. Short-chain fatty acids are usually fewer than 6 carbon atoms in length, whereas medium-chain fatty acids have 6 to 12 carbons and long-chain fatty acids have 14 or more.

During the digestive process, most lipids are absorbed ________.

> into the lymphatic system During the digestive process, most lipids are absorbed into the lymphatic system. In the stomach, gastric lipase breaks down some fat. The majority of fat digestion occurs in the small intestine. From there, short-chain fatty acids enter the bloodstream directly. The rest of the absorbed dietary fat is transported via chylomicrons into the lymphatic system. The pancreas produces pancreatic lipase, which is secreted into the small intestine via the pancreatic duct. Pancreatic lipase breaks down fats into monoglycerides, glycerol, and free fatty acids.

What is a good way to raise high-density lipoprotein (HDL) cholesterol levels and lower low-density lipoprotein (LDL) levels?

> Engage in regular exercise. A good way to raise high-density lipoprotein (HDL) cholesterol levels and lower low-density lipoprotein (LDL) levels is to engage in regular exercise. In addition to raising HDL and lowering LDL cholesterol levels, regular exercise can help reduce high blood pressure, insulin resistance, and excess body weight. Consuming no more than one alcoholic beverage per day for females and two for males has been associated with a reduced risk for cardiovascular disease. However, drinking more than this is harmful, and for some individuals, even modest alcohol consumption is not advised. Entirely avoiding consumption of dietary cholesterol is not generally recommended, as the relationship between cholesterol intake and cardiovascular health is not entirely clear. Although getting regular blood pressure screenings is a sensible health behavior, it will not help raise HDL cholesterol levels and lower LDL levels.

Which of the following is a current national recommendation regarding fat intake?

> Keep your intake of trans fatty acids as low as possible. The following is a current national recommendation regarding fat intake: keep your intake of trans fatty acids as low as possible. Current dietary fat recommendations advise people to strictly limit their trans fat intake, avoiding consumption of trans fats to the extent possible. This recommendation reflects our current understanding that trans fats are more harmful to health than any other form of dietary lipid. The AMDR for total fat is 20 percent to 35 percent of total energy, not 10 percent to 25 percent. The Institute of Medicine recommends consuming less than 300 milligrams per day of cholesterol, but there appears to be no direct link between cholesterol consumption and cardiovascular disease. The recommended intake of saturated fats is less than 10 percent of total energy intake.

Which of the following is a health benefit of omega-3 fatty acids?

> They regulate inflammation. Omega-3 fatty acids have several health benefits, including regulating inflammation, which is a factor in cardiovascular disease, cancer, and other diseases. The body uses omega-6 fatty acids, not omega-3s, to produce arachidonic acid. HDLs, not omega-3s, transport cholesterol to the liver for use or excretion. Aequate consumption of omega-3 fatty acids is associated with reduced, not increased, blood pressure. To benefit from the protective actions of omega-3 fatty acids, individuals should consume at least two servings of fatty fish weekly.

Cholesterol is __________ .

> a component of cell membranes Cholesterol is a component of cell membranes. Plant sterols, not cholesterol, are found in certain margarines. Cholesterol is a precursor for vitamin D, not vitamin A. Cholesterol is absolutely essential to human health and functioning. The effect of excessive consumption of dietary cholesterol is a subject of ongoing research.

Which of the following is likely to be the highest in saturated fat?

> animal products such as meat and dairy Animal products such as meat and dairy are likely to be the highest in saturated fat. Most saturated fat in the diet comes from animal-based foods, such as whole-milk dairy products like cheese, butter, and ice cream; fatty cuts of meat; and the skin on poultry. Saturated fats should be kept to less than 10 percent of an individual's total energy intake, because they are associated with an increased risk for cardiovascular disease. Fruits and vegetables and whole grains are naturally low in saturated fat and trans fat and are cholesterol free. Vegetable oils, such as soybean, corn, and canola oils, as well as soybeans, walnuts, peanut butter, flaxseed, and wheat germ are good sources of unsaturated fats.

The Acceptable Macronutrient Distribution Range for total fat intake is _______.

> between 20 percent and 35 percent of a person's daily energy intake The Acceptable Macronutrient Distribution Range for dietary fat is between 20 percent and 35 percent of a person's daily energy intake. A very low-fat diet (providing less than 20 percent of daily energy from fat) that is consequently high in carbohydrates may cause an increase in fat in the blood and a decrease in HDL cholesterol—not exactly a beneficial combination for the heart. Consuming more than 35 percent of total daily energy from fat could contribute to obesity, which is a risk factor for cardiovascular disease, and it could cause too low an intake of protein and carbohydrates. Healthy individuals over the age of two are advised to limit their dietary cholesterol—not their total fat intake— to less than 300 milligrams daily, on average.

The "backbone" of both a triglyceride and a phospholipid is a ____ molecule.

> glycerol The "backbone" of both a triglyceride and a phospholipid is a glycerol molecule. Glycerol is an alcohol containing carbon, hydrogen, and oxygen. Three fatty acid chains join to the glycerol backbone to form the triglyceride. Phospholipids have only two fatty acids and a phosphate group connected to the glycerol backbone. Sterols are lipids that do not contain glycerol or fatty acids. Instead, they are composed mainly of four connecting rings of carbon and hydrogen. Glucose is the most abundant sugar in foods and the primary energy source for the body.

The lipoprotein that removes cholesterol from the tissues and delivers it to the liver to be used is ________.

> high-density lipoprotein (HDL) The lipoprotein that removes cholesterol from the tissues and delivers it to the liver to be used as part of bile and/or to be excreted from the body is high-density lipoprotein (HDL). Because it gets rid of excess cholesterol, it is known as the good cholesterol carrier. Very-low-density lipoprotein (VLDL) delivers fat made in the liver to the tissues. VLDL remnants are converted into low-density lipoprotein (LDL), which delivers cholesterol to body cells with LDL receptors. Increased levels of LDL cholesterol can contribute to cholesterol deposits in the walls of the arteries. Because this can lead to atherosclerosis and cardiovascular disease, LDL is referred to as the bad cholesterol carrier. Chylomicrons are a type of lipoprotein that carry digested fat into the lymphatic system and, from there, into the blood.

The majority of trans fats in foods are created by food manufacturers through the process of _________.

> hydrogenation The majority of trans fats in foods are created by food manufacturers through the process of hydrogenation. During hydrogenation, hydrogen atoms are added to unsaturated fats to make them more saturated. Trans fats were initially used in many processed foods because they provide a richer texture, a longer shelf life, and better resistance to rancidity than unsaturated fats. Trans fats are worse for heart health than saturated fats because they raise LDL cholesterol and lower HDL cholesterol. Transamination is the process by which an amine group is transferred from one amino acid to another to make a new amino acid. Active transport is a mechanism whereby a substance is carried across a cell membrane against its concentration gradient by means of a carrier protein and energy (ATP).

All of the following organs play a role in the digestion of lipids EXCEPT the ________. (large intestine) (gallbladder) (pancreas) (liver)

> large intestine The large intestine, the final organ of the gastrointestinal tract, eliminates waste and absorbs water and some nutrients. It is not involved in lipid digestion. The gallbladder, pancreas, and liver are the accessory organs that assist in the digestion of lipids. The liver produces bile, which is stored in the gallbladder. Bile secreted from the gallbladder emulsifies lipids in the small intestine. The pancreas produces pancreatic lipase, which is released into the small intestine, where it attaches to lipid droplets and helps to further break them down.

Which of the following foods are the richest sources of omega-3 fatty acids?

> salmon and other fatty fish Salmon and other fatty fish are the richest sources of omega-3 fatty acids. Omega-3 fatty acids are also known as essential fatty acids; because the body can't make them, it is essential that they be obtained through the diet. Most fish contain the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), but fatty fish such as salmon, herring, and sardines are especially rich sources. Vegetable oils, nuts, and flaxseed are good sources of other essential fatty acids.

Consumption of which of these dietary components raises low-density lipoprotein (LDL) cholesterol the most?

> saturated fat Saturated fat consumption raises low-density lipoprotein (LDL) cholesterol the most. Research suggests that dietary cholesterol intake has less of an impact on blood cholesterol levels than saturated fat intake. Consumption of soluble fiber and plant sterols can actually help lower LDL cholesterol.

The primary lipid in the body is _____.

> triglycerides The primary lipid in the body is triglycerides. Each triglyceride compound is made up of three fatty acid chains connected to a glycerol "backbone." The body stores excess triglyceride in adipose tissue (body fat). Cholesterol is another type of lipid but is not as abundant as fat. Lecithin is a phospholipid found in cell membranes and used as an emulsifier in some foods. Chylomicrons are lipoproteins that transport fat from a meal into the lymphatic vessels, which carry them to the bloodstream.

Which of these food items contains the most dietary cholesterol per serving?

> whole milk Whole milk contains more dietary cholesterol per serving than salad dressing made with olive oil, french fries cooked in canola oil, or walnuts and almonds. Dietary cholesterol is found only in foods from animal sources, including meats, egg yolks, and dairy products.