Lipids: Focusing on Fats and Cholesterol

Flashcards of key vocabulary terms and definitions from the lecture notes on Lipids.

Lipids

Fats, oils, and cholesterol. Organic nutrients that don’t dissolve in water. A major source of energy for the body. Provides 9 calories/ gram. AMDR is 20 to 35%. AHA recommends 30%.

Lipid Functions

Provide and store energy, maintain cell membranes, produce hormones, insulate against cold temperatures, regulate blood pressure and inflammation, cushion against bumps, blows, and falls, absorb fat-soluble vitamins and phytochemicals, contribute rich flavor, smooth texture, and appetizing aroma of foods

Triglycerides

Composed of three fatty acid molecules attached to a glycerol “backbone” molecule. Each fatty acid has a chain of carbon atoms bonded to each other and to hydrogen atoms. Fatty acids can be saturated or unsaturated. Fatty acids have an omega end and an acid group. Comprise 95% of lipids in the body and food.

Saturated Fatty Acids

Carbon chain is filled with hydrogen atoms. Animal fats, coconut, palm, and palm kernel oils

Monounsaturated fatty acid

Has one double carbon bond between the carbon chain lacking two hydrogens. Avocados, olive, peanut, and canola oils

Polyunsaturated fatty acid

Have two or more double bonds in the carbon chain. Lacks more than two hydrogens. Safflower, sunflower, grapeseed, and soybean oils

Essential Fatty Acids

Must be consumed in the diet as the body cannot make two polyunsaturated fatty acids. Necessary for good health. Used to make hormone like substances. Regulate blood pressure and the immune system’s inflammatory response. Signs of deficiency include poor growth (infants), scaly skin, hair loss, and poor wound healing.

Alpha-linolenic acid

An omega-3 fatty acid. Cells use alpha-linolenic acid to produce eicosapentaenoic acid and docosahexaenoic acid.

Linoleic acid

An omega -6 fatty acid. Cells can convert linoleic acid to arachidonic acid.

Trans Fats

Unsaturated fatty acids that have an unusual type of chemical structure. Some are naturally occurring (milk, milk products, butter, meat). Hydrogenation converts many of an oil’s naturally occurring unsaturated cis fatty acids into trans fatty acids and saturated fatty acids. Many processed foods contain Trans fat (pizza, snack foods, fast food, cakes, cookies, chips, etc.)

Cholesterol

A sterol that the body makes. Sterols have a different chemical structure than triglycerides and fatty acids. Carbon is arranged in rings. Cholesterol is only found in animal foods.

Cholesterol Functions

Not an essential nutrient, but performs important functions. Found in cell membranes. Especially brain cells. Makes vitamin D. Makes certain hormones, such as estrogen and testosterone. Makes bile salts.

Phospholipids

Chemically similar to a triglyceride except one fatty acid is replaced by chemical groups that contain phosphorus and often, nitrogen. The phosphate head is water soluble. The two fatty acid tails are not water soluble. Needed for normal function of nerve cells especially in the brain. Major structural components of cell membranes. Cell membranes are composed of a phospholipid double layer. Soluble in fat and water. Act as emulsifiers.

Chylomicrons

A type of lipoprotein. Lipoproteins transport lipids through the bloodstream. Too large to directly enter the bloodstream, enter the lacteals of the villi, travel through lymph, and eventually enter the bloodstream.

Cardiovascular disease (CVD)

Heart disease and stroke. Among the top five leading causes of death in the US. Accounts for nearly 20% of all deaths in the US.

Atherosclerosis

A long-term process that negatively affects arteries. Characterized by the buildup of plaque in arteries. Begins with an excess cholesterol, glucose, or bacteria, which irritates the lining of an artery.

Arteriosclerosis

Hardening of the arteries. Caused by plaques that reduce the flexibility of arteries. Hypertension develops due to inflexible arteries.

Angina

Chest pain that results when arteries to the heart muscle are partially blocked. The tissue dies and a heart attack occurs.

Stroke

Happens when a clot blocks an artery in the brain, and brain cells that are nourished by the blood vessel die.

Peripheral vascular disease (PVD)

Occurs when an artery that carries blood to tissues other than the heart or brain are affected.

Lipoproteins major types

Chylomicron (high triglycerides), VLDL (high triglycerides), LDL (high cholesterol; transports cholesterol and lipids to tissues), HDL (transports lipids back to the liver).

Very low-density lipoprotein (VLDL)

Excessive alcohol and refined carbohydrate intakes stimulate VLDL production in the liver. Carries a large amounts of triglycerides. High blood triglyceride levels increase risk of CVD.

Low-density lipoprotein (LDL)

Small, dense LDLs are involved in plaque formation. Free radicals can damage small dense LDLs. The damage results in oxidized LDL cholesterol, which is taken up by the plaque -forming arterial cells. Smoking increases oxidized LDLs. If LDLs are high atherosclerosis is likely to develop

Statins

Drugs that reduce blood cholesterol levels by blocking cholesterol production in the liver.

High-density lipoprotein (HDL)

Transports cholesterol away from tissues and to the liver, where it can be eliminated. Often referred to as “good cholesterol”. A healthy level of HDL may protect against heart attack and stroke.

Recommendations to Reduce Risk of CVD

Reduce saturated fat intake to less than 7% of total calories. Reduce cholesterol intake to less than 200 mg per day. Limit trans fat intake as much as possible. Increase intake of soluble fiber. Consume foods rich in omega-3 fatty acids, such as fatty fish or fish oil supplements. Consume plant sterols or stanols. Quit smoking. Manage weight. Control blood glucose levels. Control blood pressure

Plant sterols/stanols

Chemicals that are similar to cholesterol. Block absorption of cholesterol.

Dietary Fat Recommendations

Consume 20-35% of total calories from fat. Keep saturated fat intake below 10% of total calories. Limit trans fat intake as much as possible.