5. Lipids

Antioxidant

A compound that generally stops the damaging effects of reactive substances seeking an electron. The prevents the oxidizing of substances in foods or the body, particularly lipids.

Monounsaturated fatty acid

A fatty acid containing one carbon-carbon double bond. Olive Oil, Canola Oil, and Peanut Oil

Polyunsaturated fatty acid

A fatty acid containing two or more carbon-carbon double bonds. Corn oil, Fish oil, sunflower oil and safflower oil

Long-chain fatty acid

A fatty acid that contains 12 or more carbons. Fat in beef, pork, lamb, and lard.

Cis fatty acid

A form of an unsaturated fatty acid that has the hydrogens laying on the same side of the carbon-carbon double bond. The cis bond causes the fatty acid backbone to bend.

Trans fatty acid

A form of an unsaturated fatty acid, usually monounsaturated in food, in which the hydrogens on both carbons forming the double bond lie on opposite sides of that bond. The trans bond allows the fatty acid backbone to be straighter. Margerine, shortening, fried foods, pastries or flaky bread, chips, and french fries.

Glycerol

A three-carbon alcohol used to form triglyceride.

How is dietary fat absorbed?

Large fat droplets enter small intestine, bile and lecithin emulsify fats into smaller particles, lipase breaks down fats into fatty acids and monoglycerides which are absorbed into the brush border and repackaged into triglycerides. The short and medium chain fatty acids enter the bloodstream while triglycerides combine with protein, cholesterol, and phospholipids form chylomicrons that enter the lymphatic system.

Foam cells

Lipid-loaded white blood cells that have surrounded large amounts of fatty substance, usually cholesterol, on blood vessel walls.

VLDL

Lipoprotein containing mainly triglycerides that carries lipids made and taken up by the liver to cells.

Chylomicrons

Lipoprotein containing mainly triglycerides that carry dietary fat from the small intestine to cells.

LDL

Lipoprotein in blood containing mainly cholesterol; elevated levels of this is linked to large risk for cardiovascular disease.

HDL

Lipoprotein in blood that picks up cholesterol from dying cells and other sources, and transfers it to the liver, or other lipoproteins in the blood stream for excretion. Low levels of this increases risk of cardiovascular disease.

rancid

containing products of decomposed fatty acids that have an unpleasant flavor or odor.

Monoglyceride

A breakdown product of triglyceride consisting of one fatty acid attached to a glycerol backbone.

Diglyceride

A breakdown product of triglyceride consisting of two fatty acids bonded to a glycerol backbone.

Atherosclerosis

A buildup of fatty material in the arteries, including those surrounding the heart.

Plaque

A cholesterol-rich substance deposited into blood vessels containing various white blood cells, smooth muscle cells, proteins, cholesterol and other lipids and calcium.

Sterol

A compound containing a multi-ring (steroid) structure and a hydroxyl (-OH) group. Cholesterol is a typical example.

Lipoproteins

A compound in the bloodstream containing a core of lipids with a shell of protein, phospholipid, and cholesterol that serve as a vehicle for transporting lipids from the small intestine and liver to the body tissues. Chylomicrons, VLDL, HDL, LDL

Emulsifier

A compound that can suspend fat in water by isolating individual fat droplets, using a shell of water molecules or other substances to prevent the fat from coalescing.

Oxidize

An electron that has been lost, or an oxygen that has been gained by a chemical substance. This typically alters the shape and/or function of the substance.

Lipoprotein Lipase

An enzyme attached to the cells that form the inner lining of blood vessels; breaks down triglycerides into free fatty acids and glycerol.

Omega-6 Fatty Acid

An unsaturated fatty acid with the first double bond on the sixth carbon from the methyl end. Linoleic acid is one of these.

Omega-3 Fatty Acid

An unsaturated fatty acid with the first double bond on the third carbon from the omega (methyl) end. Alpha-linolenic acid is one of these. Increased uptake of this reduces inflammation and reduces the formation of blood clots.

Phospholipid

Any of a class of fat-related substances that contain phosphorous, fatty acids, and a nitrogen-containing base. It is an essential part of any cell that participates in fat digestion, transport, and absorption.

Lipase

Fat-digesting enzyme produced by the salivary glands, stomach, and pancreas.

Essential fatty acids

Fatty acids that must be supplied by the diet to maintain health. Only linolenic acid and alpha-linolenic acid are considered essential.

Lecithin

Phospholipid; A group of compounds that are major components of cell membranes.

Scavenger cells

Specific forms of white blood cells that bury themselves in artery walls and accumulate LDL. They contribute to the development of atherosclerosis.

Hydrogenation

The addition of hydrogen to a carbon-carbon double bond which produces a single carbon-carbon bond with two hydrogens attached to each carbon. As a result, trans fatty acids are increased and the molecular shape resembles that of saturated fats.

Triglyceride

The majority of lipids in the body and in food composed of three fatty acids bonded to glycerol. Provides insulation, transports fat-soluble vitamins, and energy storage.

Cholesterol

The most common type of sterol that does not have a glycerol backbone or any fatty acids like triglycerides, but it is classified as a lipid because it dissolves in water. Functions include the synthesis of certain bile acids, incorporation into cell structure, and synthesis of certain hormones.

Systolic blood pressure

The pressure in the arterial blood vessels associated with the pumping of the blood from the heart.

Diastolic blood pressure

The pressure in the arterial blood vessels when the heart is between beats.

How are fats digested?

The stomach secretes lipase which acts mainly on short-chain fatty acids. Bile from the gallbladder acts as an emulsifier on the product of lipase action. Pancreatic lipase digests the long-chain fatty acids and triglycerides. In the small intestine, fatty acids and monoglycerides absorb into the walls of the small intestine and filters through to the portal vein to the liver, or enters circulation via the lymphatic system.

BHA and BHT

Two common synthetic antioxidants added to food.