The Queen of Fats: Why Omega-3s Were Removed from the Western Diet and What We Can Do to Replace Them

GLOSSARY

GLOSSARY ACYLTRANSFERASES—The enzymes responsible for assembling phospholipids . ALPHA LINOLENIC ACID (ALA)—An eighteen-carbon fatty acid that is the parent of the essential omega-3 family of fats; plants use it in photosynthesis and in the formation of cell messengers. It is therefore found mostly in green leaves and is the most abundant fat on the planet. Only plants can turn linoleic acid into alpha linolenic acid (by adding a double bond), but most animals, including humans, can turn alpha linolenic acid into the longer and more desaturated eicosapentaenoic acid and DHA. See linoleic acid. 159 C—C—C—C—C—C—C—C—C—C—C—C—C—C—C—C—C—C—H O HO H H H H H H H H H H H H H H H H H H H H H H H H H H H H ANTIOXIDANTS—Naturally occurring compounds that neutralize free radicals (see below) before they can cause cell damage. ARACHIDONIC ACID (abbreviated AA, or sometimes ARA)—A twentycarbon omega-6 fatty acid, found throughout the body, that is the source of the most potent and inflammatory eicosanoids. Most ani- mals, including humans, can make AA from linoleic acid. It can also be consumed ready-made; foods particularly rich in AA are meats and other animal products. ARRHYTHMIA—A disturbance in the coordinated rhythmic contraction of the heart muscle. CANOLA OIL—A vegetable oil developed in Canada during the late 1960s and early 1970s and introduced into the United States in 1985. Canola oil is extracted from a hybrid form of rapeseed that is very low in erucic acid, a twenty-two-carbon monounsaturated fatty acid that had been found to cause fatty deposits in the hearts of test animals. Most rapeseed contains more than 30 percent erucic acid, but the kind used to make canola oil has only 0.3 to 1.2 percent. Canola oil gets its name from a melding of Canada and oil; it is also called LEAR (low erucic acid rapeseed) oil. It is known for having a significant alpha linolenic acid content (and for being low in saturates and high in monounsaturates), but none of these attributes is fixed; and, as is also true of soy and other oil seeds, new varieties of canola are being developed all the time. CHLOROPLASTS—Specialized structures within plant cells that contain stacks and stacks of membranes in which the many proteins involved in photosynthesis are embedded. The membrane, called the thylacoid membrane, is the most abundant thing on the planet. Thus its major fat, alpha linolenic acid, is the most abundant fat. Shown below is an electromicrograph of one of the many chloroplasts in a cell from the leaf of a tobacco plant (Nicotiana tobacum), courtesy of Richard McAvoy and Mariya Khodakovskaya. 160 GLOSSARY CIS CONFORMATION—A double bond in which the two hydrogens are on the same side, thus forming a kink or bend in the molecule that dramatically lowers its melting point (the temperature at which it goes from being a solid to a liquid). In most naturally occurring fats, all the double bonds are in the cis conformation. GLOSSARY 161 DESATURASES—Enzymes that introduce double bonds into specific sites on fatty acids. Only plants have the delta-12 and the delta-15 desaturases that can turn oleic acid into linoleic acid and linoleic acid into alpha linolenic acid (by adding double bonds before the twelfth and fifteenth carbons—the sixth and the third, if you count backward ). Animals (and some plants) have the delta-5, delta-6, and delta9 desaturases. DESATURATION—The removal of hydrogen atoms to create a double bond between two carbons. See unsaturated bonds. DOCOSAHEXAENOIC ACID (DHA)—A twenty-two-carbon omega-3 fatty acid that is found in the largest amounts in a body’s most active tissues : the brain, eyes, and heart. With twenty-two carbons and six double bonds, DHA is the longest, most unsaturated fatty acid in most living things. Most animals, including humans, can make DHA from alpha linolenic acid and eicosapentaenoic acid, or it can be consumed already-made. Foods that are rich in DHA include brains and fish, fish oils, and other seafoods, including some seaweeds. DOUBLE BOND—A chemical bond in which two pairs (rather than a single pair) of electrons are shared between two atoms. When double bonds form between carbon atoms, those carbons do...