Vegetable oil that has been modified by the addition of hydrogen. Hydrogenation is an industrial process that adds hydrogen atoms to double bonds of oils, polyunsat-urated FATTY ACIDS. Hydrogenation creates a more saturated FAT (filled up with hydrogen atoms) and thus hardens or solidifies vegetable oils. Most commercially available polyunsaturated oils (CORN OIL, SOYBEAN OIL, SAFFLOWER oil, SUNFLOWER oil, and COTTONSEED OIL) are partially hydrogenated to retard rancidity, to increase shelf-life, and to make them thicker and more spreadable.
The degree of hydrogenation varies with the type of product. Solid fats like stick MARGARINE and vegetable SHORTENING are the most hydrogenated. Vegetable shortening is highly hydrogenated vegetable oil, the equivalent to LARD, although less saturated than BEEF TALLOW. Tub margarine is made of partially hydrogenated oils and is 20 percent saturated. However, it is much less saturated than BUTTER, which is 66 percent saturated. Partially hydrogenated vegetable oils are somewhat more saturated than untreated oils. For example, soybean oil is initially 15 percent saturated and ends up 20 percent saturated after partial hydro-genation.
During hydrogenation some of the polyunsatu-rated fatty acid content is converted to monounsat-urates with a single double bond instead of multiple double bonds. Also during hydrogenation,
a fraction of the polyunsaturated fatty acids are converted to TRANS-FATTY ACIDS, in which some of the existing double bonds straighten. Trans-fatty acids raise cholesterol levels and are associated with an increase in the risk of heart attack. Whether the risk is greater than with saturated fats is unknown. Hydrogenated vegetable oil supplies 80 percent of the trans-fatty acids Americans ingest. The long-range health effects of these industrial by-products are unknown.
Partially hydrogenated vegetable oils, including soybean, cottonseed, corn, and rapeseed oils, are commonly added to increase the flavor and taste of processed foods. Foods with partially hydrogenated or hydrogenated vegetable oils include foods such as most kinds of CHIPS (potato chips, corn chips, and the like), CRACKERS, rye crisps, margarines, shortening, frozen pizzas, salad dressing, low-cholesterol MAYONNAISE, and even FROZEN ENTREES. Food labels presently list fat content and often use the term PARTIALLY HYDROGENATED OIL without further explanation, which provides little detailed information. Nonetheless, added oil indicates added calories. The general recommendation is to cut back on all fats and oils to lower the risk of cancer and heart disease. Eating an excess of saturated fat, whether it is animal fat or hydrogenated vegetable oil, increases the risk of CARDIOVASCULAR DISEASE.