Chapter 23 - Nutritional Aspects of Soybean Oil and Soy Proteins

Abstract

In normal individuals, typical edible fats and oils are digested and absorbed to a high degree. Soybeans have an oil content of about 20% on a dry weight basis. Soybean Oil (SBO) is the major edible oil used in the United States for producing salad dressings, baking and frying fats, margarines, and salad and cooking oils. Refined SBO is composed of approximately 98% triglycerides, less than 1% free fatty acids, and less than 1% unsaponifiables. SBO is composed of Polyunsaturated Fatty Acids (PUFA), Monounsaturated Fatty Acids (MUFA), and Saturated Fatty Acids (SAFA). The amount of total fat in the diet and degree of Fatty Acid (FA) unsaturation has a significant effect on normal immune response and on the expression of inflammatory diseases. The n-6 PUFAs (EFA) are necessary for normal immune function by virtue of the arachidonic acid metabolites, prostaglandins, leukotrienes and other bioactive eicosenoids, which regulate a broad range of cell mediated immune responses. Another component of soybeans that appears to have positive nutritional effects is isolated soy protein. The independent cholesterol-lowering effects of soy protein have been known for years. Recently, however, it has been demonstrated that significant reductions in plasma cholesterol can be achieved in moderately hypercholesterolemic individuals with reasonable levels of soy protein and provided in nutritionally acceptable food products.