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Nutritional composition of hazelnuts and its effects on glucose and lipid metabolism

Alphan, E., M. Pala, F. Ackurt, T. Yilmaz, 1997.  Nutritional composition of hazelnuts and its effects on glucose and lipid metabolism. In: Kosal AI, Oky Y, Gunes NT, eds. Proceedings of the Fourth International Symposium on Hazelnut. Acta Hort. 445:305-10.

Turkey holds the first place is the world with respect to hazelnut production and export. Besides its economic importance, the high nutritional value of hazelnut makes it a special food. Hazelnuts are rich in protein, complex carbohydrates, dietary fiber, iron, calcium, potassium and vitamin E. Nutritional analyses conducted in our laboratories have revealed a high protein content (16.9%). Its protein quality (66.6%) is also high in comparison to many proteins of plant origin. It appeared to be one of the best sources of plant origin for iron (5.8 mg/100g), calcium (160.0 mg/100 g), and zinc (2.2 mg/100g), which are the most important minerals for growth and development. Hazelnuts were also found to be rich in potassium(655 mg/100g), which is necessary for nerve stimulation and functioning of muscle tissue. Hazelnuts were found to be good sources for vitamins B1 (0.33 mg/100g), and B2 (0.12 mg/100g), and very good sources for vitamin B6 (0.24 mg/100g) and Vitamin E (31.4 mg/100g). VitaminsB2 and B6 are especially important nutrients for the school-age children. The hazelnut is also the second best source of vitamin E after plant oils. This vitamin is essential for the normal functioning of muscle tissue and the reproduction system. It protects the organism against cancer. Vitamin E also prevents the hemolysis of erythrocytes, and thus protects the body against anemia. Chemical and nutritional compositions of hazelnut are shown in table. 1 (Pala et al., 1995).  The average fat content of hazelnuts analyzed in our laboratories was found to be 62.7% and 82% of this high yield was assessed to be oleic acid. This monounsaturated fatty acid was shown by many workers to increase the level of high density lipoprotein (HDL), in blood. HDL, in turns, lowers blood cholesterol and thus protects against atherosclerosis. According to a long term survey conducted in the United States over 20,000 subjects (Loma Linda University, 1990), the risk of death from coronary heart disease is lowered by half in people consuming nuts at least once a day as compared with those who don’t. Because of their chemical and nutritional compositions, hazelnuts have potential beneficial health effects. Diet is a cornerstone of therapy for patients with non-insulin-dependent diabetes mellitus (NIDDM). The goal of diet therapy in patients with diabetes is not only to improve control of hyperglycemia but also to reduce the risk of coronary heart disease by optimizing plasma lipid levels. Currently recommended high carbohydrate, low fat diets increase triglyceride and lower high density lipoprotein (HDL) cholesterol concentrations (Garg et al., 1988; Koskinen et al., 1992