Dietary Triglyceride Structure Affects lipid and Glucose Metabolism in Gerbils. - (:unkn) unknown (Petaling Jaya : MPOB, 2005)
Interesterified fats are increasingly used in the food industry as substitutes for partially hydrogenated fats high in trans fatty acids (TFA), which negatively impact CHD risk (1, 2). In the interesterification process fully hydrogenated vegetable oils, which are rich in stearic acid, are interesterified with unhydrogenated oils. This results in interesterified (IE) fat blends with altered positional distribution of fatty acids especially higher proportion of SFA in sn-2 position compared to natural oils. Studies have shown that positional distribution of fatty acids in dietary triglyceride (TG) may alter their metabolism. Palmitic acid in the sn-2 position has been shown to enhance fat and palmitic acid absorption in rats (3) and human infants (4), adversely affect lipoproteins in infants (5), and increase atherosclerosis in rabbits (6). However, fat blends with modest amounts of IE palmitic acid in sn-2 position compared to natural fat blends were not found to affect plasma TC or other lipid parameters in human adults (7, 8). Sanders et al (9) reported that randomization of stearic acid rich cocoa butter resulted in decreased postprandial TG factor VII response compared to native cocoa butter, suggesting that higher stearic acid in sn-2 position improved the postprandial lipid response. Similarly, IE palm oil (with higher sn-2 palmitic acid) was also shown to decrease postprandial plasma TG compared to native palm oil (10). However, other studies have indicated that IE fats may have some undesirable health effects (11,12). Baer et al (11) reported that a diet rich in IE stearic acid derived from fully hydrogenated soybean oil (FHSBO) increased plasma fibrinogen, IL-6, and E-selectin concentrations compared to a diet rich in oleic acid, indicating increased inflammation with the IE - 18:0 diet. Further, Sundram et al (12) recently found that a high stearate IE fat blend of FHSBO and SBO resulted in increased postprandial glucose levels and fasting plasma LDL-C/HDL-C levels compared to a natural palm olein enriched diet. In many of these studies fatty acid composition of the diets were different in addition to changes in positional distribution of fatty acids, thus making it difficult to discern the effects of TG molecular structure. Further, very few studies have examined the long term effects of IE fats on glucose/insulin metabolism and type 11 diabetes risk. In the present study we investigated the effects of IE fats and partially hydrogenated trans fatty acids on lipid and glucose metabolism in gerbils, while keeping the fatty acid composition of diets similar. We also tested the hypothesis that the hypercholesterolemic effects of TFA would be influenced by dietary linoleic acid intake. Gerbils are extremely sensitive to dietary fatty acid manipulations (13) and therefore present an excellent model to study the effects of TG structure and TFA.
Interesterified fats are increasingly used in the food industry as substitutes for partially hydrogenated fats high in trans fatty acids (TFA), which negatively impact CHD risk (1, 2). In the interesterification process fully hydrogenated vegetable oils, which are rich in stearic acid, are interesterified with unhydrogenated oils. This results in interesterified (IE) fat blends with altered positional distribution of fatty acids especially higher proportion of SFA in sn-2 position compared to natural oils. Studies have shown that positional distribution of fatty acids in dietary triglyceride (TG) may alter their metabolism. Palmitic acid in the sn-2 position has been shown to enhance fat and palmitic acid absorption in rats (3) and human infants (4), adversely affect lipoproteins in infants (5), and increase atherosclerosis in rabbits (6). However, fat blends with modest amounts of IE palmitic acid in sn-2 position compared to natural fat blends were not found to affect plasma TC or other lipid parameters in human adults (7, 8). Sanders et al (9) reported that randomization of stearic acid rich cocoa butter resulted in decreased postprandial TG factor VII response compared to native cocoa butter, suggesting that higher stearic acid in sn-2 position improved the postprandial lipid response. Similarly, IE palm oil (with higher sn-2 palmitic acid) was also shown to decrease postprandial plasma TG compared to native palm oil (10). However, other studies have indicated that IE fats may have some undesirable health effects (11,12). Baer et al (11) reported that a diet rich in IE stearic acid derived from fully hydrogenated soybean oil (FHSBO) increased plasma fibrinogen, IL-6, and E-selectin concentrations compared to a diet rich in oleic acid, indicating increased inflammation with the IE - 18:0 diet. Further, Sundram et al (12) recently found that a high stearate IE fat blend of FHSBO and SBO resulted in increased postprandial glucose levels and fasting plasma LDL-C/HDL-C levels compared to a natural palm olein enriched diet. In many of these studies fatty acid composition of the diets were different in addition to changes in positional distribution of fatty acids, thus making it difficult to discern the effects of TG molecular structure. Further, very few studies have examined the long term effects of IE fats on glucose/insulin metabolism and type 11 diabetes risk. In the present study we investigated the effects of IE fats and partially hydrogenated trans fatty acids on lipid and glucose metabolism in gerbils, while keeping the fatty acid composition of diets similar. We also tested the hypothesis that the hypercholesterolemic effects of TFA would be influenced by dietary linoleic acid intake. Gerbils are extremely sensitive to dietary fatty acid manipulations (13) and therefore present an excellent model to study the effects of TG structure and TFA.
Keywords: Acido graso trans; Ácidos grasos saturados.; Alimentación de los animales.; interesterificación; Lipidos plasmaticos; Metabolismo de lípidos.; Triglicéridos.