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Title: Effect of dietary fatty acid structure and composition on postprandial lipid metabolism
Author: Zampelas, Antonios
ISNI:       0000 0001 3576 7293
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1993
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In this thesis effects of dietary fatty acid composition and of positional distribution of fatty acids in dietary TAG, on postprandial lipid and hormone responses, were investigated. A6 week fish oil supplementation period (2.7 g n-3 fatty acids per day) decreased fasting TAG and increased TC (p<0.05) and LDL-C (p<0.05) levels in normal subjects. Postprandial plasma TAG responses to a test meal were also significantly reduced following the fish oil supplementation period (area under the response curves, p<0.001). Apolipoproteins A-I and B responses did not alter in response to chronic fish oil supplementation. Type II diabetics responded differently to normal subjects to fish oil supplementation. Fasting lipid and apolipoprotein levels were not significantly altered, and the postprandial TAG response to a test meal showed a trend towards higher values following the fish oil supplementation period. In the study of effects of dietary TAG structure on postprandial lipid apolipoprotein (A-I, B), hormone (insulin, GIP) and glucose responses, no effect of test meals differing in the positional distribution of palmitic acid at the sn-2 or the sn-3 positions of the TAG molecule were seen. In a study of acute effects of dietary fatty acid composition in healthy male subjects, a fish oil test meal (40 g fish oil concentrate), significantly reduced plasma TAG postprandial responses compared with a mixed oil meal (containing 40 g of a mixture of oils high in SFA and mimicking the current U. K. dietary fat intake), p<0.05. Post-heparin LPL activity was also significantly increased 12 hours following the fish oil test meal (p<0.01). A 40 g corn oil test meal did not have any significant effect on postprandial lipid, hormone (insulin and GIP), and retinyl palmitate levels (the latter was administered with each test meal-700 I. U. /kg of body weight) compared with the other two test meals. A feeding study, using a rat model, showed that following two weeks of a fish oil diet (5%, w/w) the postprandial incorporation of [U-t4C]glucose into hepatic total lipids and TAG measured in vitro, was significantly reduced compared with rates measured in animals on a mixed oil diet (p<0.05). In the presence of the two anabolic hormones, insulin and GIP, in vitro rates of hepatic cholesterogenesis increased (p<0.05), and these effects of hormones were independent of the type of the diet fed. In addition, plasma TAG levels were significantly lower in the fish oil group compared with levels in the mixed oil and corn oil dietary groups (p<0.05), and plasma insulin levels were significantly higher in the mixed oil dietary group than in the other two groups (p<0.001).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Biochemistry Biochemistry Human physiology