Postprandial lipid responses to an alpha-linolenic acid-rich oil, olive oil and butter in women: A randomized crossover trial

January 1, 2011 Human Health and Nutrition Data 0 Comments

Postprandial lipid responses to an alpha-linolenic acid-rich oil, olive oil and butter in women: A randomized crossover trial

Year: 2011
Authors: Svensson, J. Rosenquist, A. Ohlsson, L.
Publication Name: Lipids in Health and Disease
Publication Details: Volume 10; Pages 106 – 115.


Postprandial lipaemia varies with gender and the composition of dietary fat due to the partitioning of fatty acids between beta-oxidation and incorporation into triacylglycerols (TAGs). Increasing evidence highlights the importance of postprandial measurements to evaluate atherogenic risk. Postprandial effects of alpha-linolenic acid (ALA) in women are poorly characterized. We therefore studied the postprandial lipid response of women to an ALA rich oil in comparison with olive oil and butter, and characterized the fatty acid composition of total lipids, TAGs, and non-esterified fatty acids (NEFAs) in plasma. A randomized crossover design (n of 19) was used to compare the postprandial effects of 3 meals containing 35 g fat. Blood samples were collected at regular intervals for 7 h. Statistical analysis was carried out with ANOVA (significant difference,  P < 0.05). No significant difference was seen in incremental area under the curve (iAUC) plasma-TAG between the meals. ALA and oleic acid levels were significantly increased in plasma after ALA rich oil and olive oil meals, respectively. Palmitic acid was significantly increased in plasma TAG after the butter meal. The ratios of 18:2 n6 to18:3 n3 in plasma-TAGs, three and seven hours after the ALA rich oil meal, were 1.5 and 2.4, respectively. The corresponding values after the olive oil meal were: 13.8 and 16.9; and after the butter meal: 9.0 and 11.6. The postprandial pTAG and NEFA response in healthy pre-menopausal women was not significantly different after the intake of an ALA rich oil, olive oil and butter. The ALA-rich oil significantly affected different plasma lipid fractions and improved the ratio of n-6 to n3 fatty acids several hours postprandially. (Authors abstract)
Increased postprandial plasma triacylglycerol (TAG) levels have been shown to increase the risk of cardiovascular disease (CVD) in women more than in men and since most of the day is spent in the postprandial state, it is important to characterize the ways in which different dietary fatty acids (FAs) influence postprandial lipaemia. Excess intake of fat, or calories in general, over a long period of time can lead to elevated levels of circulating triacylglycerol-rich lipoproteins (TRLs), especially very-low-density lipoprotein (VLDL) particles and remnants. High levels and prolonged circulation of TRLs are considered atherosclerotic risk factors for cardiovascular disease. The postprandial effect of different fatty acids may be ascribed to their variety in rate of oxidation, which in turn depends on chain length and degree of unsaturation. Men have an increased predisposition to mobilise FAs from visceral adipose tissue, but also have a higher FA uptake in these regions than women. Men and women also secrete different amounts and sizes of TRLs from the liver. Women are more prone to store and/or convert ALA to long-chain polyunsaturated FAs PUFAs. In this study, a new oil rich in ALA (ALA rich oil), which has high contents of ALA and oleic acid was produced by the enzymatic interesterification of linseed (flaxseed) and rapeseed (canola) oil.  In this study, the postprandial plasma lipid responses in healthy pre-menopausal women after meals containing the new ALA-rich oil, butter, and olive oil was investigated. The iAUC p-TAG responses after the ALA-rich oil and olive oil were approximately in the same magnitude. For the majority of the women the postprandial pTAG concentrations were within the normal range (0.45 to 2.6 mmol/L) at all times after the test meals, which provided 0.75 g fat/kg body weight. This shows that the clearance rate of pTAG is more efficient in women than in men. Estrogens and androgens may in part be responsible for the differences in lipid metabolism in men and women. The results suggest that the intake of ALA rich oil has a denoted influence on the composition of pNEFAs compared to the other meals.  After the ALA rich oil, ALA partitioned more to pTAG than to NEFA.  After the ALA rich oil meal, the iAUCs of FAs were in the order: oleic acid > ALA > palmitic acid, which corresponds to the composition of the ALA rich oil.  Subjective measures of hunger, fullness, and desire to eat using a VAS showed no difference in any of the parameters for the different meals. The authors suggest that future studies should also include quantitative analysis of the distribution, size and amount of the TRL particles, Apo B-48, and Apo B-100, to more accurately evaluate the atherogenic risk. Investigations into whether the consumption of the new ALA rich oil could affect markers of inflammation in subjects with chronic inflammatory diseases, such as obesity and atherogenesis, also appear warranted. Future food products containing an ALA rich oil can significantly affect plasma lipids and improve the n6/n3 FA ratio several hours postprandially, and thus form part of a healthy diet. (Editors comments)

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