Poster présenté par Anthony Sehl de l’équipe Nutrition Métabolisme & Santé de l’ITERG, lors de la 57ème Conférence ICBL (International Conference on the Bioscience of Lipids), 5-8 septembre 2016, Chamonix
Anthony Sehl, Laurence Fonseca, Leslie Couëdelo, Carole Vaysse, ITERG
Background : Because of their high content of alpha-linolenic acid (18:3 n-3 ; ALA), linolenic oils (such as flaxseed or rapeseed oils) may have beneficial health effects, in particular for the prevention of cardiovascular diseases. According recent epidemiological studies, consumption of ALA is nearly two times lower than the recommendations, suggesting the necessity to improve ALA bioavailability without increasing lipid intake. Our previous work has shown that the emulsification of linolenic oil with phospholipids (PL) could improve the lymphatic bioavailability of ALA. However, the relationship between the increase of lymphatic bioavailability and the hepatic bioconversion into EPA and DHA need to be confirmed.
Aim : The objective of this study is to determine whether the positive effect of the emulsification on the ALA intestinal bioavailability is preserved in the plasma during a several day diet and could impact the hepatic metabolism of ALA.
Methods : After 1 week of acclimatization to the housing conditions with a standard diet deprived of omega-3, wistar adult male rats (n = 20 rats/group) received for 10 days a normolipidic diet, where lipids were administered by gastric intubation, with one of three experimental formulas 1) flaxseed oil 2) flaxseed oil not emulsified, added to 8% soybean lecithin, 3) flaxseed oil emulsified with 8% soybean lecithin. The ALA intake was similar between all experimental groups.
Results and Discussion : Data showed a decrease in ALA levels in plasma and liver TG when flaxseed oil contained PL (without emulsification). On the other hand, EPA proportions in plasma and liver PL were lower when rats received emulsified flaxseed oil.
Moreover, our results reveal similar activities and protein expression of Δ6-desaturase regardless of the administered diet. Whereas, the protein expression level of the Δ5-desaturase is lower in rats fed with emulsified flaxseed oil (versus not emulsified oil added with PL). Even if the emulsification improves the intestinal absorption of ALA, the accretion of this FA in plasma and liver and its bioconversion into EPA seems to be limited, after a short term intake of emulsified flaxseed oil. These results suggest that the emulsified form could promote an increase of ALA oxidation to the detriment of its conversion into long chain PUFA.