Profile of fatty acid lipid fractions of omega-3 fatty acid-enriched table eggs

The omega-3 fatty acid (FA) enrichment of yolk is a key means one of the main objectives to improve the nutraceutical properties of eggs. We evaluated the effect of the dietary inclusion of extruded linseed fed to laying hens on the fatty acid composition of the polar and non-polar lipid classes of the eggs. Two groups of 36 Lohmann White Leghorn layers (65 weeks old) were each fed one of two different diets for a period of 12 weeks. The two diets consisted of a conventional cereal-based diet concentrate (C) and a diet concentrate containing 5% linseed (L). The inclusion of linseed in the diet increased the content of α-linolenic (C18:3n-3), eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids in neutral lipids, while a concomitant decrease in arachidonic acid (C20:4n-6) was observed. As regards the polar fraction, the fatty acid composition was slightly affected by the dietary treatments except for C18:0 (+1.14 fold), C18:2n-6 (+1.23 fold), C18:3n-3 (+2.8 fold) and C22:6n-3 (+1.41 fold). Principal component analysis demonstrated that very long-chain FAs were more representative of polar lipids, except for C20:5n-3, while neutral lipids were characterized by dietary n-3 FA (C18:3n-3)

Dietary linseed supplementation affects the fatty acid composition of the sn-2 position of triglycerides in sheep milk

In the human intestine, lipids are absorbed as sn-2 monoglycerides (sn-2, also named β-position), produced mainly by pancreatic lipases, which hydrolysate the triglyceride molecule in positions 1 and 3 (sn-1,3, α-position). The fatty acids esterified in sn-2 are thus preferentially absorbed, which means that the bioavailability of a single fatty acid is affected by its position on the triglyceride. This experiment is carried out with the milk used to make cheese applied in a study with 42 human volunteers. In that study the authors detected an improvement in the blood lipid profile. The aim of the present study was to examine the effectiveness of this kind of cheese in improving human health by studying how linseed supplementation affects the milk fatty acid composition of the 3 different triglyceride positions and thus the fatty acid bioavailability. The sn-2 were obtained by reacting total milk lipids with swine pancreatic lipase. The milk came from 24 sheep fed a control diet and 24 sheep fed a diet containing 200 g of extruded linseed per day. The sn-2 were separated by thin-layer chromatography. The fatty acid composition of total lipids and sn-2 was obtained by a gas chromatography-flame ionization detector apparatus equipped with a high polar 100 m length capillary column. The bioavailability of the fatty acids was evaluated by a putative preferential intestinal absorption index (PPIAi), where PPIAi 0 indicated a preferential intestinal absorption. With regard to the fatty acid composition of triglycerides, the linseed group showed a significantly higher content of both linolenic acid and rumenic acid compared with the control. As a consequence of linseed supplementation, the linolenic and rumenic acid content esterified in the β-position increased greatly. This was highlighted by the PPIAi. The results of the present study suggest that the linolenic acid and conjugated linoleic acid affinity for lyso-phosphatidic acid acyl-transferase increased with its tissue availability