Adding 10% ahiflower seed or flaxseed to chicken feed increases the alpha-linolenic acid content in egg yolks by more than six times compared to standard feed, without changing the ratio of n-6 to...
Mechanism
Synthesis from 1 study
Flaxseed gives hens a fat called ALA that their liver turns into other omega-3 fats and puts directly into egg yolks, making ALA levels rise more than six times. The total fat and omega-6 to omega-3 balance stay the same because the new omega-3s replace other fats without adding more total fat....
Most probable mechanism
When hens eat flaxseed, a specific fat called ALA enters their body, gets sent to the liver, and is converted into other omega-3 fats that are packed into yolk-building molecules and deposited directly into the egg yolk. This process increases ALA in the yolk more than sixfold without changing the total amount of fats or the balance between omega-6 and omega-3 fats.
Alpha-linolenic acid (ALA) from dietary flaxseed is absorbed in the small intestine and transported to the liver via chylomicrons and plasma lipoproteins
In hepatocytes, ALA competes with linoleic acid for binding to delta-6 desaturase (FADS2), and FADS2 preferentially converts ALA to stearidonic acid due to higher enzyme affinity
Stearidonic acid is elongated and further desaturated by hepatic enzymes to produce eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
EPA and DHA are packaged into very low-density lipoproteins (VLDL) and secreted into systemic circulation
VLDL delivers omega-3 fatty acids to the ovary, where they are incorporated into yolk lipids via vitellogenin uptake during egg formation
The total polyunsaturated fatty acid content remains unchanged because ALA replacement occurs without net increase in total fatty acid influx
The n-6:n-3 ratio remains stable because the increase in ALA and its metabolites is balanced by proportional reduction in n-6 metabolites like arachidonic acid
Less supported by current evidence, but not ruled out
Ahiflower seed provides stearidonic acid, which skips the first conversion step and is directly turned into EPA and DHA in the liver, then deposited into egg yolk without increasing ALA.
Stearidonic acid (SDA) from ahiflower seed is absorbed in the small intestine and transported to the liver via chylomicrons and plasma lipoproteins
SDA bypasses delta-6 desaturase and is directly elongated to eicosapentaenoic acid (EPA) by hepatic elongase enzymes
EPA is further desaturated and elongated to docosahexaenoic acid (DHA) by hepatic enzymes
EPA and DHA are packaged into very low-density lipoproteins (VLDL) and delivered to the ovary for yolk incorporation
ALA levels in yolk remain unchanged because SDA does not convert back to ALA and does not increase ALA synthesis
Evidence from Studies
Supporting (1)
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Contradicting (0)
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