Feeding hens a diet with 0.6 mg/kg selenium lowers the ratio of n-6 to n-3 fatty acids in their egg yolks, leading to eggs with a more balanced omega fatty acid profile.
Mechanism
Synthesis from 1 study
Selenium boosts an enzyme that shields the healthy fats in egg yolks from being broken down by oxygen. Because the healthiest fats break down easiest, they are preserved better than others, which lowers the ratio of less healthy fats to healthy ones.
Most probable mechanism
Selenium boosts an enzyme that protects fats in the egg yolk from damage by oxygen, especially the healthy omega-3 fats that break down easily. This protection keeps more omega-3 fats intact and reduces the buildup of damaged fats, which shifts the balance between omega-6 and omega-3 fats toward a healthier ratio.
Dietary selenium is absorbed and incorporated into selenocysteine, the active component of glutathione peroxidase, increasing the enzyme's concentration and catalytic activity in the liver, oviduct, and egg yolk
Elevated glutathione peroxidase activity reduces lipid hydroperoxides in the yolk by converting them to stable alcohols, preventing oxidative chain reactions that degrade polyunsaturated fatty acids
Omega-3 polyunsaturated fatty acids are more susceptible to oxidation than omega-6 fatty acids due to their higher number of double bonds, so their preservation under enhanced antioxidant activity is disproportionately greater
The selective protection of omega-3 fatty acids reduces their loss during yolk formation, while omega-6 fatty acids remain relatively unchanged, resulting in a lower overall n-6/n-3 fatty acid ratio in the egg yolk
Less supported by current evidence, but not ruled out
Selenium may influence enzymes that convert fatty acids into signaling molecules, favoring the production of compounds derived from omega-3 fats over those from omega-6 fats.
Selenium enhances glutathione peroxidase activity, which regulates the availability of arachidonic acid for cyclooxygenase-mediated conversion into prostaglandins
Reduced oxidative stress alters the substrate preference of cyclooxygenase enzymes, increasing the utilization of eicosapentaenoic acid (n-3) over arachidonic acid (n-6)
Increased synthesis of n-3-derived prostaglandins reduces the relative abundance of n-6-derived metabolites, contributing to a lower n-6/n-3 ratio in the yolk
Evidence from Studies
Supporting (1)
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