Mechanism
Synthesis from 4 studies
What the hen eats becomes the fat in her eggs because her body takes those fats from her food, sends them to her liver, and packs them into transport particles that go straight into the egg yolk. Her liver can also turn some fats into longer versions, and antioxidants in her diet help protect those...
Most probable mechanism
When a hen eats food containing specific fats, those fats are taken up by her intestines, sent to her liver, and packaged into special transport particles that deliver them directly to the developing egg yolk, changing the fat composition of the egg to match what she ate.
Dietary fatty acids are absorbed intact in the small intestine without significant modification by gut microbes or enzymatic hydrogenation
Absorbed fatty acids enter the bloodstream and are transported to the liver
In the liver, fatty acids are incorporated into triglycerides and phospholipids and packaged into very-low-density lipoproteins (VLDL)
VLDL particles carrying dietary fatty acids are taken up by the developing oocyte during vitellogenesis
Fatty acids are deposited directly into egg yolk lipids, altering the yolk's fatty acid profile to match the dietary input
Less supported by current evidence, but not ruled out
Some of the omega-3 fat the hen eats is converted in her liver into longer-chain omega-3 fats, which are then sent to the egg yolk, increasing those specific fats in the egg.
Alpha-linolenic acid from the diet is transported to the liver
Liver enzymes elongate and desaturate alpha-linolenic acid to produce eicosapentaenoic acid and docosahexaenoic acid
Eicosapentaenoic acid and docosahexaenoic acid are incorporated into lipoproteins and delivered to the developing oocyte
Long-chain n-3 PUFAs are deposited into egg yolk lipids, increasing their concentration beyond dietary input levels
Selenium in the hen's diet boosts an enzyme that protects fats in the egg yolk from damage, which helps maintain higher levels of healthy omega-3 fats and lowers the ratio of unhealthy to healthy fats.
Selenium from the diet is absorbed and incorporated into glutathione peroxidase in the liver and yolk
Glutathione peroxidase reduces lipid hydroperoxides, preventing oxidative breakdown of polyunsaturated fatty acids
Oxidative preservation of n-3 PUFAs occurs preferentially due to their higher susceptibility to peroxidation
Reduced degradation of n-3 PUFAs and altered prostaglandin metabolism lower the n-6/n-3 fatty acid ratio in the yolk
Taurine in the hen's diet changes how her liver handles fats, increasing the production of certain healthy fats and reducing cholesterol, which alters the fat profile of the egg yolk.
Taurine enters hepatocytes and upregulates expression of enzymes involved in fatty acid desaturation and elongation
Increased activity of desaturase enzymes elevates hepatic production of C18-3n and C18-2n polyunsaturated fatty acids
Taurine suppresses cholesterol synthesis by downregulating SREBP2 and HMGCR, reducing hepatic cholesterol production
Taurine enhances cholesterol excretion via ABCG5 and esterification via ACAT2, reducing free cholesterol available for yolk deposition
Elevated polyunsaturated fatty acids and reduced cholesterol are packaged into lipoproteins and deposited into the egg yolk
Evidence from Studies
Supporting (4)
Community contributions welcome
Supplementing Sacha Inchi (Plukenetia volubilis) Oil in Laying Hen Diets: Influences on Production Performance, Egg Quality and Fatty Acid Profile
Dietary Inclusion of Linseed (Linum usitatissimum) Oil on Fatty Acid Profile of Egg Yolk in Layer Chicken
Effects of dietary taurine supplementation on polyunsaturated fatty acids, cholesterol, and egg quality of egg of hens
Contradicting (0)
Community contributions welcome
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.