Hens that eat grass and plants lay eggs with more yellow-orange color and more of a plant-based vitamin called K1, which you won’t find in regular eggs.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Causally link pasture access to increased carotenoid and vitamin K1 deposition in eggs.
A randomized controlled trial with 300 hens split into three groups: indoor control, indoor with carotenoid-supplemented feed, and outdoor with pasture access (same feed), measuring egg yolk carotenoids and K1 monthly for 4 months using HPLC and LC-MS/MS.
Determine how seasonal changes in pasture affect carotenoid and K1 levels in eggs over time.
A 12-month prospective cohort study of 10 pasture-raised farms, collecting monthly egg and pasture samples to analyze carotenoid and K1 levels and correlate with vegetation composition.
Estimate the current difference in carotenoid and K1 levels between pasture-raised and non-pasture eggs in the market.
A cross-sectional study analyzing 200 egg samples from US retailers, categorized by production system, measuring total carotenoids via spectrophotometry and vitamin K1 via LC-MS/MS.