Randomised controlled crossover trial in 49 healthy adults (mean age 56, 40% women): 2 eggs/day vs. an oatmeal breakfast, each for 6 weeks with washout. Flow-mediated dilation (endothelial function) was stable and did not differ between arms; total cholesterol and LDL-C did not change in the egg arm, while the oatmeal arm produced a significant fall in total cholesterol and LDL-C. Shows the comparator (a soluble-fibre breakfast vs. eggs), not eggs per se, drove the observed lipid change — an early demonstration of the substitution-dependence of egg-trial results in a general/healthy population. relevance_note: Null average lipid/endothelial-function response to daily eggs in healthy adults when the true comparator is a cholesterol-lowering alternative breakfast, not a neutral control.