Variability in vitamin D content among eggs sampled from retail outlets in locations across the U.S. (Fig. 1) in 2010. NY location was re-sampled twice within four
months to confirm the value (NY-2 and -3). Error bars show the range for the mean in cases where a sample was analyzed in duplicate. Estimated relative standard deviation
for single values, based on control sample data: vitamin D3, 3.3%; 25-OH vitamin D3, 5.0% (1 mg vitamin D3 = 40 IU).