Hickman says that the Leghorn breed is more popular among many farmers because they are very efficient at laying eggs. In breeds that produce colored eggshells, the chickens are typically larger and require more feed and energy to produce eggs. In other words, the chicken breed that lays brown eggs costs more to feed so the eggs are more expensive at the store.
Malina Linkas Malkani, MS, RD, CDN, media spokesperson for the Academy of Nutrition and Dietetics also chimes in about the nutritional makeup and how you can determine it by the shell color alone. “Choosing between brown and white eggs is a matter of personal preference,” she says. “But it’s important for people to know that the color of the eggshell is related to the breed of the hen, not the egg’s nutrient content, flavor profile, quality, or shell thickness.”

According to Malkani, who created the Wholitarian™ Lifestyle, the nutrient content of the egg is determined by the diet of the hen that laid the egg. If hens are fed a diet high in Omega threes and vitamin D, they will have more of those specific nutrients in the eggs that they lay.
I guess you really can’t judge a book by its cover, or at least an egg by its shell.