After Sainsbury's decision to ditch brown eggs and sell only white eggs, many Brits have been asking whether there is any nutritional difference between the two types and whether the move is a reason to switch their go-to supermarket.

The reasoning behind the chain's decision to switch to white eggs is their alleged 12.7% lower carbon footprint compared with brown eggs, according to Sainsbury's own findings. This is because hens that lay white eggs consume less feed while producing the same number of eggs, reducing the resources required across the supply chain. Feed production accounts for 50–60% of the environmental impact of egg farming.

Britain consumes around 14.5 billion eggs every year, producing an estimated 4.35 million tonnes of carbon dioxide emissions in the process. If the entire industry achieved the same 12.7% reduction claimed by Sainsbury's, emissions could fall by more than 550,000 tonnes of CO2 annually, The Independent reports. That's roughly the same as removing nearly 300,000 cars from Britain's roads.

But what about the difference in quality?

For most of the 20th century, white eggs were the norm in the UK. But in the 1970s, brown eggs became the staple of Britain's middle class and ended up dominating the market. Today, most of the eggs sold are brown, and, as the posh assume, the browner the egg and the more orange the yolk, the better the quality.

In reality, however, there is very little difference between the two coloured eggs, with Sainsbury's stunt appearing to be little more than a clever marketing stunt. In fact, influencer Sunna Van Kampen, known as @tonichealth, claimed in a TikTok post that the distinctive bright orange yolks are not a marker of quality, but rather a result of what the chickens have been fed. Sunna, who has 8.5 million likes on the platform, said: "The reason why your yolks are so dark and orange… is because they feed [the hens] marigold and paprika."

This was confirmed by a 2024 study published by the National Library of Medicine. "We found that paprika improved the color of the egg yolks and affected the hens' blood cholesterol levels in different ways," the study claims. The colour of a yolk is largely determined by pigments known as carotenoids, which occur naturally in things like maize, marigold, peppers and carrots.

The colour of the egg shell is dependent on the breed of the hen. In general, white hens produce white eggs and brown hens produce brown eggs. There is no nutritional difference between white and brown shelled eggs, according to British Lion Eggs.

What is much more important, however, is looking at the code stamped on the shell. Organic eggs carry a 0, free-range eggs a 1, barn eggs a 2 and eggs from caged hens a 3 – though all major supermarkets no longer stock caged hen eggs.

So, neither the shell nor the yolk colour tells you how healthy the hen was or whether the egg will make a better omelette. What it does say, however, is that selling white eggs is much more cost-efficient for a supermarket chain like Sainsbury's. And perhaps a little more environmentally friendly.