The Sainsbury’s Egg Mystery: Why Your Next Carton Might Look Completely Different

Retailer Sainsbury’s has pledged to stop selling brown eggs under their own brand as part of their sustainability program, moving to white-shelled versions instead.

The second-largest UK supermarket chain cited animal welfare and carbon emissions when announcing the decision.

But why don’t white and brown eggs have the same environmental impact, and why are eggshells different colours to begin with?

An assessment by SAC Consulting for Sainsbury’s found that brown eggs have a 12.7% higher carbon footprint than white eggs, as the hens that produce brown eggs are larger and eat more food.

Sainsbury’s said the change would therefore “indirectly reduce demand on land and water used to grow feed crops, as well as the amount of manure produced” by the chickens.

Chicken manure emits greenhouse gases, methane and nitrous oxide as well as ammonia, which can have “detrimental impacts on the environment and… animal and human health”, per Aberystwyth University’s Farming Connect.

“White‑feathered hens typically live longer, eat less feed and lay eggs for longer, cutting carbon emissions by over 12 per cent compared with hens that lay brown eggs,” the supermarket continued.

Sainsbury’s also says that the breeds which produce brown eggs are more likely to experience feather pecking (a stressful and sometimes dangerous process in which birds peck the feathers of other birds) than those which make white eggs.

The company hopes this will help them to meet their goals to meet net zero within their own operations by 2035, and across their suppliers by 2050.

“White eggs have the same delicious taste and nutritional benefits as their brown counterparts, but result in lower emissions and better welfare outcomes for the hens that lay them,” a Sainsbury’s spokesperson said.

Speaking to HuffPost previously, Jacquie Jacob from the University of Kentucky’s department of animal and food sciences said that all eggs start off white.

For a brown egg, “At the very end of the shell-making process, the pigment gets added, almost like you’re painting a house,” she explained.

But some hens are “just not genetically programmed to do that”.

It takes more energy to produce the pigmented layer of the brown-shelled egg, she added.

In short, no. Healthline writes that all eggs are nutritionally pretty similar, no matter their size or colour.

In fact, the Retail Gazette said, white eggs were the norm in the UK until about the ’70s, “before brown eggs became dominant as shoppers increasingly associated them with being healthier or more natural”.

They add that the UK supermarket might have a bit of an issue: the British Egg Industry Council said white-egg-laying hens make up about 15% of our flocks, compared to the US, whereas white eggs account for 75% of all eggs consumed in the US.