Researchers are also increasingly interested in eggs’ naturally high choline content – a nutrient linked to brain development and cognitive function. Emerging research suggests eggs may play a particularly important role during pregnancy, childhood and adolescence, although scientists say more research is still needed.

Eggs are versatile, convenient and filling, making them an easy protein option for breakfasts, sandwiches, salads and quick dinners.

The cholesterol question

For years, eggs were treated with suspicion because yolks naturally contain cholesterol. Older advice often suggested limiting intake to three eggs a week.

But nutrition science has shifted considerably.

“We now know that saturated fat has a greater effect on blood cholesterol than the cholesterol from eggs, for most people,” Sekula says.

The Heart Foundation no longer recommends the old blanket limit of three eggs weekly for healthy people. Instead, the focus has shifted towards overall dietary patterns – particularly limiting heavily processed foods high in saturated fat.

That said, eggs are not entirely consequence-free for everyone. Some people are considered “hyper-responders”, meaning dietary cholesterol has a greater impact on their blood cholesterol levels. Those with existing heart disease or certain medical conditions may still be advised to moderate intake.

For people at increased risk of heart disease, the Heart Foundation advises up to six eggs per week as part of a healthy diet.

What do all the supermarket labels actually mean?

One of the biggest misconceptions around eggs is that more expensive automatically means more nutritious.

In reality, the nutritional differences between standard supermarket eggs are relatively small.

The main distinctions between colony, barn and free-range eggs relate more to farming systems, animal welfare and price than major changes in protein or vitamin content.

Here’s what the common labels mean in practice:

Colony eggs: Hens live indoors in colony housing systems with more room and enrichment features like perches and nesting areas. Conventional battery cages have now been phased out in New Zealand.

Barn eggs: Hens roam freely inside large barns with perches, scratching areas and nesting boxes, but do not go outdoors.

Free-range eggs: Hens have indoor shelter plus access to outdoor areas.

Organic eggs: Usually free range, with additional requirements around organic feed and farming standards.

So if free-range eggs aren’t significantly healthier, why do many shoppers still buy them?

For many people, it comes down to welfare preferences rather than nutrition.

“Some consumers choose barn, free-range or organic eggs because they prefer hens to have more space or outdoor access, while others prioritise affordability,” says Sekula.

Are there ‘better’ brands in terms of nutrition and flavour?

From a supermarket point of view, shoppers choosing between multiple brands of similarly sized free-range, barn or colony eggs are generally getting very similar products nutritionally. Differences between brands are usually more about price, farming systems, freshness and personal preference than major changes in health value.

But what about flavour? While many people swear free-range eggs taste better, dietitians say taste differences are largely subjective. Freshness, storage and what hens are fed can subtly influence flavour and appearance, but farming system, shell colour and yolk colour are not reliable indicators of superior taste or nutrition.

Does yolk colour mean anything?

The rich orange yolk has become a kind of shorthand for “better” eggs in recent years. But darker yolks do not necessarily mean the egg is healthier, fresher or more nutritious.

Yolk colour is mostly influenced by what hens are fed.

“Hens fed diets with more naturally occurring plant pigments tend to produce darker yolks,” says Dietitian NZ’s Lily Henderson.

Likewise, shell colour tells you very little beyond the breed of chicken. Brown eggs are not nutritionally superior to white ones, despite their premium reputation in some countries.

What about omega-3 eggs?

Omega-3-enriched eggs do contain higher levels of omega-3 fats because hens are fed specially formulated diets.

But before paying a large premium, it’s worth keeping perspective.

While enriched eggs may offer a modest boost, Henderson says the difference is still relatively small compared with naturally rich omega-3 foods such as oily fish.

In other words, omega-3 eggs can contribute to intake, but they are not a nutritional magic bullet.

So what should shoppers prioritise?

If nutrition differences are relatively minor, what actually makes a “good” supermarket egg?

Freshness matters. Choose clean eggs with uncracked shells and store them in the fridge at home. Egg size also matters more than many people realise, particularly for baking.

“Many baking recipes in New Zealand are developed using standard large eggs, commonly size 7,” Henderson says. “Using much smaller or larger eggs can slightly affect the final result.”

Beyond that, most buying decisions come down to budget, values and intended use.

If you’re scrambling eggs for weekday breakfasts or baking a cake, a more affordable colony or barn egg may make perfect sense. If animal welfare is a priority for you, you may prefer to spend more on free-range or organic eggs.

The important thing is understanding what you are – and are not – paying for.

Because despite decades of confusion, fear and marketing hype, the humble egg remains one of the supermarket’s simplest whole foods.

Herald contributor Nikki Birrell has worked in food and travel publishing for nearly 20 years.