Many of us start the day with eggs. But how do you decide which ones to buy?

Eggs laid by free-range chickens from small flocks may be significantly higher in nutrients than eggs from caged hens, an investigation by CBC Marketplace reveals.

Canadians spend more than $2 billion on eggs a year. While more than 90 per cent of eggs produced in Canada are from conventional battery cage farms, "ethical" egg labels, including free-run, free-range, "enriched furnished," organic, even "hens on pasture" have become increasingly common on supermarket shelves.

Many consumers who buy free-range, small-flock or organic eggs may be motivated by concerns over animal welfare, but these farming methods can also have an impact on vitamin and fat content, the Marketplace test found.

"You are what you eat. and that applies to the hen as well," says Harry Pelissero, general manager of Egg Farmers of Ontario.

Marketplace also investigated how different eggs taste and what different farming methods mean for the animals.

Vitamin, fat differences

Marketplace tested six brands of eggs from a variety of farming methods, with samples sent for nutritional testing to an ISO 17025-certified lab in Mississauga, Ont., that specializes in nutritional analysis.

Canadians spend more than $2 billion on eggs a year. More than 90 per cent of eggs produced in Canada are from conventional battery cage farms, where six to eight hens live in each small cage. (CBC) The samples included conventionally farmed eggs from two of Canada's leading companies, Burnbrae and Gray Ridge, whose hens are raised in battery cages, small cages that house six to eight birds. Marketplace also tested four cage-free brands, including Gray Ridge free-run, Burnbrae organic, Organic Meadow, and Small Flock's Delight, from an operation managed by Ontario Mennonite farmers.

Marketplace bought a small sample of eggs off store shelves in October 2015 at the end of pasture season, and experts say the nutrition could be different at different times of year.

Each of the samples tested met or surpassed the nutrients listed on the carton's nutrition facts panel for calories, protein, fat and iron.

But the vitamin A, E and D and omega-3 fatty acid content varied considerably between conventional and pastured eggs.

Organic Meadow eggs scored the highest, with noticeably higher nutritional content than other brands. The eggs contained twice the amount of vitamin D compared with some of the other samples tested. They also were the highest in vitamin E.

Christy Brissette, a dietitian at Princess Margaret Cancer Centre in Toronto, analyzed the test results for Marketplace.

She found that the Organic Meadow eggs also had a healthier balance of fats, including the ratio of omega-3 fats to omega-6 fats, important for an anti-inflammatory diet. North American diets, she says, have too high a ratio of omega 6s, "which has been named as a potential factor in chronic disease risk."

Small Flock's Delight, eggs from flocks of up to 500 hens, also had higher levels of vitamin A and vitamin D than the conventional brands.

Catherine Heard, from Toronto, who preferred the taste of the Organic Meadow eggs over the other brands, says she’ll keep spending a few extra dollars. 'It’s reassuring to know that, along with the flavour goes better nutrition as well.' (CBC) Brissette says that a number of living conditions could affect the eggs' nutrition, including sunshine, and the inclusion of grass and insects in the hens' diet, instead of the corn-based diet that many conventionally raised hens eat.

"I would expect some variation based on what the hens are fed," says Brissette.

While the Marketplace test only looked at a small number of samples, the findings are consistent with other studies that have looked at how farming methods affect nutrition.

One 2010 study from Penn State College of Agricultural Sciences found eggs from hens allowed to forage in pastures are higher than conventional eggs in some beneficial nutrients, including fat-soluble vitamins and omega-3 fatty acids.

Cost also a factor

While conventional eggs can be found at $3.69 a dozen in many places, other options come at a price. Eggs from hens raised on pasture can be more than twice that, as much as $7.99 a dozen.

Pelissero says price is the driving factor for many consumers.

"By and large, what consumers tell you for a survey versus what they actually do and buy, they're still buying 90 per cent of the eggs from a conventional housing unit," he says.

"There's a choice there."

Cindy Fair, a mother of two from Mississauga, Ont., says she'll stick to buying conventional eggs. "There's other sources of food that you can get vitamin D and that type of thing, so as long as we're getting a healthy, balanced diet," she says.

Others, though, are willing to pay a few extra dollars for what they consider a more ethical egg.

Catherine Heard, from Toronto, who preferred the taste of the Organic Meadow eggs over the other brands, says she'll keep spending a few extra dollars. "It's reassuring to know that, along with the flavour goes better nutrition as well."