A carton of eggs.

Back in the 70s, a kind of hysteria evolved among health experts and consumers in the U.S. because of a possible association between eggs and cardiovascular disease. “Eggs were viewed almost as poison pills because they are high in cholesterol,” says Walter Willett, M.D., Dr.P.H., a professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health.

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Eggs are indeed high in cholesterol, and high cholesterol levels in the blood raise the risk of heart disease. But no studies at the time had shown that eating eggs could increase the risk of a heart attack. And in fact more recent studies suggest that eating eggs doesn’t seem to raise the levels of cholesterol in your blood by much, anyway.

That research, coupled with the impressive assortment of vitamins, minerals, and other essential nutrients in eggs, has given this simple food a renewed place in Americans’ refrigerators as a cheap and healthy addition to any diet. However, while they don’t have as much of a negative impact on your heart as experts once believed, that doesn’t mean egg-lovers can eat them with abandon. Here’s what you need to know about the health benefits and downsides of eggs, and the best ways to select and store them.  

A Medley of Nutrients

One large egg gives you 70 calories, 6 grams of protein, 2 grams of saturated fat, about 185 milligrams of cholesterol, and a long list of important nutrients.

Eggs contain lecithin, a type of fat that's an important component of cell membranes. And they're one of the few foods that have high levels of choline, an essential nutrient that aids brain development. Egg yolks also contain phosvitin, a protein that maintains healthy skin, and carotenoids—such as carotene, lutein, and zeaxanthin—compounds that have antioxidant and anti-inflammatory properties and are thought to play a role in reducing macular degeneration and age-related cataract formation.

If you see an omega-3 claim on a label, it means that hens were given feed that included flax, marine algae, fish oils, or other ingredients to boost the level of omega-3 fatty acids in their eggs. Omega-3s are polyunsaturated fats that are important for heart and brain health. But the amount in eggs varies and is typically far less than the amount of omega-3s in a serving of fatty fish, such as salmon or sardines.  

What About All That Cholesterol?

In the past, the Dietary Guidelines for Americans suggested limiting dietary cholesterol intake to no more than 300 mg per day, because high cholesterol in your blood can cause plaque buildup in your arteries and increase the risk of heart attack and stroke.

Given that, the 185 mg of cholesterol in a large egg may seem like a lot, but scientists have largely debunked the claim that eating eggs can raise the cholesterol levels in your body. A small study published in the journal Nutrients in 2013 found that college students who ate two eggs for breakfast five times a week for 14 weeks had cholesterol levels that were no different from those who ate an egg-free breakfast for the same amount of time. Similar results have been found in middle-aged men, pre- and postmenopausal women, and adults ages 40 to 65.

And it’s becoming clearer that other factors, such as ethnicity, genes, weight, age, and hormonal changes after menopause, may have more of an effect on cholesterol levels than the food you eat.

As a result, public-health experts have removed the upper cholesterol limit in the 2015-2020 Dietary Guidelines for Americans, saying instead to limit your intake. The guidelines also emphasize the importance of keeping the amount of saturated fat in your diet to no more than 10 percent of total calories. Eggs are low in saturated fat; a large one has 2 grams compared with about 6 grams in 3½ ounces of top sirloin steak or about 7 grams in a tablespoon of butter.  

How Many Should You Eat?

Studies do suggest that eggs may increase the risk of heart disease in people already at higher risk, such as those who have diabetes or those who are “hyper-responders”—people who have unusually high spikes in their cholesterol after eating cholesterol-rich foods. They should watch their intake, Willett says.

However, newer studies are beginning to complicate this picture.

small randomized controlled study, published in The American Journal of Clinical Nutrition in May, followed 128 Australians for a year (all had prediabetes or type-2 diabetes and were on weight-loss regimens). Those who ate up to 12 eggs per week were no more likely to have elevated cardiovascular risk factors—such as higher cholesterol, blood sugar, or blood pressure—than those who ate fewer than two eggs per week. (The Australian Egg Corporation provided research funding for the study, however, the authors note.)

More research is needed, so for now, it's still best to approach your egg-eating habits the way you would any food—in moderation. "Research suggests that an egg a day is fine,” says Maxine Siegel, R.D., who heads Consumer Reports' food-testing department.

Also keep in mind that many claims you see on cartons (see “Decoding Egg-Label Lingo,” below) don’t have much bearing on the actual nutrition of an egg. There’s also no nutritional difference between brown and white eggs. “Many people believe brown eggs are ‘healthier,’” says Siegel, “but egg color depends on the breed of the chicken and has no bearing on the nutrients inside.”  

How to Keep Your Eggs Fresh and Safe

The fresher the egg, the better it will taste, so buy them with a carton date as far in the future as possible. But even if you're eating the freshest egg, you still need to watch out for nasty bacteria.

“If salmonella is present in a laying hen’s reproductive tract, the bacteria may contaminate the egg during its formation,” says James Rogers, Ph.D., director of food safety and research at Consumer Reports. “The egg industry has attempted to reduce the numbers of infected hens, but there is still always the possibility of foodborne illness if you eat undercooked or raw eggs.”

About 79,000 people are sickened each year from eating eggs contaminated with salmonella, and 30 people die, according to the Food and Drug Administration (FDA). These tips will help you reduce the chances of getting food poisoning from eggs. 

Keep them cold. Always purchase eggs that have been kept refrigerated at the grocery store. And store them in your fridge at 40° F or below as soon as you get home. To avoid temperature swings, don’t put them in the fridge door; instead, place them on a back shelf.

Check for cracks. A broken or cracked shell can allow bacteria from the outside in. Check your eggs for cracks before you buy and cook them. If you spot a cracked egg, toss it.

Store them in their carton. The cushioning of the cardboard prevents cracking and also keeps them from absorbing smelly fridge odors and food flavors.

Eat them quickly. Eggs can keep for up to a month in your fridge, but the sooner you eat them, the better they’ll taste. (A cloudy egg white is a sign of a fresh egg, according to the Department of Agriculture.) The FDA recommends you eat them within three weeks of purchasing them.

Decoding Egg-Label Lingo

Cage-free, farm-fresh, natural, pasture-raised—what does it all mean? In some cases, nothing at all, says Charlotte Vallaeys, Consumer Reports’ senior policy analyst and food-label expert. “Egg labels can sometimes amount to little more than marketing hype,” she says.

Many egg labels refer to the way the chickens were fed or raised, and may mislead consumers. The best animal-welfare standards for laying hens give the birds what they need to engage in natural behavior—such as perching and foraging—and provide adequate light, space, and fresh air. “Certain terms seem to imply that the chickens are raised under such conditions, but that’s not what they mean at all,” Vallaeys says.

Here’s how to separate the reality from the hype on egg cartons.  

  • American Humane Certified and Certified Humane. On their own, these labels mean that the eggs came from chickens that were raised in better conditions than conventional laying hens. For example, the hens can't be kept in cages, although in some cases they may still be raised in confined conditions, and outdoor access isn't required. Even better is when they accompany the claims “free-range” or "pasture-raised” (see below), which means that the chickens must be able to go outdoors.
  • Cage-free. The chickens weren’t raised in a cage, Vallaeys says, but they may still be packed into a building with tens of thousands of other birds with little ability to roam and peck. If the egg carton is also labeled American Humane CertifiedCertified Humane, or carries the USDA Grade shield, it means this claim is verified.
  • Farm-fresh. Since all eggs come from farms, Vallaeys points out, this labeling claim has no value. “The ‘farm’ can be a huge building where the chickens are packed into a bunch of cages,” she says. The term “fresh” also carries no weight, because it generally means the product hasn’t been frozen. “While you may want to know that when buying meat or poultry, no one is freezing eggs,” Vallaeys says.
  • Free-range. This is potentially one of the most misleading terms on an egg carton. The birds can't be kept in cages and must have access to an outdoor area, but they can still be housed in crowded conditions, and the outdoor area can be as small as a tiny porch. Or the area may be accessible only by a single door, which the vast majority of chickens can’t reach, Vallaeys says. However, if you also see the American Humane Certified or Certified Humane seal alongside this claim, it verifies that the birds were actually able to access a spacious outdoor run.
  • Natural. “People often mistake ‘natural’ for ‘organic,’ ” Vallaeys says. But the two terms are very different. “ 'Natural' has no clearly defined meaning on egg labels, while eggs labeled 'organic' [see below] must meet a set of stringent criteria,” she says. “As far as egg producers are concerned, all eggs are natural."
  • No Added Hormones. By law, chickens that produce eggs and those that are sold for meat can't be given hormones, so eggs with this claim on the package label are no different than eggs sold without this claim.
  • Pasture-raised. This label is one of the best for chicken welfare, Vallaeys explains, especially if accompanied by the American Humane Certified or Certified Humane seal, which verifies that specific standards were met. It requires that chickens have access to lots of pasture with enough space for them to roam, flap their wings, and peck for bugs. However, if you see "pasture-raised" on a package without an accompanying verification seal, buyer beware, Vallaeys says.
  • United Egg Producers Certified. This organization is a trade group for egg producers, and its standards are little better than the way conventional laying hens are raised, according to Vallaeys, but not by much. “There's an upper limit for ammonia levels in the air at 25 parts per million," she says, "which is better than no upper limit, but is still pretty high and certainly doesn't qualify as 'fresh air.' " The guidelines also allow hens to be confined in crowded cages without natural light, fresh air, or space to move around. White laying hens (a type of chicken), for example, can be kept in a cage with at least 8.2x8.2 inches of space and the ability to stand upright. "That’s a space smaller than a sheet of paper, and it provides no space for the chicken to move or even stretch her wings,” Vallaeys says.
  • USDA Organic. This indicates the eggs were laid by cage-free hens raised on organic feed and
 not given antibiotics (antibiotics are never allowed on organic farms). Note, though, that while the organic standards require outdoor access for all animals on organic farms, some certifying agencies interpret a small concrete porch to meet this requirement. So if you’re looking for organic eggs from hens that were able to go outdoors, don’t rely only on the organic seal alone. Look for a “free-range” or “pasture-raised” claim accompanied by the American Humane Certified or Certified Humane seal.

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