Eggs

What’s In An Egg?

Most folks, whether they are chicken keepers or not, are familiar with egg anatomy, but lots probably don’t understand what each of those parts does and why they are good for us. I’ve previously written about how an egg is made; this post is about what is actually inside those little orbs and how they can benefit us if we eat them.

You’re probably aware that commercial eggs are graded by size and against a standard of perfection. Those that don’t make the cut are relegated to be used as an ingredient in manufactured food rather than be sold in egg form.

Those of us with small flocks know that eggs are often imperfect. We’ve probably seen eggs of different sizes and colours, and maybe a few oddities along the way. Regardless of the packaging what’s inside is more important.

If you’ve ever wondered what’s in an egg read on.

Nutrition Facts

Two large (105g) Grade A eggs contain 13g of protein, 11g fat, 400 mg cholesterol, 130 mg sodium, 1 g carbohydrates and 160 calories. 

They also contain the following health boosting substances:

Vitamin A: Helps maintain healthy skin and eye tissue; assists in night vision.

Vitamin B12: Helps protect against heart disease.

Vitamin D: Most of us get this vitamin from sunlight, but eggs are one of the few dietary sources of vitamin D. It strengthens bones and teeth; may help protect against certain cancers and autoimmune diseases.

Vitamin E: An antioxidant that plays a role in maintaining good health and preventing disease.

Choline: Plays a strong role in brain development and function.

Folate: Helps produce and maintain new cells; helps prevent a type of anemia, helps protect against serious birth defects if taken prior to pregnancy and during the first 3 months of pregnancy.

Iron: Carries oxygen to the cells; helps prevent anemia 

Lutein and Zeaxanthin: Maintains good vision; may help reduce the risk of age-related eye diseases, such as cataracts and macular degeneration.

Protein: Eggs are one of the few foods considered to be a complete protein, because they contain all 9 essential amino acids, which are considered the building blocks for the body because they help form protein. The albumen contains less protein than the yolk.

Selenium: Works with vitamin E as an antioxidant to help prevent the breakdown of body tissues.

What About Cholesterol?

Growing up we ate eggs without any concern for potential negative health impacts. Then came the news that eggs were naturally high in cholesterol, so we were advised to eat them in moderation. Now the pendulum has swung back as studies have shown that eggs don’t seem to raise cholesterol levels the way other cholesterol-containing foods do, such as trans and saturated fats. More harmful are the foods sometimes associated with eggs like bacon or sausages and other fried foods.

Healthy adults can have an egg a day without increasing their risk of heart disease. According to the American Heart Association, lutein found in egg yolks also protects against early heart disease.

Can I Eat Fertilized Eggs?

All eggs are fertile, meaning they carry the genetic contribution from a hen and have the potential to develop into an embryo, but only if they are fertilized by a rooster. Some folks are reticent to eat fertilized eggs for fear they may be eating baby chicks. Fertilized eggs require incubation before developing, so if eggs are collected daily and stored properly there is no chance that an embryo can develop. Fertilized eggs are essentially the same as their unfertilized counterparts.

Does Eggshell Colour Make A Difference?

When I was a kid I only remember ever seeing white egg shelled eggs in the supermarket. We associated brown eggshells with the ones that came from the farm. For lots of city folks brown eggshells have become synonymous with free-ranging hens, despite that not always being the case.

Eggshell colour is dependent on genetics and has nothing to do with nutrition or health benefits for those of us who eat them. The contents of an egg are created by what a hen eats.

My hens lay a range of colours: white, cream, pink, varying shades of brown, blue, green and olive. Although they may all be the same on the inside my customers love opening the little jewel box of coloured eggs.

What’s In The Yolk?

Most of an egg’s vitamins and minerals are found in the yolk: iron, vitamins A and D, phosphorus, calcium, thiamine and riboflavin.

Yolk colour is created by two components: a yellow base color and red to deepen it. Lutein and zeaxanthin are the carotenoids that provide yellow; canthaxanthin provides red.

You can influence the yolk colour by tweaking your flock’s feed. For more on tips read this.

What Are Blood Spots?

Ovaries contain blood vessels, which can rupture leaking blood into an egg yolk. Blood (or meat spots) found in the albumen originated in the oviduct rather than the ovary. Blood spots are often related to stress such as: sudden loud noises, poor housing, or inadequate feed and water. Other factors that may cause blood spots include activity level, vitamin deficiency and genetics.

Commercial egg producers inspect, grade and candle their eggs. Only 1% of white shelled eggs that have blood spots slip past quality control, whereas brown eggs are more difficult to candle and have a higher incidence of blood spots in eggs that make it to the grocery store.

Although they are not uncommon, I’ve never found a blood spot in any of my eggs. They aren’t particularly appetizing, but are totally edible.


If I was stranded on a desert island and only had 10 foods at my disposal, eggs would be one of them. Not only are they nutritious, eggs are also tasty and versatile. So next time you sit down to a meal containing eggs thank your hens for providing them and enjoy the health benefits they offer.

Credits: Get Cracking – Eggs; Harvard School Of Public Health; Dr Jacquie Jacobs (Poultry Extension). Feature photo: My Recipes

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