Cracking open a perfect-looking egg only to find an unsightly blood spot can be alarming.
Many assume that these eggs aren’t safe to eat.
Not only can this assumption ruin your breakfast, but throwing out eggs with blood spots can contribute to food waste as well.
This article explains why blood spots occur in eggs and whether they’re safe to eat.
Blood spots are droplets of blood sometimes found on the surface of egg yolks.
Although egg producers consider them a defect, blood spots form naturally during the egg-laying cycle in some hens.
Contrary to popular belief, they do not indicate that an egg has been fertilized.
Blood spots are the result of the rupturing of tiny blood vessels in the hen’s ovaries or oviduct — the tube through which eggs pass from the ovaries to the outside world ().
A hen’s ovaries are full of tiny blood vessels — and occasionally one will break during the egg-laying process.
When the spot is connected to the yolk, the bleeding most likely occurred in the ovary when the egg was released from the follicle.
The follicle is a fluid-filled sac that contains several blood vessels. It may burst during the egg-laying process, and if any blood vessels rupture, blood can deposit on the egg yolk.
Blood spots can also occur in the egg white, which means that the bleeding occurred after the egg was released into the oviduct.
Another type of spot found in egg yolks and whites are meat spots. Unlike blood spots, meat spots appear on the egg white as brown, red, or white deposits.
Meat spots are most commonly found in the egg white and typically formed from pieces of tissue picked up by the egg when passing through the oviduct.
Summary Blood spots are usually found in egg yolks and occur due to ruptured blood vessels in the hen’s ovaries or oviduct. On the other hand, meat spots are typically found in the egg white and are formed from pieces of tissue.
Finding an egg with a blood spot in its yolk is pretty uncommon.
In fact, the frequency of blood and meat spots is less than 1% in all eggs laid in commercial factories ().
Egg color is a factor in the occurrence of blood spots.
The incidence of these spots is around 18% in hens that lay brown eggs, compared to only 0.5% in white eggs ().
Additionally, older hens at the end of their egg-laying cycle and younger hens who just began laying eggs tend to lay more eggs containing blood spots.
Poor nutrition — including a lack of vitamin A and vitamin D — and stress can also increase the chances.
How Do Egg Manufacturers Detect These Spots?
Manufacturers go to great lengths to ensure that eggs with blood spots aren’t sold to consumers.
Commercially sold eggs go through a process called “candling” — a method that uses a bright light source to detect imperfections within the egg.
During the candling process, the egg is discarded if imperfections are discovered.
However, some eggs with blood and meat spots slip through the candling process unnoticed.
What’s more, blood spots in brown eggs are harder to detect using the candling process, as the shell is a darker color. As a result, brown eggs with blood spots are more likely to pass through the candling process undetected.
People who eat farm-fresh eggs may find more blood spots than those who consume commercially produced eggs since eggs from local farms or backyard hens don’t usually go through a candling process.
Summary Blood spots are more common in brown eggs than white ones. Commercially produced eggs go through a candling process to detect imperfections.
It’s understandable that you may be concerned about eating eggs with blood spots.
Consuming raw or undercooked eggs, whether they contain blood spots or not, increases your risk of salmonellosis — infection with Salmonella bacteria that can lead to diarrhea, fever, and abdominal cramps ().
Also note that eggs with whites that are tinted pink, green, or red may contain bacteria that cause spoilage and should be discarded (5).
What to Do If You Find a Blood Spot
If you happen to crack open an egg and find a blood spot, there are several ways to handle the situation.
If it hasn’t caused you to lose your appetite, simply mix it into the rest of the egg when cooking.
If you don’t feel comfortable consuming the blood spot, take a knife and scrape it off of the yolk before preparing your meal.
The same methods can be used for meat spots.
Summary Regulatory agencies like the USDA agree that eggs with blood spots are safe to eat. They can be eaten along with the egg or scraped off and discarded.
Blood spots are uncommon but can be found in both store-bought and farm-fresh eggs.
They develop when tiny blood vessels in the hen’s ovaries or oviduct rupture during the egg-laying process.
Eggs with blood spots are safe to eat, but you can scrape the spot off and discard it if you prefer.