Brown eggs get blood spots more often than white eggs because the breeds that lay them have a genetic tendency toward small blood vessel ruptures during egg formation. When a hen ovulates, the yolk releases from her ovary and travels through the oviduct, where the white and shell form around it. If a tiny blood vessel breaks at any point during that process, a small droplet of blood gets trapped inside the egg. This happens in all egg-laying breeds, but it’s dramatically more common in brown-egg layers.
How Blood Spots Form
Each egg begins as a yolk developing inside a follicle on the hen’s ovary. That follicle is surrounded by a network of tiny blood vessels that supply nutrients as the yolk grows. When the yolk is mature, the follicle ruptures to release it, and the yolk enters the oviduct, a long tube where the egg white, membranes, and shell are added over roughly 25 hours.
A blood spot appears when one or more of those small blood vessels ruptures during ovulation or as the egg moves through the oviduct. The blood gets sealed inside the egg before the shell forms. Spots found on the yolk typically come from the ovary itself, while spots floating in the egg white usually result from bleeding further along the oviduct. The USDA confirms this is a normal biological event, not a sign of fertilization or contamination.
Why Brown Eggs Are Far More Affected
The difference between brown and white eggs is striking. Research comparing Rhode Island Red hens (a common brown-egg breed) to White Leghorns (the standard white-egg breed) found that brown-shell eggs had an average blood and meat spot frequency of about 64%, while white-shell eggs came in at just 1.4%. Even older estimates that used less sensitive detection methods put the gap at 18% for brown eggs versus 0.5% for white.
This isn’t about shell color directly. It’s about the genetics of the breeds. Brown-egg breeds like Rhode Island Reds, Plymouth Rocks, and similar heritage breeds are simply more prone to these small vascular ruptures. White Leghorns, which dominate commercial white-egg production, have been intensively selected over decades for traits that include extremely low blood spot rates. That selection pressure has been less aggressive in brown-egg lines, partly because the darker shell makes spots harder to detect during candling (the light-based inspection process used in egg processing plants).
Other Factors That Increase Blood Spots
Genetics is the biggest driver, but several other factors raise the odds. Nutritional deficiencies play a role: researchers have long observed that hens fed diets low in vitamin A produce eggs with more frequent blood spots. Low vitamin K levels, sometimes caused by insufficient green forage like alfalfa in the diet, have also been linked to higher incidence. Both vitamins are involved in maintaining healthy blood vessels and normal clotting, so deficiencies make ruptures more likely.
Stress matters too. Sudden disturbances, temperature swings, overcrowding, and other environmental stressors can increase blood spot frequency in a flock. As hens age and move further into their laying cycle, their reproductive tissues experience more wear, and some research suggests the rate of these defects can shift over an extended laying period. Backyard flocks, where diet and conditions vary more than in commercial operations, often see blood spots at higher rates than store-bought eggs.
Blood Spots vs. Meat Spots
Not every inclusion inside an egg is a blood spot. Meat spots are a related but different defect. Blood spots are red or dark red and consist of actual blood from a ruptured vessel. Meat spots are brown or tan and contain small pieces of tissue that sloughed off the wall of the oviduct or the surface of the ovary as the egg formed. Both can appear on the yolk or suspended in the white, and they often get grouped together in research because they share similar causes. The USDA classifies both as rare but normal occurrences that don’t affect safety or quality.
Are They Safe to Eat?
Yes. A blood spot is not a sign of disease, bacterial contamination, or a developing embryo. It’s a cosmetic defect. The USDA states clearly that blood spots are caused by a rupture of small blood vessels during ovulation and do not indicate the egg is unsafe. You can scoop the spot out with the tip of a knife if it bothers you, or simply cook and eat the egg as normal.
Commercial egg producers remove most eggs with visible spots during candling, which is why you rarely see them in store-bought white eggs. Brown shells are harder to see through, so more spotted eggs slip past inspection. If you buy farm-fresh brown eggs or keep backyard hens, finding a blood spot every few eggs is completely expected.