What Causes Differences in Egg Yolk Color and Its Significance?
KEY TAKEAWAYS
- Egg yolk color is determined by the pigments in the hen’s diet, not its nutritional content.
- The color spectrum of egg yolks ranges from pale yellow to deep orange.
- Factors influencing yolk color include the types of feed the hens consume, such as corn or alfalfa meal
- Yolk color does not affect the nutritional value of the egg.
When cracking open an egg, one of the first things that catches our attention is the yolk. Its bright and vibrant color serves as a visual delight, but have you ever wondered why egg yolks come in different hues?
The color of an egg yolk can range from a pale yellow to a deep orange, and each shade carries its own significance. In this blog, we explain why eggs have different egg yolk colors and how their nutrition is affected.
What Determines The Egg Yolk Color?
Egg yolks come in a wide spectrum of colors, ranging from pale yellow to deep orange.
The color of an egg yolk is not determined by the nutritional value of the yolk itself (as many believe) but rather by the pigments present in the hen’s diet. These pigments are absorbed by the hen’s body and deposited into the yolk as it develops.
Different pigments, such as xanthophylls, carotenoids, and chlorophyll, can give rise to different colors in the yolk.
The type and amount of pigments in the hen’s diet play a significant role in determining the final color of the egg yolk.
Here’s a great chart from Hill To Holler – a small family farm in West Virginia, US – that shows the various egg yolk colors and their meaning.
Here is a handy table we created with egg yolk colors, the pigments that cause them, and foods containing those pigments:
| Egg Yolk Color | Pigments | Foods Containing the Pigment |
|---|---|---|
| Yellow | Xanthophylls | Corn, alfalfa, yellow flowers, kale, spinach, broccoli |
| Orange | Carotenoids | Carrots, sweet potatoes, red peppers, apricots, cantaloupe |
| Red | Canthaxanthin | Red peppers, paprika, pink salmon, flamingo feathers |
| Pale Yellow | Lutein and Zeaxanthin | Marigold flowers, kale, spinach, turnip greens |
| Olive Green | Chlorophyll | Alfalfa, grass, nettles |
| Gray | Pheomelanin | Sunflower seeds, pumpkin seeds |
| Blue/Green | Biliverdin | Goose feet, duck weed |
| White | Lack of pigments | Grains, white cornmeal, sorghum |
DID YOU KNOW? Some commercial egg producers may supplement chicken feed with synthetic pigments like canthaxanthin to enhance the yolk color.
Does the nutritional value of egg yolk change based on egg yolk’s color?
Is egg yolk nutrition impacted by yolk color?
As we saw earlier, the color of egg yolks depends on what the chickens eat. Now, most of the nutrients in the yolk don’t really affect the color much. The differences in yolk color happen because chickens eat different things based on the season, location, and what extra food they’re given.
Chickens that eat a varied diet with lots of fresh plants and insects tend to lay eggs with yolks that are a richer, more vibrant yellow-orange color.
So in general, a darker yellow or orange yolk color comes from chickens eating a healthy, balanced diet full of vitamins and natural pigments that get passed into the egg. But the yolk color alone doesn’t tell you everything about how nutritious the egg is.
Having said that, some research showed that egg yolk’s nutrition profile is affected by what the chicken eats.
For example:
- A 1998 study published in the journal Poultry Science, looked at adding a marine microalgae product rich in omega-3 fatty acids, like DHA, to chicken feed. The researchers found that including this microalgae product in the hens’ diets increased the levels of beneficial omega-3s in the egg yolks.
- According to a 2012 study, adding certain nutrients like astaxanthin, tocotrienols, and tocopherols (antioxidants) to chicken feed can increase the levels of these beneficial nutrients in egg yolks. The study found that higher nutrient levels in the feed led to higher levels in the yolks, without significantly changing the eggs’ properties like color or texture. The research showed a way to boost the nutritional value of eggs by modifying the chickens’ diets.
- Another study published in 2019 in the Czech Journal of Animal Science found that adding freeze-dried carrot and beetroot meals to chicken feed can increase the nutritional value and color of egg yolks. Carrot meal made yolks more orange in color, while beetroot meal increased the levels of vitamin A (retinol) in the yolks.
So, it appears that the nutritional value of egg yolks changes based on what chickens are fed. And as we saw earlier, the color of the yolks is also affected by the chicken’s diet.
KEY TAKEAWAY: The main thing to know is that all eggs have about the same amounts of carbs, fats, and protein. But the vitamins, minerals, and healthy omega-3 fats can be different based on what the chickens ate. Eggs with darker orange yolks usually mean the hens had a better diet with more fresh foods, which is healthier for the chickens. So while yolk color alone doesn’t prove nutrition, it can be a good sign of happy, well-fed hens.
Free-range vs. Factory-farmed Eggs
Some studies suggest that eggs from pasture-raised hens may have more omega-3s and vitamins but less cholesterol due to their healthier feed.
More specifically, a study by Mother Earth News compared the nutrition in eggs from chickens that were allowed to roam freely on pastures (outdoor areas with grass and insects) and eggs from chickens kept in cages inside barns.
They found that the pastured eggs, which are eggs from the chickens that could go outside, had much higher levels of important vitamins and nutrients compared to the eggs from caged chickens.
Here are the main findings:
- Pastured eggs had over 3.5 times more Vitamin E than caged eggs.
- Pastured eggs had 4 times more Vitamin D than caged eggs.
- Pastured eggs had over 1.5 times more Vitamin A than caged eggs.
- Pastured eggs had 8 times more Beta Carotene (a nutrient that’s good for your eyes) than caged eggs.
- Pastured eggs had 3 times more Omega-3 fatty acids (healthy fats) than caged eggs.
Another study by Pennsylvania State University and the USDA (United States Department of Agriculture) also found that pastured eggs had:
- Two times more long-chain Omega-3s (a specific type of healthy fat) than caged eggs.
- Two and a half times more total Omega-3s than caged eggs.
- Half the ratio of Omega-6 to Omega-3 fats compared to caged eggs. A lower ratio is better for your health.
So, in simpler terms, eggs from chickens that were allowed to roam outside and eat grass and bugs had much higher levels of important vitamins and healthy fats compared to eggs from chickens kept in cages inside barns.
A 2022 study published on Foods journal, compared eggs from hens raised on grass-fed beef by-products (GFB) to those from hens on regular diets.
The GFB-fed hens’ eggs had more nutrients like carotenoids and omega-3 fatty acids, and less omega-6 fatty acids compared to regular eggs. They also had different types of healthy fats.
Conclusion
To conclude, the pale yolks and light yellow yolks are usually caused by feeding chickens with grains, white cornmeal, soy, yellow corn etc.
On the other hand golden and dark orange yolks usually occur because chickens eat more naturally and nutrient dense foods such as carrots, red papers, tomatoes etc.
In the end, the color of an egg yolk doesn’t directly make the egg more or less nutritious. However, it does give us a hint about the chicken’s diet.
Darker orange yolks typically mean the hens ate a varied diet full of fresh plants and bugs which provide beneficial vitamins and nutrients.
So while yolk color alone can’t judge an egg’s nutrition, it can be a good sign that the chicken was healthy and well-fed.
For the most nutritious eggs, look for hens raised on high-quality, natural feed sources rich in vitamins and omega-3s.
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