How much K2 is in one egg?: Decoding Vitamin K2 in Your Diet

October 12, 2025 •

4 min read

According to research published in the journal Nutrients, the vitamin K2 content in eggs can differ substantially, with levels in egg yolks ranging widely. The crucial question of how much K2 is in one egg? is not so simple, as the answer depends on the source and diet of the laying hen.

Quick Summary

The quantity of vitamin K2, specifically the MK-4 form, in eggs is highly variable. Pasture-raised hens produce eggs with higher MK-4 levels than conventionally-farmed hens, making diet and environment key factors in determining an egg's K2 content.

Key Points

Hen's Diet is Key: The amount of vitamin K2 (MK-4) in an egg is primarily determined by what the laying hen eats, with diet-dependent ranges shown in research.
Pasture vs. Conventional: Eggs from pasture-raised hens typically contain higher levels of MK-4 compared to those from conventionally-raised, grain-fed hens.
Biofortified Eggs: Some commercially available eggs are biofortified, meaning the hen's feed is supplemented to increase the final vitamin K2 content.
K2 is in the Yolk: The vast majority of K2 in an egg is concentrated in the yolk, not the egg white.
Health Benefits: Vitamin K2 is vital for activating proteins that help with calcium metabolism, supporting bone and heart health.
Other Sources: While eggs are a good source, fermented foods like nattō and certain animal fats (e.g., goose liver pâté) are also rich in K2.

The Complexity of Vitamin K2 in Eggs

Vitamin K2, or menaquinone, is an essential fat-soluble nutrient that plays a crucial role in bone and cardiovascular health by activating proteins that manage calcium. Unlike vitamin K1, which is found predominantly in green leafy vegetables, the MK-4 form of vitamin K2 is derived almost exclusively from animal products, including egg yolks. While eggs are a reliable source, determining the precise amount of K2 in a single egg is complex due to several influencing factors.

Why K2 Content Varies

The primary factor dictating the vitamin K2 (MK-4) content in an egg is the hen's diet. Studies have consistently shown that the nutrient profile of eggs, including their vitamin K2 levels, directly reflects what the chickens are fed and their living environment.

Pasture-Raised Hens: Chickens that roam on pastures and consume a natural diet of grasses, seeds, and insects tend to produce eggs with significantly higher vitamin K2 levels. The nutrient-rich pasture and varied diet contribute to a more robust nutrient profile. The fat-soluble nature of MK-4 means it is primarily stored in the egg yolk, which appears richer and darker in eggs from pasture-raised hens.
Biofortified Hens: Some producers actively fortify chicken feed with vitamin K, including vitamin K3, which can be converted to MK-4 by the hen. This process, known as biofortification, can effectively increase the MK-4 content in eggs. One study found that eggs from hens on biofortified feed contained a mean range of 46–51 µg of MK-4 per 100g of whole egg.
Conventionally-Raised Hens: Chickens raised in confined conditions and fed a standard grain-based diet typically produce eggs with lower vitamin K2 levels. While their feed may contain some synthetic vitamins, the natural synthesis of MK-4 is not maximized due to the lack of access to pasture and insects.

The K2 Per Egg Breakdown

To answer the question, how much K2 is in one egg?, we need to calculate based on the egg's weight and the hen's diet. The yolk is the primary source, containing up to 30 times more K2 than the egg white. An average large egg yolk weighs approximately 17 grams. Using data from various sources, we can estimate the ranges of MK-4 in one yolk:

For biofortified eggs: A study reported 46–51 µg per 100g of whole egg. Since the yolk is the main source, and constitutes about 33% of the whole egg, a 100g whole egg would have a yolk of ~33g. This is a complex calculation due to inconsistent reporting in research, but focusing on 100g of yolk is more useful. One study found that egg yolks contained 22.30 µg of MK-4 per 100g in control (non-biofortified) eggs, rising to over 45 µg per 100g in biofortified eggs. For a standard 17g yolk, this is about 3.8 µg for conventional and 7.7 µg for biofortified.
For pasture-raised eggs: Some sources suggest a range of 37-60 µg of K2 per 100g of pasture-raised egg yolk. For a 17g yolk, this would be approximately 6.3–10.2 µg.

Comparing K2 Content in Different Egg Types

The following table summarizes the typical vitamin K2 (MK-4) content per 100 grams of egg yolk, based on the chicken's diet:


Egg Type	Typical MK-4 Content (µg per 100g yolk)	Factors Influencing Level
Conventional/Grain-Fed	~22.3 µg	Limited access to pasture; synthetic vitamins in feed.
Biofortified	~46–51 µg	Feed is intentionally enriched with vitamin K compounds.
Pasture-Raised	37–60 µg	Rich diet of grasses and insects leads to higher natural levels.

It is important to note that these values can vary based on specific feed composition, breed of hen, and research methods. Choosing pasture-raised or biofortified eggs is the most reliable way to increase dietary intake of vitamin K2 from eggs.

Beyond Eggs: Other Important K2 Sources

While eggs are a good source of vitamin K2, especially the pasture-raised variety, other foods also provide significant amounts. These include:

Nattō: This fermented soybean product is exceptionally rich in MK-7, another form of K2. It is considered one of the richest dietary sources.
Hard and Soft Cheeses: Certain cheeses, particularly aged varieties, can be excellent sources of various menaquinones (MKs).
Goose Liver Pâté: This is a top source of the MK-4 subtype.
Butter: From grass-fed cows, butter contains the MK-4 form.
Chicken Liver: A nutritious organ meat containing MK-4.

Conclusion

Determining the exact amount of vitamin K2 in a single egg is challenging due to the significant variation based on the hen's diet and living conditions. The research clearly indicates that choosing eggs from pasture-raised or biofortified hens is the most effective way to boost your dietary intake of MK-4, the fat-soluble K2 form found in animal products. By focusing on the source of your eggs and incorporating other K2-rich foods, you can ensure a robust intake of this important nutrient for optimal bone and heart health.

For more detailed information on vitamin K and its functions, a helpful resource is the National Institutes of Health (NIH) fact sheet on the topic.

Frequently Asked Questions

Cooking methods like poaching or frying do not significantly impact the vitamin K2 content in eggs, as shown in studies where cooked eggs maintained similar MK-4 levels to raw eggs.

Eggs contain primarily vitamin K2 (MK-4), which is synthesized by the hen from vitamin K1 in her diet. K1, found in leafy greens, plays a primary role in blood clotting, while K2 helps with calcium distribution in the body.

Not necessarily. The key factor is whether the hens are pasture-raised or fed a biofortified diet, not just the 'organic' label. Pasture-raised eggs often have higher K2, which can be part of an organic farming system.

Vitamin K2 activates proteins like osteocalcin and matrix GLA protein, which direct calcium to bones and teeth while preventing it from accumulating in soft tissues like arteries and kidneys, supporting skeletal and cardiovascular health.

It is possible to get K2 from diet, especially by consuming pasture-raised eggs, aged cheeses, and fermented foods like nattō. However, intake varies widely, and many modern diets are low in K2.

For the highest potential vitamin K2 content, look for eggs labeled 'pasture-raised' or 'biofortified.' Pasture-raised hens' diets naturally result in higher K2, while biofortified eggs have K2 added to their feed.

A darker, richer-colored egg yolk can be an indicator of a hen's diet rich in nutrients like beta-carotene, which is often a characteristic of pasture-raised hens. This rich diet is associated with higher K2 levels, though color alone is not a perfect measure.