Decoding the Dairy: Does Greek Yogurt Have K2?

October 6, 2025 •

4 min read

Research shows that the specific type of bacteria used in yogurt production plays a critical role in Vitamin K2 (menaquinone) synthesis. Therefore, the answer to the question, 'Does Greek yogurt have K2?', is more nuanced than a simple yes or no and depends heavily on its processing methods.

Quick Summary

Greek yogurt is not a significant source of Vitamin K2 due to the thermophilic bacterial cultures and short fermentation time used in its production. While full-fat versions may contain trace amounts, other fermented dairy and animal products provide far more reliable and potent sources of this essential nutrient.

Key Points

Low K2 Content: Greek yogurt contains very little to no Vitamin K2 because it is fermented with thermophilic bacterial cultures, which are poor K2 producers.
Fat is Key: As a fat-soluble vitamin, any K2 present in Greek yogurt will be found in full-fat varieties, not low-fat or fat-free versions.
Not a Reliable Source: Greek yogurt cannot be considered a primary source of Vitamin K2 when compared to other fermented foods and animal products.
Contrast with Cheese: Other fermented dairy products, such as aged cheeses like Gouda and Brie, are rich in Vitamin K2 because they use different mesophilic cultures and longer ripening times.
Superior K2 Sources: Foods like natto (fermented soybeans), liver, and egg yolks are far more concentrated and reliable dietary sources of Vitamin K2.
Consider Fortification: For those interested in obtaining K2 from yogurt, some brands offer specially fortified products, which can increase vitamin levels effectively.

Understanding Vitamin K: The Two Main Forms

Before diving into Greek yogurt specifically, it's essential to understand the difference between Vitamin K1 and Vitamin K2. Vitamin K is a fat-soluble vitamin and is a family of compounds crucial for blood clotting and regulating bone metabolism.

Vitamin K1 (Phylloquinone): This form is produced by plants and is abundant in green leafy vegetables like kale, spinach, and broccoli. Our bodies are not particularly efficient at converting K1 into K2.
Vitamin K2 (Menaquinone): This form is synthesized by bacteria. It is found in animal-based foods and fermented products. Vitamin K2 plays a vital role in directing calcium to the bones and teeth, preventing its buildup in soft tissues like arteries. The subtypes of K2 (MKs) vary depending on the bacteria that produced them.

The Greek Yogurt Production Process and K2 Content

Greek yogurt is made by straining regular yogurt to remove the liquid whey, resulting in a thicker, higher-protein product. However, the bacterial cultures used in this process—primarily Lactobacillus bulgaricus and Streptococcus thermophilus—are known as thermophilic cultures because they ferment at high temperatures.

According to a study published in the Journal of Dairy Science, these thermophilic cultures typically produce little to no K2. The shorter fermentation period (6-8 hours) for yogurt, compared to the longer aging process for hard cheeses, is another limiting factor. This differs significantly from foods fermented with mesophilic cultures, like certain cheeses, which are very rich in K2.

The Critical Role of Fat Content

Since Vitamin K2 is a fat-soluble vitamin, its presence in dairy is directly correlated with the fat content. A 2017 study examining US dairy products confirmed that K2 levels were significantly higher in full-fat products compared to low-fat or fat-free versions. For instance, a full-fat Greek yogurt may contain some trace amounts of K2 derived from the milk, but fat-free Greek yogurt has virtually none. While the presence of K2 is tied to fat, the amount generated by the yogurt's cultures remains low compared to other fermented sources.

Other Dietary Sources of Vitamin K2

To reliably increase your Vitamin K2 intake, it's best to look beyond Greek yogurt. Many other fermented and animal products offer superior amounts of this crucial nutrient. These sources are known to contain various subtypes of menaquinones (MKs).

Natto: A traditional Japanese fermented soybean dish, natto is the richest food source of K2, specifically the highly bioavailable MK-7 subtype.
Cheeses: Hard and soft cheeses made with mesophilic cultures are excellent sources of K2. Gouda and Brie are particularly high in menaquinones. Aged Gouda, for example, is consistently cited as a rich source.
Animal Products: Certain animal products are good sources of the MK-4 subtype of K2. These include goose liver pate, egg yolks (especially pasture-raised), and chicken liver.
Fermented Vegetables: Sauerkraut also contains some K2 due to its fermentation process, though typically less than natto or cheese.

Comparison of K2 Content in Common Foods


Food (per 100g)	Primary K2 Subtype(s)	Estimated K2 Content	Source and Notes
Greek Yogurt (full-fat)	MK-4, MK-9, MK-11	Low (approx. 1 µg)	Fermented with thermophilic cultures, lower content compared to cheeses.
Gouda Cheese	MK-9	High (47-76 µg)	Aged cheeses fermented with specific bacteria are excellent sources.
Natto	MK-7	Very High (over 1000 µg)	Richest food source of K2 due to unique bacterial fermentation.
Egg Yolk (pasture-raised)	MK-4	Moderate (15-32 µg)	Concentration varies based on the animal's diet.
Chicken Liver (pan-fried)	MK-4	Moderate (approx. 12-14 µg)	Good source of K2, along with other vitamins and minerals.

Supplementing with K2

For those who find it challenging to consume high levels of K2-rich foods, particularly natto, supplementation is a viable option. Supplements often contain the highly bioavailable MK-7 form and can be a reliable way to ensure adequate intake. Some yogurts are also fortified with K2, which has shown to be an effective delivery method. However, for most commercially available Greek yogurt, this is not the case.

Conclusion

To conclude, while Greek yogurt is a nutritious food, especially known for its high protein and probiotic content, it is generally not a reliable or significant source of Vitamin K2. The thermophilic cultures used in its production yield minimal K2, especially when compared to foods fermented with mesophilic bacteria, like aged cheeses. For optimal K2 intake, a diet rich in other fermented foods like natto, specific cheeses (Gouda, Brie), and animal products like egg yolks and liver is recommended. Always opt for full-fat dairy products if aiming for K2, and consider supplementation or fortified products if dietary sources are insufficient. For specific health concerns, it is always wise to consult with a healthcare provider or a registered dietitian.

[Disclaimer: This content is for informational purposes only and does not constitute medical advice. Consult with a qualified healthcare professional for personalized guidance.]

Frequently Asked Questions

Greek yogurt contains less Vitamin K2 than certain cheeses because it is made using thermophilic bacteria (e.g., S. thermophilus, L. bulgaricus), which produce very little K2, while cheeses like Gouda and Brie are fermented with mesophilic cultures that are more effective at K2 synthesis.

No, fat-free Greek yogurt contains virtually no Vitamin K2. As K2 is a fat-soluble vitamin, it is only present in dairy products with sufficient fat content, such as full-fat milk and yogurt.

You can increase your K2 intake by consuming other dietary sources like natto (fermented soybeans), aged cheeses (Gouda, Brie), chicken liver, and egg yolks, especially from pasture-raised animals.

Not necessarily. While most standard yogurts use thermophilic cultures resulting in low K2, some fermented milk products and yogurts made with mesophilic starter cultures or fortified with K2 can contain higher amounts.

Vitamin K2's primary function is to activate proteins that help properly utilize calcium in the body, directing it to where it's needed for bone and dental health while preventing its deposition in arteries and soft tissues.

No, fermentation does not automatically mean high K2. The amount of K2 produced depends heavily on the specific type of bacterial cultures and the fermentation conditions. For example, some lactic acid bacteria are effective K2 producers, while others are not.

Yes, yogurts that are specifically fortified with Vitamin K2, such as the MK-7 form, can be a suitable and bioavailable source, especially for those in Western populations who may have a deficiency.