Understanding Vitamin K in Dairy
Vitamin K is a fat-soluble nutrient that comes in two primary forms: Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinones). While K1 is primarily found in plant-based foods like leafy greens, Vitamin K2 is found in animal products and fermented foods, including many dairy items. Specifically, dairy products provide various menaquinones (MK-4 through MK-13), with MK-9, MK-10, and MK-11 being particularly prevalent.
Unlike K1, which mainly supports blood clotting, K2 plays a key role in bone metabolism and cardiovascular health by helping regulate calcium. The amount of K2 in a dairy product depends on a few key factors:
- Fat Content: Since vitamin K is fat-soluble, higher-fat dairy products contain more K2. Full-fat milk, cheese, and yogurt are significantly richer sources than their low-fat or fat-free counterparts.
- Fermentation: Bacterial fermentation during cheese making is a major producer of menaquinones. Cheeses made with specific bacterial cultures and longer ripening times generally have higher K2 levels.
- Origin of Milk: The diet of the dairy animal can also influence the K2 content. Grass-fed milk, for instance, is often considered a richer source.
Dairy Products Rich in Vitamin K2
Not all dairy is created equal when it comes to vitamin K. The concentration can vary significantly, even among cheeses. Below are some of the most notable high-K2 options.
Cheeses: The Highest Concentration
Cheeses are arguably the best dairy source of menaquinones, with content levels far surpassing milk or yogurt. Certain types of cheese consistently rank higher due to their fermentation and aging processes:
- Aged Hard Cheeses: Ripened cheeses such as Gouda and Emmental contain substantial amounts of K2. As cheese ripens, the bacterial cultures produce more menaquinones.
- Blue Cheeses: Some blue cheeses, like Roquefort and Stilton, are also excellent sources due to their unique bacterial and fungal cultures.
- Soft Cheeses: While content can vary, some soft cheeses, such as Muenster and Camembert, can offer high levels of K2, with some studies showing them to have the highest concentration among cheese types.
Full-Fat Milk and Butter
While cheeses dominate the list, other full-fat dairy products also contribute to your vitamin K intake.
- Full-Fat Milk: The total vitamin K content in full-fat milk is significantly higher than in 2% or skim milk.
- Butter: Especially grass-fed butter, is a concentrated source of vitamin K2. A study quantified a notable amount of MK-4 in butter samples.
Fermented Milks
Fermented milks, particularly full-fat versions, can be a decent source of K2. For example, some full-fat yogurts have similar K2 concentrations to full-fat milk. However, content can depend heavily on the specific starter cultures used during fermentation.
Comparison of Dairy Vitamin K2 Content
| Dairy Product (Full-Fat) | K2 Content (per 100g) | Primary K2 Type | Notes |
|---|---|---|---|
| Muenster Cheese | Up to ~50 µg | MK-8, MK-9 | One of the highest concentrations. |
| Aged Gouda | ~32-66 µg | MK-9 | Ripening time increases content. |
| Roquefort Cheese | ~38 µg | MK-9 | High levels from blue mold culture. |
| Stilton Cheese | ~49 µg | MK-9 | Another high-K2 blue cheese source. |
| Butter | ~15 µg | MK-4 | Concentrated source, especially grass-fed. |
| Full-Fat Milk (4%) | ~3.8-7.7 µg | MK-9, MK-11 | Significantly higher than low-fat versions. |
| Full-Fat Yogurt | ~3.8-7.7 µg | MK-9, MK-11 | Similar levels to full-fat milk. |
Note: K2 content can vary widely depending on specific brands, processing, and origin of the milk. The figures presented are based on research findings but serve as estimates.
Maximizing Vitamin K Intake from Dairy
To boost your vitamin K intake from dairy, focus on specific, high-fat, and fermented varieties. Prioritize aged cheeses and certain blue or soft cheeses. If you consume milk, choose whole milk over lower-fat options. Incorporating grass-fed butter into your diet can also make a meaningful contribution.
Here are some practical tips:
- Snack on cheese: Incorporate slices of Gouda, Muenster, or aged cheddar into your daily snacks.
- Cook with butter: Use grass-fed butter for cooking and spreading.
- Choose full-fat: Always opt for full-fat versions of milk, yogurt, and other dairy products to ensure the highest vitamin K concentration.
- Experiment with fermented milks: Try different brands of kefir or fermented yogurt, which can contain menaquinones.
Conclusion
While leafy greens provide the more common K1, dairy products are a valuable source of vitamin K2, which is increasingly recognized for its vital roles in bone and cardiovascular health. The highest concentrations of vitamin K in dairy are found in certain aged and blue cheeses, as well as high-fat products like butter. The key is to remember that for dairy, fat content and fermentation are the primary drivers of menaquinone levels. By focusing on these specific types of dairy, you can effectively enhance your dietary vitamin K intake. For more scientific insights into vitamin K and its forms, the NIH provides detailed fact sheets on this essential nutrient.
List of High-K2 Dairy Sources:
- Muenster cheese
- Aged Gouda
- Aged Cheddar
- Roquefort
- Stilton
- Grass-fed butter
- Full-fat milk
- Full-fat Greek yogurt
- Kefir
This list provides a useful starting point for anyone looking to increase their intake of vitamin K through dairy products, keeping in mind that fermentation and fat content are key indicators of higher levels.
Common K2 Forms in Dairy
- MK-9: Frequently found in ripened cheeses like Gouda and aged cheddar.
- MK-10 & MK-11: Also present in full-fat milk and many cheeses, often alongside MK-9.
- MK-4: Found in butter, egg yolks, and certain animal products.
