The Core of Vitamin K1: Phylloquinone
At its core, the active ingredient in naturally occurring Vitamin K1 is phylloquinone. This fat-soluble vitamin is essential for synthesizing proteins necessary for blood coagulation and bone metabolism. However, the 'ingredients' that deliver phylloquinone to the body differ significantly based on the source, whether a whole food, a dietary pill, or a pharmaceutical emulsion [2.1].
Natural Ingredients in Vitamin K1 Food Sources
For most people, the primary source of K1 is diet, and the ingredients are simply the foods themselves. The richest food ingredients are chlorophyll-rich leafy green vegetables, but it is also found in some oils and fruits.
Common K1-Rich Food Ingredients
- Leafy Greens: Kale, spinach, collard greens, mustard greens, Swiss chard, and broccoli.
- Cruciferous Vegetables: Brussels sprouts and cabbage.
- Vegetable Oils: Soybean oil and canola oil contain measurable amounts.
- Certain Fruits: Blueberries, blackberries, grapes, and figs.
To increase the absorption of K1 from these plant sources, consuming them with a dietary fat, such as oil, is recommended.
Ingredients in Dietary Vitamin K1 Supplements
While food sources are ideal, supplements provide a concentrated form of K1. The key active ingredient is either phylloquinone or its synthetic equivalent, phytonadione. The inactive ingredients in supplements can include fillers, binders, emulsifiers, coatings, and preservatives, which vary by manufacturer and the form of the supplement [2.1, 2.2.1].
Ingredients in Pharmaceutical K1 Injections
For medical use, a sterile injectable emulsion of K1 is used. The active ingredient is phytonadione (synthetic Vitamin K1). Other ingredients typically include an emulsifier like polysorbate 80 or polyoxyl 35 castor oil, a base solution of hydrous dextrose and water, and often a preservative such as benzyl alcohol. pH adjusters like hydrochloric acid or sodium acetate anhydrous may also be present.
Vitamin K1 vs. Vitamin K2: A Comparison of Differences
Vitamin K is a family of compounds, and K1 and K2 differ in origin and primary function.
| Feature | Vitamin K1 (Phylloquinone) | Vitamin K2 (Menaquinones) |
|---|---|---|
| Primary Source | Green leafy vegetables and some vegetable oils. | Fermented foods (e.g., natto), animal products (e.g., egg yolks, cheese), and gut bacteria. |
| Primary Function | Liver function and blood coagulation. | Extra-hepatic activity, including bone and cardiovascular health. |
| Absorption | Poorly absorbed from plant foods unless consumed with fat. | Often better absorbed, possibly due to association with dietary fat. |
| Circulation Half-Life | Circulates for a relatively short time (hours). | Longer half-life (e.g., MK-7 lasts for days) allowing greater extra-hepatic use. |
Is Vitamin K1 Natural or Synthetic?
Naturally, K1 is synthesized by plants and is the form found in foods. However, the phytonadione used in supplements and medications is a synthetically produced version. This synthetic phytonadione is chemically identical to the naturally occurring phylloquinone. The synthesis process allows for a stable, high-purity product.
Common Ingredients Found with Vitamin K1
Some supplements combine K1 with other ingredients for synergistic effects, particularly for bone health. These are not part of K1 itself but are often included in multivitamins or specific formulations:
- Calcium and Magnesium: Minerals important for bone health.
- Vitamin D: Works synergistically with K1 and K2 for calcium metabolism.
- Other Menaquinones (K2): Some supplements combine both K1 and K2 forms to offer broader benefits.
Conclusion: Understanding the Ingredients in K1
The term "ingredients in K1" depends on the source. In food, K1 is a natural component of plants. In supplements and injections, it's a purified, often synthetic, form of the vitamin (phytonadione) combined with various inactive ingredients for stability and effectiveness. While the core active compound is the same, the formulations differ for dietary and medical uses. Always check product labels for specific ingredients, especially in supplements. For more information, the NIH Office of Dietary Supplements offers an extensive fact sheet on vitamin K(https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/).
