Vitamin K2, scientifically known as menaquinone, is a fat-soluble nutrient that activates proteins managing calcium utilization. Unlike Vitamin K1, which is primarily involved in blood clotting, K2 specifically directs calcium into bones and teeth while keeping it out of soft tissues like arteries and kidneys. Supplementation is popular because dietary sources of K2, such as fermented foods and certain animal products, are not consistently high in the Western diet, and it supports bone density and promotes arterial flexibility.
Understanding the Types of Vitamin K2
The two forms of Vitamin K2 most commonly found in supplements are Menaquinone-4 (MK-4) and Menaquinone-7 (MK-7). These forms differ significantly in structure and how the body handles them. MK-4 is the form naturally found in animal products, but the MK-4 used in supplements is typically synthetic and has a very short half-life of only a few hours. This short duration means MK-4 often requires high milligram-level doses, such as 45 mg daily, taken multiple times throughout the day to maintain consistent blood levels.
MK-7 is usually sourced from the fermentation of soybeans, such as in the Japanese food natto, and is considered the long-chain menaquinone. It possesses a much longer half-life, staying in the bloodstream for up to 68 hours, which allows for effective once-daily dosing. MK-7 is effective at much lower microgram-level doses, typically ranging from 100 to 180 micrograms (mcg) per day. MK-7’s prolonged presence in the circulation makes it highly efficient at activating the proteins that regulate calcium.
Essential Criteria for Selecting a Quality Supplement
When purchasing a Vitamin K2 supplement, consumers should carefully examine the label for quality indicators beyond just the form (MK-4 or MK-7). The stated dosage on the bottle should be clearly standardized, with MK-7 supplements typically listing amounts in micrograms (mcg). Because K2 is a fat-soluble vitamin, absorption is maximized when it is consumed with fat.
Many quality products incorporate a carrier oil directly into the capsule or liquid drops, such as olive oil or Medium-Chain Triglyceride (MCT) oil, to enhance absorption. The isomeric purity of MK-7 is also important, as only the all-trans isomer is biologically active in the body. Consumers should ensure the product contains the bioactive all-trans form, as many supplements fail to meet this quality standard.
To ensure the product contains what it claims, look for evidence of third-party testing or certification seals from organizations like the United States Pharmacopeia (USP) or NSF International. These seals confirm that the supplement has been independently verified for identity, strength, purity, and quality. Supplements are available in various formats, including capsules, tablets, and liquid drops.
Retail Options for Purchasing Vitamin K2
The choice of where to buy a Vitamin K2 supplement often depends on the buyer’s preference for immediate access versus selection and price. Physical retail locations, such as local pharmacies and health food stores, offer the advantage of immediate purchase and the ability to consult with staff. However, these locations typically carry a more limited selection of brands and forms, which can lead to higher prices compared to other options.
In contrast, online specialty retailers and direct-to-consumer brand websites provide a substantially wider array of choices, including highly specific formulations and dosages. This expansive selection allows buyers to compare different forms of K2, check for third-party certifications, and often benefit from more competitive pricing. The main drawback of online purchasing is the need for the buyer to verify the seller’s reputation and the supplement’s quality, as the market contains products that may not meet label claims.
Important Considerations Before Buying
Before incorporating a Vitamin K2 supplement into a routine, individuals must be aware of potential drug interactions, especially concerning blood thinners. Since Vitamin K plays a role in blood clotting, supplementing with K2 can interfere with the activity of anticoagulant medications. Anyone taking a blood thinner must consult with a healthcare professional before starting K2 supplementation to avoid adverse effects.
Vitamin K2 is also frequently paired with Vitamin D, as the two vitamins work together synergistically. Vitamin D increases calcium absorption in the gut, while K2 activates the proteins that direct that calcium to the bones, preventing its deposition in the arteries. For maximum efficacy, K2 supplements should be stored away from direct sunlight and heat, as this fat-soluble vitamin can degrade when exposed to harsh environments.