Best Vitamin D3 + K2 Supplements 2026

Last Updated: March 1, 2026  |  Author: Mike Hartnett  |  Category: Buyer’s Guide | Vitamins  |  Estimated Reading Time: 16 minutes

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Quick Answer: The Best Vitamin D3 + K2 Supplements in 2026

Most people who supplement vitamin D are missing half the equation. Vitamin D3 increases calcium absorption, but without adequate vitamin K2 (specifically the MK-7 form), that calcium can deposit in arteries and soft tissues instead of bones and teeth. Every major longevity expert — from Dr. Brad Stanfield to Peter Attia to Andrew Huberman — has discussed why these two nutrients belong together.

After testing five leading D3+K2 combination supplements and evaluating them on D3 potency, K2 dose and form, third-party testing, price per serving, and expert credibility, Thorne Vitamin D/K2 Liquid is our top pick for most people, with Sports Research Vitamin D3+K2 offering the best overall value.

Quick Comparison: Top D3 + K2 Supplements at a Glance

All affiliate links use rel=”sponsored nofollow” per FTC guidelines. Prices reflect typical retail pricing as of March 2026 and may vary by retailer.

Medical Disclaimer: CoreStacks reports on published research and expert opinions. We do not make health claims or recommend specific dosages. Vitamin D and vitamin K2 can interact with blood-thinning medications (warfarin, coumarin) and other prescriptions. Consult a qualified healthcare provider before starting any supplement. Nothing in this article constitutes medical advice. See our full Medical Disclaimer.

Why D3 and K2 Belong Together

This is not a marketing gimmick. The biochemistry is straightforward: vitamin D3 increases intestinal calcium absorption by up to 40%. That calcium needs to go somewhere. Vitamin K2 activates two proteins — osteocalcin and matrix GLA protein (MGP) — that direct calcium into bones and teeth while keeping it out of arteries and soft tissues.

Without adequate K2, supplementing high-dose D3 may actually increase the risk of arterial calcification. A 2017 study published in the International Journal of Endocrinology found that combined D3+K2 supplementation was more effective at preventing bone loss and reducing arterial stiffness than D3 alone. A 2019 review in the International Journal of Molecular Sciences further confirmed that K2 (MK-7 specifically) plays a critical role in calcium homeostasis when D3 intake is elevated.

Dr. Brad Stanfield has emphasized this pairing repeatedly on his YouTube channel, calling the D3+K2 combination one of the most evidence-backed supplement stacks available. He has discussed how MK-7 — the long-acting form of vitamin K2 with a half-life of roughly 72 hours — is superior to MK-4 for daily supplementation because a single dose maintains steady blood levels throughout the day.

Peter Attia monitors vitamin D levels as part of his standard blood panel protocol, targeting serum 25(OH)D levels between 40–60 ng/mL. He has noted on The Drive podcast that anyone supplementing D3 at 4,000–5,000 IU daily should consider K2 as a companion nutrient. Andrew Huberman has discussed vitamin D’s role in immune function, mood regulation, and hormone health on the Huberman Lab podcast, typically mentioning K2 alongside D3 as part of his foundational supplement stack.

For a deeper dive into the science behind this combination, see our Vitamin D3 + K2 Supplementation Guide.

Why MK-7, Not MK-4?

Vitamin K2 comes in two primary supplemental forms: MK-4 and MK-7. While both activate the same calcium-regulating proteins, they differ substantially in pharmacokinetics.

• MK-4 has a half-life of approximately 1–2 hours. To maintain blood levels, you would need to take it three times daily. The typical therapeutic dose in Japanese osteoporosis studies is 45 mg per day — a thousand times higher than common MK-7 doses.
• MK-7 has a half-life of approximately 72 hours. A single daily dose of 90–200 mcg maintains stable blood levels around the clock. It accumulates in the bloodstream over time, making it far more practical for daily use.

Every product on this list uses the MK-7 form of K2. If you see a D3+K2 supplement using only MK-4, the dosing requirements and absorption profile are fundamentally different, and it should not be compared directly to MK-7 formulas.

What to Look For in a D3 + K2 Supplement

The D3+K2 market has exploded, which means there are far more mediocre products than good ones. Here is exactly what separates a quality combination supplement from filler.

1. K2 Form: MK-7 Is Non-Negotiable

As discussed above, MK-7 is the only K2 form that makes sense for once-daily dosing. If the label just says “Vitamin K2” without specifying MK-7 or menaquinone-7, the product is probably using the cheaper MK-4 form. Check the supplement facts panel carefully.

2. K2 Dose: At Least 90 mcg MK-7

The research supporting K2’s effects on calcium metabolism and arterial health generally uses doses of 90–200 mcg MK-7. Some products include only 45 mcg, which is below the threshold where consistent benefits have been observed. We prefer products delivering 100–200 mcg per serving.

3. D3 Dose: Match to Your Blood Levels

The “right” D3 dose depends entirely on your current serum 25(OH)D level, which is why testing matters. General ranges discussed by longevity experts:

• 1,000–2,000 IU/day: Maintenance dose for people already in the optimal range (40–60 ng/mL)
• 4,000–5,000 IU/day: Common dose for people with insufficient levels (below 30 ng/mL) or limited sun exposure
• Up to 10,000 IU/day: Used by some practitioners for severe deficiency under medical supervision

Products with flexible dosing (like Thorne’s liquid dropper) allow you to dial in your exact dose. Fixed-dose capsules at 5,000 IU work for most people who know they are deficient, but may be too much for those who already have adequate levels.

4. Fat-Soluble Carrier

Both D3 and K2 are fat-soluble vitamins, meaning they absorb better when taken with fat. High-quality supplements include a lipid carrier like MCT oil, coconut oil, or olive oil in the formulation. If the product is a dry capsule with no oil base, you will need to take it with a fat-containing meal for adequate absorption.

5. Third-Party Testing

Look for NSF Certified for Sport, USP verification, or at minimum, batch-specific Certificates of Analysis from an independent laboratory. The supplement industry is self-regulated — third-party testing is the primary mechanism that verifies label accuracy.

6. No Unnecessary Fillers

Some D3+K2 products add magnesium stearate, titanium dioxide, artificial colors, or excessive excipients. These are not harmful in trace amounts, but a clean formula with minimal inactive ingredients signals that the manufacturer prioritized the product over cost-cutting.

Detailed Reviews: The Best Vitamin D3 + K2 Supplements

1. Thorne Vitamin D/K2 Liquid — Best Overall

Thorne is the supplement brand that physicians and naturopathic doctors actually recommend. Their D/K2 Liquid delivers 1,000 IU vitamin D3 and 200 mcg vitamin K2 (as MK-7) per drop from a precision dropper, allowing you to customize your dose anywhere from 1,000 IU to 5,000+ IU simply by adjusting the number of drops.

This flexibility is the product’s defining advantage. If your bloodwork shows you need 2,000 IU, take two drops. If your winter levels dip and your doctor wants you at 5,000 IU, take five drops. No pill-splitting, no buying different bottles. One product covers every dosing scenario.

Thorne holds NSF Certified for Sport certification, which is the most rigorous third-party testing standard in the supplement industry. It verifies label accuracy, tests for over 200 banned substances and contaminants, and audits manufacturing processes. This is the same certification used by professional athletes and Olympic teams.

Dr. Brad Stanfield has mentioned Thorne as a brand he trusts for supplement quality. Peter Attia has referenced Thorne products in the context of physician-grade supplementation. The brand is used in over 100 clinical trials, which speaks to its reputation in the research community.

Pros:

• Adjustable dosing from the liquid dropper — most flexible product on this list
• 200 mcg K2 (MK-7) per drop — highest K2 dose of any product reviewed
• NSF Certified for Sport — top-tier third-party verification
• MCT oil base for optimal fat-soluble vitamin absorption
• 600 drops per bottle — lasts 4+ months at typical doses
• No artificial flavors, colors, or preservatives

Cons:

• Premium pricing compared to softgel alternatives
• Liquid form requires careful drop counting — not as grab-and-go as a capsule
• Taste is neutral but oily, which some people find unpleasant
• Must be stored upright to prevent leaking

Bottom Line: Thorne D/K2 Liquid is the gold standard for D3+K2 supplementation. The combination of adjustable dosing, high K2 content, and NSF certification makes it the clear winner for anyone who wants clinical-grade quality and the flexibility to match their dose to their bloodwork.

Check current pricing for Thorne Vitamin D/K2 Liquid →

2. Sports Research Vitamin D3+K2 — Best Value

Sports Research has built a reputation for straightforward, well-formulated supplements at competitive prices. Their D3+K2 softgel delivers 5,000 IU vitamin D3 paired with 100 mcg vitamin K2 (MK-7) in a coconut oil carrier — a solid, no-nonsense formula for people who know they need a meaningful D3 dose.

The coconut oil base serves a dual purpose: it enhances absorption of both fat-soluble vitamins and keeps the formula clean without the need for artificial binders or fillers. Each softgel is non-GMO Project verified and free from gluten, soy, and artificial additives.

Sports Research provides third-party testing through Igen, an independent certification program that tests for purity and label accuracy. While not as comprehensive as NSF Certified for Sport (which also tests for banned substances), it provides meaningful verification that the product contains what the label claims.

At approximately $0.30–$0.40 per softgel, this is one of the most affordable quality D3+K2 combinations available. For the vast majority of people who want a fixed 5,000 IU daily dose with K2 coverage, this is the sweet spot of quality and value.

Pros:

• 5,000 IU D3 + 100 mcg K2 (MK-7) — clinically meaningful doses of both
• Coconut oil carrier for enhanced absorption
• Non-GMO Project verified
• Third-party tested (Igen certification)
• Excellent price per serving — among the most affordable on the market
• Small, easy-to-swallow softgels

Cons:

• Fixed 5,000 IU dose — no flexibility for people who need less
• 100 mcg K2 is adequate but not generous (compare to Thorne’s 200 mcg)
• Not NSF Certified for Sport (uses Igen instead)
• Contains coconut-derived ingredients — rare allergy concern for some

Bottom Line: Sports Research D3+K2 is the product I recommend most often to friends and family who ask what they should take. The formula is sound, the pricing is fair, and the quality verification is solid. If you want a simple one-softgel-per-day solution and you know you need 5,000 IU, this is the best value on the market.

Check current pricing for Sports Research D3+K2 →

3. NatureWise Vitamin D3+K2 — Best Budget Pick

NatureWise has been one of the best-selling vitamin D brands on Amazon for years, and their D3+K2 combination extends that reputation into the paired-formula space. Each softgel delivers 5,000 IU D3 and 100 mcg K2 (MK-7) in an organic olive oil carrier.

The olive oil base is an interesting choice — olive oil contains oleic acid, a monounsaturated fat that has its own well-documented health benefits. From a bioavailability perspective, any dietary fat carrier works for D3 and K2 absorption, so olive oil performs comparably to coconut or MCT oil.

NatureWise provides third-party testing, though their testing certifications are less prominently displayed than competitors like Thorne or Sports Research. The brand has a long track record and consistently positive consumer reviews, which counts for something in a market where fly-by-night brands appear and disappear regularly.

Pricing is typically $15–$22 for a 60-count bottle, making NatureWise the most affordable option for people who want 5,000 IU D3 with K2 coverage. For budget-conscious buyers who want a name brand rather than a generic, this is the logical choice.

Pros:

• 5,000 IU D3 + 100 mcg K2 (MK-7) — matches Sports Research on dose
• Organic olive oil carrier
• Non-GMO, gluten-free
• Lowest price point on this list
• Strong consumer track record on Amazon (10,000+ reviews)

Cons:

• Third-party testing details are less transparent than Thorne or Sports Research
• Softgels are slightly larger than some competitors
• Fixed 5,000 IU dose with no flexibility
• Not NSF or USP certified

Bottom Line: NatureWise delivers essentially the same formula as Sports Research at a slightly lower price. If cost is your primary concern and you are comfortable with a well-established Amazon brand, this is a perfectly solid choice. The tradeoff is somewhat less transparent third-party testing.

Check current pricing for NatureWise D3+K2 →

4. NOW Foods Vitamin D3 & K2 — Best for Low-Dose Maintenance

NOW Foods is the Costco of supplement brands — no-frills, good quality, excellent value. Their D3 & K2 formula delivers 1,000 IU vitamin D3 and 45 mcg vitamin K2 (MK-7) per vegetable capsule, designed for people who need a maintenance dose rather than a therapeutic one.

If your vitamin D blood levels are already in the optimal range (40–60 ng/mL) and you just want to prevent them from slipping during winter, 1,000 IU daily may be all you need. The 45 mcg K2 dose is on the lower end of what we prefer — most research supporting K2’s cardiovascular benefits uses 90+ mcg — but for a maintenance protocol, it provides baseline coverage.

NOW Foods has been manufacturing supplements since 1968. Their facility is GMP certified and the company maintains a robust in-house testing laboratory. While they do not hold NSF Certified for Sport status for this particular product, their manufacturing standards are well-regarded in the industry.

At 120 capsules per bottle for roughly $10–$15, this is the most economical D3+K2 on the market by raw capsule count. The per-serving cost is almost negligible.

Pros:

• 120 capsules per bottle — 4-month supply at one capsule daily
• 1,000 IU dose appropriate for maintenance when levels are already adequate
• Vegetarian-friendly capsule (no gelatin)
• GMP certified manufacturing
• Extremely affordable — pennies per day
• Trusted brand with 50+ year track record

Cons:

• 45 mcg K2 (MK-7) is below the 90+ mcg threshold in most research
• 1,000 IU D3 is insufficient for people with deficiency or insufficiency
• Dry capsule with no oil carrier — take with a fat-containing meal
• Not third-party certified by NSF or USP for this specific product

Bottom Line: NOW D3 & K2 is the right choice for a very specific user: someone whose vitamin D levels are already optimized and who needs an affordable daily maintenance dose. If you are starting from deficiency or want robust K2 coverage, look at the higher-dose options above.

Check current pricing for NOW Foods D3 & K2 →

5. Ritual Essential for Men/Women — Best Multivitamin with D3+K2

Ritual takes a fundamentally different approach than every other product on this list. Instead of a standalone D3+K2 supplement, Ritual includes 2,000 IU D3 and 90 mcg K2 (MK-7) inside their comprehensive daily multivitamin alongside omega-3 DHA, iron (women’s formula), folate, B12, magnesium, boron, and vitamin E.

If you are already taking (or planning to take) a multivitamin and want your D3+K2 covered within that formula rather than as a separate pill, Ritual is the cleanest option on the market. Their delayed-release capsule design is meant to deliver nutrients in the small intestine rather than the stomach, reducing the nausea that some people experience with multivitamins.

Ritual is one of the most transparent supplement companies in the industry. Every ingredient is traceable to its source (they publish supplier information), the formula uses bioavailable nutrient forms (methylated B vitamins, chelated minerals), and the product is third-party tested by USP for purity and label accuracy.

The trade-off is cost. At $35–$38 per month on subscription, you are paying significantly more than a standalone D3+K2 product. But if Ritual replaces your multivitamin plus your D3+K2, the math may actually work in your favor compared to buying both separately.

Pros:

• D3+K2 within a comprehensive multivitamin — fewer pills daily
• 2,000 IU D3 + 90 mcg K2 (MK-7) — clinically meaningful doses
• USP third-party tested
• Full supply chain transparency — ingredient sources published
• Delayed-release capsule design for reduced stomach discomfort
• Separate formulas for men, women, and 50+ demographics

Cons:

• Subscription model required — no one-time purchase option
• $35–$38/month is expensive compared to standalone D3+K2
• 2,000 IU D3 may be insufficient for people with significant deficiency
• If you do not need a multivitamin, you are paying for ingredients you may already get from other sources

Bottom Line: Ritual is not a D3+K2 supplement. It is a multivitamin that happens to include an excellent D3+K2 pairing. If you want to consolidate your daily stack and trust a transparent brand with USP testing, Ritual is a smart choice. If you only need D3+K2, the standalone options above are more cost-effective.

Check current pricing for Ritual Essential Multivitamin →

Mike’s Personal Take

I take a D3+K2 combination every single day, year-round. Living in the Northeast, my winter vitamin D levels used to crater into the low 20s before I started supplementing. After adding 5,000 IU D3 with 100 mcg MK-7 to my morning routine, my levels stabilized in the mid-40s on my last blood panel, and the difference in my winter energy was noticeable within about six weeks.

The K2 component was something I added after reading Dr. Stanfield’s breakdown of calcium metabolism. Before that, I was taking D3 alone for years without thinking about where all that extra calcium was going. Now the D3+K2 combo is the one supplement I never skip — it sits right next to my coffee maker so I cannot forget it.

For what it is worth, I currently use Sports Research D3+K2 for the value and Thorne D/K2 Liquid when I want to adjust my dose based on seasonal bloodwork. Both are excellent.

— Mike Hartnett, CoreStacks founder

What the Experts Say About Vitamin D3 + K2

One of the unusual features of the D3+K2 combination is that virtually every major longevity expert agrees on it. This is rare in a space where experts frequently disagree on everything from NMN dosing to the value of resveratrol.

Dr. Brad Stanfield

Dr. Stanfield has produced multiple evidence-review videos on vitamin D3 and K2, consistently emphasizing the importance of the MK-7 form and the synergistic relationship between D3 and K2 in calcium metabolism. He has specifically called out the risk of supplementing D3 without K2, noting that high-dose D3 alone increases calcium absorption without the signaling pathway that directs calcium to bones. On his YouTube channel, he has discussed targeting vitamin D blood levels in the 40–60 ng/mL range and using K2 (MK-7) at 90–200 mcg daily alongside D3.

Peter Attia

Dr. Attia takes a characteristically data-driven approach to vitamin D. On The Drive podcast, he has discussed supplementing with 5,000 IU D3 daily, monitoring his serum 25(OH)D levels regularly, and maintaining them in what he considers an optimal range. His broader framework treats vitamin D supplementation as a low-risk, potentially high-benefit intervention — the type of asymmetric bet he favors in his longevity practice. For a deeper look at Attia’s complete supplement approach, see our Longevity Expert Stacks Compared.

Andrew Huberman

Dr. Huberman has discussed vitamin D as part of his foundational supplement stack on the Huberman Lab podcast, covering its role in immune function, mood regulation, testosterone support, and bone health. He has mentioned taking D3 alongside K2 as a standard practice and typically references it alongside omega-3s, magnesium, and creatine as one of the highest-priority supplements for general health. For a full breakdown of Huberman’s supplementation approach, see our Brad Stanfield Supplement Protocol 2026.

Dosing Considerations: How Much D3 + K2 Do You Actually Need?

The optimal dose of vitamin D3 depends on your current blood levels, body weight, skin pigmentation, sun exposure, and geographic latitude. This is why testing matters more than following generic dosing advice.

Testing Your Vitamin D Levels

The blood test you want is the 25-hydroxyvitamin D test (also written as 25(OH)D). This is the standard clinical marker for vitamin D status. Most longevity-focused practitioners target:

• 40–60 ng/mL (100–150 nmol/L) — the range most commonly discussed as optimal
• Below 20 ng/mL — clinical deficiency
• 20–30 ng/mL — insufficiency
• Above 100 ng/mL — potential toxicity concern

You can request this test from your primary care physician, or use at-home testing services. For more on essential blood tests for longevity optimization, see our Longevity Blood Tests Guide.

General D3 Dosing Ranges (From Expert Discussions)

These are ranges discussed by longevity experts and should not be interpreted as personalized medical advice. Work with your healthcare provider to determine the right dose for your situation.

K2 Dosing

Most research supporting K2 (MK-7) benefits for cardiovascular and bone health uses doses of 90–200 mcg per day. There is no established upper limit for vitamin K2 in healthy adults, and toxicity has not been reported even at high doses. However, K2 directly affects blood clotting pathways, so anyone taking warfarin or other vitamin K-antagonist blood thinners should consult their physician before supplementing.

Frequently Asked Questions

Can I take vitamin D3 without K2?

You can, and millions of people do. Vitamin D3 on its own is safe and beneficial for most people. The concern with high-dose D3 without K2 is related to calcium metabolism: D3 increases calcium absorption, and K2 helps direct that calcium to bones rather than arteries. If you take less than 2,000 IU D3 daily and eat a diet that includes K2-rich foods (natto, hard cheeses, egg yolks), the risk is likely minimal. At higher D3 doses (4,000+ IU), adding K2 becomes a more meaningful consideration. Dr. Stanfield has framed it as an inexpensive insurance policy — the cost of adding K2 is low, and the potential benefit is significant.

When is the best time of day to take D3+K2?

Take D3+K2 with a fat-containing meal for optimal absorption. Both vitamins are fat-soluble, meaning they need dietary fat to be absorbed efficiently. Morning with breakfast or lunchtime with your meal are the most common recommendations. Some evidence suggests that taking vitamin D late in the evening may interfere with melatonin production, though this is debated. Huberman has mentioned taking his D3 in the morning as part of his routine.

How long does it take for vitamin D3 supplementation to raise blood levels?

Most studies show measurable increases in serum 25(OH)D within 2–4 weeks of consistent supplementation, with levels plateauing around 8–12 weeks. This is why re-testing 3 months after starting supplementation is the standard recommendation to see if your dose is appropriate.

Is there a risk of taking too much vitamin D3?

Vitamin D toxicity (hypervitaminosis D) is possible but uncommon at typical supplemental doses. It generally occurs at sustained intake above 10,000–40,000 IU daily over months, resulting in dangerously elevated calcium levels (hypercalcemia). At 1,000–5,000 IU daily — the range most longevity experts discuss — toxicity is exceedingly rare. Periodic blood testing is the simplest way to ensure your levels remain in the optimal range without overshooting.

Do I need to take D3+K2 in the summer if I get sun exposure?

It depends on how much sun you actually get and where you live. UVB radiation from sunlight triggers vitamin D synthesis in the skin, and 15–30 minutes of midday sun exposure on large skin areas can produce 10,000–20,000 IU of D3. However, most people working indoor jobs do not get consistent midday sun exposure even in summer. Geographic latitude matters too — north of the 37th parallel (roughly a line from San Francisco to Richmond, Virginia), UVB intensity is insufficient for vitamin D synthesis during winter months entirely. Testing your levels in both summer and winter gives you the data to decide.

Can vitamin K2 interact with blood-thinning medications?

Yes. Vitamin K (both K1 and K2) directly affects the blood clotting cascade. Warfarin (Coumadin) works by antagonizing vitamin K, so supplementing K2 can reduce warfarin’s effectiveness. If you take warfarin, coumarin, or any vitamin K-antagonist medication, do not supplement K2 without consulting your prescribing physician. Newer anticoagulants like rivaroxaban and apixaban work through different mechanisms and are generally not affected by vitamin K intake, but you should still discuss supplementation with your doctor.

The Bottom Line

Vitamin D3 + K2 (MK-7) is one of the most straightforward supplement combinations in the longevity space. The science is strong, the expert consensus is unusually unified, and the cost is low relative to almost any other supplement category. If you supplement only three things, most longevity experts would include D3+K2 alongside omega-3s and magnesium.

Our top picks:

• Best overall: Thorne Vitamin D/K2 Liquid — clinical-grade quality, adjustable dosing, NSF Certified for Sport
• Best value: Sports Research D3+K2 — strong formula at the best price per serving
• Best budget: NatureWise D3+K2 — reliable brand at entry-level pricing

Test your blood levels, match your dose to your data, and take it with a meal. That is all there is to it.

For more on what the top longevity researchers take and why, explore our Longevity Expert Stacks Compared and Dr. Brad Stanfield’s Complete Supplement Protocol.

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Keep Reading

• Is 5,000 IU of vitamin D3 too much?
• Is taking D3 without K2 dangerous?
• Do you need blood work before supplementing D3?

Medical Disclaimer: The information provided in this article is for educational and informational purposes only and is not intended as medical advice. CoreStacks reports on published research and expert opinions. We do not diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen, especially if you take medications or have pre-existing health conditions. Individual results may vary. See our full Medical Disclaimer.