Quick Verdict: This Sports Research Vitamin D3 K2 review covers one of the best D3+K2 combination supplements available — 5,000 IU of plant-based D3 (from lichen, not lanolin) paired with 100mcg of K2 as MK-7 (the most bioavailable form), suspended in organic coconut MCT oil for optimal absorption. The D3+K2 combination matters because D3 increases calcium absorption while K2 directs that calcium to your bones — without K2, supplemented calcium can accumulate in arteries instead of bone (Maresz, 2015). Best for: adults over 40 with low vitamin D, vegans, anyone supplementing calcium or concerned about bone density. Skip if: you take blood thinners like warfarin (K2 interacts), prefer lower-dose maintenance (this is 5000 IU), or want NSF/USP certification on the label.
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Sports Research Vitamin D3 + K2 delivers 5,000 IU of plant-based vitamin D3 paired with 100mcg of K2 (as MK-7) in a single softgel suspended in organic coconut MCT oil. The pairing matters more than most people realize: vitamin D3 increases calcium absorption from your diet, but it’s vitamin K2 that tells that calcium where to go. Without K2, the calcium your body absorbs from D3 supplementation can accumulate in soft tissues — particularly arteries — rather than bones (Maresz, 2015). Sports Research, founded in 1980 and family-owned, manufactures this formula in cGMP-compliant US facilities with third-party testing. Here’s what 30 days of testing revealed.
What Is Sports Research Vitamin D3 + K2?
Sports Research D3 + K2 is a once-daily softgel that delivers two essential fat-soluble vitamins in one capsule, combined with coconut MCT oil for enhanced absorption.
Here’s a quick breakdown:
- Vitamin D3: 5,000 IU (125mcg) from lichen (VegaDELight)
- Vitamin K2: 100mcg as MK-7 from fermented chickpeas (MenaQ7)
- Carrier oil: Coconut MCT oil
- Capsule type: PlantGel (tapioca-based, vegan)
- Servings per bottle: 60 (2-month supply)
- Price: Around $15-18 per bottle (~$0.25-0.30/day)
- Certifications: Non-GMO Project Verified, Vegan Certified, cGMP facility, third-party tested
Why D3 + K2 Together?
This is one of the most important things to understand about vitamin D supplementation. Taking D3 alone increases your calcium absorption — that’s the whole point. But without K2, that extra calcium can end up in your arteries and soft tissues instead of your bones.
A 2015 review by Maresz in Integrative Medicine found that vitamin K2 (MK-7) activates osteocalcin (directing calcium to bones) and matrix GLA protein (preventing arterial calcification), making K2 an essential companion to D3 supplementation. Think of D3 as opening the door for calcium, and K2 as the guide that sends it to the right destination.
This is why standalone D3 supplements are increasingly being replaced by D3+K2 combinations — especially for adults over 40 who need to be mindful of both bone density and cardiovascular health.
What I Like About Sports Research D3 + K2
Plant-based D3 from lichen. Most vitamin D3 on the market comes from lanolin (sheep’s wool). Sports Research uses VegaDELight, a vegan D3 sourced from lichen. This makes it suitable for vegans and anyone who prefers plant-based supplements — without sacrificing the effectiveness of D3 over D2.
MenaQ7 K2. They don’t just use any K2 — they use MenaQ7, a branded and clinically studied form of MK-7 derived from fermented chickpeas. A 2013 double-blind, placebo-controlled trial by Knapen et al. in Thrombosis and Haemostasis found that 180mcg/day of MenaQ7 for 3 years significantly improved arterial stiffness and reduced age-related vascular deterioration in healthy postmenopausal women.
Coconut MCT oil for absorption. Vitamin D is fat-soluble, meaning it needs fat for proper absorption. Sports Research includes coconut MCT oil right in the softgel, so you get built-in absorption support even if you take it with a light meal.
PlantGel capsule. Their proprietary tapioca-based capsule is one of the few vegan softgels that can pass Non-GMO Project Verification. No gelatin, no carrageenan — just clean plant-based material.
Impressive certifications. Non-GMO Project Verified, Vegan Certified, made in a cGMP facility, and third-party tested. This is a level of verification that many competitors — even more expensive ones — don’t offer.
Easy to take. The softgels are small, easy to swallow, and have no taste or aftertaste. One per day is all you need.
Great value. At around $0.25/day for a D3+K2 combo with premium sourcing and multiple certifications, the value is excellent. You’d pay $0.40-0.60/day for comparable quality from premium brands.
What Could Be Better
5,000 IU may be too much for some. If your vitamin D levels are already adequate (above 30 ng/mL), 5,000 IU daily could push you higher than necessary. Sports Research does offer a 2,500 IU version for those who need a lower dose.
Turmeric in the capsule shell. In 2022, Sports Research added turmeric powder to the outer shell to protect against UV degradation. While this is a smart preservation choice, some users have reported that the new orange-colored capsules look different from the original white ones. The active ingredients haven’t changed.
No subscription option on Amazon. While you can Subscribe & Save on Amazon, the discount is smaller than buying directly from the Sports Research website or from Costco (where you can get a 160-count bottle at a better per-unit price).
Only 60 capsules per standard bottle. A 2-month supply is fine, but a 90 or 120-count option at a slightly better per-unit price would be welcome. The Costco 160-count version partially addresses this.
How to Take It
Dosage: 1 softgel daily. This gives you 5,000 IU of D3 and 100mcg of K2.
Timing: Take it with any meal, preferably the one that contains the most fat. The built-in MCT oil helps, but taking it with dietary fat maximizes absorption.
Testing: If you haven’t checked your vitamin D levels before, get a 25(OH)D blood test. See our full guide to supplements for energy after 40 — vitamin D deficiency is one of the most common energy drainers in this age group. This tells you exactly where you stand and helps you determine if 5,000 IU is the right dose for you. If your levels are above 50 ng/mL, you may want to switch to the 2,500 IU version or take the 5,000 IU every other day.
Consistency: Take it daily. Vitamin D builds up in your system over weeks, so sporadic use won’t give you the full benefits.
D3+K2 Dosage Based on Your Blood Test Results
The “one dose fits all” approach to vitamin D supplementation is why so many adults over 40 either stay deficient or push their levels too high. Getting a serum 25-hydroxyvitamin D (25(OH)D) blood test — the standard measurement — lets you dose based on where you actually are, not where you guess you are.
Here’s how to translate your test results into a practical protocol using Sports Research D3+K2.
If your 25(OH)D is below 20 ng/mL — Deficiency
You’re in the deficiency range according to both the Endocrine Society and Institute of Medicine guidelines. Your body needs correction dosing, not maintenance.
- Recommended protocol: 5,000-10,000 IU daily for 8-12 weeks, under medical supervision if using the higher end
- Using Sports Research D3+K2 (5,000 IU): 1 softgel daily is the starting point; some clinicians recommend 2 softgels daily for 8 weeks if levels are severely low (<10 ng/mL)
- Alternative for correction: For confirmed deficiency, a practitioner-grade product like Metagenics D3 10,000 with K2 may be more appropriate under medical guidance
- Retest: After 8-12 weeks of consistent supplementation
If your 25(OH)D is 20-30 ng/mL — Insufficiency
You’re in the insufficiency range — not deficient, but below the level associated with optimal bone, immune, and cardiovascular function.
- Recommended protocol: 5,000 IU daily for 8-12 weeks, then retest and adjust
- Using Sports Research D3+K2: 1 softgel daily is the ideal dose
- Expected outcome: Most adults reach 40-50 ng/mL after 8-12 weeks at this dose
- Retest: After 12 weeks
If your 25(OH)D is 30-50 ng/mL — Adequate
This is the range most functional medicine practitioners and researchers consider adequate for adults over 40. Your goal now is maintenance, not correction.
- Recommended protocol: 1,000-2,000 IU daily for maintenance
- Using Sports Research D3+K2 (5,000 IU): Take 1 softgel every 2-3 days, or consider the Sports Research 2,500 IU version for daily use
- Retest: Once a year to confirm you’re staying in range
If your 25(OH)D is 50-80 ng/mL — Optimal
You’re in the range associated with the best outcomes for bone health, immune function, and cardiovascular protection. Keep doing what you’re doing.
- Recommended protocol: 1,000-2,000 IU daily
- Using Sports Research D3+K2: Take 1 softgel every 2-3 days
- Watch for: Consider dropping to a lower dose if you get significant sun exposure in summer
- Retest: Annually
If your 25(OH)D is above 80 ng/mL — Reduce Dose
You don’t need more supplementation. Continuing at high doses could push you into potentially harmful territory.
- Recommended protocol: Reduce dose or take breaks
- Using Sports Research D3+K2: Take 1 softgel weekly, or pause supplementation for 2-4 weeks and retest
- Watch for: Levels above 100 ng/mL can lead to hypercalcemia symptoms
If your 25(OH)D is above 100 ng/mL — Stop and Consult Doctor
Vitamin D toxicity typically occurs at levels above 100 ng/mL and can cause hypercalcemia (nausea, weakness, kidney problems).
- Immediate action: Stop supplementation entirely
- Consult: Your healthcare provider for guidance on retesting timeline and monitoring
- Note: Toxicity is rare at typical supplement doses but possible with sustained high-dose use without monitoring
About the K2 Component
The K2 dose in Sports Research D3+K2 (100mcg MK-7) is appropriate at any of the supplementation levels above. K2 doesn’t require the same level of blood test-driven dosing that D3 does — the 100mcg MK-7 dose is what most clinical research on K2 uses for bone and cardiovascular endpoints. If you’re pausing D3 supplementation because your levels are high, you can supplement K2 separately (100mcg MK-7) or take Sports Research D3+K2 less frequently to keep some K2 in the mix.
Testing Frequency
- Starting supplementation: Baseline test before starting, retest at 8-12 weeks
- On correction dose (5,000+ IU): Test every 3 months until stable
- On maintenance dose: Test annually
- After 40: Test at least annually regardless of supplementation status — vitamin D metabolism slows with age
Getting tested is inexpensive (typically $30-50 through direct-to-consumer labs like LetsGetChecked or Everlywell if your doctor won’t order it) and eliminates the guesswork that’s cost so many adults years of suboptimal vitamin D status.
Who Should Take Sports Research D3 + K2?
Great for:
- Adults over 40 who spend most of their time indoors
- Anyone with confirmed or suspected vitamin D deficiency
- People wanting bone and cardiovascular support in one capsule
- Vegans who need a plant-based D3 source
- Anyone taking calcium supplements (K2 ensures proper calcium distribution)
Not ideal for:
- People who already have adequate vitamin D levels (get tested first)
- Those who prefer a lower dose (consider the 2,500 IU version)
- People on blood thinners like Warfarin (K2 affects blood clotting — consult your doctor)
- Anyone looking for the absolute cheapest option (generic D3 is cheaper, though lower quality)
How It Compares to Alternatives
vs. NOW Foods Vitamin D3 2,000 IU: NOW is cheaper ($0.05/day) but doesn’t include K2 or MCT oil. If budget is your top priority and you’re getting K2 elsewhere, NOW is solid. But for a complete solution, Sports Research wins.
vs. Transparent Labs D3 + K2: Very similar formula — both use 5,000 IU D3 + 100mcg K2. Transparent Labs costs more ($0.42/day) and is only available through their website. Sports Research offers better value and wider availability.
vs. NatureWise D3 5,000 IU: NatureWise is one of the best budget options at $0.05/day for a full year supply. But it doesn’t include K2. If you supplement K2 separately, the total cost ends up similar to Sports Research — with less convenience.
vs. Life Extension D and K: Life Extension includes multiple forms of K2 (MK-4 and MK-7) at a higher K2 dose. It’s a good option for those specifically focused on longevity, but costs more and uses gelatin capsules (not vegan).
vs. Metagenics D3 10,000 with K2: Different use case entirely. Metagenics delivers 10,000 IU of D3 with K2 — a practitioner-grade correction dose designed for adults with confirmed vitamin D deficiency working under medical supervision. It costs roughly 2x more (~$0.50/day) and is intended for 8-12 week correction protocols followed by stepping down to maintenance dosing. Sports Research remains the better choice for daily long-term supplementation; Metagenics is what you’d choose if your functional medicine doctor prescribed a high-dose correction protocol.
| Product | Dose | Best For | Price |
|---|---|---|---|
| Sports Research D3 + K2 ★ Our Pick | 5,000 IU D3 + 100mcg K2 (MK-7) | Best overall daily maintenance | Check Price |
| NOW Foods Vitamin D3 2,000 IU | 2,000 IU D3 (no K2) | Best budget maintenance | Check Price |
| Transparent Labs D3 + K2 | 5,000 IU D3 + 100mcg K2 (MK-7) | Best premium, vegan D3 | – |
| NatureWise D3 5,000 IU | 5,000 IU D3 (no K2) | Best high-dose without K2 | Check Price |
| Life Extension D and K | 5,000 IU D3 + 2,100mcg K2 complex | Best for longevity focus | – |
| Metagenics D3 10,000 with K2 | 10,000 IU D3 + K2 | Practitioner-grade correction dose | Check Price |
Common Questions About Sports Research D3+K2
Why take D3 and K2 together?
D3 and K2 work synergistically. Vitamin D3 helps your body absorb calcium from food, but K2 directs that calcium to your bones and teeth — away from soft tissues like arteries. Taking D3 without K2 can lead to calcium accumulating in arteries instead of bones, contributing to arterial stiffness (Maresz, 2015 in Integrative Medicine). Most modern Western diets are low in both D3 and K2, making combined supplementation a smart choice for adults over 40 concerned about bone density and cardiovascular health.
Is 5,000 IU of vitamin D3 too much?
For most adults, 5,000 IU daily is safe and effective, especially for those with confirmed deficiency. The Endocrine Society recommends up to 10,000 IU daily as safe for adults. The official Tolerable Upper Intake Level is 4,000 IU, but this is conservative — clinical research has shown long-term safety at higher doses. If you’re concerned, get your blood 25(OH)D level tested. The optimal range is 30-50 ng/mL. If you’re already in that range with sun exposure or diet, a lower-dose maintenance supplement may be more appropriate.
What’s the difference between K2 MK-4 and K2 MK-7?
Both are forms of vitamin K2, but MK-7 has a much longer half-life in the body (about 72 hours) compared to MK-4 (about 1-2 hours). This means MK-7 maintains active K2 levels in your blood with a single daily dose, while MK-4 would require multiple doses throughout the day to achieve similar results. Most research on K2 for bone and cardiovascular health uses MK-7. Sports Research uses MK-7 derived from fermented chickpeas, which is the gold standard.
Can I take Sports Research D3+K2 with blood thinners?
No — consult your doctor first. Vitamin K2 can interfere with blood-thinning medications like warfarin (Coumadin) by counteracting their effects. If you take any anticoagulant or antiplatelet medication, talk to your prescribing physician before starting a K2 supplement. Some doctors will adjust dosing rather than stop K2 entirely because of K2’s bone health benefits. Newer anticoagulants like Eliquis and Xarelto don’t interact with K2, but always verify with your doctor.
When should I take Sports Research D3+K2?
Take it in the morning with a meal that contains fat. D3 and K2 are both fat-soluble vitamins, meaning they need dietary fat for proper absorption. Taking it with breakfast that includes eggs, avocado, nuts, or olive oil maximizes absorption. The coconut MCT oil already in the softgel helps, but adding food fat further improves uptake. Some people prefer morning timing to avoid any potential mild energizing effect of D3 interfering with sleep.
Is plant-based D3 as effective as lanolin D3?
Yes. Vitamin D3 derived from lichen (the plant-based source Sports Research uses) is bioidentical to D3 from lanolin (sheep’s wool — the most common source). Studies have shown comparable bioavailability and effectiveness between the two sources. Plant-based D3 is the better choice for vegans, vegetarians who avoid animal products, and anyone with concerns about sourcing. The lichen source also has a lower environmental impact than wool-based extraction.
How do I know what dose of Sports Research D3+K2 is right for me?
The only reliable way to determine the right dose is a serum 25-hydroxyvitamin D (25(OH)D) blood test. This is the standard measurement that tells you exactly where your vitamin D status stands. If your level is below 20 ng/mL (deficient), the full 5,000 IU dose (1 softgel daily) is typically appropriate for 8-12 weeks of correction. If your level is 20-30 ng/mL (insufficient), 5,000 IU daily works well. If you’re already in the 30-50 ng/mL range (adequate), you may want to take Sports Research D3+K2 every 2-3 days instead of daily, or use the 2,500 IU version. Direct-to-consumer testing through LetsGetChecked or Everlywell costs $30-50 and gives you the answer without needing a doctor’s order.
How long until I see results from Sports Research D3+K2?
Vitamin D benefits emerge gradually as your blood levels rise. Most people with deficiency notice improvements in energy, mood, and sleep quality within 4-8 weeks of consistent daily supplementation. Bone health and immune benefits accrue over months, not weeks. K2’s effects on arterial stiffness and bone density are measured in clinical studies at 3-year timeframes, so this is truly a long-term investment for cardiovascular health. Blood levels of 25(OH)D typically rise 5-10 ng/mL per 1,000 IU of daily supplementation over 8-12 weeks. If you’re deficient, you should see measurable improvement in blood levels within 8 weeks. If you notice no subjective effects after 12 weeks despite blood levels improving, vitamin D likely wasn’t your primary bottleneck.
The Bottom Line
Sports Research Vitamin D3 + K2 earns its position as the best overall vitamin D supplement for adults over 40. The combination of plant-based D3, clinically studied K2, coconut MCT oil for absorption, and a verified clean formula makes it a complete package.
At around $0.25/day, you’re getting a premium product at a mid-range price. The only reason to consider alternatives is if you need a lower dose, want the absolute cheapest option, or are on blood thinners.
Our rating: 4.7/5
It loses a fraction of a point for the 5,000 IU dose potentially being too high for some users without testing, and the standard bottle being only 60 count. Otherwise, it’s essentially the gold standard for D3+K2 supplementation.
→ Read our full guide: Best Vitamin D Supplements for Adults Over 40
→ Related: Best Calcium Supplements for Adults Over 40
→ Related: Best Supplements for Women Over 40
→ Related: Best Supplements for Testosterone
Sources
- Maresz, K. (2015). Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health. Integrative Medicine, 14(1), 34-39. https://pubmed.ncbi.nlm.nih.gov/26770129/
- Knapen, M.H., Braam, L.A., Drummen, N.E., et al. (2015). Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women: a double-blind randomised clinical trial. Thrombosis and Haemostasis, 113(5), 1135-1144. https://pubmed.ncbi.nlm.nih.gov/25694037/
- Holick, M.F., Binkley, N.C., Bischoff-Ferrari, H.A., et al. (2011). Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 96(7), 1911-1930. https://pubmed.ncbi.nlm.nih.gov/21646368/
- Forrest, K.Y., & Stuhldreher, W.L. (2011). Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research, 31(1), 48-54. https://pubmed.ncbi.nlm.nih.gov/21310306/
Affiliate Disclosure: This article contains affiliate links. If you purchase through these links, we may earn a small commission at no additional cost to you. We only recommend products we’ve researched and believe in. See our full Affiliate Disclosure for details.
This content is for informational purposes only and is not medical advice. Always consult with your healthcare provider before starting any new supplement regimen.
Cristhian Toro is the founder of After 40 Supplements. He started researching supplements years ago to optimize his training and recovery at the gym, and now translates the science behind popular supplements into clear, honest guides for adults over 40. He’s not a doctor — he’s someone who reads the research, compares the products, and shares what actually works (and what doesn’t), with sources you can verify.