Ingredient face-off
Best Vitamin D3 + K2 Supplements Compared: Standalone D3 vs Combined D3/K2, Dose, Form
Vitamin D3 (cholecalciferol) is the most-supplemented micronutrient in the US — Holick 2011 clinical practice guidelines estimate 40-60% of US adults have suboptimal 25-OH-D levels (below 30 ng/mL). Beyond dose, the two decisions that matter are: (1) softgel vs dry tablet delivery — D3 is fat-soluble, so oil-based softgels deliver ~2-3× the plasma D3 of dry tablets; (2) K2 co-supplementation — vitamin K2 (menaquinone-7, MK-7) helps partition calcium mobilized by D3 to bone tissue rather than soft tissues (blood vessels, kidneys), reducing the theoretical cardiovascular risk of long-term high-dose D3 supplementation. This ranks the top-scoring D3 and D3+K2 products on the Vyvata rubric. Read the rubric →
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Vitamin D3 dose and form guide
The right D3 dose depends on your baseline 25-OH-D level (blood test — Vitamin D, 25-Hydroxy). Get tested before committing to high-dose supplementation; target 40-60 ng/mL for most adults per the Endocrine Society clinical guideline.
| Your baseline 25-OH-D | D3 daily dose | K2 co-supp | Re-test in |
|---|---|---|---|
| Below 20 ng/mL (deficient) | 4,000-5,000 IU/day | Yes — 100-180 mcg MK-7 | 3 months |
| 20-30 ng/mL (insufficient) | 2,000-4,000 IU/day | Yes — 100 mcg MK-7 | 4-6 months |
| 30-50 ng/mL (adequate) | 1,000-2,000 IU/day maintenance | Optional (100 mcg MK-7 if long-term) | Annually |
| 50-80 ng/mL (optimal) | Maintenance only (1,000 IU or diet + sun) | Optional | Annually |
| Above 100 ng/mL | Stop supplementation, retest | N/A | 3 months |
Why K2 co-supplementation matters for long-term high-dose D3: Vitamin D3 mobilizes calcium from diet and bone. Without adequate K2, that calcium can deposit in vascular tissue rather than bone. Long-term high-dose D3 (5000+ IU/day) without K2 has theoretical vascular calcification risk. K2 MK-7 (menaquinone-7) at 100-180 mcg/day is the standard co-supplementation dose. Not urgent for short-term deficiency correction; important for long-term maintenance at high doses.
Why softgel with oil beats dry tablet: Vitamin D3 is fat-soluble. Oil-based softgels (MCT, olive, or safflower oil) deliver ~2-3× the plasma D3 of dry tablets per label mg. If a product is a plain compressed tablet with just cholecalciferol powder, take it with fat-containing meals to partially compensate. If you can choose, choose a softgel.
Head-to-head summary
| # | Product | Score | Tier | Strongest on |
|---|---|---|---|---|
| 1 | Pure Encapsulations Vitamin D3 & K2 100/100 Mcg — Pure Encapsulations | 83 | Elite | Formulation + Evidence |
| 2 | Solgar Vitamin D3 (Cholecalciferol) 125 mcg (5,000 IU) 240 Vegetable Capsules — Solgar | 82 | Verified | Evidence + Manufacturing |
| 3 | Pure Encapsulations Vitamin D3 Liquid - 22.5 ml | Health Supplement — Pure Encapsulations | 82 | Elite | Formulation + Manufacturing |
| 4 | Solgar Vitamin D3 5000 IU — Solgar | 80 | Verified | Evidence + Safety |
| 5 | Nordic Naturals Vitamin D3 5000 — Nordic Naturals | 77 | Verified | Evidence + Formulation |
| 6 | Nature Made Vitamin D3 2000 IU — Nature Made | 76 | Verified | Manufacturing + Evidence |
| 7 | Solgar Calcium Magnesium with Vitamin D3 150 Tablets — Solgar | 74 | Verified | Manufacturing + Safety |
| 8 | Vitamin D-3 5,000 IU High Potency — Country Life Natural Foods | 72 | Verified | Evidence + Formulation |
| 9 | Now Vitamin D3 1000 IU Softgels - 180 Count - Immune & Bone Health Support | Cholecalciferol Vitamin D Supplement — NOW | 70 | Verified | Evidence + Safety |
| 10 | Vitamin D3 & Boron Complex - Features FruiteX-B | 70 | Verified | Formulation + Evidence |
Top score: Pure Encapsulations Vitamin D3 & K2 100/100 Mcg at 83/100 — see the deep-dive for the reasoning.
Per-product deep dive
#1 Pure Encapsulations Vitamin D3 & K2 100/100 Mcg83/100 · Elite
[Rescored via evidence crawl] Previous score 78 → new 83. Evidence found: Van Ballegooijen AJ et al. The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health. Int J Endocrinol. 2017;2017:7454376. | Knapen MH et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499-2507 (MenaQ7 evidence).. Rationale: Combines 100 mcg (4000 IU) D3 with 100 mcg K2 as MenaQ7 (MK-7). This is the therapeutic-dose combination for bone and vascular calcium partitioning. Practitioner-grade hypoallergenic formulation. Elite tier.
See the full Pure Encapsulations Vitamin D3 & K2 100/100 Mcg page →
#2 Solgar Vitamin D3 (Cholecalciferol) 125 mcg (5,000 IU) 240 Vegetable Capsules82/100 · Verified
[Rescored via evidence crawl] Previous score 75 → new 82. Evidence found: Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266-81. | Bischoff-Ferrari HA, et al. Pooled analysis of vitamin D dose requirements for fracture prevention. N Engl J Med. 2012;367(1):40-9.. Rationale: Same TIER-A evidence base as the sibling 5000 IU SKU. Vegetable-capsule 240-count format (typically lichen-derived D3, vegan-appropriate). +7 uplift for TIER-A ingredient evidence at appropriate correction dose.
See the full Solgar Vitamin D3 (Cholecalciferol) 125 mcg (5,000 IU) 240 Vegetable Capsules page →
#3 Pure Encapsulations Vitamin D3 Liquid - 22.5 ml | Health Supplement82/100 · Elite
[Rescored via evidence crawl] Previous score 76 → new 82. Evidence found: Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266-281. | Pure Encapsulations Vitamin D3 Liquid: cholecalciferol in MCT oil base for flexible dosing.. Rationale: Liquid D3 in MCT enables precise, flexible dosing (drop-based titration) — ideal for pediatric, elderly, or anyone requiring non-standard doses guided by 25(OH)D testing. Practitioner-grade. Elite tier.
See the full Pure Encapsulations Vitamin D3 Liquid - 22.5 ml | Health Supplement page →
#4 Solgar Vitamin D3 5000 IU80/100 · Verified
[Rescored via evidence crawl] Previous score 73 → new 80. Evidence found: Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266-81. | Autier P, et al. Vitamin D status and ill health: a systematic review. Lancet Diabetes Endocrinol. 2014;2(1):76-89. | Bischoff-Ferrari HA, et al. Pooled analysis of vitamin D dose requirements for fracture prevention. N Engl J Med. 2012;367(1):40-9.. Rationale: TIER-A ingredient evidence for D3 in deficient populations (fracture prevention, immune modulation, PTH suppression). 5000 IU is above the RDA but within safe upper limits and appropriate for correcting documented deficiency common in US adults. D3 (cholecalciferol) form is superior to D2. +7 uplift reflects strong evidence and appropriate dose format.
#5 Nordic Naturals Vitamin D3 500077/100 · Verified
Cholecalciferol 5000 IU carried in organic extra virgin olive oil for fat-soluble uptake — meta-analyses support D3 supplementation to raise serum 25(OH)D (Autier et al. 2014). 5000 IU is above the RDA but within the IOM tolerable upper limit for adults; still enough of a dose that periodic 25(OH)D testing is prudent. Third-party tested, clean label. Verified.
#6 Nature Made Vitamin D3 2000 IU76/100 · Verified
2000 IU vitamin D3 (cholecalciferol) softgel. D3 has robust RCT support for bone (Bischoff-Ferrari 2009 meta) and 2000 IU sits within the range typically recommended for status maintenance. Cholecalciferol is the correct form. USP Verified — genuinely one of the highest-purity signals available in mainstream retail. Solid Verified: right ingredient, right form, right dose, verified purity.
#7 Solgar Calcium Magnesium with Vitamin D3 150 Tablets74/100 · Verified
[Rescored via evidence crawl] Previous score 66 → new 74. Evidence found: Tang BM, et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss. Lancet. 2007;370(9588):657-66. | Bischoff-Ferrari HA, et al. Pooled analysis of vitamin D dose requirements for fracture prevention. N Engl J Med. 2012;367(1):40-9.. Rationale: Calcium + magnesium + D3 is the evidence-backed bone-support triad. TIER-B evidence for reducing fractures in older adults (Tang 2007, Bischoff-Ferrari 2012). +8 uplift because this SKU adds the D3 that the Cal-Mag-Boron SKU omitted - making it a more complete standalone bone formula.
See the full Solgar Calcium Magnesium with Vitamin D3 150 Tablets page →
#8 Vitamin D-3 5,000 IU High Potency72/100 · Verified
[Rescored via evidence crawl] Previous score 67 → new 72. Evidence found: Pilz S, Zittermann A, Trummer C, et al. Vitamin D testing and treatment: a narrative review of current evidence. Endocr Connect. 2019;8(2):R27-R43. doi:10.1530/EC-18-0432 | Villasis-Keever MA, López-Alarcón MG, Miranda-Novales G, et al. Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial. Arch Med Res. 2022;53(4):423-430. doi:10.1016/j.arcmed.2022.04.003. Rationale: 5,000 IU/day sits at the therapeutic sweet spot — well-supported for correcting deficiency and safe in most adults short-to-medium term, with the Calgary trial's harmful bone-density signal appearing only at 10,000 IU (not 5,000). Multiple RCTs. +5 uplift to 72 crosses into Verified. Ceiling held below 80 because vitamin D benefit is highly individual (depends on baseline 25(OH)D and sun exposure) and long-term unsupervised use still warrants periodic 25(OH)D monitoring.
#9 Now Vitamin D3 1000 IU Softgels - 180 Count - Immune & Bone Health Support | Cholecalciferol Vitamin D Supplement70/100 · Verified
NOW Foods Vitamin D3 1,000 IU cholecalciferol — a well-established, RCT-supported ingredient and dose (Martineau 2017 respiratory meta-analysis; Pittas 2019 D2d trial anchor points). NOW is family-owned since 1968, runs an in-house ISO-17025 lab and is UL/GMP certified. 180-count softgel gives a fair per-day cost.
#10 Vitamin D3 & Boron Complex - Features FruiteX-B70/100 · Verified
FruiteX-B (calcium fructoborate) is a named-source, patented form of boron with human clinical evidence for joint/bone support (Reyes-Izquierdo 2012, Scorei 2011) and has better tolerability than sodium tetraborate. Pairing with D3 addresses bone/steroid-hormone synergy and is a legitimate combination. Named ingredient supplier and disclosed form pushes this to low-Verified. Held below Elite by lack of third-party certification and unclear per-tablet IU/mg splits without label view. Would move to Verified 75+ with published COAs and specific D3 IU + boron mg per serving.
See the full Vitamin D3 & Boron Complex - Features FruiteX-B page →
How the scoring works
Every product is scored on six dimensions — evidence (RCT quality supporting the active ingredients at the label dose), formulation (dose adequacy, bioavailability form, redundancy), manufacturing (third-party testing, GMP, facility audits), safety (adverse-event profile, interactions, dose ceiling), transparency (dose disclosure vs proprietary blends, honest marketing), and sustainability (sourcing, packaging, corporate practice). Tier thresholds: Elite 85+, Verified 70–84, Standard 50–69, Rejected 0–49. Rejected products stay listed with reasons. Full rubric →