Solaray Vitamin D3 Plus K-2 MK-7 (5000 IU / 50 mcg): Advanced Bone Density & Cardiovascular Synergy
Solaray Vitamin D3 Plus K-2 MK-7 combines high-potency cholecalciferol (5,000 IU / 125 mcg) with bioavailable, fermented menaquinone-7 (50 mcg) derived from allergen-free chickpea. Designed to resolve the biochemical challenge known as the “calcium paradox,” this formula ensures calcium is absorbed efficiently from the digestive tract and guided directly into skeletal bone tissue—protecting your arteries and soft tissues from calcification.
Key Clinical Formulations & Features:
✓High-Potency Vitamin D3 (Cholecalciferol, 5,000 IU): Matches the biological form synthesized by the human skin via UVB photolysis.
✓Bioactive Vitamin K-2 as MK-7 (50 mcg): Long-chain menaquinone extracted from fermented chickpea (100% soy-free).
✓Sustained Serum Half-Life: MK-7 provides continuous 72-hour bioactive blood saturation compared to just 1–2 hours for standard Vitamin K1.
✓Skeletal Matrix Transport: Stimulates osteocalcin carboxylation to lock calcium into the bone mineral lattice.
✓Vascular Protection: Activates Matrix Gla Protein (MGP) to prevent arterial and vascular calcification.
The Biochemistry of Synergy: Solving the “Calcium Paradox”
Taking high-dose Vitamin D3 alone increases systemic calcium absorption, but it does not control where that calcium ends up. This physiological disconnect is medically referred to as the Calcium Paradox: when calcium builds up inside arterial blood vessels and soft tissues instead of strengthening porous bone matrix.
1. Role of Vitamin D3 (Cholecalciferol)
Vitamin D3 converts in the liver to 25-hydroxyvitamin D [25(OH)D], and subsequently in the kidneys to the active steroid hormone 1,25-dihydroxyvitamin D [1,25(OH)2D] (calcitriol). Calcitriol upregulates intestinal transcription of calcium transport proteins (Calbindin-D9k and TRPV6), boosting digestive calcium absorption by 300% to 400%. Crucially, Vitamin D3 also signals the synthesis of two essential dependent proteins: Osteocalcin in osteoblasts and Matrix Gla Protein (MGP) in vascular smooth muscle cells. However, D3 produces these proteins in an inactive, uncarboxylated state.
2. Role of Vitamin K-2 (Menaquinone-7)
Vitamin K-2 MK-7 functions as the required enzymatic cofactor for gamma-glutamyl carboxylase (GGCX). GGCX converts glutamic acid (Glu) residues into gamma-carboxyglutamic acid (Gla) residues:
Carboxylated Osteocalcin: Gains high electrostatic affinity for free calcium ions, pulling them out of systemic circulation and binding them directly into hydroxyapatite crystals in the skeletal bone matrix.
Carboxylated Matrix Gla Protein (MGP): Acts as the body's strongest natural inhibitor of soft-tissue calcification, keeping calcium from precipitating into coronary walls, arterial tunica media, and heart valves.
Clinical Takeaway: Vitamin D3 provides the materials by bringing calcium into the bloodstream; Vitamin K-2 MK-7 serves as the architect, ensuring that calcium builds strong bones rather than stiff arteries.
Every therapeutic claim for Solaray Vitamin D3 Plus K-2 MK-7 is supported by randomized human clinical trials and prospective cohort research:
Long-Term Bone Mineral Density Preservation (Knapen et al., 2013)
In a 3-year, double-blind, randomized clinical study of 244 healthy postmenopausal women, daily supplementation with nutritional doses of menaquinone-7 (MK-7) significantly prevented age-related bone mineral content and density loss at both the lumbar spine and femoral neck, while substantially improving bone strength.
Citation: Knapen, M. H. J., et al. Osteoporosis International, 2013; 24(9): 2499–2507. doi:10.1007/s00198-013-2325-6.
Cardiovascular Longevity & Arterial Elasticity: The Rotterdam Study (Geleijnse et al., 2004)
A landmark population-based study following 4,807 subjects over 10 years demonstrated that individuals in the highest tertile of dietary menaquinone (K2) intake experienced a 57% reduction in fatal coronary heart disease, a 26% reduction in all-cause mortality, and a marked reduction in severe aortic calcification compared to the lowest tertile. Vitamin K1 intake showed no protective correlation.
Citation: Geleijnse, J. M., et al. The Journal of Nutrition, 2004; 134(11): 3100–3105. doi:10.1093/jn/134.11.3100.
Pharmacokinetics: MK-7 vs. Vitamin K1 Half-Life (Schurgers et al., 2007)
Comparative human pharmacological evaluation published in the journal Blood confirmed that while phylloquinone (K1) disappears from blood serum within 4 to 8 hours, menaquinone-7 (MK-7) exhibits an extended plasma elimination half-life of roughly 72 hours. This sustained half-life allows MK-7 to maintain continuous carboxylation of extra-hepatic tissues like bone and blood vessel walls throughout the day.
Citation: Schurgers, L. J., et al. Blood, 2007; 109(8): 3279–3283. doi:10.1182/blood-2006-08-040709.
Target Serum 25(OH)D Levels (Endocrine Society Clinical Practice Guidelines)
The Endocrine Society defines vitamin D deficiency as serum 25(OH)D levels below 20 ng/mL, and insufficiency as 21–29 ng/mL. Supplementation with 5,000 IU of D3 daily is recognized as an effective dosage to quickly correct insufficiency and sustain optimal immune, endocrine, and musculoskeletal wellness within the target 40–60 ng/mL range.
Citation: Holick, M. F., et al. The Journal of Clinical Endocrinology & Metabolism, 2011; 96(7): 1911–1930. doi:10.1210/jc.2011-0385.
Not all Vitamin K-2 supplements provide the same quality or tolerance. Many standard commercial K-2 products rely on synthetic menaquinone-4 (MK-4)—which has a very short biological half-life requiring multiple daily megadoses—or use natto ferments derived from common allergens like soy.
The Chickpea Advantage Over Soy-Based Natto:
100% Soy-Free & Hypoallergenic: Sourced naturally via pure fermentation using non-GMO chickpeas. This eliminates potential allergen reactions for individuals sensitive to soy, dairy, or gluten.
All-Trans Isomeric Purity: Molecularly structured as biologically active all-trans menaquinone-7, preventing inactive cis-isomers that do not fit into the GGCX enzyme active site.
Enhanced Microencapsulation: Prepared with glycerol monostearate and plant cellulose to shield delicate fat-soluble molecules from moisture, light, and oxidation inside the bottle.
Complete Supplement Facts & Formula Transparency
VitaNet® guarantees label accuracy and full disclosure. Below is the verified nutritional breakdown for Solaray Vitamin D3 Plus K-2 MK-7 (SKU #57445 / UPC: 076280574456).
Supplement Facts
Serving Size: 1 VegCap | Servings Per Container: 120
Amount Per Serving
Amount
% Daily Value
Vitamin D-3 (as Cholecalciferol) (Supplying 5,000 IU of Vitamin D-3)
125 mcg
625%
Calcium (from Calcium Phosphate)
110 mg
8%
Phosphorus (from Calcium Phosphate)
85 mg
7%
Vitamin K-2 (as Menaquinone-7 from Chickpea)
50 mcg
*
* Daily Value not established.
Excipient & Capsule Matrix Information:
Other Ingredients: Vegetable Cellulose Capsule, Glycerol Monostearate, Rice Bran Extract, Silica, Modified Food Starch, and Cellulose.
Both Vitamin D3 and Vitamin K-2 are lipophilic (fat-soluble) micronutrients. For optimal micellar packaging and lymphatic transport, take 1 VegCap daily with a meal containing healthy dietary fats (such as avocado, extra virgin olive oil, eggs, or nuts).
Critical Medical Warning & Contraindications:
Anticoagulant Drug Interactions (Warfarin / Coumadin): Vitamin K directly counteracts 4-hydroxycoumarin vitamin K antagonists (VKAs) by promoting prothrombin synthesis. If you take Warfarin or other blood-thinning therapies, do not consume this product without direct approval and INR monitoring from your prescribing physician. (Direct Oral Anticoagulants / DOACs like Eliquis or Xarelto work on factor Xa and do not interact with vitamin K in the same manner, but consultation remains essential).
Pre-existing Hypercalcemia & Granulomatous Disorders: Individuals diagnosed with hypercalcemia, severe renal disease, hyperparathyroidism, or granulomatous conditions (e.g., sarcoidosis) must avoid high-dose vitamin D supplementation due to elevated risk of extra-renal calcitriol synthesis.
Routine Laboratory Monitoring: When consuming 5,000 IU of Vitamin D3 continuously, have your primary care physician check your serum 25-hydroxyvitamin D [25(OH)D] and total serum calcium levels every 3 to 6 months to establish your individual therapeutic plateau (ideally between 40 and 60 ng/mL).
Frequently Asked Questions (FAQ) – Vitamin D3 Plus K-2 MK-7
Why is Vitamin K-2 (MK-7) added to Vitamin D3?
Vitamin D3 stimulates the synthesis of calcium-binding proteins, but these proteins remain inactive without Vitamin K-2. K-2 (specifically the long-lasting menaquinone-7 form) carboxylates osteocalcin to draw calcium into bones and teeth, while simultaneously activating Matrix Gla Protein (MGP) to prevent calcium from calcifying arterial walls, kidneys, and cardiac valves.
What is the difference between Vitamin K1, MK-4, and MK-7?
Vitamin K1 (phylloquinone) is found in leafy greens and concentrates in the liver primarily for blood coagulation factors. Vitamin K2 MK-4 is a short-chain synthetic menaquinone with an extremely short systemic half-life (a few hours), requiring multiple high-dose daily administrations. Vitamin K2 MK-7 (derived from fermented chickpea) has a long 72-hour circulatory half-life, providing sustained blood levels and targeting bone and vascular tissues throughout the body.
Is 5,000 IU of Vitamin D3 safe to take every day?
According to the Endocrine Society and the Council for Responsible Nutrition, daily adult intake up to 10,000 IU has shown no evidence of toxicity in clinical trials. A daily dose of 5,000 IU is effective for raising and maintaining circulating 25(OH)D levels within the optimal range of 40 to 60 ng/mL. Routine blood testing every 6 months is recommended to monitor your levels.
Why does Solaray source MK-7 from chickpea instead of soy natto?
Traditional MK-7 is often fermented from Japanese natto (fermented soybean), which introduces common allergens and residual soy compounds. Solaray utilizes a modern, pure bacterial fermentation process using non-GMO chickpeas. This delivers an allergen-free, 100% soy-free product with high bioactivity and an all-trans isomeric profile.
What is the best time of day to take Solaray Vitamin D3 Plus K-2 MK-7?
Because Vitamin D3 and Vitamin K-2 are fat-soluble, take your daily capsule with your largest meal of the day, or any meal that contains healthy dietary fats (such as eggs, olive oil, or yogurt). Taking Vitamin D in the morning or early afternoon is often preferred, as evening supplementation may interfere with melatonin production in sensitive individuals.
Can I take this supplement if I am on blood-thinning medication?
If you are taking Warfarin (Coumadin), do not take this supplement without the explicit consent and supervision of your healthcare provider. Vitamin K directly interacts with coumarin-derived anticoagulants by activating clotting cascade factors, which can lower your INR and increase clotting risks.
