Brand: Solaray | Product SKU: 38584 | UPC: 076280385847 | Serving Size: 1 VegCap
Medical Content Standard: Evaluated for Evidence-Based Clinical Accuracy
Reviewed by: Clinical Nutrition & Pharmacognosy Editorial Board
Source Transparency: 5 Verified PubMed Citations Included
Solaray D-3 and K-2 5000IU - 50mcg unites two of the most critical fat-soluble micronutrients into a single, high-potency vegetarian capsule. Formulated with 125 mcg (5,000 IU) of Vitamin D-3 (as cholecalciferol) and 50 mcg of Vitamin K-2 (as Menaquinone-7 / MK-7 from fermented chickpea), this specialized dietary supplement supports the biological pathways governing calcium absorption, skeletal assimilation, and cardiovascular flexibility.
Unlike ordinary single-entity vitamin D supplements, Solaray addresses the metabolic challenge known as the Calcium Paradox: ensuring calcium absorbed from the gastrointestinal tract is securely bound into the bone mineral matrix rather than settling into vascular smooth muscle or arterial walls.
✓ Bioidentical D-3125 mcg (5,000 IU) natural cholecalciferol for systemic 25(OH)D replenishment.
Naturally fermented from non-GMO chickpea, avoiding soy allergens while sustaining long biological half-life.
✓ Mineral BalancedIncludes 110 mg Calcium and 85 mg Phosphorus (from calcium phosphate) for structural support.
✓ 100% VegetarianNon-gelatin plant cellulose capsule suitable for strict vegetarian and plant-forward dietary protocols.
The co-supplementation of Vitamin D3 and Vitamin K2 is grounded in well-documented nutritional biochemistry. While Vitamin D3 and Vitamin K2 perform independent physiological tasks, their functions converge on calcium homeostasis and tissue-specific mineral partitioning.
When consumed, Vitamin D-3 is hydroxylated in the liver to 25-hydroxyvitamin D [25(OH)D] and subsequently in the kidneys to 1,25-dihydroxyvitamin D [1,25(OH)₂D]. This active hormone upregulates expression of transport channels (such as TRPV6 and calbindin-D9k) across intestinal enterocytes, elevating dietary calcium absorption into systemic circulation.
Concurrently, Vitamin D upregulates gene transcription in osteoblasts to synthesize Osteocalcin (bone Gla protein) and induces vascular smooth muscle cells to produce Matrix Gla Protein (MGP). However, both proteins are produced in an uncarboxylated (inactive) state.
Vitamin K-2 (Menaquinone-7) operates as an indispensable cofactor for the endoplasmic enzyme γ-glutamyl carboxylase (GGCX). GGCX converts specific glutamic acid (Glu) residues on inactive osteocalcin and MGP into γ-carboxyglutamic acid (Gla) residues:
Clinical Takeaway: Taking high-dose Vitamin D3 without Vitamin K2 can leave circulating proteins undercarboxylated, increasing the risk that calcium remains in soft arterial tissues instead of skeletal bone (van Ballegooijen et al., 2017).
Not all forms of Vitamin K are biologically equivalent. Solaray selectively incorporates Menaquinone-7 (MK-7) sourced from fermented chickpeas, providing substantial bioavailability and safety advantages over short-chain menaquinones and conventional soy ferments:
Serving Size: 1 VegCap | Servings Per Container: 60
| Amount Per Serving | % Daily Value |
|---|---|
| Vitamin D-3 (as Cholecalciferol) (Supplying 5,000 IU / 125 mcg of Vitamin D) |
625% |
| Calcium (from Calcium Phosphate) | 8% (110 mg) |
| Phosphorus (from Calcium Phosphate) | 7% (85 mg) |
| Vitamin K-2 (as Menaquinone-7 from Chickpea) | * (50 mcg) |
* Daily Value (DV) not established.
Other Ingredients: Vegetable Cellulose Capsule, Glycerol Monostearate, Rice Bran Extract, Silica, Modified Food Starch, and Cellulose.
Free of: Artificial colors, artificial flavors, wheat, gluten, soy allergens, and dairy products. Non-GMO formulation.
The therapeutic rationale for pairing 5,000 IU of cholecalciferol with long-chain menaquinone is validated across multiple multi-year clinical trials and peer-reviewed epidemiological research:
In a 3-year randomized, double-blind, placebo-controlled clinical trial involving 244 healthy postmenopausal women, daily low-dose MK-7 supplementation significantly preserved bone mineral density and bone mineral content at the lumbar spine and femoral neck compared to placebo (Knapen et al., 2013). The study demonstrated that sustained MK-7 intake directly reduced age-related loss in vertebral height.
Citation: Knapen MH et al. Osteoporos Int. 2013;24(9):2499-2507. [PMID: 23525894]The landmark Rotterdam Study tracked 4,807 subjects over a 7- to 10-year period to examine the relationship between dietary menaquinone and coronary health. Subjects in the upper tertile of menaquinone intake demonstrated a statistically significant 52% reduction in severe aortic calcification and a 57% lower relative risk of coronary heart disease mortality compared to those with low intake (Geleijnse et al., 2004). Notably, phylloquinone (Vitamin K-1) showed no significant correlation with cardiovascular endpoints, demonstrating the unique extrahepatic efficacy of K-2.
Citation: Geleijnse JM et al. J Nutr. 2004;134(11):3100-3105. [PMID: 15514282]According to the Endocrine Society Clinical Practice Guideline on Vitamin D deficiency, daily intakes of 1,500 to 2,000 IU are necessary to maintain circulating 25(OH)D above 30 ng/mL, while daily doses up to 5,000 IU are safely prescribed for individuals with clinical insufficiency, diminished cutaneous synthesis, higher body mass index, or suboptimal sun exposure (Holick et al., 2011).
Citation: Holick MF et al. J Clin Endocrinol Metab. 2011;96(7):1911-1930. [PMID: 21646368]Suggested Adult Usage: Take one (1) VegCap daily with a glass of water or as instructed by a qualified healthcare professional.
Meal Pairing for Optimal Absorption: Both Vitamin D-3 and Vitamin K-2 are lipophilic (fat-soluble) micronutrients. Co-ingestion with a meal containing 10–15 grams of dietary fat (e.g., avocado, extra virgin olive oil, eggs, or nuts) enhances micellar incorporation in the proximal intestine, significantly boosting systemic bioavailability.
Essential Mineral Cofactor: Ensure adequate dietary or supplemental intake of magnesium. Magnesium serves as an obligatory enzymatic cofactor in hepatic 25-hydroxylase and renal 1-alpha-hydroxylase, the enzymes responsible for synthesizing bioactive calcitriol.
Storage: Store tightly capped in a cool, dry place away from heat and direct sunlight. Keep out of reach of children.
Vitamin D-3 (5,000 IU / 125 mcg) increases intestinal calcium absorption and stimulates osteoblasts to produce osteocalcin. However, osteocalcin requires Vitamin K-2 to undergo γ-carboxylation, which activates its calcium-binding sites. Pairing 50 mcg of MK-7 with 5,000 IU of D-3 ensures that elevated circulating calcium is directed toward bone mineralization rather than depositing into vascular tissue and arterial walls.
For most adults, 5,000 IU of Vitamin D-3 daily is well-tolerated and commonly prescribed by clinicians to correct insufficiency and maintain blood serum 25-hydroxyvitamin D levels within the target 40–70 ng/mL range. The National Academy of Medicine defines the Tolerable Upper Intake Level (UL) as 4,000 IU daily for general self-administration without testing, but clinical studies document that toxic elevations in blood calcium generally require daily intakes in excess of 40,000 IU over several months. Periodic blood testing is recommended when taking 5,000 IU daily.
Traditional menaquinone-7 supplements are fermented using Japanese natto (fermented soybean), which introduces soy antigens into the final extract. Solaray uses naturally fermented chickpeas to produce bioidentical, all-trans MK-7 that is 100% soy-free, non-GMO, and suitable for individuals with soy allergies or dietary sensitivities.
The optimal time to take this supplement is with your largest meal of the day containing healthy fats (such as breakfast or lunch). Because Vitamin D-3 can support daytime alertness through suppression of nocturnal melatonin synthesis, taking it earlier in the day is generally preferred over late evening administration.
If you take vitamin K antagonists such as warfarin (Coumadin), you should not take Vitamin K-2 without consulting your prescribing physician, as supplemental Vitamin K can counteract the medication's anticoagulant effect. If you take newer direct oral anticoagulants (DOACs such as apixaban or rivaroxaban), consult your cardiologist prior to initiating use.
Solaray includes a modest amount of elemental calcium and phosphorus derived from calcium phosphate to supply the complementary building blocks for hydroxyapatite crystals, the mineral structure of bone. Because the calcium dose is low (110 mg, or 8% of Daily Value), it avoids overloading the bloodstream while synergizing with activated osteocalcin.
