About the Product
Marvelous Nutrition's MK-7 is a combined supplement of Vitamin K2 (Menaquinone MK-7) and Vitamin D3 (Cholecalciferol) in bovine gelatin capsules, formulated to support bone health, cardiovascular health, and calcium metabolism. The two fat-soluble vitamins work in essential synergy: Vitamin D3 increases intestinal calcium absorption (up to 30-40% with D3 vs. 10-15% without D3), while Vitamin K2 MK-7 activates vitamin K-dependent proteins that channel absorbed calcium to the bones (via osteocalcin) and prevent its deposition in arterial walls (via Matrix Gla Protein). Without K2, calcium absorbed by the action of D3 can accumulate in soft tissues and arteries instead of being incorporated into the bone matrix. 2 capsules with breakfast. Not vegan (bovine gelatin).
Ingredients: Bovine Gelatin + Menaquinone (Vitamin K2 MK-7) + Cholecalciferol (Vitamin D3) + Colourant (Iron Oxide).
Benefits
The D3 + K2 synergy: the inseparable vitamin duo for bone and cardiovascular health:
The combination of Vitamin D3 + Vitamin K2 MK-7 is currently recognized as the most important vitamin synergy for long-term bone and cardiovascular health. The two vitamins are not just complementary — they are functionally interdependent, and each amplifies and completes the action of the other in a way that is not possible with each vitamin alone. Vitamin D3 is the "accelerator" of calcium absorption and availability; Vitamin K2 is the "GPS" that ensures calcium reaches the right destination (bones) and not the wrong destinations (arteries and soft tissues). Supplementation with D3 without K2 can paradoxically increase the risk of arterial calcification by raising serum calcium levels without activating the mechanisms for channeling it to the bone.
Vitamin D3 (Cholecalciferol): the sunshine vitamin, essential for European athletes:
Vitamin D3 (cholecalciferol) is the biologically active form of vitamin D produced endogenously in the skin through exposure to solar UVB rays, and it is the nutrient with the highest prevalence of insufficiency in the European population — it is estimated that 40 to 70% of the European population has serum 25(OH)D levels below 50 nmol/L (the sufficiency threshold defined by SACN and EFSA). Portugal, despite high sun exposure in summer, has a high prevalence of vitamin D insufficiency in winter months and in populations who work indoors. Specifically for athletes, vitamin D3 has documented functions beyond calcium metabolism: vitamin D receptors (VDR) are present in skeletal and cardiac muscle cells, where they modulate muscle protein synthesis, muscle strength, immune function (reducing the risk of respiratory infections), and mood. The meta-analysis by Beaudart et al. (2014) involving 30 clinical trials documented that vitamin D supplementation improved muscle strength and physical performance in adults with vitamin D deficiency.
Vitamin K2 MK-7: the form of K2 with the longest half-life and greatest tissue biodistribution:
Vitamin K2 exists in multiple forms (MK-4, MK-7, MK-8, MK-9, etc.), and MK-7 (menaquinone-7) is the form with the most clinical relevance for oral supplementation for three reasons. MK-7 has the longest plasma half-life of all forms of K2 (~72 hours vs. ~1 hour for MK-4 and vitamin K1), which means that a single daily dose of MK-7 maintains stable plasma levels over 24 hours. MK-7 also has the greatest tissue biodistribution — unlike MK-4 (which is mainly retained in the liver and adrenal gland) and vitamin K1 (retained in the liver for coagulation), MK-7 is efficiently distributed to extrahepatic tissues such as bones and arteries, where it exerts its most relevant effects. The main mechanisms of K2 MK-7 are the activation of two vitamin K-dependent proteins of enormous clinical importance: osteocalcin (a bone protein that, when activated by K2-dependent carboxylation, incorporates calcium into the bone's hydroxyapatite matrix) and Matrix Gla Protein (MGP) (a protein that, when activated by K2, inhibits calcium deposition in arterial walls and soft tissues). The study by Knapen et al. (2015), published in Osteoporosis International with 244 postmenopausal women over 3 years, documented that supplementation with 180µg/day of MK-7 increased vertebral bone strength and reduced bone loss compared to placebo.
Prevention of arterial calcification: the critical role of K2-activated MGP:
Matrix Gla Protein (MGP) is the most potent documented protein for inhibiting vascular calcification among all proteins in the human body. MGP is expressed by vascular smooth muscle cells (VSMCs) and chondrocytes as a physiological defense mechanism against ectopic calcification. Inhibitory MGP requires carboxylation of its glutamic acid residues to γ-carboxyglutamic acid (Gla) — a reaction catalyzed by γ-glutamyl carboxylase, which uses vitamin K2 as an essential cofactor. In K2 deficiency, MGP remains uncarboxylated (dp-ucMGP, desphospho-uncarboxylated MGP) and is inactive — it does not inhibit arterial calcification. The proportion of dp-ucMGP in the blood is the most sensitive and specific biomarker of vitamin K2 status in vascular tissues, and high levels of dp-ucMGP are associated with greater coronary calcification and higher cardiovascular risk. The Rotterdam study by Geleijnse et al. (2004), published in the Journal of Nutrition with 4807 participants followed for 10 years, documented that higher dietary intake of K2 (not K1) was associated with lower mortality from coronary heart disease and less aortic calcification.
Bone health: activated osteocalcin and bone mineralization:
Osteocalcin is the most abundant non-collagenous protein in bone, produced by osteoblasts as a marker of bone formation and incorporated into the hydroxyapatite matrix. Carboxylated osteocalcin (cOC, activated by K2) has a higher affinity for calcium and hydroxyapatite crystals — it is literally the "cement" that anchors calcium to the protein matrix of the bone. Uncarboxylated osteocalcin (ucOC) cannot efficiently incorporate calcium into the bone matrix. Vitamin K2 MK-7, by promoting osteocalcin carboxylation, ensures that absorbed calcium (via Vitamin D3) is effectively incorporated into bones instead of circulating in the blood or depositing in soft tissues. This D3/K2 synergy at the level of osteocalcin and MGP is the biological foundation for combining the two vitamins in the same supplement.
Usage
Recommended dose: Take 2 capsules with breakfast. Vitamins D3 and K2 are fat-soluble — intestinal absorption is significantly higher when taken with a meal containing fat (breakfast with butter, olive oil, egg, or nuts is ideal). Do not take on an empty stomach.
