Cholecalciferol + menaquinone-7 (D3+K2 combo)

D3+K2 combo is marketed for «bone health» and osteoporosis prevention. Small Japanese trials on K2 (menatetrenone) showed modest fracture reduction in postmenopausal women, but large European RCTs (NPHS, ECKO) did not confirm the effect. ESCEO and NICE recommend in osteoporosis: calcium 1000-1200 mg/day, vitamin D3 800 IU/day, physical activity, and bisphosphonates, denosumab or anabolics in confirmed disease. Additional K2 is not in the recommendation. If the combo was recommended «for bones», discuss evidence-based therapy with your doctor based on DXA and FRAX. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

D3+K2 combo is marketed as a «longevity formula» on the hypothesis of vitamin D effects on immunity, telomeres, methylation, plus K2 on vessels. Cochrane 2014 on vitamin D and mortality: no reduction in all-cause mortality in non-deficient people; in deficient patients the small positive effect is limited. VITAL 2019 found no mortality reduction from vitamin D in the general US population (unselected by deficiency). No large longevity RCTs exist for K2. If the combo was recommended «for slowing aging», consider seeking a second opinion. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

D3+K2 combo is heavily marketed on the biohacker argument: «K2 directs calcium into bone and removes it from vessels, preventing atherosclerosis and cardiovascular events». The large VITAL 2019 RCT (25 871 participants, mean 5.3 years) found vitamin D without K2 did not reduce cardiovascular events or cancer vs placebo. Cochrane 2014 on vitamin D and all-cause mortality confirmed: vitamin D does not reduce mortality in non-deficient people. No large cardiovascular outcome RCTs exist for K2. ESC 2021 does not recommend any vitamin-mineral complex for primary or secondary cardiac prevention in non-deficient people. If the combo was recommended «for heart and vessels», consider seeking a second opinion. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.