If you're working to rebuild bone density or correct a vitamin D deficiency, this pairs a correction-level dose of **Vitamin D3** at 4,000 IU with **Vitamin K2** at 100 mcg, both landing inside their clinically studied ranges. The 4,000 IU of D3 sits right at the upper safe daily limit, well above a maintenance dose, so it's built to raise low blood levels rather than just hold them steady. Taken with a meal, the fat-soluble D3 absorbs well and backs bone, immune, and muscle function.

The pairing is a genuine synergy. D3 drives calcium absorption from your gut, while K2 directs that calcium into your bones and teeth instead of letting it settle in your arteries. At 100 mcg, the K2 falls within the 90–200 mcg studied range, dosed high enough to do that job alongside the heavy D3 load.

Two things are worth knowing. Since you're taking 4,000 IU daily, it's worth having your vitamin D blood levels checked periodically, as that's a correction dose rather than a lifelong maintenance amount. And if you take warfarin or another blood thinner, the K2 can interfere with that medication, so check with your doctor before starting.