Complete Bone Formula With Vitamin D-3 and Vitamin K-2 Calcium and Magnesium are minerals that are known to be essential for bone health. Along with these two important minerals, NOW Cal-Mag DK Caps provide Vitamins D and K. Vitamin D-3, a fat soluble vitamin, has been shown to play a critical role in bone metabolism, as well as in the absorption of Calcium and Magnesium in the intestine. Vitamin K-2 is a nutrient that further supports bone health through its participation in healthy bone calcification.