Studies indicate that most Americans are deficient in vitamin D3 and its natural partner vitamin K2. Both are key players to overall health and work in tandem. Vitamin D (calcitriol) is the “physiologically activated” form of vitamin D, though it’s technically not a vitamin but a potent neuroregulatory steroidal hormone that influences nearly 3,000 of your 25,000 genes. It literally turns genes on and off that can exacerbate or prevent many health states, including calcium deposition in bone, depression, back pain, cancer, insulin resistance, impaired immunity, and macular degeneration. And strong evidence demonstrates that vitamin K reduces cancer risk. Specifically, it’s vitamin K2 that directs calcium to your skeleton, while preventing it from being deposited in your organs, joint spaces, and arteries. In other words, without the help of vitamin K2, the calcium that your vitamin D so effectively lets in might be working against you, building up your coronary arteries rather than your bones. There is even evidence that the safety of vitamin D is dependent on vitamin K, and that vitamin D toxicity (although very rare with the D3 form) is actually caused by vitamin K2 deficiency.