ADK Vitamins+ by Codeage

If your Vitamin D, 25-Hydroxy is on the low side or you rarely get midday sun, a vitamin D3 and K2 combo fits. It also suits adults who eat few leafy greens (low vitamin K intake) or who take calcium but want it going into bone, not soft tissue. The added vitamin A helps if your diet is light on liver, eggs, or full-fat dairy. For established deficiency, you’ll often need a higher standalone D3 repletion plan first, then step down to a combo.

D3 raises calcium absorption from the gut and helps normalize parathyroid hormone (PTH, the signal that pulls calcium from bone). K2 activates osteocalcin and matrix Gla protein (vitamin K–dependent proteins that load calcium into bone and keep it out of arteries). Vitamin A modulates bone turnover and keeps barrier tissues healthy, but too much A can counter D-driven signaling. Together, D3 and K2 improve calcium handling; in responders you’ll see PTH drift down with stable Calcium within 4 to 12 weeks.

Take one capsule daily with a meal that contains fat for better absorption. If your Vitamin D, 25-Hydroxy is meaningfully low, a higher-dose D3 phase is usually more practical, then switch to this for maintenance. Retest Vitamin D, 25-Hydroxy in 8 to 12 weeks, and consider PTH and Calcium if you’ve needed higher D3. Avoid doubling up with cod liver oil or separate high-dose vitamin A unless a clinician is tracking your total retinol intake.

Skip K2 if you use warfarin (a blood thinner that works by blocking vitamin K), unless your prescriber plans INR checks with a stable, consistent K intake. Avoid extra preformed vitamin A if you’re pregnant or trying to conceive; choose prenatal formulas that use beta-carotene instead. Use caution with a history of high calcium, kidney stones, sarcoidosis, or lymphoma, and loop in your clinician. Heavy alcohol use or liver disease also warrants careful vitamin A management.