vitamin d3
6 interactions related to vitamin d3
vitamin d3 + vitamin k2
Vitamin D3 increases calcium absorption and stimulates production of vitamin K-dependent proteins (osteocalcin, matrix Gla protein) that require vitamin K2 to be activated. Taking the two together is a common, well-tolerated pairing that supports bone health. A separate, established interaction matters here: vitamin K2 reduces the effect of warfarin and other vitamin K antagonists.
phenobarbital + vitamin d
Phenobarbital is a strong inducer of liver enzymes that speed the breakdown of vitamin D, so long-term use can lower 25-hydroxyvitamin D and, over months to years, contribute to softened bones (osteomalacia in adults, rickets in children) and higher fracture risk. Children and older or housebound adults are most vulnerable. The drop in vitamin D is well documented; some experimental work also suggests phenobarbital may slow vitamin D activation, though that mechanism rests on animal and cell studies. Have vitamin D and bone-related labs reviewed and discuss ongoing vitamin D with your doctor or pharmacist.
probiotics + vitamin d
Vitamin D and probiotics act on overlapping pathways in the gut. Vitamin D supports vitamin D receptor (VDR) activity in the intestinal lining, which probiotics rely on for their anti-inflammatory and barrier-strengthening effects, while some probiotic strains appear to modestly raise circulating vitamin D. Randomized trials suggest combined supplementation can outperform either alone for some inflammatory and gut-barrier endpoints, though the evidence base is still limited.
vitamin d3 + vitamin a
Vitamin D and vitamin A act through partnered nuclear receptors. Vitamin D's active form binds the vitamin D receptor (VDR), which pairs with the retinoid X receptor (RXR) — whose ligand comes from vitamin A — to switch on genes for immunity, epithelial health, and bone. Adequate levels of both support this signaling, but at extreme doses they can work against each other for calcium and bone endpoints, where a controlled human study showed high preformed vitamin A blunting vitamin D's calcium response.
phenytoin + vitamin d
Phenytoin induces the liver enzymes that break down vitamin D, accelerating clearance of 25-hydroxyvitamin D and lowering circulating levels over time. The downstream result can be reduced calcium absorption, a compensatory rise in parathyroid hormone, and an increased risk of softened bones (osteomalacia) and fractures with long-term use.
carbamazepine + vitamin d
Carbamazepine activates the pregnane X receptor and induces the liver enzymes (including CYP3A4 and CYP24A1) that break down vitamin D, accelerating the clearance of 25-hydroxyvitamin D into inactive metabolites. A meta-analysis and observational studies consistently show lower 25(OH)D in long-term carbamazepine users, along with a secondary-hyperparathyroidism pattern and reduced bone density that raises fracture risk over years of therapy.