Is it true that you should avoid spinach while taking prednisone because its vitamin K interferes with the medication?

No spinach (vitamin K) does not interfere with how prednisone works. Prednisone’s effectiveness is not reduced by vitamin K–rich foods like spinach, and there is no clinical guidance to avoid vitamin K when taking prednisone. ^[1] What often causes confusion is that vitamin K can counteract the effect of the blood thinner warfarin, not prednisone; people on warfarin are advised to keep vitamin K intake consistent, which sometimes gets mistakenly generalized to steroids. ^{[2] [3]}

Why the confusion happens

• Warfarin and vitamin K: Vitamin K (found in leafy greens such as spinach) can lower the anticoagulant effect of warfarin, so those taking warfarin are counseled to maintain a steady vitamin K intake rather than avoid it completely. ^{[4] [5]}
• Prednisone is different: Prednisone is a corticosteroid used for inflammation and immune conditions, and its action is not antagonized by vitamin K in food. ^[1]

What food does to prednisone absorption

• Standard tablets: Food does not meaningfully reduce the bioavailability of prednisone/prednisolone from typical (non–enteric‑coated) tablets, so eating with meals is generally acceptable and often preferred to reduce stomach upset. ^[1]
• Enteric‑coated prednisolone: If you are on enteric‑coated prednisolone (a different formulation), heavy meals can delay or make absorption unpredictable; in that specific case, taking it at least 2 hours away from meals is suggested. ^[6]

Important interaction to know if you also take warfarin

• If someone takes both a corticosteroid (like prednisone) and warfarin, the interaction concern is with warfarin, not vitamin K foods: corticosteroids can alter warfarin response, so clotting tests (INR) should be monitored more closely and doses adjusted as needed. ^{[7] [8]}

Practical guidance

• You can continue eating spinach and other leafy greens while on prednisone. There is no evidence that dietary vitamin K blunts prednisone’s anti‑inflammatory effect. ^[1]
• If you are on warfarin, keep your vitamin K intake consistent day‑to‑day and discuss any major diet changes with your clinician, since sudden increases or decreases in vitamin K can change your INR. ^{[2] [9]}
• For stomach comfort, many people take prednisone with food; that’s reasonable for regular tablets. ^[1]
• Special case: If your prescription is specifically enteric‑coated prednisolone, consider timing it at least 2 hours away from meals for more predictable absorption. ^[6]

Bottom line

• Spinach and other vitamin K–rich foods do not reduce prednisone’s effect, and you do not need to avoid them when taking prednisone. ^[1]
• The vitamin K caution applies to warfarin therapy, not to prednisone itself. ^{[2] [3]}