Why can't you take vitamins and herbs before surgery. instruction sheet says no vitamins or herbs 10 days before.

Bleeding: Some medications, vitamins, and herbal remedies can affect how your body bleeds and/or stops bleeding. If you bleed too easily or are unable to clot/stop bleeding during surgery, it puts you at higher risk for complications.

My idea...: You often don't know what's in some "vitamins" and "herbs" nowadays; these are unregulated and may contain goodness-knows-what. There may be glucocorticoids (a common adulterant) to interfere with healing, something that might affect platelet function, or even caffeine with when you don't take the morning of surgery could give you a headache necessitating postponing the operation.