Most people are de-hydrated whether they realize it or not during the winter months because since your not sweating as much you don't think you need to drink as much. I doubt the powdered veggies are the culprit unless your not adding enough water when you use them? I'd ask your doctor about the blood thinners and any other medication you take? Unless your meds cause a change of urine color, the rule of thumb is you drink till you pee as clear as possible still holds true warm or cold weather.