Function

• Foods with high Vitamin K content may weaken the effects of Coumadin on the blood, whereas decreasing Vitamin K intake can increase the effects of the medication, leading to dosage changes.
  
  

Considerations

• The daily recommended Vitamin K allowance for men is 120 mcg, with 90 mcg of Vitamin K suggested for women. Doctors may recommend lower allowances for individuals taking Coumadin.
  
  

Warning

• People taking Coumadin should avoid green, leafy vegetables, which typically contain more than triple the recommended Vitamin K allowance. Spinach contains 1,189 mcg of Vitamin K per cup.
  
  

Identification

• Herbs and greens such as parsley, kale, broccoli, Brussels sprouts, onions and lettuce all contain high levels of Vitamin K and should be eliminated or closely monitored.
  
  

Prevention/Solution

• Coumadin ineffectiveness is prevented through diets offering moderate to low Vitamin K content foods such as grains, meat, seafood, fruits and root or bulb vegetables.