Vitamin E thins the blood, according to Andrew Weil, M.D. Other supplements that offer blood-thinning effects include St. John's wort, feverfew, coenzyme Q10 and dong quai, and omega-3 acids also have an anticoagulant effect. In large doses, vitamin C may thin the blood, adds the New York Times.
Vitamin E prevents platelets from clumping together, thereby thinning the blood, as HowStuffWorks explains. This property is beneficial in helping to prevent strokes and heart attacks, which occur when clots form in arteries and restrict or block blood flow.
A number of oils, such as safflower, corn, sunflower, soy and olive oil, are rich in vitamin E, as stated by Healthline. Fruits and vegetables including tomatoes, spinach, broccoli, mangoes and kiwi contain vitamin E; in addition to sunflower seeds and peanut butter.
Some spices have a blood-thinning effect as well, as noted by Healthline. Garlic, aniseed, ginger and celery seed can all act as anticoagulants.
Anyone who takes Coumadin or any other blood-thinning medication should let his doctor know about any supplements or vitamins he takes, warns Dr. Weil. Ingesting too many foods, spices, vitamins or supplements that provide anticoagulant effects while also taking blood-thinning medications can lead to problems with excessive bleeding.