Millions of Americans take anti-clotting medications, or "blood thinners," including aspirin and warfarin (Coumadin), to prevent clots and reduce the risk for such conditions as heart attack and stroke.

These drugs are extremely effective. Daily aspirin, for example, can reduce the risk for a first heart attack by 44%, according to data from the Physicians' Health Study.

The downside: Even at low doses, every anti-clotting agent can cause bleeding-often from the stomach, gums or intestines—as a side effect. Sometimes, gastrointestinal bleeding can occur even without causing noticeable symptoms.

In addition, warfarin, one of the leading blood thinners, doubles the risk for intracerebral hemorrhage (bleeding in the brain).

Natural Blood Thinners

The good news is that certain herbs and other supplements can be used for their anti-clotting properties—and may have a reduced risk for side effects, such as bleeding.

This approach is not intended to replace medications-patients with a high risk for clotting need to take such drugs. Under a doctor's supervision, these supplements can be combined with blood-thinning medications to boost the drugs' effectiveness and potentially allow you to take a lower dose, thus reducing the risk for bleeding.

Those with only a slight risk for clots (due to family history, for example) may want to consider using natural anticoagulants alone, under a doctor's supervision, to promote better circulation.

Bonus: Natural blood thinners usually have anti-inflammatory properties. This is important because most chronic diseases, including heart disease, rheumatoid arthritis and stroke, are caused in part by inflammation.

The supplements below can be taken alone or in combination, depending on the degree of protection that's required.

Some of these supplements may interact with prescription medications, so consult a doctor who is knowledgeable about supplement use.* Best choices…

  • Fish oil. Studies of large populations show that people who eat a lot of cold-water fish, such as salmon and mackerel, tend to have lower heart attack death rates than people who don't eat fish.

The omega-3 fatty acids in cold water fish are strong anti-clotting agents. Fish oil is thought to inhibit platelet aggregation clumping), part of the clotting process. One report, published in The Annals of Pharmacotherapy, found that taking fish oil along with warfarin caused an increase in anti-clotting activity.

Typical dose: Depending on other risk factors, such as elevated cholesterol and high blood pressure, one tablet twice daily of Vectomega's Whole Food Omega-3 DHA/EPA Complex-it provides 292 mg of omega-3s (DHA and EPA balanced) in a phospholipid peptide complex, in which the fish oil is bound to peptides to increase absorbability. Or one teaspoon twice daily of Nordic Naturals Ultimate Omega Liquid, which provides 1,626 mg of EPA and 1,126 mg of DHA.

  • Ginger and curcumin. Ginger reduces levels of fibrinogen, a precursor to fibrin, a protein that is a major component of blood clots. Curcumin has only modest effects on coagulation but is a stronger anti-inflammatory agent. That's why I advise patients to take these herbs together. Studies have shown that both ginger and curcumin can reduce inflammation in the body. An Australian study found that substances in ginger inhibited the activity of arachidonic acid, part of the chemical sequence involved in clotting.

*To find a doctor who has experience treating patients with supplements, consult the American Association of Naturopathic Physicians, 866-538-2267,

In the study, ginger compounds were more effective than aspirin at blocking platelet activity.

Typical dose: Twice daily, 50 mg to 100 mg of ginger and one or two 375-mg capsules of curcumin

Good products: Gaia Herbs' Ginger Supreme Phyto-Caps and EuroPharma's Cura Med curcumin complex.

  • Nattokinase. Extracted from soybeans, nattokinase is an enzyme that helps prevent clot formation-it also makes platelets less likely to clump together. Unlike warfarin, which only prevents clots, nattokinase appears to break down clots that already have formed.

Typical dose: Depending on other risk factors, one to two capsules or tablets (2,000 fibrin units per 100 mg) twice daily.

Important: I recommend taking nattokinase between meals. The anticlotting properties are strongest when it is taken without food.

  • Vinpocetine. This supplement is extracted from periwinkle. It's extremely important to take vinpocetine under a doctor's supervision. Vinpocetine is the most potent natural substance for preventing clots-and, like prescription anti-clotting agents, it can cause internal bleeding in some patients. For this reason, I recommend it mainly for high-risk patients who are unable to take warfarin because of side effects and/or complications.

Typical dose: 2 mg total-in divided doses twice daily. Higher doses 6 mg total in divided doses) might be needed, but don't increase from the starting dose without talking with your doctor. Should be taken without food.

  • Ginkgo. The extract from the dried leaves of the ginkgo biloba tree has traditionally been used to treat intermittent claudication, leg pain caused by insufficient blood flow, as well as cognitive impairments (such as memory problems) due to poor blood circulation in the brain.

Ginkgo is effective at reducing clots and also acts as a vasodilator that helps improve blood flow to the brain, heart and other parts of the body. I don't recommend it as often as other anticoagulants because it has little effect on inflammation. If you use ginkgo, ask your doctor about combining it with curcumin or other anti-inflammatory herbs/supplements.

Typical dose: About 40 mg, three times daily.

  • Garlic. Studies have shown that patients who take garlic supplements have a lower risk for clots. Use only those products that list a high allicin content--the main active ingredient in garlic. This can be found frequently in fresh garlic supplements.

Typical dose: The optimal dose for garlic hasn't been definitively established. However, some studies indicate that you need at least 180 mg of allicin twice daily.

Good brand: Allimax.

Important: In general, natural therapies should be started at low doses that are slowly increased, under a doctor's supervision, over time. I recommend that the supplements described in this article be used at least twice daily to ensure that adequate levels of the therapeutic compounds are maintained in the body.

Tall People at Higher Risk for Blood Clots

In taller people, blood must be pumped a longer distance, so there may be reduced blood flow in the legs—raising clot risk. Clot risk is greatest in men who are tall and heavy. Obese men who are five feet, 11 inches tall have five times the risk of normal weight men who are about five feet, seven inches tall or less. In obese, tall women—more than five feet, six inches—the risk is 29 times greater than in normal weight women, who are five feet, 2.6 inches tall or less.

White-Fleshed Fruits Fight Strokes

White-fleshed fruits and vegetables may protect against stroke.

Recent finding: The more apples, bananas, cauliflower, cucumbers, pears and other white-fleshed produce people ate, the more their stroke risk was reduced-by up to 52%. Other fruits and vegetables did not affect stroke risk, but they have health benefits as well.

High Radiation Risk

Post-heart attack cardiac imaging can pose high radiation risk. Cancer risk rises with cumulative exposure to radiation from catheterization, angioplasty and nuclear scans and some of these tests may not be necessary.

Self-defense: Ask your doctor which tests you really need.

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