Do any supplements cause thrombosis (blood clots)?

Supplements That Can Cause Blood Clots

Several dietary supplements can increase the risk of blood clots or interfere with blood coagulation, particularly vitamin E, ginger, ginkgo, and fish oil supplements, which should be discontinued at least 2 weeks before any surgical procedure to prevent bleeding complications.

Supplements with Anticoagulant Effects

Vitamin E

• High doses of vitamin E can interfere with blood coagulation and increase bleeding risk 1
• Vitamin E supplements may induce bleeding risks by decreasing γ-carboxylation of prothrombin, a vitamin K-dependent factor in the coagulation cascade 1
• Individuals taking anticoagulant drugs like warfarin should not take vitamin E supplements without medical supervision due to increased bleeding risk 1
• Paradoxically, one study found vitamin E supplementation (600 IU on alternate days) may actually reduce the risk of venous thromboembolism in women 2, though this finding conflicts with other evidence

Herbal Supplements with Anticoagulant Effects

• Ginger: Laboratory evidence shows inhibition of thromboxane synthetase with decreased platelet aggregation 1
• Ginkgo: Ginkgolide B displaces platelet-activating factor from binding sites, decreasing coagulation; interacts with warfarin 1
• Turmeric/Curcumin: Prolongs activated partial thromboplastin time 1
• Fenugreek: Prolongs prothrombin time 1
• Bromelain (from pineapple): Has anti-inflammatory and antiplatelet effects 1
• Garlic: Associated with surgical bleeding independent of anticoagulants 3
• Hawthorn: Strongly associated with surgical bleeding independent of anticoagulants 3

Fish Oil/Omega-3 Fatty Acids

• Can cause inhibition of platelet-to-platelet adhesion and platelet-stimulated thrombin generation 1
• High doses (20g daily) have been associated with gastrointestinal bleeding, particularly when combined with cortisone and antibiotics 4
• However, in a large placebo-controlled trial, there was no increase in perioperative bleeding with fish oil supplementation 1

Perioperative Considerations

The Society for Perioperative Assessment and Quality Improvement (SPAQI) recommends:

• Discontinuing supplements that could affect hemostasis or sedation 1-2 weeks before surgery 1
• Specific supplements to hold for 2 weeks before surgery include:
  • Ginger
  • Ginkgo
  • Glucomannan
  • Glucosamine
  • Goldenseal
  • Grapefruit extract
  • Guarana
  • Gymnema
  • Horse chestnut
  • Moringa 5

Special Considerations

Patients on Anticoagulants

• Patients taking anticoagulant medications should exercise extreme caution with supplements, particularly:
  • Vitamin E 1
  • Ginkgo biloba
  • Turmeric
  • Chamomile
  • Fenugreek
  • Milk thistle 3

Surgical Patients

• In a survey of surgical patients taking dietary supplements:
  • 19% were taking supplements with potential drug interactions affecting coagulation
  • 12.5% of these patients experienced intraoperative hemorrhage 1

Clinical Approach

1. Always ask patients about supplement use, as many don't report this to physicians
2. For patients on anticoagulants, advise against taking supplements with anticoagulant properties
3. For patients undergoing surgery, recommend discontinuing all supplements with anticoagulant effects at least 2 weeks before the procedure
4. For patients with bleeding disorders, recommend avoiding supplements with anticoagulant effects entirely

Conclusion

While some supplements may have beneficial effects, many can interfere with blood coagulation and increase bleeding risk. The evidence regarding supplement safety is often limited by lack of standardization and quality control. Caution is warranted, particularly for patients on anticoagulants or those undergoing surgical procedures.