Headlines like “As a neurosurgeon, I’m shocked: this vitamin can cause a stroke overnight” are misleading. There is no vitamin that has been shown to cause a stroke overnight in the general population when taken at recommended doses.
Here’s what the evidence says:
- Most vitamins do not increase stroke risk when used as directed to treat or prevent deficiency.
- Very high doses of some supplements can be harmful, but that does not mean they directly cause strokes.
- Some supplements can interact with medications, which may indirectly affect stroke risk.
Examples include:
- Vitamin K does not cause strokes, but it can interfere with the blood thinner warfarin if your vitamin K intake changes dramatically. People taking warfarin are usually advised to keep their vitamin K intake consistent, not eliminate it.
- Vitamin E in high doses may increase the risk of bleeding, especially if taken with blood thinners.
- Some non-vitamin supplements (such as certain herbal products) can also affect blood clotting or blood pressure.
The biggest proven stroke risk factors are:
- High blood pressure (the most important)
- Smoking
- Diabetes
- High cholesterol
- Atrial fibrillation
- Obesity and physical inactivity
