How Much Vitamin Is Too Much?

Did you know that some vitamins and herbs can cause a stroke?

Vitamins are good for you, right? Usually. We need vitamins so that our body can carry out basic physiological functions and maintain good health. But, sometimes vitamins, and even herbs, can actually cause serious problems if overdone. Too much of a good thing can be dangerous.

Which vitamins and herbs can cause stroke?

Vitamin K

Vitamin K is essential for blood clotting.

  You need to form a blood clot whenever you have a cut anywhere in the body. This allows your body to heal, protects you from infection and prevents blood loss. A blood clot is nature’s natural Band-Aid whenever body tissue is injured. The mechanism of blood clot formation, the clotting cascade, involves organized coordination of platelets, proteins, and connective tissue. Vitamin K is necessary for activation of the clotting process.

However, when Vitamin K levels are too high, people can form excessive blood clots quickly, which can cause stroke, heart attack and blocked blood flow anywhere in the body. The ideal Vitamin K dose is approximately 90 micrograms/day for adults. This is one of the vitamins that should be taken very conservatively, if at all. There are a number of dietary sources of Vitamin K, including spinach, kale, asparagus, broccoli, cabbage, beans, eggs and meat.  It is unlikely to overdose on Vitamin K through food- so enjoy your spinach and egg omelet!

Vitamin E

Vitamin E is necessary for immunity and protection from disease.  However, too much Vitamin E can increase your risk of bleeding, which can lead to hemorrhagic stroke, a serious and difficult to treat the condition. The recommended dose of Vitamin E is approximately 15 mg/ day. Good sources of Vitamin E include eggs, spinach, fruit, meat, nuts, and vegetable oils.

Vitamin A

Vitamin A is important for skin and eye development. But excessive amounts of one of the forms of Vitamin A can cause an increase in cerebrospinal fluid, which is the fluid that surrounds the brain and spinal cord. This condition is called increased intracranial hypertension. When this happens, the excess fluid surrounding the brain exerts pressure on the brain and the optic nerves, the nerves that control vision. Some of the symptoms include headaches, vision loss, blurred vision and severe neck pain and dizziness that may resemble a stroke. But, these symptoms are not a sign of stroke. Instead the fluid pressure on the nerves that control vision and eye movement directly impairs vision and eye movement. This condition can progress quickly and usually requires treatment consisting of removal of the cerebrospinal fluid with a procedure called a lumbar puncture.

The recommended dose of Vitamin A should not exceed 800 micrograms/day unless prescribed or recommended by your doctor. Accutane, a medication used for acne, is a powerful Vitamin A derivative.

It can be effective for difficult to treat acne, but can also cause side effects. Simple and safe ways to get Vitamin A include carrots, yams, squash, mango, liver, and green leafy vegetables.

Ginkgo Biloba

Ginkgo Biloba is a supplement that has been advertised for prevention of stroke, prevention of dementia, and for improvement of memory.

However, it can increase bleeding. In fact, it is likely that the blood thinning, the anti-clotting effect can prevent strokes, and thus protect from vascular dementia. To play it safe, do not use ginkgo biloba if you have a bleeding or blood clotting problem, or if you are taking any blood thinners, such as aspirin, Plavix, or coumaden.


Ginger is a natural herb that can help relieve nausea and some types of pain. Ginger is available as a spice, a vegetable, in tea, candy, gum and pill forms. It is generally safe, but in excessive quantities, it may increase the risk of bleeding, which can increase the likelihood of hemorrhagic stroke in those who are at risk. The recommended dose is approximately no more than 1000 mg/day. If you have a bleeding disorder or a blood clotting disorder, you should check with your doctor before using ginger as a health remedy.


Tsai HH, Lin HW, Lu YH, Chen YL, Mahady GB, A review of potentially harmful interactions between anticoagulant/antiplatelet agents and Chinese herbal medicines, PLoS One, May 2013

Shalansky S, Lynd L, Richardson K, Ingaszewski A, Kerr C, Risk of warfarin-related bleeding events and supratherapeutic international normalized ratios associated with complementary and alternative medicine: a longitudinal analysis, Pharmacotherapy, September 2007

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