Although your body needs vitamins to function properly and stay healthy, consuming too much of a certain vitamin can be harmful. Vitamins can be broken down into two categories: water-soluble and fat-soluble. The kidney removes water-soluble vitamins from your body that are not needed. Fat-soluble vitamins are absorbed and stored by bile acids. Vitamins that are water-soluble can leave your body quickly and pose less of an overdose threat.
Vitamin A
Vitamin A falls into the fat-soluble vitamin group. You can find vitamin A in liver, fish, dairy products, and darker colored fruits and vegetables. A healthy adult should consume about 3,000 mcg of vitamin A. Symptoms common with a vitamin A overdose are nausea, vomiting, headaches, dizziness, unclear vision and liver problems. If you consume a lot of alcohol, already have liver problems, have high levels of cholesterol or don't get enough protein, you are more susceptible to the effects of vitamin A.
B Vitamins
All of the B vitamins fall into the water-soluble vitamin group. This means that you are less likely to overdose on these than another fat-soluble vitamin. It is more likely you could develop a deficiency because these vitamins are not stored in your body. No major side effects are associated with a B vitamin overdose, but a few to look for are upset stomach, redness of skin and trouble walking.
Vitamin C
Vitamin C is another water-soluble vitamin that is found commonly in fruits and vegetables. You'll find the highest concentration of vitamin C in citrus fruits. A healthy woman should consume about 75 mg of vitamin C and men should consume 90 mg. Vitamin C toxicity is not believed to have any serious side effects. Possible side effects include upset stomach, nausea, diarrhea and stomach cramps.
Vitamin D
Unlike the other vitamins discussed, vitamin D toxicity can be potentially dangerous. Vitamin D is not commonly found in your diet, most of your intake comes from fortified foods and exposure to direct sunlight. People who live further north often don't get enough vitamin D. A vitamin D overdose likely occurs if too many supplements are taken. If too much vitamin D is consumed, it can cause calcium deposits to build up in your bloodstream. Common symptoms are nausea, vomiting, constipation, weakness, confusion, kidney stones and abnormal heart rhythm.
Vitamin E
Vitamin E is found in vegetable oils, grains, nuts, seeds, meats, fruits and vegetables. Not much is known about the metabolic function of vitamin E. There are no adverse side effects associated with the consumption of too much vitamin E. If you are taking anticoagulants, your vitamin E intake should be monitored.
Vitamin K
You can find vitamin K primarily in green vegetables such as broccoli, spinach and Brussels sprouts. Similarly to vitamin E, there are no major side effects associated with too much vitamin K, and if you are taking anticoagulants your intake should be monitored.
References
- National Institutes of Health; Multiple Vitamin Overdose; October 2009
- Institute of Medicine: Dietary Reference Intakes: Vitamins
- Mayo Clinic; Vitamin D Toxicity: What if You Get Too Much Vitamin D; Katherine Zeratsky; December 2010
- Office of Dietary Supplements: Vitamin A and Carotenoids
- Office of Dietary Supplements: Vitamin C
- FDA; Fortify Your Knowledge About Vitamins; February 2009
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