Just because something is labeled natural, does not always mean that it is safe. Many nutritional supplements, natural or otherwise, can have serious side effects if taken in large quantities. A well-balanced diet should provide a wide spectrum of nutrients. Natural vitamins should only be taken under the direction of a health care provider.
Fat Soluble Vitamins
The main vitamins which cause problems if taken in excess are the fat soluble vitamins, A, D and E. Hypervitaminosis, or vitamin overdose, of beta carotene is toxic. It can cause liver problems, loss of bone density and birth defects in pregnant women. High doses of vitamin D can lead to tissue calcification of the heart and blood vessels. Immediate effects include heart arrhythmias and loss of appetite.
Vitamin E is a natural blood thinner. Taking excessive amounts of this supplement can lead to an increased risk of bleeding. The National institutes of Health further warns that vitamin E may also interfere with certain prescription medications. Consult a health care practitioner before using fat soluble vitamins.
B Vitamins
B vitamins work together in the body to nourish nerves and other tissue, and play a role in metabolism. Some may supplement with single B vitamins to aid in weight loss or provide other therapeutic value. However, large quantities of individual B vitamins can have adverse effects. Hypervitaminosis of vitamin B-3, or niacin, causes flushing, or redness of the skin, burning, itching and tingling. It may also cause headaches, dizziness and upset stomach. The National Institutes of Health warns that niacin also can increase the risk of stroke, liver problems and stomach ulcers. Talk to your doctor before trying B vitamins.
Vitamin C
Vitamin C, also known as ascorbic acid, is an antioxidant found in fruits and vegetables, notably citrus fruits. It is sometimes taken in supplement form to strengthen the immune system, especially during cold and flu season. Although overdose is rare, very high doses of vitamin C can cause severe gastrointestinal disturbances. It may lead to nausea, gas, bloating and diarrhea. And, like vitamin E, it may interfere with certain medications. Individual tolerance levels vary, however, between 1,800 and 2,000 mg of vitamin C daily are generally considered safe. Talk to your medical doctor before using vitamin C for medicinal purposes.
Minerals
In addition to vitamins, excessive consumption of certain minerals, mainly iron and calcium, can have harmful effects. The Office of Dietary Supplements explains that because the body does not excrete a lot of iron, toxicity is a real risk with supplementation. 40 to 45 mg per day is considered safe. However, higher doses can lead to iron deposits in the tissues and organs, and even death. Excessive amounts of calcium can cause constipation, but worse, they can interfere with the absorption of other minerals, namely iron and zinc. Between 2,500 and 3,000 mg is considered safe for adults and teenagers. Talk to your doctor before taking iron or calcium supplements.
References
- National Institutes of Health: Office of Dietary Supplements: Vitamin A
- National Institutes of Health: Office of Dietary Supplements: Vitamin D
- National Institutes of Health: Office of Dietary Supplements: Vitamin E
- National Institutes of Health: Medline Plus: Niacin
- National Institutes of Health: Office of Dietary Supplements: Vitamin C
- National Institutes of Health: Office of Dietary Supplements: Iron
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