Vitamins and minerals are essential for normal metabolism, and for the maintenance of energy and good health. A deficiency can lead to various disorders and diseases. On the other hand, consuming abnormally high levels of several vitamins and minerals can be toxic to the human body and cause adverse effects.
Vitamin D
According to the U.S. Department of Agriculture, or the USDA, the recommended daily amount of vitamin D for those 51 to 70 years old is 400 international units, or IU, and 600 IU for those over 70 years old. Vitamin D toxicity develops when adults take 50,000 IU every day for several months. People with this vitamin toxicity will have abnormally high levels of calcium in their bloodstream, called hypercalcemia, because vitamin D increases the absorption of calcium from the intestines. They may have nausea and vomiting, nervousness and fatigue.
Vitamin A
The USDA lists 400 to 600 retinol activity equivalents, or RAE, as the recommended daily amount for vitamin A. A child who accidentally takes more than 100,000 RAE can be poisoned, as can adults taking more than 30,000 RAE daily for several months. Those taking a daily dose of more than 1,500 RAE daily can develop osteoporosis, writes Dr. Larry Johnson, associate professor of geriatrics and family and preventive medicine at the University of Arkansas, in "The Merck Manual for Healthcare Professionals." The symptoms include headache, cracked lips, and dry eyes and skin. If a pregnant woman takes isoretinoin to treat her acne, a form of vitamin A, the child could be born with birth defects.
Vitamin B6
People who take 200 mg of vitamin B6 every day can have neurological problems, for the recommended daily amount is 1.7 mg a day for men 51 years and older, and 1.5 mg a day for women in the same age range. They may have problems keeping their balance, which gets worse when their eyes are closed, and not have reflexes in their ankles. It can take months or years for the symptoms to stop, and there are cases in which the damage is irreversible, says Dr. Roger Simon in the journal "Clinical Neurology."
Vitamin K
Vitamin K supplements come in two forms: phylloquinone and menadione. High amounts of phylloquinone are not toxic, but very high doses of menadione can damage the liver and kidneys and cause small hemorrhages in the eyes. The daily requirement for women over 51 years old is 90 micrograms, or mcg, a day and 120 mcg daily for men. People taking more than 500 mcg a day may develop rashes, writes G. Richard Braen, chairman of the Department of Emergency Medicine at the State University of New York, in "Tintinalli's Emergency Medicine."
Vitamin E
The recommended daily amount of vitamin E for both women and men over 51 years old is 15 mg a day. Johnson writes in "The Merck Manual for Healthcare Professionals" that many people can take 400 to 800 mg every day for years and not have any symptoms, while others may develop diarrhea, fatigue, weak muscles and nausea. Those taking more than 1,000 mg a day can start to bleed. Some studies suggest high amounts can lead to strokes.
Iron
Iron is the No. 1 cause of death from poisoning in children, according to Gerald O'Malley, clinical associate professor at the Department of Emergency Medicine at Thomas Jefferson University Hospital in "The Merck Manual for Healthcare Professionals." Symptoms depend on the amount of iron, but toxicity starts at 9 mg per pound. A child who is 1 to 3 years old should consume no more than 7 mg of iron each day, while those 4 to 8 years old need no more than 10 mg a day.
References
- "Clinical Neurology"Professionals: Vitamin A; Dr. Roger Simon et al; 2009
- Merck Manual for Healthcare Professionals: Vitamin A
- The Merck Manual for Healthcare Professionals: Vitamin E
- "Tintinalli's Emergency Medicine: A Comprehensive Study Guide"; Dr. Judith Tintinalli et al; 2004
- USDA: Dietary Reference Intakes
Member Comments