Vitamins and minerals serve essential functions in the body. They are needed in relatively small amounts compared to water, carbohydrates, proteins and fats. However, they are needed for good health. At the same time, excessive vitamin and mineral use can be toxic. It is important to consult with a dietitian, physician or other healthcare professional regarding individual needs for vitamin and mineral intake, in particular because some people will need more or less depending on age, gender and general health conditions.
Toxicity of Minerals
The kidneys tightly regulate mineral balance in the body, so it's unusual, but not impossible, to encounter toxicity from mineral overdoses in healthy people. Certain medications or health conditions, such as kidney disease, make mineral imbalances and toxicity more frequent. Problems with other organs or organ systems can also lead to mineral excesses, such as imbalances of many of the hormones synthesized by the adrenal gland. The muscles and nerves, including the brain, are particularly sensitive to mineral toxicity.
Vitamins with Lower Toxicity
A 2009 report in "Clinical Toxicology" notes that in 2008, 60,719 cases of vitamin overdose were reported to poison control centers, with 8 major adverse outcomes and no deaths. The majority occurred in children ages 5 and under. Many vitamin overdoses cause rash and gastrointestinal symptoms such as nausea, vomiting and diarrhea. Some vitamins have a lower toxicity than others. Thiamine, riboflavin, cobalamin and folate having a lower toxicity. Thiamine can produce some dangerous symptoms such as weakness, blood pressure changes, heart irregularities and seizures, notes the report.
Toxic Water Soluble Vitamins
Pyridoxine, niacin and vitamin C tend to be more toxic than the above vitamins. Pyridoxine causes nerve problems such as tingling, pain and difficulty with balance and body position. Niacin causes flushing of the skin, vomiting, nausea and diarrhea. Other symptoms may include headache and wheezing; rarely liver damage can result. Vitamin C can cause GI symptoms such as vomiting and nausea. It also can increase the risk of kidney stones.
Toxic Fat Soluble Vitamins
Fat soluble vitamins include vitamins A, D, E and K. These tend to be more toxic than the above water soluble vitamins because they reside in the fatty tissues and are cleared more slowly by the body. Vitamin A can cause birth defects, liver damage and failure, reduced bone density, skin, mucous membrane and hair problems, nerve problems and GI upset. Vitamin D can cause increased calcium with constipation, nerve problems and heart irregularities. Vitamin E can cause GI problems and a decreased ability of the blood to clot and stop bleeding. Vitamin K can cause damage to blood cells in infants and adversely affect oral blood thinning, or anticoagulant medications.
References
- "Clinical Toxicology"; "Annual Report of the American Association of Poison Control Centers' National Poison Data System"; A.C..Bronstein et al.; 2009
- "Principles and Methods of Toxicology"; A. Wallace Hayes; 5th Ed 2007
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
- "Nutrition Concepts and Controversies"; Frances Sizer, Ellie Whitney; 11th Ed 2007
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