Zinc is considered an essential trace element, meaning your body needs small amounts of zinc to stay healthy. Zinc is involved in numerous important biological processes throughout the body, including brain and nervous system function. Although zinc is generally regarded as non-toxic, in high doses it may cause adverse health effects. As with any health supplement, consult your doctor before taking zinc supplements.
Neuropathy
The role of zinc in neuropathy, a type of nerve damage, appears to be very complex. While nerve damage is not widely recognized as a symptom of zinc poisoning, limited laboratory data suggests that zinc may cause neuronal cell death in certain situations, reports a paper published in the June 2005 issue of the medical journal "Nature Reviews Neuroscience."
Animal Studies
The majority of evidence indicating zinc can cause nerve damage was demonstrated in laboratory and animal studies. Zinc is not obviously toxic to human tissues like other metals such as lead or cadmium. However, studies using isolated nerve cells grown in laboratory dishes suggest that under certain conditions, high levels of zinc can trigger cell death, explains the "Nature Reviews Neuroscience" paper. Studies using laboratory animals also suggest that zinc may play a role in the neuronal death that follows certain types of head injuries such as stroke or blunt trauma.
Side Effects in Humans
Despite these laboratory findings, evidence linking zinc consumption to neuropathy in humans is relatively scarce. The National Institutes of Health and other large medical agencies do not list neuropathy or nerve damage as a possible side effect from excess zinc consumption, according to the Office of Dietary Supplements of the National Institutes of Health. The most common symptoms of a zinc overdose include diarrhea, nausea, vomiting, headache and abdominal cramps.
Long-Term Health Effects
Long-term exposure to high doses of zinc, such as more than 40 mg per day, can lead to a variety of chronic side effects, including dizziness, drowsiness, loss of muscle coordination, hallucinations, alcohol intolerance and increased sweating, reports the University of Maryland Medical Center. Additionally, chronic exposure to high levels of zinc can disrupt the balance of copper and iron in the body, leading to additional side effects such as anemia.
References
- "Nature Reviews Neuroscience"; The Neurobiology of Zinc in Health and Disease; Christopher J. Frederickson et al.; June 2005
- "Annual Reviews of Neuroscience"; Zinc and Brain Injury; Dennis W. Choi and Jae Y. Koh; March 1998
- Linus Pauling Institute at Oregon State University: Zinc; Jane Higdon et al.; February 2008
- University of Maryland Medical Center: Zinc
