Zinc is essential to immune function, wound healing and protein synthesis. The mineral also has antioxidant properties, which may help prevent the development of heart disease and cancer. The body does not require much zinc and when taken in excess, it can be dangerous to your health. Consult your health care provider before adding zinc supplements to your diet.
Taking more than the daily recommended amount of zinc can cause abdominal cramps, nausea, diarrhea and headaches. The Linus Pauling Institute states that dosages of 225 to 450 mg of zinc can result in toxicity and lead to vomiting. A 1998 issue of "Journal of Toxicology" reported an instance of a 17-year-old male at St. Anthony Family Medicine Residency in Denver, Colorado, who experienced severe nausea and vomiting within 30 minutes of taking zinc supplements. Doctors classified this as an overdose as the patient had reportedly ingested 85 tablets of zinc totaling 570 mg of zinc. No long-term effects were reported in this case.
Taking too much zinc can lessen the amount of copper your body absorbs and can lead to a copper deficiency. Copper deficiencies can lead to neurological disorders. A study cited in the January 2005 issue of the "American Journal of Clinical Pathology" reported several patients suffering from copper deficiency due to zinc excess. When their bone marrow was examined, three patients were diagnosed with anemia and copper deficiency caused by an excessive intake of zinc.
Low HDL Cholesterol
High dosages of zinc can lower your high-density lipoprotein or "good" cholesterol, according to a study cited in the May 1982 issue of "The American Journal of Clinical Nutrition." In this study, 32 women were given zinc supplements over eight weeks as their cholesterol was monitored. After the eight-week study, the women who were receiving 100 mg of zinc per day showed an average 8.4 percent decrease in HDL cholesterol level. HDL levels seem to only be affected in excessive dosages of zinc. In a similar study conducted in 2002 by The American Society for Nutritional Sciences, patients who received dosages of 80 mg of zinc daily showed no change in HDL levels over a five-year period.
Zinc is naturally present in some foods and also available in supplement form. Your body only absorbs about 20 to 40 percent of the zinc from food. Your body absorbs zinc from meat and poultry more easily than the zinc from plant foods, such as mushrooms and green beans. You can buy zinc supplements from pharmacies and health food stores, and you should take them with water or juice. Daily zinc needs for an adult range from 8 to 11 mg. The Office of Dietary supplements says adults should take no more than 40 mg of zinc per day. Consult your doctor before taking any zinc supplements, as they may interfere with medications or affect other medical conditions.
- "The American Journal of Clinical Nutrition"; Effect of Zinc Supplementation on Plasma High-Density Lipoprotein Cholesterol and Zinc; J.H. Freeland-Graves, et al.; 1982
- "American Journal of Clinical Pathology"; Zinc-Induced Copper Deficiency: A Report of Three Cases Initially Recognized on Bone Marrow Examination; M.S. Willis, et al.; January 2005
- Office of Dietary Supplements: Zinc
- "Journal of Toxicology: Clinical Toxicology"; Zinc Gluconate: Acute Ingestion; M.R. Lewis, et al.; 1998
- Linus Pauling Institute; Zinc; Jane Higdon; December 2003
- "The Journal of Nutrition"; The Effect of Five-Year Zinc Supplementation on Serum Zinc, Serum Cholesterol and Hematocrit in Persons Randomly Assigned to Treatment Group in the Age-Related Eye Disease Study; The American Society for Nutritional Sciences; April 2002