Excess Vitamin A: Doses greater than 1000,000 mcg or 3000,000 IU daily can cause toxicity. Doses of 33,000 mg or 100,000 IU daily can cause chronic toxicity. Vitamin A toxicity includes irritability, weight loss, dry itchy skin in children and nausea, headache, diarrhea in adults.
Excess Vitamin C: More than 2,000 mcg daily can cause anemia, kidney stones, and diarrhea.
Excess Vitamin E: Do not take more than 800 to 1,000 mg daily.
Excess Copper: Can prevent the absorption of zinc.
Excess Iron: Can cause stomach distress, nausea, diarrhea, constipation, and high infection risk.
Zinc: Do not take more than 34 to 40 mg daily.
Some of this information was taken from Winning Sports Nutrition by Linda Houtkooper, PhD, RD, FACSM, Jaclyn Maurer Abbot, PhD, RD and Veronica Mullins, MS, RD, CSCS.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional, such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.