That is my last word on this.
http://www.ncbi.nlm.nih.gov/pubmed/6471270 You don't read the tags at the end of your studies very well.
an aptly named study on zinc toxicity. reviewing the abstract, 300mg of elemental
zinc per day is certainly an 'excessive intake'. how did they get 11 healthy suckers to voluntarily overdose at 7.5x the tolerable upper intake levels, yikes.
a 50mg zinc citrate pill delivers 15mg elemental zinc, so when you take 100mg per day you get 30. plus whatever's in food and a multi. 1/10th of the dose described in that toxicity study. CORRECTION i think they often label pills with the elemental number. so when you take 100 mg per day you'd get 1/3 of the amount used in the toxicity study.
more studies...http://www.nlm.nih.gov/medlineplus/drug ... l/982.html
What dose is used?
The following doses have been studied in scientific research:
•For treating the common cold: one zinc gluconate or acetate lozenge, providing 9-24 mg elemental zinc, dissolved in the mouth every two hours while awake when cold symptoms are present.
•For diarrhea in malnourished or zinc-deficient children: 10-40 mg elemental zinc daily.
•For preventing and treating pneumonia in undernourished children in developing countries: 10-70 mg/day.
•For hypogeusia (sense of taste is abnormal): 25-100 mg zinc.
•For the eating disorder anorexia nervosa: 100 mg of zinc gluconate daily.
•For treating stomach ulcers: zinc sulfate 200 mg three times daily. [jl note: that's ~50 mg elemental zinc for a total of ~150mg per day]
•For muscle cramps in zinc deficient people with liver disease: zinc sulfate 220 mg twice daily. [jl note: 50mg b.i.d = 100 mg elemental zinc]
•For osteoporosis: 15 mg zinc combined with 5 mg manganese, 1000 mg calcium, and 2.5 mg copper has been used.
•For sickle cell disease: zinc sulfate 220 mg three times daily. [jl note: total 150mg elemental zinc]
•To increase growth and weight gain in children with sickle cell disease who have not reached puberty: 10 mg elemental zinc per day.
•For treating attention deficit-hyperactivity disorder (ADHD) in children: doses of zinc sulfate 55 mg (15 mg elemental zinc) to 150 mg (40 mg elemental zinc) daily.
•For treating acne: 30-135 mg elemental zinc daily.
•For treating age-related macular degeneration (AMD): elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily.
studies of excessive dosages and impacts....
Health Risks from Excessive Zinchttp://ods.od.nih.gov/factsheets/zinc-H ... fessional/
Zinc toxicity can occur in both acute and chronic forms. Acute adverse effects of high zinc intake include nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches . One case report cited severe nausea and vomiting within 30 minutes of ingesting 4 g of zinc gluconate (570 mg elemental zinc) . Intakes of 150–450 mg of zinc per day have been associated with such chronic effects as low copper status, altered iron function, reduced immune function, and reduced levels of high-density lipoproteins . Reductions in a copper-containing enzyme, a marker of copper status, have been reported with even moderately high zinc intakes of approximately 60 mg/day for up to 10 weeks . The doses of zinc used in the AREDS study (80 mg per day of zinc in the form of zinc oxide for 6.3 years, on average) have been associated with a significant increase in hospitalizations for genitourinary causes, raising the possibility that chronically high intakes of zinc adversely affect some aspects of urinary physiology .
luckily no-one is suggesting 570mg, 450, 300, 150, 80 or even 60mg elemental
zinc here, and what does go in is not going in without proper copper balancing.