Nutrition 101: Are You Overdoing the Zinc?

By , SparkPeople Blogger
Zinc is a lustrous bluish-white metal found in group IIb of the periodic table. It is also one of the most important minerals used by the body. Just 2-3 grams, about the weight of a penny, is found in the body and serves as a key building block for about 100 enzymes which are necessary for cell growth, reproduction and repair and regulating the body's immune response, insulin metabolism and wound healing. The RDA for zinc for adults is about 11 mg per day for men and 8 mg per day for women (12 mg if you are pregnant or breastfeeding). Zinc is found in water and food and should be included in the diet each day since the body does not have a storage mechanism for zinc.

Oysters are the richest source of zinc and the other best sources including beef, lamb, pork, crabmeat, turkey, chicken, lobster, clams and salmon. Good sources of zinc include dairy such as milk, yogurt and cheese as well as yeast, peanuts, beans, whole grain cereals, brown rice, whole wheat bread and potato. Pumpkin seeds offer one of the most concentrated non-meat food sources of zinc but the zinc from meat sources is four times more bio-available than the zinc from grain sources.

If you are healthy and eating a well-balanced diet, supplements are generally not needed to meet your body's zinc needs. However, many multivitamin supplements include zinc and provide 11-15 mg themselves which is the daily recommended intake. Safe upper intake levels of zinc are set at 40 mg per day for adults.

So why am I focusing on zinc?

Zinc intake of more than 50 mg from diet and supplements can lead to improper copper metabolism, altered iron function, a reduction of HDL’s (the good cholesterol) and reduced immune function. Research suggests that chronic and excessive zinc intake can cause neurological disorder and disease. There is also ongoing research related to iron, copper and zinc and their role in Alzheimer’s disease.

Zinc is found in many cold lozenges and some over-the-counter drugs sold as cold remedies. They can be in several different forms such as zinc gluconate, zinc sulfate and zinc acetate. The percentage of elemental zinc used by the body will vary depending on the form. For example, 23% of zinc sulfate is available as elemental zinc so 220 mg of zinc sulfate contains 50 mg of elemental zinc. You can find the elemental zinc content for specific products in the Supplemental Facts panel on the supplement container.

Being exposed to more than 10 times the recommended amount of zinc can result in zinc poisoning. Neuropathy or nerve disorder has been seen in those that wear dentures due to suspected zinc poisoning. Overuse of adhesive creams to fix ill-fitting dentures is felt to be a culprit. Because adhesives are not FDA controlled, zinc concentrations have been found to range from 17-34 mg per gram of denture cream.

The bottom line – the right amount of zinc daily is good – more is not necessarily better. Zinc is a heavy metal and can lead to heavy metal poisoning when consumed in large amounts over time. Using large amounts of denture cream to fix ill fitting dentures or taking large amounts of zinc containing vitamins or cold supplements can result in consumption of too much zinc, especially if you already have a zinc rich diet.

If you eat a well balanced diet AND you take a multivitamin with zinc AND/OR take other supplements containing zinc or are using larger amounts of denture cream because you have lost weight and your dentures aren’t fitting as well – now is the time to do a zinc check. Take a look at what you are routinely getting from your diet in zinc. Now take a look at other zinc sources and see if you are routinely exceeding 50 mg/day. If you are and you have any of the following neurological symptoms, please see your medical provider to be sure there are no toxicity issues.

Symptoms of neuropathy include :
  • numbness of tingling in the arms, legs, fingers and/or toes
  • unexplained pain in the extremities
  • a diminished ability to move the arms, hands, legs and/or feet
  • poor balance
  • unsteady gait or stride

Also, if you have family members that wear dentures and you have noticed any recent changes in their balance or walk or if they have made comments about numbness or tingling, it would be a great idea to find out how much denture cream they may be using. More than 2 tubes a week is most likely a problem that needs to be further investigated and new dentures fitted.

Is zinc something you have ever worried about or ever paid attention to in your diet or supplements? Will you do a zinc check?

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Scary stuff. I don't have dentures or east shellfish but take suppliments so will definately monitor my zinc consumption to see where I fall. Report
Wow - I am a huge user of Zicam, which I believe has lots of zinc? I will definitely check it out, but I have never had any problems with it (tingling, etc.), and I would be devastated if I had to stop using it - it's the only thing that gets me thru colds! Report
Just wanted to point out that neuropathy can be the result of a whole bunch of different things including diabetes, an auto-immune disease, CTS, or other nutritional deficiencies, even without excessive zinc consumption. Since neuropathy is more common in people over 55, and denture creme use is also more common in people over 55, I have to wonder if that isn't at least some of the effect of that study. It would be interesting to know the degree of neuropathy of those using a lot of zinc laden deture creme that are under 55 or have none of the other conditions more typically associated with neuropathy. Report
OMG - What an alarming article. I had some idea that multi-vitamins were not necessary if I were eating well balanced meals. But I'm also aware that much of the vitamins and minerals are often cooked out of foods. So, I think I better check with my doctor about taking supplements.
Because I've had malignant melanoma, and because of one of my medications, I need to avoid sunlight. When I'm going to be in the sun, I use a largely zinc-based sunblock, and lots of it on any exposed skin.

Is there any chance that zinc can be absorbed through the skin, and I should be concerned? Thanks for your information~ Report
Same problems can occur with B6 vitamin overdose. I would love to see an article devoted to that kind of poisoning, which made me very sick last year and of which people are usually not aware. Report
I'd hate to wear dentures. Report
I took zinc supplements for nearly a year. Then I started to get tingling sensations and leg pains.could zinc be the cause ? who knew?! Report
who knew? Thanks for teaching me about zinc consumption. Report
I will check on people who use denture cream. I wear dentures but they fit nice and I don't use anything on them to keep them in. I've worn them for 17 years or more. I have dropped them and they still don't break and they still fit good. They are starting to get loose but I still don't use denture cream because they stay in. Howeever we have a health class at a place I go to and I will bring up the idea to them so they can discuss it for everyone. Thanks for letting me know Report
Thank you, I take a zinc supplement but I'll drop it because I eat healthy and I take a multivit. also. Report
This is a very informative article.

The next time I have a doctor's appointment I will suggest a zinc check up.

Keep up the good work on the great articles. Report
It's as if this article was meant just for me...a godsend! I just posted to someone that my nutrient totals come up consistently low on zinc. I didn't even consider that there can be too much of zinc, or any other vitamin/mineral.

The mention of food sources was a huge help, too. Have to back to making that red clam sauce! I love clams that way! Great article! Thanks, SparkPeople Report
Thanks for the info, i will check my zinc intake since i have a hard time keeping my HDL where its suppose to be. Report
Thanks for the tip! I take a lot of nutritional supplements so I have to stay very well-informed about the quality and safety of those supplements. I'll be much more wary about trying some of those new cold medicines that contain a lot of zinc. Report
Clearly, this is valuable information to be stored away and hopefully recalled if/when ever needed! Thanks! Report
I haven't thought about it, but I am sure going to do so now. I try not to take medicines with zinc in them unless prescribed by my doctor due to having Rheumatoid Arthritis. It's been known to interfere with RA drugs. Report
Being diabetic I am most concerned here, now. I didn't know this. I will most definitely check my zing mg's and my diet intake. Thanks a bunch for doing this article. Report
Very cool article. This gives me more incentive to cut down on shellfish consumption. Though you lost me on the denture stuff, the entire article is a good read for all ages because it's never too early for prevention. Report
I just want to say, I love how this blog covers a wide range of issues. Keep up the good work. Also, I love that pic of the adults on the swings. Report
Wow, I had no idea, but I will definitely keep tabs on this! Thanks for sharing the info regarding denture cream, Tanya. I had no clue that this could be a possibility. Report
I use zinc combined with another supplement during the winter months for colds. I will be more conscious of my zinc intake in the future. Report