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 :
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?