What are the differences between zinc, zinc picolinate, chelated zinc and zinc gluconate?

“Oysters are by far the best food source of zinc�a single serving will give you about 10 times the recommended daily intake! Seeds and nuts, peas, whole wheat, rye, and oats are not nearly as high in zinc, but you can get about 3 mg per serving of these foods.

Zinc can also be taken as a nutritional supplement, in one of many forms. Zinc citrate, zinc acetate, or zinc picolinate may be the best absorbed, although zinc sulfate is less expensive. When you purchase a supplement, you should be aware of the difference between the milligrams of actual zinc the product contains (so-called elemental zinc) and the total milligrams of the zinc product.”

Source

“Zinc Sulfate is most commonly used in research, but it is available by prescription and in over-the-counter supplements. Drug companies tend to favor this form.
Zinc Gluconate is preferred over the sulfate form by companies that sell supplements directly to the consumer. Scientific research shuns zinc gluconate because it is less concentrated than zinc sulfate, although, zinc gluconate used in lozenges has shown to speed recovery of the common cold.”

Chelated Zinc – Medical journals contain virtually no information about the safety of chelated zinc. Though gluconate or acetate forms have replaced zinc sulfate in a few studies, chelated zinc has not. As with all chelated minerals, the zinc form costs considerably more than zinc from other sources.”

Source

Hmm, very insightful info. Do you know if GNC sells Zinc Sulfate supplements?