Sunday Nov 24, 2013 (foodconsumer.org) -- A review in Journal of Diabetes Research suggests that zinc supplements may help protect against diabetic retinopathy in type 2 diabetes mellitus patients.

Authors Xiao Miao from The Second Hospital of Jilin University in Changchun, China and colleagues reviewed 91 research reports and found zinc supplementation "seems beneficial for the patients with diabetes to control glucose levels. 

Type 2 diabetes mellitus and its complications such as diabetic retinopathy have something to do with increased oxidative stress.  And zinc as an antioxidant can attenuate reactive oxygen species through induction of Metallothionein, according to the review.

The review also shows that zinc supplements "might protect retina from ROS induced pericytes apoptosis, capillary leakage, and neovascularization."  That is, zinc supplementation may render a protective effect against diabetic retinopathy.

Some basics about zinc

It has been known that zinc supplementation can be used to treat the common cold, age-related macular degeneration, diabetes mellitus, and HIV/AIDS.

Zinc is an essential mineral or trace element that plays a role in human physiology.  It is needed for catalytic, structural and regulatory functions in the body.  The Recommended Daily Allowance for zinc is 11 mg per day and 8 mg per day for adult men and women respectively.

Zinc deficiency can cause impaired growth and development in children, pregnancy and immunity and increased susceptibility to various infections.

Zinc rich foods include meat, eggs, and seafood (oysters have the highest zinc) and its bioavailability in these foods is high.  Zinc bioavailability in plant foods such as whole grains and legumes is not as good due to the presence of phytic acid which can inhibit the absorption of the mineral.

Supplemental zinc may come from any of these zinc compounds, zinc acetate, zinc gluconate, zinc picolinate, and zinc sulfate.

Caution:  When used for a long term, zinc supplements in a dose of greater than the tolerable upper intake level (40 mg/day for adults) may lead to copper deficiency.   Copper is another important trace element that humans need. (David Liu, PHD)