Background
Leg ulcers affect up to one percent of people at some time in their life. Leg ulceration is chronic in nature with ulcers being present for months and in some cases years without healing, and with a high risk of recurrence. Management approaches include dressings and the treatment of underlying medical problems such as malnutrition, lack of minerals and vitamins, poor blood supply or infection.

Objectives
To assess the effectiveness of oral zinc in healing arterial or venous leg ulcers.

Search strategy
For this update we searched the Wounds Group Specialised Register (November 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) ( Issue 4, 2008), Ovid MEDLINE (2007 to November Week 2 2008), Ovid EMBASE (2007 to 2008 Week 47) and Ovid CINAHL (2007 to November Week 3 2008). In the original version of the review a company manufacturing zinc sulphate tablets was asked for references to relevant trials.

Selection criteria
Randomised controlled trials comparing oral zinc sulphate with placebo or no treatment in people with arterial or venous leg ulcers were eligible for inclusion. There were no restrictions on date or language of publication.

The main outcome measure used was complete healing of the ulcers. Trials were eligible for inclusion if they measured ulcer healing objectively by documenting time to complete healing, proportion of ulcers healed during the study, or healing rates of ulcers.

Data collection and analysis
All data extraction and assessment of trial quality were done by both authors independently.

Main results
Six small trials (183 participants) were eligible for inclusion. Four trials considered people with venous ulcers, one trial arterial ulcers and one people with mixed ulcers. In four trials, serum zinc was measured at baseline or during the trial. Pooling the four trials that compared oral zinc sulphate with placebo in people with venous ulcers showed no statistically significant difference between the two group (RR 1.22, 95%CI 0.88 to 1.68). Overall, there was no evidence of a beneficial effect of treatment with zinc sulphate on the number of ulcers healed.

Authors' conclusions
Oral zinc sulphate does not appear to aid healing of arterial and venous leg ulcers, however all included studies were small and of mediocre quality.

Plain language summary
Oral zinc supplements for treating leg ulcers
Leg ulcers (open sores) usually heal with good wound care and dressings. However they may take a long time to heal (weeks or months) despite good wound care and can cause distress to patients as well as being very costly for the health service. Failure to heal may be due to poor nutrition which reduces the ability of the body to repair itself. Minerals such as zinc are necessary for good healing and so it has been thought that taking zinc sulphate tablets might aid healing of ulcers. We found six trials that used zinc to treat leg ulcers but all were too small to pick up on any benefit, if such a benefit exists. In addition the quality of these trials was mediocre. On the basis of the evidence we have so far it appears that taking zinc tablets does not improve leg ulcer healing, however more good quality trials are needed.