You will be presented with a collection of medical randomized controlled trial (RCT) reports addressing a shared clinical question -- for instance, the efficacy of a medical intervention on a disease or condition. Given the titles and abstracts of these reports, your task is to generate the conclusion of the systematic review article synthesizing the key findings. Your conclusion should be a few sentences long. In your response, include only the conclusion and no other text. The RCT reports are below.



Title 1:
DOUBLE‐BLIND TRIAL OF ZINC SULPHATE IN THE TREATMENT OF CHRONIC VENOUS LEG ULCERATION
Abstract 1:
Summary .— The results of a double‐blind trial of zinc sulphate in patients with chronic venous leg ulceration are reported . No significantly increased rate of healing was observed in the zinc‐treated group


Title 2:
Acceleration of wound healing in man with zinc sulphate given by mouth.
Abstract 2:
Abstract The need for zinc in the optimal healing of wounds was demonstrated by the acceleration of healing of granulating wounds caused by excision of pilonidal-sinus tracts in young , healthy airmen who were given zinc sulphate U.S.P. , 220 mg . t.i.d . by mouth during the period of repair . The rate of healing was determined by measurements of the wound volumes and the number of days for complete repair .  Ten r and omly selected controls ( mean age 25·0 years and wound volume 32·3 ml . ) were matched against ten who were given the drug ( mean age 24·6 years and wound volume 54·5 ml . ) .  The days ±S.E. for healing averaged 80·1±13·7 in the controls and 45·8±2·6 (


Title 3:
[Lack of effect of oral zinc sulfate on wound healing in leg ulcer].
Abstract 3:
The effect of oral zinc on the healing of chronic venous leg ulcers  has been investigated in 91 hospitalized patients aged approximately 70 years . The patients were divided into three groups : group A consisted of patients with serum zinc concentrations in the upper normal range ( Zn greater than or equal to 1.0 mg/l ) who received no zinc therapy .  Groups B and C consisted of patients with serum zinc concentrations in the lower normal range ( Zn less than 1.0 mg/l ) who received either 3 daily doses of 220 mg zinc sulphate  ( group B ) or placebo  ( group C ) . In group B , a marked increase in serum zinc concentration occured within one month ( from 0.9 to 1.25 mg/L ) . In group A , serum zinc levels decreased slightly during the observation period of three months ( from 1.1 to 1.0 mg/l ) while a slight rise was seen in group C ( from 0.9 to 1.0 mg/l ) . The healing rate of the ulcers in group A was not superior to that in group C. Zinc substitution in the low zinc group B did not improve healing as compared to placebo-treated low zinc group C. A favourable effect of oral zinc on wound healing in patients with initially low serum zinc concentrations could not be demonstrated . Initial ulcer areas were significantly smaller in patients with higher serum zinc levels than in patients with lower serum zinc levels . Low serum zinc levels appear to be a consequence of insufficient nutrition , an observation which may indicate a correlation between nutritional deficiency and ulcer area . The healing rate did not depend significantly upon age , sex , weight or cause . It was , however , accelerated in the case of larger ulcers


Title 4:
[Tolerance of large doses of oral zinc sulfate].
Abstract 4:
The toxicity of oral zinc was investigated in patients hospitalized for chronic leg ulcers .  Untoward effects were monitored by reference to clinical tolerance , hematological , hepatic and renal parameters , and serum concentrations of copper and iron . The investigation was conducted by comparing two groups of patients who initially did not differ significantly with regard to ulcer area , hemoglobin , leukocytes , copper , iron and zinc .  Both groups had serum zinc concentrations in the lower normal range . One group was treated with 3 daily doses of 220 mg oral zinc sulfate and the other with placebo , and hence , untoward effects of zinc should have become manifest in the zinc-treated group . This was not the case . Therefore , oral zinc appears to be well tolerated clinical ly and does not cause hematological , renal or hepatic toxicity . In view of the increasing interest in and range of indications for zinc , particularly in conditions associated with cellular immunological hyporeactivity , this finding is a prerequisite for the institution of clinical zinc therapy


Title 5:
Oral zinc sulphate in leg ulcers.
Abstract 5:
Abstract A hundred and four in patients of various ages with ulcers of the lower limb were included in a controlled trial of oral zinc sulphate . Identical capsules containing 220 mg . of lactose ( placebo ) or zinc sulphate were given three times a day to equal numbers of controls and treated patients . Ulcers healed more quickly in the treatment group . The ulcers of the treatment group healed in 32 on average , as against 77 days for the control group . There was no significant dependence on age or sex . Mild diarrhœa in three patients was the only toxic effect of zinc-sulphate therapy . Oral zinc sulphate would seem to have a place in the treatment of chronic leg ulcers which do not respond to topical treatment . Prolonged or repeated courses should , however , be avoided since not enough is known about the side-effects of systemic zinc salts


Title 6:
Serum-zinc and healing of venous leg ulcers.
Abstract 6:
Abstract In a double-blind trial in twenty-seven patients , the healing of chronic venous leg ulcers  was investigated with respect to the serum-zinc level and to the effect of an effervescent preparation of oral zinc sulphate or placebo .  Ulcers in patients with a serum-zinc level higher than 110 μg . per 100 ml . initially , or after oral zinc sulphate 200 mg . three times a day , healed significantly faster than did those in patients with a low serum-zinc level . No haematological or biochemical evidence of toxicity was found during 4 months of zinc administration


Title 7:
Zinc and the healing of chronic leg ulcers.
Abstract 7:
Summary An objective method of determining the healing rate in patients with chronic leg ulcers has been used in forty patients to date . Almost all patients showed improvement on a regimen of cleanliness and external support . The serum zinc levels of twenty-four of the patients ranged from 39 to 219 μg per cent , but there was no correlation between the healing rate and the serum level . The addition of supplemental oral zinc to the therapeutic regime did not acclerate the healing rate in any patient


Title 8:
Venous leg ulceration: evaluation of zinc treatment, serum zinc and rate of healing
Abstract 8:
The results of a double‐blind study of zinc sulphate treatment in patients with venous leg ulceration are reported . No significantly increased rate of healing occurred in the zinc treated group . The serum zinc concentration at the onset of treatment did not significantly influence the rate of healing in zinc‐treated patients , but patients with an initial low serum zinc showed a more rapid rate of healing than those with a high zinc level irrespective of treatment . This finding could be accounted for by a defect of distribution of zinc in patients with venous leg ulceration
Overall , there is no evidence that oral zinc increases the healing of arterial or venous leg ulcers .