Patients with acne have lower serum levels of zinc compared with patients without acne, and topical and/or systemic zinc supplementation appears to be associated with a significant reduction of inflammatory papules, according to findings from a meta-analysis published in Dermatologic Therapy.
Zinc has been implicated in reducing inflammatory cytokines, leading some to believe the anti-inflammatory component of this essential trace element could play a role in acne pathogenesis. To test this theory, a research group conducted a systematic review and meta-analysis of randomized controlled trials and observational cohort studies that previously examined serum zinc levels and/or the clinical effect of topical/systemic zinc therapy in patients with acne vulgaris.
The primary outcome was the efficacy of zinc therapy on acne. The mean inflammatory papule was used as a surrogate for this outcome.
The review and meta-analysis included 25 studies – including 12 randomized controlled trials and 13 prospective observational studies – with a total of 2445 participants. Patients ranged in age from teens to late 20s, and the majority of patients were men. In 12 studies with 690 patients with acne and 594 control patients, the mean serum zinc level was 96.308±4.053 μg/dl in patients with acne and 102.442±3.744 μg/dl in healthy control patients (mean difference, -12.292 μg/dl; 95% CI, -24.098 to -0.486; P =.041).
In 7 studies with 374 patients assigned to zinc and 371 patients assigned to a comparator, the standard mean difference (SMD) in the number of acne papules was significant after treatment (SMD, 0.730; 95% CI, 0.339-1.122; P <.005) and favored zinc over placebo. Similar findings were reported for subgroup analyses of zinc compared with placebo (SMD, 0.816; 95% CI, 0.144-1.487; P =.017) and zinc compared with active interventions (SMD, 0.681; 95% CI, 0.157-1.206; P =.011).
For 4 studies with 136 participants assigned to zinc and 130 participants assigned to a comparator group, the SMD in the number of acne pustules was significantly different after treatment (SMD, 0.728; 95% CI, 0.230-1.226; P =.004), favoring zinc. Subgroup analyses revealed that the SMD of the number of acne pustules was significantly different with topical zinc vs comparators in 2 studies (SMD, 1.001; 95% CI, 0.659-1.343; P <.005) but not different with oral zinc vs placebo in another 2 studies (SMD, 0.252; 95% CI, -0.219-0.722; P =.294). No differences were found between zinc supplements vs comparators in terms of the incidence of adverse events.
Limitations of this analysis were the exclusion of non-English based literature as well as the inclusion of studies with a population of mostly men.
The researchers noted that additional studies are needed “to determine the optimal goal for serum zinc level, duration and formulation of zinc therapy,” and to examine the efficacy of zinc vs “other topical and systemic treatments for acne vulgaris.”
Yee BE, Richards P, Sui JY, Marsch AF. Serum zinc levels and efficacy of zinc treatment in acne vulgaris: a systematic review and meta-analysis. Published online August 29, 2020. Dermatol Ther. doi:10.1111/dth.14252