Effect of oral alpha-lipoic acid (ALA) on sperm parameters: a systematic review and meta-analysis.

Background: Male fertility has gradually become a worldwide problem with limitations in the treatment. Alpha-lipoic acid, has been applied to improve the quality of sperm in clinical practice. However, there was currently no high quality of systematic review to evaluate the effects of alpha-lipoic acid on sperm parameters.

Material and methods: The Cochrane Library, MEDLINE, EMBASE, Web of Science, Clinicaltrials.org, China National Knowledge Infrastructure Database, China Biology Medicine Database, etc., were retrieved. Related randomized controlled trials had be collected and selected up to March 10, 2022. English literature and Chinese literature were searched using terms including "male infertility", "semen", "sperm", "alpha-lipoid acid", "α-lipoid acid", "alpha lipoid acid", "thioctic acid". All statistical analyses were conducted by RevMan 5.3.

Results: A total of 133 participants in three studies included. Compared with sham therapy, treated with alpha-lipoic acid has significant improvement in the following sperm parameters, including abnormal sperm forms (mean difference[MD] = -1.06, 95% confidence interval [CI] = -1.29-0.84, p < 0.00001), sperm concentration (MD = 3.98, 95%CI = 2.28-5.67, p < 0.00001), sperm total motility (grade a+b+c) (MD = 6.68, 95%CI = 4.88-8.48, p < 0.00001) and progressive motility(grade a+b) (MD = 6.90, 95%CI = 5.62-8.17, p < 0.00001) and semen volume(MD = -0.17, 95%CI = -0.31-0.02, p = 0.03).

Conclusions: In this meta-analysis of three randomized controlled trials, compared with other treatments, alpha-lipoic acid could improve normal sperm forms, sperm concentration, sperm total motility and progressive motility, but more stringent randomized controlled trials must be conducted.