Across 3 studies (1 beneficial, 2 neutral), Vitamin E shows mixed evidence for improving sperm morphology in men with infertility. The only beneficial effect was moderate-sized in a 2022 RCT in patients with asthenozoospermia and teratozoospermia (100 mg three times daily for 90 days), while two smaller RCTs found no significant benefit over placebo or comparator interventions. Effects are predominantly neutral, though the evidence base is too small to draw firm conclusions.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. Both neutral studies used Vitamin E as a control or comparator, not as monotherapy, which may confound comparisons.
only progressive sperm motility and morphology improved in the control group
percentage of normal morphology changed from ... 2.0 ± 0.9% to 2.6 ± 1.2% in placebo ... The improvements in M. sativa group are significantly better than placebo group (P = 0.00, 0.01 and 0.04, respectively).
morphology (p = 0.001 Cohen's d = .93) ... were significantly higher in the carob group