Chang et al. demonstrated that the NOAEL ('No Observed-Adverse-Effect Level') was in excess of 200 mg/kg/day, far greater than doses used in dietary supplements, which are typically <0.5 mg/kg/day.
Xu et al. concluded that meso-zeaxanthin has no acute toxicity and no genotoxicity and the use of meso-zeaxanthin is safe at a dose of 300 mg/kg body weight per day in rats from a 90-day feeding study.