Safety assessment of [3S, 3'S]-astaxanthin--Subchronic toxicity study in rats.

Astaxanthin, a naturally occurring xanthophyll, is commercially used as a coloring agent in salmon feed, but also marketed as a dietary supplement. The objective of this study was to investigate the subchronic toxicity of synthetic [3S, 3'S]-Astaxanthin in rats. A powder formulation containing approximately 20% [3S, 3'S]-Astaxanthin was administered via the diet to groups of 10 male and 10 female Wistar rats at concentrations of 5000, 15,000 and 50,000 ppm for a period of 13 weeks. A formulation of comparable composition but without [3S, 3'S]-Astaxanthin served as a placebo control. There were no effects observed on survival, clinical examinations, clinical pathology, estrous cycle as well as on sperm parameters. At terminal necropsy, a macroscopically visible brown-blue discoloration of the gastrointestinal contents was noted which was considered to be secondary to the violet-brown color of the test material. No other significant or dose-related abnormalities were found in the tissues collected at termination. Our observations support that ingestion of [3S, 3'S]-Astaxanthin of up to 700-920 mg/kg bw/day in rats in a gelatin/carbohydrate formulation is without adverse effects.