10 Dec 2019 --- Natural astaxanthin (AX), a carotenoid pigment found in some algae and increasingly popular in supplements, are safe in doses up to 24 mg per day. This is according to a safety review published in Phytotherapy Research. While recommended or approved doses in different countries currently range between 2-24 mg per day, the researchers reviewed 87 human studies, none of which found safety concerns with natural AX supplementation. However, the researchers are calling for further studies to be conducted with synthetic AX, noting it is necessary to establish a different acceptable daily intake (ADI) for the separate forms.