Carotenoid

Astaxanthin is the red carotenoid that colours salmon, shrimp and crayfish. Supplements usually contain an extract of the microalga Haematococcus pluvialis. It is sold as a very strong antioxidant, and pooled trials do show a modest fall in the lipid-peroxidation marker malondialdehyde. The effects that matter clinically are small or inconsistent. Meta-analyses find a little more skin moisture and elasticity but no change in wrinkle depth, no reliable effect on blood lipids or blood pressure in the general population, and no gain in endurance performance. Its safety at up to 8 mg a day is well studied.