There is no conclusive research on astaxanthin.

I did a lot of research on the literature on the effects and effectiveness on astaxanthin, but it's inconclusive. I still bought many bottles for my mom, at her request. This is the brand I bought: BioAstin Natural Astaxanthin (from Puritan's). 12mg doesn't necessarily mean the quality is better; it's just that there is more of the effective component. Taking three of 4mg capsules should be the same as taking one 12mg capsule, I think. My mom told me that she saw exactly the same brand in China, but it's twice or three times more expensive than in the States.