[jannet.duff]

Here's a write up on this on Examine.com (great resource, and this is not even one of their better/completed articles).

When I've looked at this supplement before, it was in relation to antioxidants and their role in vision.

https://examine.com/supplements/astaxanthin/


10.1. Testosterone
A combination of Astaxanthin and Saw Palmetto has been shown to increase testosterone while decreasing Dihydrotestosterone via inhibiting the 5-alpha reductase enzyme, at a dose of 800mg.[81] Both compounds seem to be able to inhibit 5-AR independently.[82]
A study in infertile men (16mg astaxanthin for three months) has failed to note an increase in serum testosterone relative to baseline and placebo treatments.[83]

10.2. Estrogen
Astaxanthin has been implicated in reducing serum levels of estradiol in humans when supplemented in conjunction with Saw Palmetto at 2000mg daily.[81]

10.2, as I recall SP will do that on its own too.