Astaxanthin: Pretty in Pink?

Astaxanthin is the orange-red pigment that makes flamingoes and salmon pink. It's now being promoted as the next super supplement.
Promoted on talk shows and all over the Internet, astaxanthin is said to fight heart disease, reduce cancer risk, improve fertility, relieve reflux, ease joint problems, enhance muscle endurance, promote healthy skin and eyes, and slow aging. You name it, it does it--or so marketers say.
Astaxanthin is a member of the carotenoid family, which also includes beta carotene. Made by certain algae and other microorganisms, it's thought to help protect against ultraviolet rays from the sun. Crustaceans (like krill and shrimp) that feed on algae store the pigment in their shells. In turn, fish (like wild salmon and trout) that eat the crustaceans (or the algae) store it in their skin and tissue. Some birds, like flamingoes, have pink feathers due to the astaxanthin in their diets. Humans get it primarily from seafood.
Astaxanthin's main commercial use has been as a feed ingredient in aquaculture to make farmed salmon pink. It's also "generally recognized as safe" by the FDA as a colorant for use in a number of foods.
Where's the astaxanthin proof?
Research, mostly in animals and test tubes, has shown that astaxanthin acts as an antioxidant and helps reduce inflammation. A handful of studies in people have found that the supplements lower C-reactive protein (a marker for inflammation in the body) and blood pressure and improve aspects of the immune system. In a company-sponsored study in Atherosclerosis in 2010, astaxanthin increased HDL ("good") cholesterol and decreased triglycerides. In a more recent study in the British Journal of Nutrition, it reduced substances in red blood cells that, at least in theory, might be linked to dementia.
But the few human trials have been small and short term, with mixed results. Supplement marketers cite numerous studies on websites that sound promising but were not well designed and/or have not been published in peer-reviewed journals.
Moreover, the Natural Standard, which evaluates complementary and alternative medicine, gives astaxanthin a C rating--unclear or conflicting evidence--for its use for high cholesterol, male infertility, muscle strength, musculoskeletal injuries, carpal tunnel, and rheumatoid arthritis. There's limited or no research at all to support its use for eye problems, asthma, dementia, exercise capacity, sunburn protection, or other conditions for which it's promoted.
More red flags
We don't recommend astaxanthin. The supplements seem to be safe, but that's what we used to think about beta carotene pills, which, at high doses, were eventually shown to increase lung cancer risk in smokers. Not only is the science behind astaxanthin supplements less than solid, but interactions with some drugs, as well as side effects (including yellow- or orange-colored skin, orange or red feces, unwanted hair growth, lowered calcium levels, decreased libido, and male breast enlargement) are possible. You should be especially cautious about taking astaxanthin if you're being treated for hypertension or have asthma, parathyroid disorders, or osteoporosis.

-Berkeley Wellness Newsletter, University Of California