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What To Expect & Dosage Tips For Supplementing With Astaxanthin

Kirsten Nunez, M.S.
February 24, 2022
Kirsten Nunez, M.S.
Contributing writer
By Kirsten Nunez, M.S.
Contributing writer
Kirsten Nunez is a health and lifestyle journalist based in Beacon, New York. She has a Master of Science in Nutrition from Texas Woman's University and Bachelor of Science in Dietetics from SUNY Oneonta.

When it comes to antioxidant supplements, nutrients like vitamin C and vitamin E often steal the show. And for good reason, too—these antioxidants are crucial for skin health, immune function, and more.* However, it might be time to add another antioxidant to the list.

Consider astaxanthin (asta-ZAN-thin), an antioxidant that's gaining popularity in the world of wellness. But before taking the supplement, it's a good idea to understand the possible side effects, along with how much to take. Let's explore what you can expect from taking astaxanthin, below.

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What is astaxanthin?

In case you missed it above, astaxanthin is a powerful antioxidant. Specifically, it's a type of carotenoid1, or a natural pigment that gives foods like pumpkin and carrots their red-orange-yellow hue. Astaxanthin is also responsible for the iconic reddish-orange color of marine animals like salmon and shrimp2, who receive the phytonutrient from the algae they consume.

Other noteworthy carotenoids include beta-carotene (a specific form of vitamin A), lycopene, lutein, and zeaxanthin. And while carotenoids, in general, are associated with brain, eye, and cardiovascular health, astaxanthin is particularly impressive.* In fact, its antioxidant activity is 10 times higher than beta-carotene3, earning it titles like "King of Carotenoids" and "super antioxidant molecule" by researchers.* 

And get this: Astaxanthin is estimated to be 6,000 and 100 times stronger than vitamins C and E, respectively.* (We don't want to forget, however, that vitamin C and E are also vital parts of the collagen synthesis process—so even if they have less antioxidant potency, they're still very important for skin function, not to mention other essential roles in our body.*) After all, it's not a competition. The more diverse our nutrient and phytonutrient intake and array are, the better.

But what makes astaxanthin so special, exactly? According to a 2018 comprehensive review article, it comes down to its molecular structure. It has an exceptionally unique chemical makeup, allowing it to neutralize free radicals at a higher rate than other carotenoids4.* Astaxanthin can also enter the layers of cell membranes, ultimately helping to protect the cell from oxidative stress.*

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Side effects & cautions.

Astaxanthin is a safe antioxidant. Case in point: According to a 2019 scientific article, it's been used as a supplement for more than two decades, and there are no documented negative side effects to date.

Still, there are a few things to keep in mind. Consider the following potential side effects:

  • Yellow-orange skin color. When consumed in excess, carotenoids can temporarily cause lighter skin tones to develop a yellow-orange color. Very rarely, this happens due to an extremely high and chronic intake of beta-carotene5 (i.e., not typical levels from diet or supplements), but it's possible that astaxanthin could theoretically have a similar pigment effect, but that has not been documented broadly in the scientific literature.
  • Red poop. At concentrated doses consumed over time, it's possible for astaxanthin to cause red poop, according to Casey Kelley, M.D., AboIM, integrative and functional practitioner and founder of Case Integrative Health. Understandably, this can be alarming, but try not to freak out; it's totally normal for your poop to change color after eating pigmented nutrients. (However, if you stop taking astaxanthin and your symptoms persist, talk to your doctor, says Kelley.)
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Considering these side effects were noted when taken in excess, let's talk dosage; the appropriate dosage for supplements is at least 3 milligrams per day, according to research. However, the strongest results have been observed at 6 milligrams a day6.  

You can also get astaxanthin naturally through salmon, but you'd need to eat a lot of it every day to get the recommended amount. One salmon filet contains about half a milligram of astaxanthin, meaning you'd have to chow down on 12 filets in order to get those 6 milligrams. Needless to say, that's more salmon than what the average would (or could!) eat, so a supplement is way more practical. It's also a more economical approach, and you receive the astaxanthin benefits minus the potential contaminants from large quantities of fish (e.g., heavy metals).

Long-term positive side effects.

Over time, astaxanthin can cause a variety of positive "side effects." These health benefits of astaxanthin span multiple areas of wellness, below:*

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It's good for skin health.

As it turns out, biotin and collagen aren't the only superstar skin supplements.* The skin benefits of astaxanthin are totally noteworthy, and it's all thanks to its potent antioxidant properties.* After all, antioxidants combat oxidative stress, a major cause behind skin concerns like skin inflammatory pathways and photoaging2.* A pair of clinical studies7 also found that astaxanthin can improve the appearance of age spots, wrinkles, and skin elasticity in both men and women.* This is due to the astaxanthin's ability to help support the collagen layer and enhance your skin's photoprotection, ultimately paving the way for a healthy skin complexion.*


It can promote heart health.

Carotenoids in general are associated with heart health, and astaxanthin is no exception.* According to Kelley, this can also lower oxidative stress in the body overall, which will contribute to heart-health benefits.* Here's how that shakes out in published science: According to a 2021 scientific review, as astaxanthin exerts antioxidant effects, it may also help promote healthy blood pressure8.* And a 2020 study found that due to its antioxidant properties, astaxanthin may support overall cardiovascular health.* 

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It can protect your brain over time.

As astaxanthin supports the heart, it may also benefit the brain.* That's because the brain relies on a constant supply of blood and oxygen from the heart9. Additionally, antioxidants like astaxanthin could protect the brain by neutralizing oxidative stress.* Research in humans is still ongoing, but the available studies so far have been promising. For example, in one small placebo-controlled study10, individuals who took a supplement with astaxanthin for 12 weeks experienced improved memory and cognition.*


It can support healthy eyes and vision.

Astaxanthin, like other carotenoids, can contribute to healthy peepers. Its antioxidant properties exert anti-inflammatory effects, which have been shown to improve natural hydration levels in the eyes11.* Astaxanthin supplements can also promote visual acuity and blood flow to our retinas, plus relieve tired eyes12 after looking at a screen for too long.* (We've all been there!)

The takeaway.

Overall, astaxanthin is a safe supplement for most people. It isn't associated with negative or long-lasting side effects. But as always, we recommend checking with your doctor before taking a supplement, astaxanthin or otherwise.

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.