The most commonly reported astaxanthin side effects are harmless pigment changes, such as a slightly orange tint to the skin or to stool. Even at high doses, no toxic effects have been observed, either in animals or humans. Other, less common astaxanthin side effects have a greater impact, and side effects such as low blood pressure and shifts in hormone levels can have serious health implications.
Astaxanthin is most commonly used as an additive to animal feed, and it adds pigment to crabs, shrimp, lobsters and salmon, giving them their familiar reddish orange color. As an animal feed supplement, astaxanthin is generally recognized as safe, according to the United States Code of Federal Regulations, and most people are able to consume astaxanthin-fed seafood without any reaction at all. In 1999, the U.S. Food and Drug Administration cleared astaxanthin as a food ingredient for human consumption.
As a dietary supplement, astaxanthin is most often used as an antioxidant to reduce cholesterol. Advocates also recommend astaxanthin to improve eye health and treat carpal tunnel syndrome, arthritis, muscle injury, gastrointestinal complaints and male infertility. It should be noted, however, that there is insufficient evidence to support any of these claims, and there is no proven health benefit to this supplement.
Common astaxanthin side effects include increased pigmentation, hair growth, shifts in hormone levels and low blood pressure. Reduced calcium levels, decreased libido and breast enlargement in men have also been observed, but these astaxanthin side effects are rarer. Allergic reactions also are possible and can be quite dangerous. Astaxanthin and astaxanthin-fed foods should be avoided by anyone with a known allergy to the substance.
Drug interactions are another serious concern. For instance, blood pressure medication might be amplified by astaxanthin and can cause blood pressure to dip dangerously low. Hormone treatments and birth control can be affected by the supplement’s effects on hormone levels. Similar cross-reactions have been observed with some antihistamines, and asthma medications might not react well to astaxanthin. Liver enzymes, which are responsible for removing a variety of drugs from the blood, also can be affected, resulting in increased levels of these drugs remaining in circulation.
Reactions also are possible with other supplements and herbal remedies. Saw palmetto, black cohosh or other medications that affect hormones might react unpredictably. Astaxanthin side effects such as low blood pressure and reduced calcium levels can be amplified by substances with similar effects. Use of other carotenoid antioxidants, such as beta carotene and lycopene, with astaxanthin will reduce absorption and is not recommended.
Astaxanthin Drug Interactions
Anybody taking astaxanthin should be aware of potential interactions with other drugs. One such interaction may occur if astaxanthin is mixed with nonsteroidal anti-inflammatory drugs — also known as NSAIDs. Some NSAIDs increase the risk of internal bleeding, and when combined with astaxanthin, the risk may increase.
The drug is also known to exacerbate the effect of many other medications. This includes antidiabetic medicines such as metformin and insulin, which can lead to lower blood glucose levels as well as lower blood pressure, both of which can be dangerous if left unchecked. Astaxanthin may also increase the impact of blood-thinning agents such as warfarin and asthma medications such as azelastine.
These drug interactions are the result of astaxanthin’s ability to alter the liver’s metabolization rate. Most medication is processed by the liver via enzymes that respond to a drug’s active ingredients. Astaxanthin may interfere with this process, however, by increasing the activity of these enzymes, which in turn may increase the effect of various medications and cause a dangerous drug interaction.
Astaxanthin Side Effects Hormones
In addition to its known drug interactions, astaxanthin can interfere with your hormones, too. The most significant example of this is its ability to inhibit testosterone’s conversion to dihydrotestosterone (DHT). This conversion is a process that naturally occurs in the body, but an abundance of astaxanthin may interfere by hindering the enzymes that trigger the conversion.
As a result, people taking astaxanthin will likely have a higher concentration of testosterone. In women, this may cause symptoms such as excessive body hair, hair loss, and acne. In men, it can cause high blood pressure, acne, and problems with the heart or liver. These symptoms vary widely from person to person, though, and depend on each individual’s unique biological makeup.
Interestingly, some men who take astaxanthin also report that they experience gynecomastia, or male breast development. This phenomenon is typically associated with an increase in estrogen or estradiol, but there is no clinical evidence suggesting that astaxanthin increases these hormones.
How Much Astaxanthin per Day
Despite its drug interactions and impact on hormones, there are many benefits that astaxanthin supplements can offer. It is known to support the function of the immune system, reduce the risk of cancer, and minimize inflammation. In order to take advantage of all these benefits, though, how much astaxanthin should you be consuming per day?
The answer depends on your wellness goals as well as your current health, but most supplements are intended to be taken at dosages ranging from 2mg to 12mg. Some studies have confirmed positive results in response to doses as small as 4mg per day — and other studies recommend doses as high as 24mg — so you should determine your dose based on advice from your doctor.
Remember that in addition to supplements, you can get a daily dose of astaxanthin by consuming foods that are naturally rich in astaxanthin. A serving of fresh salmon, for example, can contain 2mg to 3mg of astaxanthin. Other types of seafood such as shrimp and crab are similarly beneficial.