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Astaxanthin Interactions With Warfarin (and other anticoagulants)


Posted by Dr. Robert Corish

"Can I take Warfarin with Astaxanthin?"

I have been asked to clarify the question about astaxanthin’s influence on anticoagulants, namely Warfarin. This question was raised by a pharmacist. Understandably, it is the pharmacists who are the ‘Guardians’ of our pharmacopeia and rightly so should be concerned for our welfare.

Background on Astaxanthin

Before I address the question directly, I would like to provide a little background.

1. Astaxanthin has been around for millennia, it is one of 700 known carotenoids - the compounds that give our plants, fruits, and vegetables their vibrant colours. Astaxanthin's main biological functions revolve around photosynthesis and free radical scavenging,  i.e phyto-defences. 

2. Main sources of Astaxanthin are salmon, krill, shrimp, trout, and algae - an evolutionary food chain that has been consumed by humans for thousands of years.  Astaxanthin is ‘blood red’ and the red-orange colour of the salmon flesh is astaxanthin (the redder the salmon the healthier the fish), as is the orange colour of shrimp and krill.

3. Astaxanthin is an oxycarotenoid, it is a non-provitamin A carotenoid and it has the greatest free radical scavenging capacity of all the carotenoids - additionally, it never becomes a pro-oxidant and therefore never changes into a free radical.  

4. Its unique structure allows astaxanthin to span itself across the cell membranes and therefore influence three domains; the hydrophilic exterior, lipophilic central layer, and the hydrophilic cytosol – thereby extending exceptional free radical protection to the cell (this also applies to the mitochondria).

Interaction between Astaxanthin and Warfarin - Scientific Opinion

Warfarin Astaxanthin Interaction

Warfarin is a medication that is commonly used as an anticoagulant/ blood thinner, as a treatment for blood clots. Warfarin works by blocking an enzyme called vitamin K epoxide reductase that reactivates vitamin K1.

Astaxanthin does not contain Vitamin K and therefore does not compete with Warfarin to inhibit the vitamin K dependent clotting factors. 

Where the issue of astaxanthin’s interaction has arisen from, is the Natural Standards cautionary statement over astaxanthin’s ability to induce the P450 mixed oxidase system and in particular the CYP-1A enzymes. This fact is true! Astaxanthin has been shown to induce P450 and CYP-1A and other CYPs. However, in other studies, astaxanthin has also been shown NOT to induce these enzymes and therefore demonstrates that astaxanthin may have both up-regulating and down-regulating influences over cell signaling pathways. 

This was not pointed out by Natural Standard – “the authority for Integrative medicine.”

In the scenario where astaxanthin DOES induce CYP-1A, a significant dose is required.  

Research on Astaxanthin Interactions

Astaxanthin can alter CYP1A-dependent activities via two different mechanisms: induction of protein expression and inhibition of NADPH P450 reductase-dependent electron transfer

In this study, a large dose of 30mg /kg of astaxanthin failed to induce CYP-1A levels significantly, and therefore this part of the experiment was ‘benched’. The next reported dose was 100mg/Kg and this DID increase CYP-1A levels to a significant level. (Allow me to point out that this would equate to a dose of 10,000mg of astaxanthin in a 100 kg person or 2,500 capsules of AstaSupreme/day…Quite unfathomable!)

The assertion is that at these elevated levels, the CYP-1A would then increase the metabolism of Warfarin (and others) and potentially cause an alteration to the therapeutic effects of the anticoagulant.  Please recall that at 30mg/kg -  (3000mg in a 100 mg subject) that there was no significant change in the CYP-1A induction.

However, there is an important factor that is not addressed in these biochemical reactions… and that is the role of NADPH (nicotinamide adenine dinucleotide phosphate) – this important reducing agent (Coenzyme) plays a crucial role in the functionality of the mixed oxidase system and is responsible for donating an electrical charge to the CYP-1A.  This is a necessary step in order for the CYP-1A to become ‘Activated’. Without this catalytic activation of the CYP-1A, it remains indolent and unarmed. When we re-visit the studies where astaxanthin caused an increased induction of CYP-1A, it is important to note: that the astaxanthin did NOT cause a corresponding increase in NADPH and in some studies actually caused a reduction.  Therefore, despite an increase in the CYP-1A (albeit at super unrealistic doses of astaxanthin) the lack of ‘Activation’ will have no effect on the metabolism of Warfarin. This seems to be validated by the historical track record of the consumption of astaxanthin by patients who are concomitantly taking warfarin and other anticoagulants including NSAIDs - where there are no reported untoward effects or alteration in prothrombin times or INR values.


Astaxanthin does not contain Vitamin K and therefore does not compete with Warfarin to inhibit the vitamin K dependent clotting factors. 

Astaxanthin is consumed as a supplement at doses ranging from 4mg/ day all the way up to 20mg/day, (dramatically lower than the studies which show enzyme induction).There are no human clinical trials, or evidenced based reports to support that astaxanthin may interfere with bleeding profiles. 

As always, we subscribe to the credo that all patients should check with their physician before undertaking any natural supplements and this also applies to astaxanthin. Therefore, for those patients taking anticoagulants, it is advised that they should closely monitor their INR and prothrombin time whenever taking nutritional supplements. 

I hope that this response generates greater confidence in the use of astaxanthin as a nutritional supplement, it is truly a unique antioxidant which has demonstrated multiple human health benefits. It would be unfortunate to lose sight of these wonderful benefits, whilst becoming distracted by a mirage.


Advanced Immune Support with AstaNZ Natural Astaxanthin

Supreme Health Immune Support

Supreme Health Advanced Immune Support is formulated with pure, natural ingredients to provide you with outstanding support for your overall immune system and wellbeing. Using AstaNZ™ Natural Astaxanthin as a key ingredient in this formulation, This formulation aims to improve general health and wellbeing.

  • Modulating under or overactive immune system
  • Increase energy and endurance
  • Protects immune cells and DNA from oxidative stress/ injury
  • Supports cellular energy production
  • Decrease inflammatory pathways

NOTE: We do not recommend Advanced Cardiac Support if taking blood thinning medications or Warfarin therapy due to other ingredients in the product. Consult your healthcare professional before taking the product. 


Research article references

- Astaxanthin can alter CYP1A-dependent activities via two different mechanisms: Induction of protein expression and inhibition of NADPH P450 reductase-dependent electron transfer. Marumi Ohno a, Wageh S. Darwish a,c, Yoshinori Ikenaka a, Wataru Miki b, Mayumi Ishizuka aM. / Food and Chemical Toxicology 49 (2011) 1285–1291

- Astaxanthin and canthaxanthin do not induce liver or kidney xenobiotic-metabolizing enzymes in rainbow trout (Oncorhynchus mykiss Walbaum). Comp Biochem Physiol C Toxicol Pharmacol. 2002 Nov;133(3):443-51. Page GI, Davies SJ.

-  Metabolism and CYP-inducer properties of astaxanthin in man and primary human hepatocytes. Arch Toxicol. 2002 Jan;75(11-12):665-75  Kistler A, Liechti H, Pichard L, Wolz E, Oesterhelt G, Hayes A, Maurel P. Vitamins and Fine Chemicals, Human Nutrition and Health, F. Hoffmann-La Roche Ltd, Basel, Switzerland.

- Effects of provitamin a or non‐provitamin carotenoids on liver xenobiotic‐metabolizing enzymes in mice,  Nutrition and Cancer, Volume 27, Issue 3, 1997, pages 245- 249,  Pierre Astorga, Sandra Gradeletb, Joel Leclercb & Marie‐Hélène Siessb


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