Does fish oil cause blood thinning?

27. October 2009 William Davis (20)
Omega-3 fatty acids from fish oil have the capacity to "thin the blood." In reality, omega-3s exert a mild platelet-blocking effect (platelet activation and "clumping" are part of clot formation), while also inhibiting arachidonic acid formation and thromboxane.

But can fish oil cause excessive bleeding?

This question comes up frequently in the office, particularly when my colleagues see the doses of fish oil we use for cardiovascular protection. "Why so much fish oil? That's too much blood thinning!"

The most recent addition to the conversation comes from a Philadelphia experience reported in the American Journal of Cardiology:

Comparison of bleeding complications with omega-3 fatty acids + aspirin + clopidogrel--versus--aspirin + clopidogrel in patients with cardiovascular disease.(Watson et al; Am J Cardiol 2009 Oct 15;104(8):1052-4).

All 364 subjects in the study took aspirin and Plavix (a platelet-inhibiting drug), mostly for coronary disease. Mean dose aspirin = 161 mg/day; mean dose Plavix = 75 mg/day. 182 of the subjects were also taking fish oil, mean dose 3000 mg with unspecified omega-3 content.

During nearly 3 years of observation, there was no excess of bleeding events in the group taking fish oil. (In fact, the group not taking fish oil had more bleeding events, though the difference fell short of achieving statistical significance.) Thus, 3000 mg per day of fish oil appeared to exert no observable increase in risk for bleeding. This is consistent with several other studies, including that including Coumadin (warfarin), with no increased bleeding risk when fish oil is added.

Rather than causing blood thinning, I prefer to think that omega-3 fatty acids from fish oil restore protection from abnormal clotting. Taking omega-3 fatty acids from fish oil simply restores a normal level of omega-3 fatty acids in the blood sufficient to strike a healthy balance between blood "thinning" and healthy blood clotting.
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Comments (20) -

  • Marc

    10/26/2009 9:46:32 PM |

    Long time reader, first comment.
    Thank you for so freely sharing all the information.

    Marc

  • Daniel

    10/26/2009 11:02:46 PM |

    Thank you for this!  I have had this question for a long time given the number of things I take that "thin the blood."

  • Kevin

    10/26/2009 11:44:45 PM |

    As a veterinarian I've dispensed fish oil capsules for several years.  Some owners give so many that the dogs smell 'fishy' when seen for routine care.  The owner doesn't smell it since they're with the dog a lot.  The coats are gorgeous, something that doesn't often happen in Wyoming at 7000ft altitude.

  • Dr. William Davis

    10/26/2009 11:47:45 PM |

    Hi, Kevin--

    My two Boston terriers jump for their fish oil capsules, two every day!

    I'm glad to hear from a veterinarian that the coat sheen is indeed from the fish oil.

  • Rich

    10/27/2009 1:27:09 AM |

    Due to an afib episode a couple of years ago, I was taking 20 mg of warfarin per day, plus around 5000 mg of EPA+DHA, and never had bleeding issues.  

    My INR was always a stable 2.0.

    As I've not had an afib reoccurrence, I've replaced the 20mg coumadin with 325mg aspirin daily, and still take around 5000 mg EPA+DHA.  No bleeding issues with that combo either.

  • Catherine

    10/27/2009 3:55:32 AM |

    Glad this topic came up.
    Over the last 5 years, I've had to periodically eliminate my fish oil intake as I would start to bruise badly. My internist said she has seen this occasionally with fish oil and called it "capillary fragility." I bruise easily anyway, but it would really get bad with fish oil. So there must be some quality in fish oil that influences this.

    Then about 6 months ago I started a strong supplement change to help with my low bone density--already taking magnesium and calcium but added:
    Boron, K2, silica,pomegrantate juice, and BIG increase in vitamin D.
    I also increased omegas to 3,000 a day which I was not able to tolerate before.

    It has been over 4 months since I have had ANY bruise---which is just unheard of for me. I usually have 3-4 different bruises on arms/legs. So something in these supplements  strengthened my capillaries I guess, and I can now take high fish oil doses!
    Anyone else had a bruising problem with fish oil?

  • Dr. William Davis

    10/27/2009 11:04:59 AM |

    Hi, Catherine--

    Fascinating observation!

    I'll bet it has something to do with the vitamin D, more than anything else. Vitamin D seems to strengthen structural tissues in bones, muscle, heart valves, and perhaps capillaries and other small blood vessels.

  • trix

    10/27/2009 11:59:37 AM |

    Several years ago I bruised easily for a while and attributed it to taking garlic supplements daily.  I started taking Vit C and the bruising stopped.  I don't think it had to do with fish oil (in my case); I don't think I was taking fish oil at the time.

  • Daniel

    10/27/2009 9:37:33 PM |

    I too achieve rapid blood thinning when taking 2400mg of EPA/DHA per day. That's only 4 pharmaceutical grade capsules. Even after my vitamin d levels were normalized I still got bruising.

    I now take Vitamin K2 (MK-7 natto extract) twice a week and it's allowed me to bump my EPA/DHA up to 3600mg with no ill effects or bruising.

    It was either supplement or eat a lot of aged cheese, they both seemed to do the trick in my particular case.

  • Healthy Oil Guy

    10/27/2009 9:53:51 PM |

    Thank you for sharing this study with us.  It helps clarify whether there is a risk for blood thinning from taking fish oils.  This information may help individuals who are taking blood thinning medications and considering adding fish oils to their daily diet.

  • Dave

    10/28/2009 2:22:01 AM |

    Catherine,

    Without a doubt, your cessation of bruising was due to vitamin k2. I routinely take nattokinase, large doses of fish oil, curcumin, and other blood thinning agents, and if I don't take vitamin K2, I will begin bruising. (I also take high doses of Vitamin D). When I take K2, I have absolutely no bruising.

    Vitamin K2 has many clinical trials showing that it helps endothelium  integrity and elasticity.

    Also, grapeseed extract and pine bark extract (specifically oligomeric proanthcyanins) has the same beneficial effect.

  • Catherine

    10/28/2009 4:41:41 PM |

    Daniel,

    That's really interesting! There is a lot of research on K2's effect on strengthening weak bones. Bone fractures go down considerably when high doses of K2 are used (Japan is using K2 as osteoporosis treatment) BUT studies show it needs to be in conjunction with adequate calcium and Vitamin D---they work synergistically for bone strength.  So it makes sense that K2 and D could do the same with strengthening fragile capillaries. I am also taking the M7 natto form.

  • Catherine

    10/29/2009 12:01:36 AM |

    Dave,

    Thanks for sharing your experience with this, you've really confirmed it now for me.  I can't believe I have suffered with this for most of my life with no answers (tried high dose Vit C, grape seed, etc) and now within months on K2, there's no bruising and I can tolerate fish oil. Hope my bones are responding this well!
    This blog is so helpful....

  • Mina

    10/29/2009 12:21:31 PM |

    Thanks for posting this. The question recently came up in our office. I like your assertion that omega-3s restore the blood to normal and remove abnormal clotting. And to comment on a post above, our dog has a beautifully shiny coat and takes 2 pure EPA capsules each day!

  • Term papers

    1/26/2010 3:40:08 PM |

    I have enjoyed reading That During nearly 3 years of observation, there was no excess of bleeding events in the group taking fish oil. (In fact, the group not taking fish oil had more bleeding events, though the difference fell short of achieving statistical significance.

  • Viagra Online

    8/23/2010 6:41:39 PM |

    I've been drinking fish oil for many year and I don't have any chance in my body people use to said me that but I think it is just a rumor.

  • buy jeans

    11/3/2010 10:19:55 PM |

    I'm also especially gratified that a woman now holds our record. I'm uncertain why, but the ladies have been shy and the men remain the dominant and vocal participants in our program. Speak up, ladies!

  • moseley2010

    12/7/2010 2:37:16 AM |

    I haven't heard of this problem
    fish oil supplements. But now we know what to tell them when this sort of concern comes up. Fish oil or Omega-3 is really beneficial to health. It's just important that it comes from clean waters.

  • Jack

    3/12/2013 7:03:38 PM |

    What is an appropriate dose of fish oil for someone taking coumadin?

  • dorange

    6/15/2014 3:53:03 PM |

    Dr. Davis, when  person is taking Tamoxifen...
    (1) is it safe to take vitamin k2 or K1?
    (2) will fish oil have a role in preventing blood clots?

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The Vitamin D Newsletter
June 2008



This month we feature a remarkable series of letters from a mother of an autistic son who treated her child with vitamin D. It is the first case report in the medical literature suggesting vitamin D has a treatment effect in autism.

First, a brief case report and then a more detailed exchange of emails between the mother and me.

Case Report:

John is a seven-year old boy living in the northeastern U.S. with a long-standing diagnosis of autism. Symptoms include temper tantrums, repetitive self-stimulatory behavior, impaired language, mood swings, fear of being alone, toileting problems, dysbacteriosis, and impaired muscle strength. John spends a lot of time outdoors starting in the spring and his mother noticed a distinct seasonal variation in his symptoms in that he improved in the summer and regressed in the winter. A 25-hydroxy-vitamin D in April of 2008 was 25 ng/ml and obtained after John had begun to play outside. Due to the seasonality of John's symptoms the mother consulted me. I advised the mother to stop all products containing vitamin A including cod liver oil and begin John on 5,000 IU of vitamin D3 per day for two weeks followed by 2,000 IU per day in the form of powdered vitamin D dissolved in juice. Within a week of starting the vitamin D, John's language began to return and he was no longer as fearful of being alone. At the end of two weeks his language showed further improvement, he began to toilet himself, counted to 10 and knew the spelling of his name. After three weeks language continued to improve and some improvements were noted in his dysbacteriosis. After four weeks of vitamin D treatment, the mother noted improvements in muscle strength as well as continued improvements in language. A repeat 25-hydroxy-vitamin D is pending while John continues taking 2,000 IU of vitamin D per day.

Before you read the series of emails between the mother and me, I'd like to caution that this is only a case report of sorts and does not prove a treatment effect. Spontaneous remissions, while rare in autism, have been reported, thus the supplemental vitamin D may have had nothing to do with his improvement. If the response is due to vitamin D, there is no assurance it will prove lasting. I think it unlikely that older autistic children or individuals with severe autism will show these sorts of apparent improvements. Furthermore, autism is a multifactorial disease with strong genetic roots and it is highly unlikely that treatment of vitamin D deficiency in all autistic children will result in similar improvements. Finally, I did not examine this child, and I am relying on the child's mother to report both his condition and his apparent response to vitamin D treatment. However, the mother agreed to speak with the press about her son and allow for independent confirmation of the apparent treatment response.

Below are the emails, edited for brevity, clarity, and confidentiality.



Dear Dr. Cannell:

I am writing because I believe my son John is strongly affected by vitamin D and I need some advice. John is seven and autistic and weighs 50 pounds. We live in the northeastern part of the United States . He starts spending lots of time outside in May and continues until September. Every year, like clockwork, he has the same patterns of behavior and ability. After about six weeks of sun exposure, every July, he begins feeling much better, seems to be comfortable in his skin, does not have as much self-stimulatory behavior, can eat a variety of foods and has language. This past summer, he was using 14-word sentences. By the end of November, he can't even ask you for a cup of juice. He becomes more exclusive, has emotional highs and lows, has tantrums and is easily frustrated.

His 25(OH)D level on April 15th was 25 ng/ml but he had already been going out in the sun so his level must have been lower in the winter. I have had his genetics tested (Nutrigenomic) and he has mutations in his vitamin D receptors:

VDR Bsm/Taq ++
VDR Fok --
VDR Taq ++

My first question, does it sound like the changes in his behaviors and abilities could be caused by lack of vitamin D? Could you elaborate on the time it would take to get adequate amounts of vitamin D to start seeing positive results? For example, even if he starts going out in the sun in May, it's usually not until July that I see positive changes. Then would it take a month or two to go back to being deficient, thus explaining his 'regression' by the time November comes around. Secondly, I am looking at different forms of vitamin D therapy: a vitamin D lamp, vitamin D3 cream, or oral vitamin D. Can you tell me what might be the best form during the winter months?

Thank you very much for your time and attention.

Jane, Boston MA



Dear Jane:

Yes, it is possible your son's autism is related to vitamin D. Such seasonality has been reported before in autism, both in an individual and in autistic children at a summer camp. Although suggestive, such seasonality does not prove a vitamin D connection. Sun exposure, unless it is full body, takes several months to get vitamin D levels up. If sunblock or clothes are worn sun exposure will not get 25(OH)D levels much above 30 ng/ml. As far as the "mutations" you list, they are actually vitamin D receptor (VDR) polymorphisms and not referred to as mutations although all such changes occurred through mutations at some time in the past. VDR polymorphisms are simply the different structures of the vitamin D receptor that different people have and they are widely distributed. A pilot study of actual VDR receptor mutations did not detect VDR mutations in 24 autistic individuals but they did not assess for VDR polymorphisms. However, a highly significant association exists between one VDR polymorphism and larger head size. Mean head circumference is larger in autism.

Yan J, et al. Vitamin D receptor variants in 192 patients with schizophrenia and other psychiatric diseases. Neurosci Lett 2005;380(1-2):37-41.

Handoko HY, et al. Polymorphisms in the vitamin D receptor and their associations with risk of schizophrenia and selected anthropometric measures. Am J Hum Biol 2006;18(3):415-7.

Lainhart JE, et al. Head circumference and height in autism: a study by the Collaborative Program of Excellence in Autism. Am J Med Genet A 2006;140(21):2257-74.

Lainhart JE, et al. Macrocephaly in children and adults with autism. J Am Acad Child Adolesc Psychiatry 1997;36(2):282-90.

I emailed the world's foremost expert on VDR polymorphisms asking him about your son's polymorphisms and his reply, quite technical, is below.



Dear John:

I apologize for the delay in getting back to you regarding VDR polymorphisms. Initial studies by Eisman and coworkers many years ago suggested that several of the polymorphs identified above in the VDR gene (Bsm/Tag) correlated strongly with osteoporosis. Despite the hoopla, subsequent analyses by many different investigators did not really confirm these results, i.e. only a very modest (3%) correlation. This spawned multiple studies searching for correlations between VDR polymorph's and cancer, autoimmune disease and so forth. It is fair to say from all of these studies that the correlation is at best weak, and in most cases non-existent. Part of this may be due to the fact that the Bsm and Taq polymorphs are located in VDR gene introns and as a first approximation cannot affect the VDR protein's function. This is not an absolute statement, however, as our work is now showing that regulatory regions that control the VDR's expression are located within introns as well as upstream. Therefore the possibility exists that these polymorphs could affect expression, although we have not found these regions to contain enhancers yet. This is clearly where gene and disease studies are going. The only polymorph that could affect function is the Fok1 site, which we identified many years ago following our initial cloning and structural analysis of the human VDR gene. The presence of this site leads to the expression of a shorter VDR protein (424 aa) that is purported to have a slight increase in transcriptional activity (10%?) vs the large protein (427 aa). The above analysis suggests that this polymorph is absent, leading to production of the larger perhaps less active protein. On a single patient basis, it is really difficult to conclude anything regarding this finding. Indeed, despite large numbers of patients, the VDR polymorph have not really revealed any significant insight. Given the summer correlations, it is probably more likely that the individual is low in vitamin D3 in winter.

Sincerely,

Professor John Doe




Thus, one of your son's polymorphisms may have less functionality but that should be easily overcome by higher vitamin D levels. The first thing to do is stop all vitamin A, multivitamins containing vitamin A, or cod liver oil and start vitamin D. As you will see below, vitamin A antagonizes the action of vitamin D and he should have plenty of vitamin A if he eats colorful vegetables, colorful fruit, eggs and fortified oatmeal. As far as vitamin D, I think the easiest way to give vitamin D is powdered capsules, not a cream. You can open the capsule and put the powder in about anything, such as juice. To buy the capsules, go toBio Tech Pharmacal and buy both a bottle of the 5,000 and the 1,000 IU capsules. He should take one 5,000 IU capsule a day for two weeks then take 2,000 IU per day. After a month, go to the doctor and have another 25-hydroxy-vitamin D blood test. Do not let your doctor order a 1,25-dihydroxy-vitamin D as it will give you and your doctor false information about your son's vitamin D status. The other option is buying a Sperti vitamin D light. Daily use of the light on both sides of his trunk will raise levels fairly quickly but he should still have a 25(OH)D blood test every month to assure his levels rise to the mid level of normal ranges, about 70 ng/ml. Vitamin D is very safe. Your son would have to take more than 10,000 IU a day for more than a year to have any risk of toxicity. If he improves and his level is 50 ng/ml, the next question is would he improve even more if his level was 70 ng/ml? Some lifeguards have levels of 80-100 ng/ml; normal ranges in the labs in the USA are 30 -100 ng/ml (ideal ranges are 50 -100 ng/ml.) If you have any more questions, let me know. I certainly want to know how he is doing.

Sincerely,

John Cannell



Dear Dr. Cannell:

It has been one week on 5,000 IUs of vitamin D3 daily and already we're getting some language back! We haven't had original language since probably around the end of November. The only language we have had in the past five months has been verbal scripting. Today John has already told me "turn off the TV" and "clean up the water". This is all very exciting. Will it last? I will continue to keep you updated on progress and change in behavior. One more thing, all winter long he was afraid to be by himself anywhere. Now he is starting to be able to be in another room or outside by himself.

Thanks so much,

Jane



Dear Jane:

I can't tell you how happy I am for you. I suspect John will continue to improve. Do you have any parent rating scales or does his treating pediatrician have any objective rating scales? If you have before and after rating scales or his treating doctor does then it becomes important to track his progress on an objective measure. Jane, if you are a member of any autism discussion groups, you should post about this, including doses used. If your son's case is typical, then hundreds of thousands of autistic children may be helped with vitamin D.

John Cannell



Dear Dr. Cannell:

It has been two weeks on 5,000 IU per day and I want to inform you that we are having continued success with language. Continued in the sense that it is consistent, it wasn't just a one day fluke. In addition, he is taking himself to the bathroom; this is another thing that goes away in winter months. I usually have to catch him holding it in and then suggest he go, but now he is going completely by himself. In therapy last week, he started drawing again. He drew a bee and then ran around the room buzzing. His toileting is consistent with his therapists, not just mommy. Last night, I asked him to count to 10 for me and he did - quite enthusiastically. Then I said what does J-O-H-N spell? It took him a bit but then he said "John."

Unfortunately, the last scale taken was when he was 3 when he had his first developmental evaluation. But we do track behavior and language on a weekly basis. The forms we fill out give a good indication as to how he is doing.

I belong to a parent forum. It was created by a doctor named Amy Yasko. She's a PhD, a researcher, not a medical doctor. It was through her that I got John's genetics tested. She advocates vitamin D as being very crucial. I will post something on her forum for the parents there. However, if the parents on the forum are following her recommendations, they should be taking it already - 2000 IUs in winter and 1000 IUs in summer is her recommendation. I will post something on the forum to really emphasize how important vitamin D is.

Jane



Dear Jane:

I'm glad the improvements are continuing. I see Dr. Yasko recommends 10,000 IU of vitamin A/day as well as cod liver oil. I strongly disagree. Make sure your son is taking neither vitamin A nor cod liver oil. Rather, make sure he eats colored fruits and vegetables as well as fortified oatmeal. Vitamin A interferes with vitamin D's function, especially at the doses Dr. Yasko recommends.

Vitamin A antagonizes the action of vitamin D. In humans, even the vitamin A in a single serving of liver impairs vitamin D’s rapid intestinal calcium response. Furthermore, the consumption of preformed retinols, even in amounts consumed by many Americans in both multivitamins and cod liver oil appears to be causing low-grade, but widespread, bone toxicity, perhaps through its antagonism of vitamin D. In a recent dietary intake study, Kyungwon et al found high retinol intake completely thwarted vitamin D’s otherwise protective effect on distal colorectal adenoma and they found a clear relationship between vitamin D and vitamin A intakes as the women in the highest quintile of vitamin D intake also ingested almost 10,000 IU of retinols/day. As early as 1933, Hess et al warned about vitamin A consumption, concluding, “as to a requirement of thousands of units of vitamin A daily, the unquestionable answer is that this constitutes therapeutic absurdity, which, happily, will prove to be only a passing fad.”

Rohde CM, Deluca HF. All-trans retinoic acid antagonizes the action of calciferol and its active metabolite, 1,25-dihydroxycholecalciferol, in rats. J Nutr. 2005;135(7):1647-1652.

Johansson S, Melhus H. Vitamin A antagonizes calcium response to vitamin D in man. J Bone Miner Res. 2001;16(10):1899-1905.

Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr. 2006;83(2):191-201.

Oh K, Willett WC, Wu K, Fuchs CS, Giovannucci EL. Calcium and vitamin D intakes in relation to risk of distal colorectal adenoma in women. Am J Epidemiol. 2007;165(10):1178-1186.

Hess AF, Lewis JM, Barenberg LH. Does our dietary require vitamin A supplement? JAMA. 1933;101:657-663.

Unfortunately, Hess’s prophecy of a passing fad proved premature and many Americans continue to consume “absurd” and dang