Retrospective #453: Fish oil supplementation, triglycerides and platelet formation

Eighteen years ago, I began taking 4 grams of fish oil a day (plus a can of sardines for lunch!) After a few months, I lowered the fish oil to 3 grams and then to 2, which I take to this day. During this time I dramatically lowered my triglycerides from 143mg/dl (aver. of 11 tests) to 49mg/dl (aver. of 25 tests) 5 years later.

In discussing fish oil supplementation with a friend recently, the risk of high-dose fish oil “causing bleeding” came up. Googling “fish oil, bleeding” dredged 2 articles at Evidence-Based Medicine Consult (EBM Consult), a free searchable, online medical education database. The first discusses the mechanism for how Omega-3 fatty acids could increase the risk of bleeding; the second discusses the bleeding risk. Both were revelatory for me.

“As it relates to CVD, fish oil is most commonly used to treat high triglycerides. When clinicians refer to the use of ‘fish oil,’ they are generally referring to omega-3 fatty acid, a polyunsaturated fatty acid (PUFA)). This specific omega-3 fatty acid includes both DHA and EPA compounds. For the most part, neither DHA nor EPA causes any major side effects or clinically relevant drug interactions, but they are known to influence platelet formation.”

“As such, some clinicians perceive that this can put the patient at greater risk of bleeding, especially during surgical procedures or while on medications that are known to affect coagulation and platelet aggregation.” So, if you’re going to have surgery, or you have CVD and take Coumadin (Warfarin) or another blood thinner, your doctor might advise you against taking more than 1 gram of fish oil, or to stop taking it before surgery. 

In the mechanism article, what caught my attention was not about bleeding but about platelet aggregation. It turns out “omega-3 fatty acids compete with [the omega-6] arachidonic acid (AA) for incorporation into the platelet cell membrane, thereby increasing the ratio of omega-3 fatty acids:AA.” In other words, they inhibit platelet aggregation.

I’ve been writing for years that the Standard American Diet (SAD) is very high in omega-6s, with a ratio of omega-6 to omega-3 of at least 20 to 1 (20:1) vs. the 2:1 or 1:1 ideal. And that supplementation with fish oil alone is not enough to reverse that ratio. We must also lower the Omega 6’s by avoiding fried foods and “vegetable” (seed) oils, baked goods and some nuts. It seems I may have been too successful at taking my own advice! For the last 11 years my Complete Blood Count (CBCs) have consistently been slightly out-of-range on platelet (and related) counts.

The EBM Consult site is intended to educate doctors and other medical professionals, but the gist is still comprehensible to me. Too much DHA and EPA from fish oil supplementation has anti-platelet effects that 1) interfere with intracellular pathways, 2) increase prostaglandin formation and 3) decrease the production of platelet activating factors. Eureka, my overcorrected ratio may be the cause of my out-of-range CBC counts!  (NB: the cause, my doctor thinks, may instead be the radiation therapy I had many years ago that could have killed some stem cells that create new red blood cells.)

The other EBM Consult article, concerning the bleeding risk, concludes with a simple (paraphrased) message:

●        The AHA recommends 1 gram of fish oil per day for patients with coronary artery disease and 2 to 4 grams per day for patients with high triglycerides. They also advise those who take more than 3 grams per day do so under the care of a physician “since high doses could cause excessive bleeding in some patients.”

●        In an analysis by the National Lipid Association, of 4,357 patients who took 1.6 to 21 grams [not a typo!] of DHA/EPA per day in combination with some type of prescription anti-platelet or anticoagulant, only 1 patient developed blood in their stool and 1 other experienced a gastrointestinal bleed.

●        Clinical trial evidence to date does not support an increased risk for bleeding in patients taking fish oil supplements…even when combined with other medications known to increase the risk of bleeding [!].

If you take more than 3 grams of fish oil a day, or have out-of-range Complete Blood Count (CBC) labs, or are concerned about bleeding, you should read these two EBM Consult articles. Otherwise, I would conclude that taking fish oil supplementation is a good way to treat high triglycerides. It sure worked with me, to a fare-thee-well.