Fish oil, containing omega-3’s, is one of the most commonly used supplements worldwide. Is fish oil good for the heart? Should we all being taking one? It’s thought to decrease inflammation, decrease the risk of blood clots, improve brain health, and decrease the risk of heart disease. Let’s look at the evidence.

What are omega-3’s?

Omega-3’s are essential polyunsaturated fatty acids, meaning they are fats that our body doesn’t produce and so we must consume them. Omega-3 fatty acids play an important role in brain function, inflammation, and normal growth and development.

There are three types of omega-3s, long-chain fatty acids DHA and EPA, and short-chain fatty acid ALA. Good sources of DHA and EPA can be found it fatty fish like salmon and sardines, while good sources of ALA can be found in many nuts and seeds (flax seeds, chia seeds, pumpkin seeds, and walnuts). The body can convert some amount of ALA to DHA & EPA, but typically not very much. There is some limited evidence that vegan and vegetarians may be more efficient in doing so.

Individuals deficient in omega-3 fatty acids may be at increased risk of cardiovascular disease, some cancers, and other chronic conditions. Given this, you may be thinking that supplementation should be a no brainer. We used to think that for some time, but it’s just not that simple.

Is fish oil good for the heart? Does it prevent heart disease?

The science has been quite mixed. Until recently, we had several large trials and meta-analyses with both low level, supplement dosing (1-2 grams of EPA/DHA) and high dosing (4 grams) with very inconsistent results. Most of the trials demonstrating promise were slightly older trials prior to the use of more modern cardiovascular medications. However, a recent meta-analysis of 40 clinical trials found that supplementation with fish oil reduced risk of heart attacks and fatal heart disease, with benefits increasing with higher doses. 

We got a major update recently with two trials presented at the American Heart Association 2020 demonstrating no heart health benefit. One trial found no benefit of 2 grams DHA/EPA a day to prevent additional heart attacks in elderly patients, and the other trial was stopped early due to a lack of benefit of high dose 4 grams DHA/EPA in individuals at high risk of heart disease. Neither trial demonstrated increased risk of bleeding, but there was a concerning trend toward increased risk of atrial fibrillation in the omega-3 supplementation group. Blood levels of DHA and EPA were measured in both groups, and compliance was found to be good.

Is there any situation in which taking fish oil is recommended?

Yes. A trial in patients with established heart disease who also had high triglycerides and were given a high dose (4 grams) of EPA only found a significantly reduced risk of heart events. A follow up trial (in a small number of patients) also found improvement in blockages in the artery. In these specific patients, a prescription strength EPA only pill (Vascepa) should be considered.

We also know that fish oil is effective at lowering triglycerides in individuals who are unable to lower them with diet alone.

Does the omega 3/6 ratio matter?

Possibly. The Standard American diet is typically quite high in omega-6, and lower in omega-3’s.

Some research indicates that many Americans are consuming 20 times the amount of omega-6 compared to omega-3. A large consumption of omega-6 is linked to increased risk of obesity, autoimmune disease, inflammation, and heart disease.

One consideration is to correct this ratio by instead decreasing the amount of omega-6 consumed, rather than focusing on increasing omega-3’s. Omega-6 is found commonly in many seed oils (canola, safflower, sunflower, peanut, and sesame), margarine,  fried food, and packaged/processed food. Algae or avocado oil can be used in place of these oils for high heat cooking, and olive oil for medium to low heat and dressings. While we don’t really have much evidence this is effective, generally decreasing consumption of processed and packaged foods is very good for heart health anyway.

I still want to take fish oil supplements for heart disease. What should I take?

If you choose to take fish oil supplements, be aware that many of the commonly found over the counter fish oil supplements actually contain a large percentage of other oils. In one study of leading fish oils supplements, only 30% was EPA/DHA, while the rest were saturated fats and other fats. Gross.

As with all supplements, if are going to take them, you want to make sure that they have what they are supposed to have in them and don’t have what they aren’t. You can look for a USP verified symbol or other independent laboratory verification for quality and purity.

It’s also worth noting that several trials have found a trend toward increased rates of atrial fibrillation, and in some cases bleeding, in the high dose omega-3 group. Before taking any supplement, it’s a good idea to discuss the risks & benefits with your doctor.

How do I get my omega-3’s in a plant based diet?

Most plant based sources only have ALA, which the body must convert to DHA/EPA. Good sources of ALA include flax seeds, chia seeds, hemp seeds, pumpkin seeds, Brazil nuts, and walnuts. You can also get DHA/EPA from the same place the fish get it from - the algae.

Algae oil supplements are increasingly available - however, as with the caution above regarding fish oil supplements, do be sure of quality prior to purchasing.