In a rush to justify our ideological beliefs, it is easy for any of us to make rational arguments to support our beliefs. Our confirmation bias is active in religion, politics, and even in our diet. We find some evidence that supports a belief and grab onto it. Then we find more evidence that confirms our initial choice. And to keep our beliefs intact we tend to find evidence that supports our initial choice and reject evidence against it. Social media algorithms reinforce our beliefs until we live in an echo chamber of our own beliefs. In this article I will look at 5 scientific studies of fish oil that people have pointed at to claim (again) that fish oil is useless. However, when examined carefully, beyond the article summary, these studies actually reveal benefits that could bring you much happiness, like not dying from a heart attack.
OMEMI Study: More Fish Oil to Norwegians Is Useless
Kalstad et al published the OMEMI study in 2021 in the American Heart Association’s journal Circulation. The main conclusion from the 1,027 person study that tested 1.59 g EPA + DHA a day was that these elderly people who had a previous heart attack didn’t receive any benefit from taking fish oil to prevent future cardiovascular events. So, the headline says, “High-dose fish oil didn’t work.”
Now, here is the rest of the story. Context is critical here. The study was conducted in Norway, where I gather fish eating is rather common. So is taking cod liver oil. After all, Norway is the birthplace of the practice of taking cod liver oil and the heart of the fish oil industry. And about 200 people were taking cod liver oil, up to a teaspoon a day, in this study. As I mentioned in a previous blog, the blood levels of EPA and DHA are what are important, not how much you take. But there was no mention of the Omega 3 Index in this article, but it explains everything.
High Omega 3 Index at Beginning, No Further Benefit
At the beginning of the trial the Omega 3 Index was 8.0% and 7.75% in the placebo and omega-3 groups, respectively. That is right in the protected range, where omega 3 fats are known to give you great benefits. And after 2 years in the trial it was up to 11.7% in the treatment group, which is just higher in the treatment range.
So, if you are already protected, do you expect more protection from a little bit more fish oil? Not really. The people who get massive value from fish oil are those who start with a Omega 3 Index less than 4%. Get them up to 8-11% and you will get great results.
What do you learn from this study? In Norway, people eating a lot of fish and those taking cod liver oil already didn’t get further benefit from adding a bit more fish oil to their diet. This study was not proof that fish oil didn’t work at all.
STRENGTH Study: Conflict of Interest?
The STRENGTH randomized controlled trial was published by Nichols and coworkers in JAMA in 2020. Now, I have noticed, and maybe you have too, that JAMA is no friend of beneficial outcomes from anything other than drugs. Almost every study they publish on supplements is a negative outcome, while nutrition journals are FULL of positive outcomes from nutrients and supplements. JAMA provides further confirmation bias for doctors who rely on the AMA for their education.
Anyways, this study reported no benefit from taking a high dose (4 grams per day) of a pharmaceutical form of fish oil in those people at high risk of cardiovascular disease. Again, the headline, “Fish oil is useless.”
The Omega 3 Index here was 5.61% and 5.60% at the baseline for the placebo and intervention group. So, it was intermediate. Not dangerously low, but not really protective either. The intervention group’s average Omega 3 Index was 9.41% at the 12-month mark of the study, mostly from an increase in EPA. So, there should be a good result here, as the Omega 3 Index increased into the middle of the protective range.
Honestly, this study result is a bit of a mystery. It is the only one of the 5 studies that I cannot clearly explain. There are some clues, but not a clear answer.
Why No Fish Oil Benefit?
First, I’ve never seen such a long conflict-of-interest statement on an article before. Of the 22 authors on the article, 17 of them had declared connections with pharmaceutical companies. After all, the study “drug” was made by Astra Zeneca. So, that kind of makes sense. And it was their formula, but still. Maybe it wasn’t in the best interest of the company to really make fish oil look good? Sales of statins might be more important than sales of fish oil. I don’t know. I’m just wondering.
Second, this fish oil product was not normal. It was modified to make the absorption even easier as a carboxylic acid rather than as a triglyceride. Maybe that is a problem. I’m not sure, but it isn’t how we normally get our fats. So.
Third, this study was conducted in 22 different countries at 675 sites on all 6 continents not covering the South Pole. Maybe a lot of people did different things in other countries to stay alive in addition to taking statins and the fish oil drug? I don’t know, but it seems hard to get a consistent result across such a broad, diverse population base.
Fourth, it could be that the Omega 3 Index was high enough, at 5.6%, that in addition to statins and modern cardiovascular care that there was no great benefit from this fish oil. That is possible. So, if you take the statins, with their side effects, instead of fish oil, with its side benefits of better joint health, brain health, lower chronic inflammation and better mood support, you might get equal protection from cardiovascular disease. At least fish oil is a nutrient, whereas statins are foreign to the body. But you could choose statins instead of fish oil. Your choice.
So, the STRENGTH study didn’t show a benefit from fish oil. But there are questions of conflict of interest, a different, unusual form of fish oil, a population with some protection already from omega 3 oils, and a very wide, culturally diverse test group, and maybe some protection from statins. Anyways, fish oil did not get vindicated in my analysis either.
ASCEND Study: Fish Oil is Useless! Not So Fast…
The ASCEND study was published in 2018, so it isn’t that new. In this study 15,480 people with diabetes were randomized to get 1 gram capsules of omega 3 oil or olive oil, with over 7 years of follow-up. The dose was 460 mg of EPA and 380 mg of DHA, or 840 mg combined omega 3 fats. This is about equivalent to taking 3 capsules of ordinary strength fish oil a day. This is a good amount and should give you some benefit.
Anyways, the main result was that there was no significant difference between groups for serious heart or stroke events. Another, “Fish oil is useless!” kind of study.
Read the Data in Table 4: Fish Oil Prevents Stroke and Heart Attack Death
Except that down in Table 4 there is a clear statistical benefit in lower vascular death (2.5% vs 3.1%) in the omega 3 fat group. There is an 18% lower risk of vascular deaths (strokes and heart attacks combined) from taking the fish oil.
And the Omega 3 Index did improve in this study as well. The baseline went from 7.1% to 9.1% in the omega 3 group, while it remained at 6.6% to 6.5% in the placebo group. There was some protection to start with, but in this diabetic population they got benefit from taking omega 3 fats to get their Omega 3 Index above 9%.
But I guess that wasn’t one of the pre-defined outcomes they were testing, so it didn’t make the news. What? They didn’t think ahead of time to make death from strokes or heart attacks an outcome worth measuring? There was about the same number of serious strokes and heart attack events in both groups, but fewer people died who were taking fish oil. Isn’t that news?
Apparently not, but in my book that counts toward some success. Fish oil did indeed have some benefit. And others noticed that there was a benefit, too. Still others, though, still summarized the study by citing that no positive effects were found. These other “experts”, writing for the American College of Cardiology literally omitted the truth. And we are supposed to “trust the science.” Please, experts, stop patronizing us.
So, there was a clear 18% lower risk of vascular death in the ASCEND study, but fish oil is useless? Really?
REDUCE-IT Study: Fish Oil is Useless Because Bad Placebo?
The fourth study said to show fish oil doesn’t work is the REDUCE-IT study. A highly purified form of EPA was used in this study at a dose of 4 grams total per day, taken as 2 grams twice a day. A total of 8,179 people with high triglycerides participated and were followed for 4.9 years. There was a 25% reduction in major heart events like fatal and non-fatal strokes and heart attacks, or heart surgery. Sounds like a winner to me, so what was the problem?
Mineral Oil: Is it a Killer?
Well, the problem was that the placebo was mineral oil, not corn oil. There was an increase in C-reactive protein in the placebo group, from 2.1 to 2.8 mg/L, but no change like that in the treatment group. Was this due to the mineral oil? Was there a benefit from fish oil, or was there just a 25% higher kill rate from taking 4 grams of mineral oil a day? So, some people discount the 25% improvement in cardiac events, saying that mineral oil is just killing more people.
Was there a benefit from fish oil, or was there just a 25% higher kill rate from taking 4 grams of mineral oil a day? But wait, mineral oil is a common laxative.
The theory that mineral oil is dangerous sounds good, except that mineral oil is actually approved for use as an over the counter laxative. The recommended dose is 15 to 45 ml a day, taken at bedtime. Now, if 4 grams a day would increase your risk of heart attacks, there is NO WAY that you could get a dose of 15 to 45 ml (12-36 grams) just over the counter at any pharmacy in a 16 fluid ounce bottle. So, crying wolf on this study is not justified. Mineral oil isn’t great for you, especially taken with food, but it isn’t a killer.
Maybe the mineral oil, and the elevated CRP was questionable, but it didn’t account for all 25% of the decreased risk seen among those taking the EPA. Maybe the result was only 20%, like what is seen in many other fish oil studies. That is still significant. And mineral oil has been used in other studies as a placebo as well. This isn’t the first study to do that.
So, the REDUCE-IT study in no way shows that fish oil doesn’t work. In fact, it is one of the clearest positive results.
VITAL Study: Is a 50% Reduction in Heart Attack Deaths Useless?
One more. The VITAL Research Group gave 840 mg of EPA + DHA or a placebo to 25,871 people who they followed for over 5 years, looking to prevent cancer or their first heart attack or stroke. And they reported no benefit from taking fish oil.
So, what was the Omega 3 Index in this group?
The mean (±SD) plasma n−3 index was 2.7±0.9% in each group. That is very, very low. Among the 1,583 participants who also provided a blood sample at 1 year, the mean n−3 index rose to 4.1% (an increase of 54.7%) in the n−3 group and changed by less than 2% in the placebo group.
So, this level is still way below optimal levels for Omega 3 Index. You would not expect great results from just this little increase that was still way below the protective level in the intervention group. But for people down this low, even a bit higher is helpful apparently.
But the authors reported no benefits from fish oil.
Significant Results from VITAL Study
But again, you have to look at the table of results (reproduced down below), because they actually reported several significant results from taking fish oil. I put the table here because you might not belive me if I just told you. Here is a list:
- 28% decrease in total myocardial infarction (heart attacks)
- 22% decrease in angiolasty surgeries and stent placements
- 17% decrease in cardiovascular disease (heart attacks and surgeries)
- 50% decrease in death from heart attacks
Since the fish oil didn’t lower the risk of strokes, the positive heart attack results got swallowed up in the analysis so no total cardiovascular benefit (heart attacks and strokes) were seen. See how you can hide stuff in journals? I don’t understand how this stuff ever passes an honest peer-review process.
So, indeed, taking 840 mg of EPA + DHA did have beneficial results for people’s heart in the VITAL study, even though the final Omega 3 Index wasn’t optimal.
Is Fish Oil Useless? No Way!
So, of the 5 studies that were claimed to show fish oil is useless and has no benefit, only one of them shows anything of the sort. Even if we give that one away and say that the result of the STRENGTH study was totally legitimate, that leaves 4 other large studies that show benefits from fish oil. And my recent article on fish oil and cardiovascular disease tells of 9 more newer studies and a review that show benefits of fish oil. So, it isn’t just these 4 studies. Or those other 9. There are older studies as well. It is a mountain of evidence.
What’s Your Takeaway from this article?
First, fish oil is indeed beneficial. If you have optimal levels of omega 3 fats, measured by the Omega 3 Index, then taking more won’t help. Just stay at the optimal level.
Second, examine the evidence yourself, or exam the biases of those you trust very carefully. Confirmation bias is a strong phenomenon. Many people whom we expect to be non-biased scientists are actually human beings with very strong biases and agendas. Many people’s eyes were opened to this during the Covid hysteria.
Third, be careful who you trust. Don’t be a blind follower. Don’t blindly trust me either. The links to the studies are in the article. I will make mistakes and have blind spots. Trust, but verify.