The Skeptical Cardiologist has previously agreed with widespread that encourage most adults to consume a variety of fish, preferably oily types (e.g., salmon, sardines, tuna, and mackerel), at least twice a week for the prevention of cardiovascular disease.
Much of my faith in fish and fish oil, however, was based on observational data and one randomized trial from the mid-90s in patients following heart attacks (the trial). The strongest evidence for the benefit of eating fatty fish has always come from observational studies that show individuals with a higher intake of omega-3 fatty acids (e.g., EPA and DHA) and with a higher red blood cell level of EPA and DHA have lower cardiovascular risk.
By early 2021, based on several new trials of fish oil supplements, that "there is no compelling evidence for you to take over-the-counter fish oil supplements for primary or secondary prevention of cardiovascular disease." This is the same advice I have been giving since 2013.
The study, which showed absolutely no benefit of supplementing with EPA/DHA on reducing a composite cardiovascular endpoint, has triggered me to start looking more closely at the quality and strength of the evidence for the fish recommendations in general.
The study found no significant association between fish intake and any health outcome after adjustment for known confounders.
These findings and an old Welsh randomized trial have caused me to question whether eating fish does, indeed, protect us against atherosclerotic complications like stroke and heart attack.
The Downsides to Fish Consumption
If there are no special benefits to fish consumption, perhaps its limitations mean individuals don't need to worry about consuming it twice a week.
Eating fish the FDA considers healthy requires studying charts based on mercury intake. See the FDA's "."
There are other considerations that complicate the fish farrago. Many articles caution against farm-raised salmon due to a higher level of contaminants and a lower level of omega-3 fatty acids. But fresh wild salmon costs up to four times as much as farm-raised, and these prices put it out of the reach of many Americans.
My palm tree trimmer recently was kind enough to gift me a ziplock bag with a piece of fresh tuna he had caught the day before in the ocean nearby. It made for a wonderful meal but the FDA says I should have checked advisories before eating it and avoided fish for the rest of the week:
What about fish caught by family or friends? Check for to tell you how often you can safely eat those fish. If there is no advisory, eat only one serving and no other fish that week. Some fish caught by family and friends, such as larger carp, catfish, trout and perch, are more likely to have fish advisories due to mercury or other contaminants.
Some guidelines emphasize the manner in which your fish is prepared, which makes a lot of sense. In restaurants, lots of fish is served as fish and chips wherein the fish is dipped in batter and deep-fried in oil or beef tallow. Clearly, the nature of the oil used for frying and how often this is changed could have a massive influence on the overall nutritional quality of the dish.
I hope to share my fishy analysis with you soon.
Anthony C. Pearson, MD, is a noninvasive cardiologist and professor of medicine at St. Louis University School of Medicine. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at , where a first appeared.