Is Fish Oil the New Snake Oil?

Americans spend hundreds of millions of dollars on fish oil supplements every year, but studies have never been able to prove their effectiveness

Snake oil via Shutterstock    

Snake oil has a bad reputation.

Originally an integral part of Oriental medicine, the product was derived from the Chinese water snake. But it's perhaps best known because it was used so heavily by Chinese immigrants who moved to the Western United States—where there are no Chinese water snakes. Still, word spread about this secret healing elixir and knockoffs quickly appeared. Sold in a carnival-like atmosphere, with over-the-top production and boisterous claims, these potions were made from other snakes—including rattlesnakes—beef fat, red pepper oil, camphor, turpentine and a host of other non-therapeutic liquids.

The original substance contained roughly 20 percent eicosapentaenoic acid (EPA), a type of omega-3 polyunsaturated fatty acid (omega-3 PUFA), but the amount found in the knockoffs fluctuated wildly. This is the same type of omega-3 found in fish like salmon, which contain a maximum of around 18 percent EPA, less than real Chinese snake oil.

Today, the claims of fish oil and other sources of omega-3 PUFAs. like krill. are hawked with no less vigor than the snake oils of old. But are they any more useful?

In terms of cardiovascular benefit, fish oil has been examined in two different contexts within two different settings. Fish oil has been studied in populations that consume lots of fish. These groups were checked for cardiovascular (CV) endpoints and the fish oil was determined by extrapolation to be the causative factor, much like antioxidants are presumed to be responsible for the beneficial CV effects seen with moderate wine consumption.

And fish oil has been studied in settings where pills and formulations are currently being sold and taken. These CV endpoints have been examined in two particular contexts: primary and secondary prevention. Primary prevention refers to preventing the occurrence of a pathological CV condition in a person or population where it does not currently exist. It prevents or reduces the incidence of CV disease in those who take it. Secondary prevention refers to preventing a recurrence of CV disease events in those who already have the disease. A great example is aspirin. For those who already have cardiovascular disease, aspirin is of benefit and a recommended therapy for secondary prevention. It prevents about 40 events per 1,000 people with cardiovascular disease who take the therapy.

In looking at primary prevention studies, most that examine fish consumption show a decrease in all cause mortality and a reduction in CV events. Translation: Eating a diet rich in fish is good for you. It reduces your risk of death and events related to cardiovascular disease, like a heart attack. When these studies were examined to tease out if using fish oil supplementation was as efficacious (or better) than eating fish, it was found that the "available studies were too heterogeneous in terms of study design, duration, background diet, methods of assessment, and outcomes to allow even indirect comparison to be meaningful."

A few large studies (examining over 14,000 people), including the JELIS (Japan Eicosapentaenoic acid (EPA) Lipid Intervention Study), looking at the addition of high-dose fish oil (1800mg EPA/day) to those taking a low-dose statin medication for primary prevention found no benefit. Translation: We have no idea if taking fish oil or other omega-3 PUFAs supplementally, in pill or any other form, prevents CV events.

In examining secondary prevention the same trend seems to hold. Those consuming a diet rich in fish have a reduction in cardiovascular events. A very recent meta-study looked at the value of fish oil supplementation in high-risk populations by examining previous research; If there is a benefit to supplementation, it should be clearly evident in this group. The combination of studies yielded an examination of over 20,000 patients, and yet there wasn't a significant reduction in "the risk of overall cardiovascular events, all-cause mortality, sudden cardiac death, myocardial infarction, congestive heart failure, or transient ischemic attack and stroke" with fish oil supplementation of either eicosapentaenoic acid or docosahexaenoic acid (DHA).

While the commercials may declare Food and Drug Administration (FDA) approval for fish oil therapy—they are approved by the FDA for use to lower triglycerides—the evidence for either primary or secondary benefit in reducing cardiovascular events with supplementation is lacking. We've seen this before: Potential agents for benefit, like omega-3 PUFAs in fish oil or antioxidants in wine, are identified. These agents are packaged in proprietary supplemental form. Potential benefits for taking these supplements are intimated with the sly wink and nod of a huckster, but no guarantees are on the bottle or documented in any legal way. Then the sideshow begins. Why, because sales for products like Lovaza, the prescription FDA-approved fish oil supplement, topped $1 billion worldwide and over $600 million in tbe U.S. in 2010.

A diet rich in real fresh fish and seafood is good for you and your heart. The data support this bit of common sense. Fish and other seafood contain a myriad of beneficial compounds, including taurine, which was recently found to possibly reduce cardiovascular risk in women with CV disease. Common sense also tells us that there is no magic pill nor elixir of health and immortality. That did not stop the sale of snake oil because peddlers oversold promises and preyed on hope and fear. Unfortunately, I see many patients with cardiovascular disease and others spending precious dollars on bottles of unproven supplements for the same reasons.

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