#WTF Is Fish Oil (And Should I Be Taking It?)

As far as supplements go, fish oil capsules have been marketed as the MVP of the bunch: They’re chock-full of polyunsaturated omega-3 fatty acids, which boast benefits like reducing the risk heart disease, lowering blood pressure, stopping cognitive decline, and even alleviating asthma [1] [2] [3]. Do the health claims behind fish oil hold water, or are they as slippery as the marine animals themselves?
  

The Lowdown           

The popular pills contain oil pressed from actual chunks of fish that have been steamed, separated, and purified. Appetizing, right? The fishy oil contains a concentrated dose of omega-3 fatty acids, plus some added vitamin E to prevent spoilage. Some pill manufacturers boost (possible) health benefits by adding other vitamins and minerals like calcium, iron, or vitamins A, B, C, or D into the mix. Most capsules contain 1,000 mg of fish oil, although the actual dosage of omega-3 fatty acids in each pill varies between brands, usually from 200 mg to 600 mg.
Omega-3 fatty acids (often just called omega-3s) are essential healthy fats the human body can’t produce but requires for functions as diverse as controlling blood clotting, forming cell membranes, absorbing vitamins, and keeping skin and hair healthy. There are two main categories of omega-3s: ALA (alpha-linolenic acid), which comes from vegetarian sources like flaxseed, nuts, and various vegetable, nut, and seed oils, and EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid — try saying that five times fast), which we can get via fatty fish and algae. Salmon, herring, mackerel, and anchovies are particularly good sources of these EPA and DHA omega-3s. (A note to vegetarians: The body can convert some ALA fatty acids to EPA and DHA, so it’s possible to skip the flounder and still get the benefits.)
Although they’re often lumped together (and usually mixed up inside fish oil capsules or gummy vitamins), EPA and DHA do different jobs in the body. EPA works as an anti-inflammatory throughout the body, including the brain. DHA is essential in the maintenance and creation of fluid cell membranes. Both types of omega-3 fatty acid can reduce triglyceride levels and increase “good” HDL cholesterol in the body. Fish oil’s alleged benefits have made it a one-stop shop for a number of medical problems — regardless of whether or not the science behind it is legit. Because of its beneficial associations with lowering triglycerides and increasing good cholesterol, fish oil has a strong (although perhaps overexaggerated) link to heart health, and it's often recommended to those at risk of heart attacks and strokes. EPA’s link to brain blood flow means it’s become a home remedy-type treatment for depression, ADHD, Alzheimer’s, and other brain disorders. Fish oil is also prescribed to keep eyes moist and treat glaucoma and age-related macular degeneration.

The Buzz — Why Do People Care Now?

There’s something a bit fishy about all the health claims surrounding these magical, health-boosting pills, and last year, scientists harpooned some of fish oil’s purported benefits. A team of Greek researchers analyzed 20 studies on fish oil that, when combined, looked at more than 68,000 patients. They found that, based on results from these 20 studies, fish oil supplements did not lower risk of stroke, death, or cardiovascular disease (including heart attack) [4] [5]. Recent research has also debunked the idea that omega-3s can altogether prevent cognitive decline and dementia in older adults [6]. Scientists from Yale were unwilling to totally reject the idea that fish oil can treat depression, but they concluded swallowing extra omega-3 fatty acids had a “small, non-significant benefit” for curing the blues [7].
It’s important to remember that omega-3s don’t exist in a vacuum. The body requires both omega-3s and their close cousins, omega-6 fatty acids, to function properly. These days, the average Westerner consumes between 10 and 25 times more omega-6s (usually in the form of vegetable oils) than omega-3s. Studies have shown that a ratio closer to 2:1 or even 1:1 is best for health [8]. The imbalance of omega-6s and omega-3s can result in inflammation, which causes many of the disorders that fish oil can “cure.” In many cases, fish oil is recommended to correct the imbalanced ratio, stanching inflammation that’s caused by a dietary overload of omega-6s.
Getting too jazzed about the miracle pills can have negative effects, too: Overdosing on the supplement (according to Greatist Expert Eugene Babenko, that means popping over 20 grams of fish oil a day) can have side effects like nausea, nosebleeds, headaches, short-term memory loss, high blood sugar, and a weakened immune system. Recent studies have also linked high doses of omega-3s with increased prostate cancer risk, but the theory is so new and untested that it’s hard to say if fish oil is at all to blame [9].
Fish oil isn’t just controversial in the medical arena — the capsules of fish juice raise the same environmental and health issues that a tasty fillet grilled salmon or dish of tuna tartare might [10]. A significant percentage of all fish oil comes from a stinky member of the herring family called Atlantic menhaden. It’s loaded with omega-3 fatty acids, which is both a blessing and a curse. Menhaden is lower in harmful mercury, dioxins, and PCBs that contaminate many of its fishy friends like tuna or farmed salmon. But, perhaps thanks to the popularity of fish oil supplements, the fish is now a hot commodity and wild populations have plummeted in the menhaden’s favorite coastal hangouts.

The Verdict

Right now, researchers still don’t know exactly how fish oil affects healthy bodies. While some of fish oil’s claims have been debunked in the lab and by prominent docs, other studies are still proving that the stinky substance might, in fact, help keep us healthy in the long run.
The question of whether to take fish oil supplements remains a toughie. Greatist Expert Dr. John Mandrola explains that nearly all pro-fish oil research is a bit murky (dare we say, fishy?) because different studies routinely use varying strengths of omega-3s. These days, most docs (including the American Heart Association) recommend getting plenty of omega-3s by eating at least two servings of fish per week. Adding healthy oils and fats to the diet via other sources doesn’t hurt, either.
For a more specific “yes or no” answer, talk to your doctor, and study up on the subject beforehand. If the recent media uproar about fish oil has taught us anything, it’s that the supplement might make a difference for certain conditions, but it probably won't cure everything that ails us.