The bottom line
Given the ludicrous sums of money spent on fish oil each year (creeping up over $1.5 billion a year), we need to take a hard look at evidence on fish oil and pain.
When you supplement with fish oil, it’s just one tiny portion of the fat you eat during the day. The type of fat you eat is extremely important for inflammation, and if you supplement with two grams of fish oil out of fifty total grams of fat eaten in a day, which of those two is morely likely to impact inflammation?
Omega-3s may generally decrease inflammation, but neither those nor the occasionally inflammatory omega-6s should be the base for your diet, especially since common oils rich in these fatty acids can easily go a bit rancid. It might not sound like an aggressive pain treatment plan, but instead of fish oil pills, think about eating a mix of healthy fats like olive oil, nuts, grass fed meat, and actual fish. Just because there aren’t many trials exploring dietary fats for pain doesn’t mean it’s a worse strategy than supplementing with fish oil (in fact, it may be quite a bit better).
Hype has made fish oil ubiquitous
Fish oil is the most widely-used supplement for pain. It must work then, right? Unfortunately, most people (including most physicians) haven’t reviewed all the important trials on fish oil and pain. Usually, heart health studies get all the attention.
It turns out that there’s waaaaaaaay less evidence for fish oil impacting pain than there is for fish oil impacting heart disease. And in recent years, we’ve found that fish oil doesn’t really have as strong of a benefit for heart disease (in many studies, virtually no benefit) as researchers thought a decade ago. This should give you a clue as to the what the pain evidence shows.
And when a pain trial comes out, it’s typically misreported. For example, a study came out on 2012 looking at fish oil for pain in arthritic dogs. Dogs need pain relief as much (or more!) than humans, so human pain therapies are often tried on canines.
The study found NO PAIN BENEFIT from fish oil when compared to placebo. But the study reported that “owners of dogs that had taken fish oil were significantly happier with the treatment at the end visit and did significantly better at guessing what group their dogs had been in.” So basically, the study looked at a bunch of variables and didn’t find an actual benefit. Does the dog care that one out of ten outcomes came out positive? Probably not, if the one outcome wasn’t pain reduction.
A brief history of omega-3s and pain
Chances are good that your parents and grandparents didn’t use fish oil before you were born. But that’s not because fish oil didn’t exist. Cod liver oil had been used for centuries in northern Europe, as a rich source of vitamins A and D. As far back as the 1700s, fish oil was seen as an option for addressing pain issues. Back then, fish oil was not a neatly encapsulated product that was carefuly refined and deodorized. It went rancid more easily, and the nasty smell that comes from oxidation did fish oil no favors.
Nowadays, fish oil is big business, and not just because it’s used in supplements. Over a quarter of caught fish are too bony or oily to be appetizing, so they’re broken down into many products including fish oil. A huge chunk of this oil is actually used as feed for farmed fish.
Since the benefits of fish oil now come without a major risk of puking from rancid fishy odor, there’s quite an incentive to research the health benefits of fish oil.
Chemical soups promote pain
When you have chronic inflammatory pain, a chemical soup of irritators (such as TNF-α) helps keeps the pain sticking around longer than you’d like. If you normalize the type of soup being made, you may end up with less pain. Most people are born with the ability to regulate their post-injury soup. But you can get in trouble and mess up your ability to make quality soup, through stress, bad diets, and genetics among other factors.
Extending this soup analogy further (too far?), let’s say you have a nice tomato soup, but are in an unpleasant setting. Like prison. The soup isn’t going to be as important as the setting, which can drown out the tastiness of the soup. The same thing happens with the chemical soup in your body — two people might have the same soup in a joint space, but one experiences pain because their brain / nervous system has an excess of unpleasant neurotransmitters. As an example, fibromyalgia patients have more of a pain-related neurotransmitter called “substance P“.
So long story short: just because a pill reduces inflammation in a joint, doesn’t mean it reduces pain. And different types of pain have different chemical soups and nervous system involvement. Let’s see how fish oil impacts different pain types.
Fish oil for muscle soreness
Delayed Onset Muscle Soreness after working out (DOMS) is typically just annoying. But some people either don’t feel comfortable with the pain, or need to return to full functionality quicker. Since DOMS doesn’t have many good treatment options (using “treatment” loosely, since the temporary soreness is not dangerous), fish oil has been investigated a few times for this purpose, with mixed results.
Why might fish oil work not work for this type of pain? First the good: fish oil increases production of compounds called “3-series eicosanoids”, which are less inflammatory than their hated cousins the “2-series eicosanoids”. Theoretically, this means less inflammation and less pain. But pain isn’t actually correlated with inflammation on a 1:1 basis — DOMS is due to both muscle damage and a variety of biochemical changes, and these changes aren’t necessarily all addressed by fish oil.
Fish oil for back pain
If you had really bad back pain, would you rather have surgery or take fish oil? Okay, that one was easy. So it’s no wonder that surgeons and sports medicine docs often recommend fish oil or other supplements before considering surgery. But controlled trials are lacking in this area.
One study had neurosurgeons recommend fish oil (to the tune of 1200 mg per day) to patients with back/neck pain. The study authors concluded that fish oil worked pretty well. Just one problem: the study design sucked. It wasn’t comparing fish oil to anything, and well over half of the patients stopped taking the fish oil. Over 20% of those who stuck with the fish oil took double the recommended dose. Sixty percent said that their pain improved, but 88% said they would continue taking the fish oil. Why might that be? Perhaps because their neurosurgeon had recommended it? This study is total suckage.
You can have neuropathic pain in a variety of conditions, like fibromyalgia, back pain, and carpal tunnel. It’s scary, because it’s totally unlike the dull and aching pain that most experience, and can involve sensations like burning and tingling.
Fish oil doesn’t have good evidence for most types of neuropathic pain. One study reported on five patients who took high doses of fish oil (from 2400 to 7200 mg) over time periods up to 1.5 years, and found improved pain measurement from both objective tests and patient surveys. That’s the good part — there’s some objective measurement. The bad part should be obvious … it wasn’t an actual trial, and there were only five patients. Could anything else happen over the course of 1.5 years to improve pain? You bet. There needs to be some nice, large randomized trials on fish oil and neuropathic pain, because as of now we don’t know much about its effect.
PMS / Menstrual cramps
Did you know that over 80% of PainDatabase readers are women? Tis true. And that makes sense, because physicians are less likely to believe women (and minorities) when they come in for pain complaints. The Internet is sometimes more informative than your dismissive doctor, unfortunately.
Fortunately, menstrual pain is one area that fish oil has some good evidence for. Both Iranian womenand Danish women have benefited from fish oil in randomized trials. The Danish study found that combining fish oil with vitamin B12 was a bit better than fish oil alone. Interestingly, B12 has also shown some success with low-back pain. Be careful with both though — taking several fish oil pills a day could make bleeding issues more severe, and B12 has been linked to acne formation.
Everything else — rheumatoid arthritis, lupus, etc.
In summary, evidence is preliminary (and often mixed) for a variety of painful conditions, typically with just one or two small studies per condition. On the flip side, fish oil has been studied for rheumatoid arthritis since the 1980s, with a few trials showing benefit. In my personal opinion, dietary interventions and supplements like fish oil are more likely to benefit rheumatoid arthritis than most other pain conditions, because of the obviously inflammatory nature of the pain and centralization in specific joints.
Fish oil may not be as strong an option for other pain conditions such as fibromyalgia and lupus, since these conditions are relatively more complex. Don’t take any study’s results as gospel without knowing that the methods were sound. For example, one lupus study with positive results used a massive dose of fish oil (20 grams daily) and also used some wonky statistical comparisons.