In the 1970s, epidemiologic studies discovered that Inuit (the indigenous people of the Arctic regions Canada, Alaska, and Greenland), whose diet was extremely rich in fish, had a much lower rate of heart disease than Americans and Europeans. Scientists attributed this to the omega-3 polyunsaturated fatty acids (PUFAs) in fish, which seemed to protect and stabilize the delicate membranes that surround every cell in the body, especially those in the heart and brain. Later studies, which tracked fish consumption per capita against development of heart disease and fatal heart attacks, showed the Japanese, who eat far more fish than Americans and Europeans, also enjoyed a lower rate of heart disease deaths.
Now it’s 40 years later and fish oil is the top-selling nutritional supplement in the Western world. Unless you are a strict vegetarian, if you’re reading this Health Tip you most likely take (or at least own) a bottle of fish oil capsules. Many of you have told me you buy them but, because of the unpleasant fish-burp, let them sit in your vitamin graveyard gathering dust.
Unfortunately, the many research studies that followed the earliest ones were not particularly dramatic. They attempted to see if daily fish oil capsules provided the same heart protection enjoyed by the blubber-chewing Inuit or sushi-eating Japanese, but the conclusions were variations of “Yeah, maybe, not sure really, won’t hurt.”
Everyone did agree, however, that collecting data for meaningful studies was problematic, especially for a condition like heart disease that involves a constellation of variables beyond fish consumption. You had to factor in exercise, diet, tobacco use, blood pressure, and family history as well as what fish had been eaten and how was it prepared. Moreover, as the studies progressed, researchers noted two things. First, that people taking fish oil supplements took better care of their overall health and, second, that people who ate a lot of fish didn’t get further heart benefits by pushing up their blood levels of omega-3 by taking fish oil capsules.
Even if a person never supplemented with fish oil, if she had a good amount of omega-3 in her blood from her diet she was well protected from early heart disease.
Many of these studies were also flawed because people as a rule don’t accurately remember what they’ve eaten. Those reporting “I eat fish once a week” would, when they kept an actual food diary, turn out to have actually eaten fish just once a month. It turned out that huge numbers of both Americans and Europeans virtually never ate any fish, or limited themselves to deep-fried versions (deep frying reduces the omega-3 content by 85%). It was in this virtually omega-3-free group that regularly taken fish oil capsules might have some meaning.
Just last month, an immense analysis of previously collected data was published in the June issue of JAMA Internal Medicine, and it finally puts the fish oil matter to rest. Researchers reviewed 19 epidemiologic studies from 16 countries, a total of 45,637 individuals, to determine if fish oil actually makes a difference in health and longevity.
The answer is yes
If you eat non-deep-fried, oily fish two or three times a week, you probably have levels of omega-3 in your blood high enough to protect you from a fatal heart attack. If you don’t eat this amount, then a couple of high-quality fish oil supplements taken daily will cover you.
However, it’s definitely important to differentiate “fatal heart attack” from “heart disease.”
When someone dies of a heart attack, either on the street or within a few days of arriving in the hospital, the killer is usually a major disturbance of heart rhythm (called an arrhythmia), either ventricular tachycardia (VT) or ventricular fibrillation (VF). With VT, the person might get warning signs, like lightheadedness, palpitations, and shortness of breath. These occur because the affected person feels her heart rhythm change and the output of blood from her heart suddenly drop. VF, on the other hand, unless quickly converted to a normal rhythm, is fatal. With VF, there’s no blood being pumped from the heart and the person quickly loses consciousness and dies.
Fish oil, which increases omega-3 blood levels, protects against fatal arrhythmias. Chronic coronary heart disease (CHD) is a much slower process. It’s with CHD that you may experience chest pain with exertion (angina), shortness of breath (congestive heart failure), and other heart rhythm abnormalities (such as atrial fibrillation). These are called benign arrhythmias because they’re rarely associated with sudden death.
Boosting omega-3s with fish oil may be helpful, but the stats aren’t dramatic
Here’s a summary of what we know about fish oil and heart disease:
- If you eat oily fish regularly, you’ll enjoy statistically significant protection from a fatal (arrhythmia-induced) heart attack.
- If you’re not a fish eater, you’ll enjoy the same protection by taking fish oil as a nutritional supplement.
- Fish oil prevents arrhythmias by strengthening the membranes surrounding your heart’s cells. Weak membranes predispose you to rhythm abnormalities. In autopsy studies, the cell membranes from Japanese hearts were thicker and stronger than those of Americans and Europeans.
- Fish oil is also helpful for its anti-inflammatory properties. High levels of inflammation in your body are linked to chronic heart disease, diabetes, macular degeneration, and autoimmune disorders. Eating fish or taking fish oil capsules is probably (repeat, probably, not fully proven) helpful.
- Fish oil can be fractionated to isolate its separate clinical benefits. One particular fraction, called specialized pro-resolving mediators (SPM), can be used as a potent anti-inflammatory alternative to the NSAIDs, like Aleve or Advil, but without the side effects. SPM Fish Oil is made by Metagenics and is available in our apothecary.
- Remember, however, that when it comes to preventing chronic heart disease, taking fish oil is less useful than making healthy lifestyle choices. For this, you’ll need to keep your weight in check, be physically active, not smoke, eat a high-nutrient diet (including lots of colorful vegetables and good fats), and drastically cut your sugar intake.
- Allay your concerns about mercury by heeding this advice from the National Resources Defense Council: Avoid a few key species. King mackerel, marlin, orange roughy, shark, swordfish, tilefish, ahi tuna, and bigeye tuna all contain high levels of mercury. Women who are pregnant or nursing or who plan to become pregnant within a year should avoid eating these fish. So should children younger than six. (Also, farmed salmon may contain PCBs, chemicals with serious long-term health effects.)
- When it comes to selecting a fish oil, like buying paint or tires you’ll get what you pay for. The low-priced generics are often accompanied by the unpleasant fish-burp. I recommend any of the fish oil products manufactured by Integrative Therapeutics, Metagenics, or OrthoMolecular.
David Edelberg, MD