Alternative to eating fish
People who don’t like fish or who are vegetarian can get its key nutrients from other healthy foods, except for its long-chain omega-3 fats EPA and DHA. It’s your total dietary pattern that’s most important.
If you’re a vegetarian for health rather than ethical reasons, it’s worth noting that a 2015 study in JAMA Internal Medicine reported that pescovegetarians—who eat fish but who are otherwise vegetarians—had a lower risk of colorectal cancer. Pescovegetarians were 43 percent less likely to develop the cancer over 7.3 years—a lower risk than vegans or vegetarians overall.
Omega-3s from plants
Some plant foods—notably flaxseeds, walnuts, and soybean and canola oil—contain an omega-3 fat called alpha linolenic acid (ALA). While fish can convert ALA from algae and other sea plants into EPA and DHA, humans can do so only to a very limited degree—less than 1 percent is converted, according to some estimates.
Most researchers question whether it’s possible to consume enough ALA to end up with as much EPA and DHA as you’d get by eating fatty fish. That is, ALA cannot replace the omega-3s from fish. On the positive side, some older studies suggest that ALA may reduce the risk of heart disease and have other health benefits of its own. The “Adequate Intake” for ALA, set by the Institute of Medicine, is 1,100 milligrams a day for women and 1,600 milligrams a day for men.
Adding omega-3s to foods—such as breads, spreads, cereals, frozen waffles, and even pasta and cheese—is certainly a good marketing ploy. But do these fortified foods reel in the same health benefits as natural sources of omega-3s?
You have to read the label to find out the actual amount—anywhere from 30 to 1,000 milligrams. How meaningful these amounts are depends on the type added, typically ALA. Some products, such as margarines, contain both fish oil and flaxseed—and thus have all three types of omega-3s (ALA, EPA, DHA). The same goes for eggs from hens that are fed flaxseed, fish oil, and/or algae. Some cows are fed special diets with DHA to increase the omega-3s in their milk.
Most fortified foods provide only a fraction of what’s recommended for potential benefits. A cup of fortified orange juice, for example, has 50 milligrams of EPA and DHA—virtually nothing compared to salmon.
Choosing fish oil pills
What about taking fish oil capsules instead of eating fish? About 8 percent of American adults take fish oil (omega-3) capsules, which are among the most widely used dietary supplements. Since 2004 the FDA has allowed such supplements to carry a “qualified” health claim linking them to a reduced risk of heart disease, though the label has to state that the evidence is “not conclusive.”
On the plus side, compared to fish, fish oil supplements are low in contaminants, since they are typically made from smaller species (such as anchovies and sardines), which accumulate fewer contaminants, or from algae. (If you’re vegan or vegetarian, make sure to choose supplements that state they are made from algae.) And since mercury is water-soluble, it tends to accumulate in the flesh of the fish, not in the fat or oil. Moreover, many manufacturers process their products to remove contaminants.
On the downside, tests have found fish oil pills sometimes contain less omega-3s than the labels claim, while other products may be spoiled.
The science on supplements
Recent research suggests that the “not conclusive” disclaimer about the scientific evidence for heart benefits from fish oil pills is putting it mildly. Well-designed clinical trials on the supplements have produced mostly inconclusive or disappointing findings, perhaps because the benefits of eating fish may come at least in part from other components of fish than the omega-3s.
Most recently, in Mayo Clinic Proceedings in January 2017, a meta-analysis that included 18 clinical trials, most of which used supplements, found no statistically significant benefit overall for prevention of coronary artery disease in the general population. It did find a 15 percent reduction in coronary events, on average, in people at elevated risk because of high LDL (“bad”) cholesterol or high triglycerides.
In a 2016 scientific advisory published in Circulation, the American Heart Association (AHA) reviewed the clinical research on fish oil supplements and concluded that there is insufficient evidence from clinical trials to support the use of omega-3 supplements for prevention of cardiovascular disease in the general population. There was no consensus about supplements for people who are at high risk but have no history of cardiovascular disease. Only people who have coronary artery disease or heart failure should consider taking them, the advisory said. That goes along with the AHA’s prior recommendation that such people should consume 1,000 milligrams of omega-3s a day, preferably from fatty fish, which would mean eating fish almost daily. Fish oil may also be prescribed for people with high triglycerides.
These and other recent disappointing findings run counter to early studies with more promising results for fish oil pills. This may be because far more participants at elevated cardiovascular risk are taking “state-of-the-art” medication, such as statins and blood pressure drugs, compared to early studies. Even if omega-3 pills provide benefits, these would be hard to detect against the backdrop of the much larger benefits of these drugs. That could also make the supplements all the more unnecessary.
Natural sources of alpha linolenic acid
|Walnuts, 30 grams (1 ounce)||2,600 mg|
|Flaxseeds, ground, 1 tablespoon||1,600 mg|
|Canola oil, 1 tablespoon||1,280 mg|
|Soybean oil, 1 tablespoon||925 mg|
|Soybeans, green, cooked, 1 cup||640 mg|
|Beans, kidney, 1 cup cooked||300 mg|