The Lure of Fish Oils
By Rosie Mestel, Los Angeles Times Staff Writer
Eyeing some salmon or sardines in the grocery store, you may soon notice some not-very-snappy words on the labels, suggesting the contents may be good for you.
Last month, the Food and Drug Administration allowed the following "qualified" health claim for certain foods containing fish oils: "Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease."
Or, as Madison Avenue might prefer to put it: "Fish oils! They're healthy! And they're not just about fish anymore!" Or they won't be for long if food companies have anything to do with it.
As studies pile up linking omega-3 fish oils (and possibly plant ones too) to healthy hearts, food businesses - cognizant of the fact that fish is not universally adored - are busy figuring out how to get omega-3s into juice, yogurt, salad dressings, margarine, meat, milk, bread, you name it.
Consumers who weathered the fiber fad and other flash-in-the-pan
nutrient crazes may be forgiven for rolling their eyes. The two fatty acids
in question - eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) -
are purported to help your heart, your immune system, your mood, your aging
brain and your dimming eyes, and possibly even to ward off cancer. The list
seems optimistically long. Perhaps it's just a matter of time before this
latest miracle-food-on-the-block fizzles.
Or maybe it won't.
Nutrition scientists and cardiologists wax enthusiastic on the matter of fish oils because they believe the oils' benefits in lowering death from heart attacks have been well shown. (The other health links, although intriguing, remain tenuous.) The American Heart Assn. recommends that healthy adults consume two servings of preferably oily fish per week and that people who already have heart disease or elevated blood levels of triglycerides aim for even higher levels of omega-3 fatty acids in their diet. In August, a panel of scientists helping update the Dietary Guidelines for Americans (government eating advice that shapes federal nutrition policy) also recommended that Americans raise their fish intake to two 4-ounce servings per week; Americans, on average, consume less than 3 ounces of nonfatty fish.
The FDA action marks the second time the agency has allowed a qualified health claim for a conventional food product; earlier this year, the agency granted a claim linking walnuts and certain other nuts to a reduction in heart disease risk.
"I know we got burned with vitamin E, and fiber was another one, and I think that soy protein was another, but this seems to be more constant," says Alice Lichtenstein, a professor at the Friedman School of Nutrition Science and Policy at Tufts University in Boston. "All the results seem to be going in about the same direction…. [The link is] very consistent and strong."
In fact, some scientists suspect that, when it comes to oils,
our diet these days is plain out of balance. Compared to what people ate in
the past, levels of omega-3s have steadily declined, nudged out by other types
of oils.
Greenland connection
Omega-3 fatty acids are long chains of carbons that are polyunsaturated, meaning they contain several double bonds. They're called omega-3s because the first double bond in the string is positioned three places from the chain's end. When three of the fatty acids are linked to a chemical called a glycerol, they make an oil.
Grandma may have sworn by cod liver oil, but to scientists the fish oil-heart health link dates from the late 1970s, forged by Danish investigators studying the indigenous peoples of Greenland. The scientists noted that although the Inuit had diets loaded with fat, their death rates from heart attacks were significantly lower than the Danes'.
Perhaps, reasoned the investigators, this might have something to do with the type of fats being eaten - a lot of oils from seal and fish for the people of Greenland compared with saturated fats from the milk-, cheese- and meat-rich diets enjoyed by the Danes.
Other population studies and animal studies fueled this hypothesis. For instance, when monkeys and dogs were fed fish oil-rich diets, their hearts were less likely to go into spasms (known as arrhythmias) after heart attacks. Such arrhythmias prevent the heart from pumping blood.
Carefully designed clinical trials also support the antiarrhythmia link.
In one large Italian study, 11,324 men and women with preexisting heart disease were given 850 milligrams a day of fish omega-3s, a placebo or vitamin E. The vitamin and placebo did nothing. But 3 1/2 years later, fish oil-takers were 15% less likely to have died or had a nonfatal heart attack or stroke. Most strikingly, their rate of sudden death - in other words, death within one hour of the heart attack - was 45% lower than for those who took placebos.
In another study, men who had suffered heart attacks were counseled to eat more oily fish - and, two years later, were 29% less likely to have died, especially of a fatal heart attack.
Scientists now believe that the fish oils act by taking up residence in the membranes of heart cells and alter the cells' electrical properties, making it harder for the dangerous spasms to start.
"If you have a heart attack - heaven forbid - the fatty acids are already in the heart … and prevent arrhythmia," says Dr. Alexander Leaf, emeritus professor of clinical medicine at Harvard Medical School and Massachusetts General Hospital.
The link to arrhythmias is the most substantiated, but fish oils may also have other heart-friendly effects, such as lowering the levels of triglycerides in the blood, reducing inflammation, slowing coronary artery thickening and reducing the tendency of blood to clot.
And the oils' reach may turn out to stretch beyond the heart. For instance, population studies in the Netherlands and the United States have reported that people who said they ate fish once weekly or more were 60% less likely to develop Alzheimer's disease in subsequent years. Greg Cole, associate director of UCLA's Alzheimer's Disease Research Center, says this could be because DHA is crucial for the proper working of brain cells and is destroyed during the course of Alzheimer's disease.
Cole and co-workers recently reported that mice with an Alzheimer's-like condition performed better in memory tests when fed DHA than when fed safflower oil, which does not contain omega-3s. Scientists in Oregon are conducting a small pilot study to see if Alzheimer's progression is slowed by fish oil supplements in men and women with mild cognitive impairment.
Mood too has been linked to levels of fish oil consumption - maybe again because a lack of omega-3s in the brain contributes to some abnormalities therein. In 1998, Dr. Joseph Hibbeln of the National Institutes of Health published a survey revealing that countries with the highest rates of depression ate the least fish, while those with the lowest ate the most.
Several small clinical trials have reported that fish oils helped improve psychiatric symptoms. One found that bipolar patients given fish oils had improved symptoms, another that supplements of EPA were more effective than placebos at improving the mood of depressed patients.
There are also data suggesting omega-3s may be helpful for a raft of other ills such as aggression, attention-deficit disorder, macular degeneration, autoimmune diseases and breast cancer. "You'll hear all sorts of things," says Penny Kris-Etherton, distinguished professor of nutrition at Pennsylvania State University in University Park, who co-wrote the American Heart Assn.'s recommendations and reviewed omega-3s for the next version of America's dietary guidelines. "I think this definitely is an emerging area."
What to consider
Ultimately, even if omega-3s are proven only to reduce the risk of deadly arrhythmias after a heart attack, that's ample reason to pay attention. According to the National Institutes of Health, more than 1 million people in the U.S. have a heart attack and 515,000 die each year, usually from arrhythmias.
Here, gleaned from omega-3 experts, are things to consider when thinking about increasing your fish oil intake:
Potomac, Maryland 20854