Fish aids heart by replacing junk food, study says
A UH professor doubts the touted benefit of fish for the heart
Fish has a reputation as healthful fare, but a University of Hawaii researcher says its chief benefit may be that it replaces less-healthful entrees like red meat.
Claudio R. Nigg, an associate professor at the John A. Burns School of Medicine, also says fish devotees tend to eat vege- tables rather than side dishes like french fries.
Nigg and others report in the current issue of the American Journal of Cardiology that there is no evidence that fish itself is healthful, although omega-3 fatty acids in fish have been credited with decreasing the risk of heart disease.
People who eat a lot of fish may be healthier, but it's not because of the fish, says a University of Hawaii researcher.
It's because fish-eaters aren't eating red meat and other things that aren't good for you, says Claudio R. Nigg, associate professor of social behavioral health, Public Health Sciences Department, John A. Burns School of Medicine.
"It may be a gateway to a healthier diet," he said. "It may or may not itself have all the healthy things (omega-3 fatty acids) it's touted to have, but in its way it carries healthier side dishes and starches.
"When you choose fish, what kind of sides are you going to choose? Are you likely going to choose french fries? Or are you likely to choose vegetables with it?"
Nigg said many papers tout the health benefits of fish to decrease the risk of coronary artery disease but that there is no supporting evidence.
He and his colleagues, Dr. David Keith Cundiff of the Los Angeles County and University of Southern California Medical Center and Amy Joy Lanou of the University of North Carolina, analyzed data from a diabetes study involving 1,400 people.
Their findings are reported in the current issue of the American Journal of Cardiology.
Suzanne Murphy, a researcher in cancer, diet and nutrition at the Cancer Research Center of Hawaii, noted an Institute of Medicine report that balances the benefits and risks of seafood choices.
It says evidence is insufficient to assess whether benefits of fish associated with cardiovascular disease are due to an increase in omega-3 fatty acids or a decrease in saturated-fat consumption.
"So, they're saying the jury is still out," Murphy said. "We can't really separate the two possibilities. ... It doesn't contradict what Claudio is saying."
Nigg said he and his colleagues initially thought the diabetes study data would tell them what a heart-protective diet looks like. "But when Dr. Cundiff pushed a little more, he said, 'There's something a little fishy about this.' "
Omega-3 fatty acids are considered healthful fats from fish, but the researchers saw "an inverse correlation with calories," Nigg said. "People who eat fish eat less calories."
He added: "They also have less percent of calories from bad fats -- saturated fatty acids. We also found a correlation with dietary fiber, vegetables, fruits and grains."
At this point, Nigg said, he and his colleagues haven't proved anything. "But what we raise is the issue that it may not be the fish per se, but fish may be a marker of a healthier diet, which then is a good thing to promote."
Don Weisman, American Heart Association of Hawaii spokesman, pointed to the AHA Web site, which recommends eating fish ("particularly fatty fish") at least two times a week. It says omega-3 fatty acids "benefit the heart of healthy people," but that how it works is still being studied.
The Web site refers to a 1996 AHA study, "Fish Consumption, Fish Oil, Lipids and Coronary Heart Disease," that it says cites evidence from clinical trials showing omega-3 fatty acids reduce cardiovascular risks.
Nigg said a randomized control trial in which everything is the same except fish intake is needed to clear up the confusion.
Murphy said some good observational studies have shown a beneficial health association with seafood. But she supports the idea of a randomized trial to learn whether something in the fish is providing the health benefit or whether it's something fish displace in the diet.
"It's not possible at this time to separate out those two alternatives," she said.