A team of Canadian scientists is calling dietary guidelines to eat more fish unwise and shortsighted.
The report's lead author told CBC News he expects the analysis to be controversial because it's an argument against health advice based, in part, on environmental concerns.
"You know, this could definitely stir the pot, generally," said Dr. David Jenkins of St. Michael's Hospital in Toronto.
He and report co-author Ussif Rashid Sumaila, acting director of the Fisheries Centre at UBC, analyzed the science behind guidelines throughout the world suggesting people in developed countries eat at least two servings of fish per week.
The study found there is some evidence to support the theory that fish and fish oils, which are rich in omega-3 fatty acids, prevent coronary artery disease.
However, evidence also suggests fish eaters have generally healthier lifestyles than the rest of the population, so the benefit to eating fish is unclear.
Jenkins said that evidence has been ignored in the past.
"There have been areas where fish have been explored, in relation to heart disease, that haven't turned out the way we would have expected … and these are not being discussed," Jenkins said.
Not enough fish in the sea
While the benefit is uncertain, the researchers write, the cost of this fish-eating advice is very clear.
"It means more demand for fish, which are simply not available. [They're] becoming less and less available in the ocean," Sumaila said.
"Scientists around the world have shown that declines in fish stocks are really serious … so the evidence there is very strong."
The public has the impression, Sumaila said, that there are plenty of fish in the sea — but that's not the case.
"When you go into the supermarket, you find fish all over and you say, 'C'mon, there's fish all over.' But actually, they're coming from sources we didn't tap into before and there are consequences for that," he said.
If the high demand for fish in developed countries continues, Sumaila said, future generations may not have wild fish to eat.
"If this high demand for fish continues, given the limited supplies, we are pushing the envelope and that can lead to problems in the near future for us and also for our children and grandchildren," he said.
Other pathways to heart health
In the publication, the researchers write, "it would seem responsible to refrain from advocating to people in developed countries that they increase their intake of long-chain omega-3 fatty acids through fish consumption."
The responsible course, they argue, would be to forego guidelines to eat fish and focus on acts with certain health benefits, like eating fruits and vegetables and getting exercise.
"There are many other things that you should be doing and paying attention to, if you're that enthusiastic about your health," Jenkins said.
"What I'm saying is, in that we have many ways of looking after our heart, we should be using those, instead of using the environment."
The peer-reviewed analysis, called "Are dietary recommendations for the use of fish oils sustainable?" will be published in the Canadian Medical Association Journal on Tuesday.
The report's other co-authors are John L. Sievenpiper, Dr. Daniel Pauly, Cyril W.C. Kendall and Farley Mowat.