For years, doctors, nutritionists and even your mother have issued a common entreaty at the dinner table - eat more fish.
Conventional thinking has it that the marine fare can do everything from help hearts recover from surgery to boost brain power and lower cholesterol.
But in a unique paper to be published Tuesday, doctors and fisheries scientists are questioning the health benefits of heavy fish consumption, especially when the world's stocks are being severely depleted.
"There is a benefit from fish, but we are not certain that all people will benefit from fish," said David Jenkins, a physician and professor at the University of Toronto medical school who co-wrote the analysis in the Canadian Medical Association Journal.
"There may be some groups who do not benefit from fish intake and we have no idea just how much benefit people would get from fish if they were leading an otherwise healthy lifestyle."
The team of health and science specialists cited several studies in recent years that found patients with varied heart conditions either showed little or no benefit from the consumption of fish products.
In one controversial study, patients suffering from angina were advised to take fish oil, but were later found to be at greater risk of dying.
Others have cited only moderate improvements in health following a diet that included steady amounts of the omega-3 fatty acids found in fish products.
The problem, Jenkins said, is that earlier studies proclaiming the benefits of fish for heart conditions may not have looked at all lifestyle factors that can contribute to overall good health
"Although I'm sure that fish may have contributed to their health, it may not be the reason why they have such blindingly clear health because there were other factors at play," he said from Toronto.
The opinion comes at a time when federal health agencies, heart organizations, nutritionists and physicians continue to promote fish consumption as a way to improve brain development, mental health, cancer prevention and autoimmune diseases.
Health agencies recommend that people should eat two servings of oily fish a week to prevent chronic disease, according to the paper.
Jenkins says the general claim might be overstated and clinical research needs to be done to determine the benefits of fish, the consumption of which health officials have said should be increased by three-fold in recent years.
There are also concerns that the recommendation that people should eat three times more fish than they had been should be rationalized as fish stocks grow thinner.
Rashid Sumaila, a fisheries expert at the University of British Columbia, said the renewed emphasis on fish consumption in recent years has placed undue stress on fish stocks.
The demand for fish in developed countries like the United States and in European countries has climbed dramatically as fish consumption is encouraged, he said.
That also means developing countries are exporting their fish or selling licences, Sumaila said, and depriving their populations of local, healthy food sources.
"If we in the West realize that we don't actually need so much fish to keep us healthy, then the demand will go down," he said, adding that about 40 per cent of the fish caught globally is traded.
"And that will help them add value locally in Africa and improve the food security and also employ people."
The paper also recommends that more work be done on alternative sources of omega-3 fatty acids, which Jenkins said can be produced from unicellular organisms like algae.
