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Health Options
Alan Titchenal |
Wild or farmed,
salmon is safeA study published this month in the journal Science triggered headlines such as "Farmed salmon more contaminated than wild." Although this study was valuable, the results were not surprising, as they only confirmed previous research. Putting this type of research into perspective is necessary to reverse unnecessary consumer fears.
Question: What did the salmon study show?
Answer: Researchers analyzed about 700 farmed and wild salmon from a variety of locations in Northern Europe and North and South America for a variety of contaminants. The chemicals of most concern were dioxins -- a group of chemicals, including polychlorinated biphenyls, or PCBs. European farmed salmon contained the greatest levels of these compounds, and wild Alaskan salmon had the least.
Q: What are dioxins?
A: Dioxins are formed by the combustion of fuels such as wood, coal, gas or municipal waste, or when paper is bleached. They are even found in cigarette smoke, although in small amounts.
Since discovering that dioxins are toxic, the Environmental Protection Agency has worked with the U.S. Food and Drug Administration, the European Union and the World Health Organization to reduce dioxin omissions. Dioxins have decreased over the last 30 years, but because the breakdown of chemicals is very slow -- and because natural dioxins are formed through natural processes such as forest fires -- dioxins will always be a part of the environment. One benefit of the Science article is to encourage the aquaculture industry to lower organic toxin levels even further.
Q: How long have dioxins been found in our food?
A: Dioxin accumulation has been known since the 1920s, but it was only in the 1970s that dioxin toxicity was recognized as a human safety issue.
Q: Do levels of dioxins in farmed salmon exceed established safety levels?
A: No. The new study clarifies that current feeding practices for farmed salmon often increase organic toxin levels above those in wild salmon. But this does not raise any new food safety concerns because the amounts are still considered low. The levels remain below safety limits set by the FDA, EU and WHO.
"It's the dose that makes the poison," toxicologists say. In other words, people consuming normal amounts of salmon should not have a problem.
Q: Is farmed salmon as nourishing as wild salmon?
A: Farmed salmon has greater amounts of fish oils, providing more health-promoting omega-3 fatty acids than ocean-run salmon. On the other hand, because organic toxins accumulate in the body fat of fish, salmon that are fatter tend to carry a bit more of these toxins.
Salmon, including farmed salmon, has lower levels of mercury than most fish. It is a good substitute for fish such as swordfish and tuna that have higher mercury levels.
See the Columnists section for some past articles.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, UH-Manoa. Dr. Dobbs also works with the University Health Services and prepares the nutritional analyses marked with an asterisk in this section.