by Craig Weatherby
Two new scientific reports released yesterday reinforce what we heard at last year’s Seafood & Health conference:
- The benefits of fish to human health outweigh the risks, with certain specific exceptions for children and pregnant/nursing women.
- Fatty, short-lived wild fish such as sardines and Alaska salmon or sablefish are the most beneficial species and the safest as well.
While they differed in their assessments of the benefits of seafood—with the Harvard study expressing more confidence—both reports called fish beneficial to human health, and concluded that most fish are safe for most people to eat.
Harvard study takes firmer stance in favor of fish
The Harvard study concluded, based on the evidence available, that consumption of fish reduces the risk of coronary deaths by 36 percent and total mortality by 17 percent.
Its authors were Dariush Mozaffarian, MD, DrPH and Eric B. Rimm, ScD, with whom we spoke at last year’s Seafood & Health conference in Washington, DC.
They searched all of the available sources to identify reports evaluating four things:
- Intake of fish or fish oil and cardiovascular risk
- Effects of mercury and fish oil on brain development in early childhood
- Risks of mercury to cardiovascular and brain health in adults
- Health risks of dioxins and PCBs in fish
When possible, they analyzed groups of similar studies to pinpoint the benefits and risks as precisely as possible.
The conclusions of their new evidence review give fish the strongest possible endorsement:
“For major health outcomes among adults, based on both the strength of the evidence and the potential magnitudes of effect, the benefits of fish intake exceed the potential risks. For women of childbearing age, benefits of modest fish intake, excepting a few selected species, also outweigh risks.”
Some observers, such as Consumer’s Union, took issue with the extent of the risk reductions or the degree of risk to fetuses, nursing babies, and young tuna-eating children from mercury.
But as Dr. Mozaffarian told the New York Times’ Marion Burros, “While one can argue over the precise size of benefits, even if the benefit is only one-half or one-quarter as large, it still greatly outweighs the risk.”
IOM report takes more cautious tone
A committee established by the US Institute of Medicine (IOM) yesterday issued a report whose conclusions, while definitely positive, were more guarded with regard to the benefits of fish.
The IOM provides independent advice to policymakers, but is best known for setting the dietary allowances for vitamin, minerals, and other nutrients.
These were the five key points made in the IOM report (our comments in parentheses):
- Adult men and women may reduce their risk for cardiovascular disease by consuming seafood regularly.
- There may be additional benefits from fatty fish with high levels of EPA and DHA (such as salmon, sablefish, and sardines).
- Fatty fish such as salmon have lower mercury levels than many lean fish (Note: our young, low-weight albacore tuna is much lower in mercury than standard light or albacore tuna. Likewise, our young, low-weight halibut is much lower in mercury than the much older, larger halibut that dominates the market).
- Women who are or wish to become pregnant may benefit from consuming seafood, especially species like salmon with higher levels of omega-3s. They should avoid shark, swordfish, tilefish, and king mackerel. A reasonable fish intake for them would be two 3-ounce (cooked) servings per week, but they can safely consume 12 ounces per week, and can consume up to 6 ounces of albacore tuna per week (This mimics the current FDA/EPA advice).
- The levels of dioxin and PCBs in commercial fish generally do not pose health risks (Most farmed salmon are much higher in dioxin and PCBs compared with wild salmon, but the IOM found that even these higher levels are too low to present a significant risk).
- Institute of Medicine. Seafood Choices: Balancing Benefits and Risks. Accessed online October 17, 2006 at http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=11762
- Mozaffarian D, Rimm EB. Fish Intake, Contaminants, and Human Health Evaluating the Risks and the Benefits. JAMA. 2006;296:1885-1899.
- Burros M. One Study Calls Fish a Lifesaver, Another Is More Cautious. Accessed online October 18, 2006 at http://www.nytimes.com/2006/10/18/dining/18fish.html.