Dear Dr. Garner,
I really enjoy fish, particularly sushi. It’s one of my summer dinner staples since I don’t like to cook when the temperature rises.
However, I’m concerned about mercury poisoning.
What is your advice for people who love fish, but don’t want to consume too much mercury? What are some of the symptoms that might occur when someone’s mercury levels are too high?
Dear Mercury Worries,
The answer to your question is not black and white. Fish and shellfish are important parts of a healthy diet. They contain essential nutrients, are low in fat, and contain Omega-3 fatty acids, essential for heart health. A well- balanced diet that includes a variety of fish and shellfish, can contribute to overall well-being.
The problem is that nearly all fish and shellfish contain traces of mercury. The mercury comes from the natural environment, such as the crust of the earth, and also from industrial waste.
Quantity and Mercury Levels
The risks from mercury depend on the amount of fish and shellfish eaten and the levels of mercury in the fish. The FDA recommends that pregnant women avoid certain types of fish known to be high in mercury. These include: shark, swordfish, King mackerel and tilefish.
They also suggest eating two or three servings per week of fish and shellfish that are low in mercury. Five of the fish with the lowest levels are shrimp, canned light tuna, salmon, pollock and catfish.
A commonly eaten fish, albacore tuna has more mercury than canned light tuna. If you prefer albacore tuna, do not exceed six ounces (one average meal per week). It is important to check local advisories regarding mercury safety of fish caught by family and friends in local rivers and ocean areas. If no advice is available, then eat up to six ounces (one average meal) per week. Fish sticks and fastfood sandwiches commonly have very low levels of mercury.
Symptoms of mercury poisoning include: depression, fatigue, memory loss, confusion, the shakes, a metallic taste and hair loss.
When patients who have these symptoms stop eating fish with high levels of mercury, their symptoms resolve. While no reliable data is available in humans regarding mercury and cancer, studies in rats and mice show mercury can cause increase in several types of tumors, and has caused increased numbers of kidney tumors in male mice.
To find out your level of mercury, your blood, urine and hair samples would need to be analyzed. These tests can be ordered by your doctor and are easy to do. To present a balanced view, governmental agencies believe that as long as one does not consume excessive amounts of the fish highest in mercury then fish can be safely eaten, and its extensive health benefits can be realized.
As a matter of fact, the FDA is considering changing its policy for the majority of fish, realizing their health benefits can outweigh the risks. This new policy would increase the recommended portions of fish per week.
Be Wary When Dining Out
One story reported a couple of years ago regarding sushi was quite disturbing. Sushi from restaurants in New York City were analyzed and results showed mercury levels so high that the FDA could take legal action to remove the fish from the market. The offending sushi was tuna sushi. Mercury levels in bluefin tuna were the highest.
The response from restaurant owners varied from vowing to look for fish with lower mercury levels to not selling tuna sushi any more.
At a popular Park Slope sushi restaurant, the owner said he was aware that bluefin tuna had higher mercury concentrations and that the restaurant typically told parents with small children not to let them eat “more than one or two pieces.”
Here’s what I would suggest:
1. Avoid consuming large quantities of tuna sushi.
2. Eat two to three servings of fish each week, avoiding fish known to have high mercury levels.
3. When using tuna from a can, purchase “light tuna” as opposed to albacore tuna.
4. Pregnant women and children should discuss with their physicians the benefit of eating fish, versus getting essential nutrients from other sources.
I believe most physicians will suggest a moderate approach — not excluding fish, but encouraging eating fish low in mercury two or three times a week.
5. If you’ve been a big sushi eater, and have any symptoms mentioned, ask your physician about testing your mercury level.
Dr. Steven Garner is a Fidelis Care provider who is affiliated with New York Methodist Hospital, Park Slope. He also hosts “Ask the Doctor” on The NET, Tuesdays at 8 p.m. on Channel 97 Time Warner and Channel 30 Cablevision.