I recently saw the movie “The Perfect Storm” for the first time. In the scene where George Clooney and Mark Wahlberg are hauling enormous swordfish onto their boat, all I could think was: Excellent source of omega-3, but WAY too much mercury. That’s what happens when you write about health and nutrition every day – it finds its way into just about everything you do.
In an e-Alert I sent you last spring (“Fish in fashion” 4/10/02), I told you about new research on the benefits of fish oil. In two new studies, scientists reported that the omega-3 fatty acids found in fish oil can significantly improve cardiovascular health and cut your risk of heart attack in half. And that’s great news. But in the HSI Forum, a member named Nico asks: “Fish oil capsules are always recommended to overcome the mercury problem, but which fish are they derived from? Wouldn’t they contain mercury too?”
Excellent question. And an important one. And I’ll get to the answer to that in a moment, but first we’ll look at fish. Because I’ve come across some new information that demonstrates just how serious the mercury contamination problem is.
Mercury gets into water primarily through solid-waste incinerators, mines and power plants. Algae absorbs the mercury, tiny zooplankton animals eat the algae, small fish eat the zooplankton, and from there the mercury works up through the aquatic food chain, with the large fish at the top of the chain carrying the highest mercury concentration.
The next step in the food chain, of course, is you and me. And the unfortunate truth is that whether you’re eating a tuna sandwich at the deli or tekka-maki at your favorite Japanese restaurant, you’re almost certainly ingesting mercury, which is highly toxic to humans. Studies show that at high levels, mercury may cause cardiovascular disease, and impair the brain, the nervous system and the immune system.
Last week’s San Francisco Chronicle carried an article about a local doctor of internal medicine who conducted a mercury study with the assistance of her patients. Dr. Jane M. Hightower describes her patients as “coastal affluent” bankers, CEOs, lawyers, etc., who frequently eat ocean fish such as tuna, swordfish, halibut and sea bass.
Dr. Hightower selected 89 patients for evaluation, each of whom either showed symptoms of mercury poisoning (joint pain, memory loss, headache, fatigue) or reported eating large amounts of the types of fish known to carry mercury. Sixty-three patients had blood-mercury levels that were more than twice the recommended “safe” level established by the Environmental Protection Agency (EPA) and the National Academy of Sciences (NAS). Nineteen had four times the safe level.
When Dr. Hightower told her subjects to remove fish from their diets entirely for 6 months, she reported that mercury levels fell dramatically, although some of the patients didn’t show reduced levels for almost half a year.
Are you at risk of mercury poisoning? If you restrict your intake to moderate servings of fish that tend to carry low mercury levels, such as salmon, sole, sardines, tilapia, or small shellfish, then you probably are not at risk. But if you eat tuna, as so many do, you should probably keep your intake as low as possible. And this is especially true of children (who are more susceptible to mercury poisoning than adults) and pregnant women (who may inadvertently harm the developing brain of a fetus).
The EPA and NAS have recommended that a 120-pound person should not eat more than 38.5 micrograms of mercury per week. Six ounces of canned albacore tuna contains 35 micrograms of mercury, while the same amount of fresh tuna contains almost double that amount. Less common in the average diet, but still very popular in restaurants, swordfish contains a whopping 170 micrograms of mercury per 6 ounce serving.
Now, back to Nico’s question about the possibility of fish oil capsules containing mercury. I’m going to let another HSI member, named Lance, field the answer to that one. In the HSI Forum Lance posts this response to Nico:
“I’ve seen independent lab reports on 30-40 different fish oil products. From the cheapest to the most expensive, none of the products contained detectable levels of impurities. That’s probably because most of the fish oil caps sold in this country come from sardines and anchovies caught off the coast of South America. Stillif you want to make absolutely sure there are no toxic contaminants in your fish oil caps, you must ensure they are ‘molecularly distilled.'”
As I’ve mentioned several times in recent e-Alerts, for optimum cardiovascular health, it’s important to keep your intake of omega-3 fatty acids high to maintain a good ratio between omega-3 and omega-6 fatty acids. With the unfortunate presence of mercury in the water cycle, fish oil capsules offer an excellent source of this important nutrient.
To Your Good Health,
Jenny Thompson
Health Sciences Institute
