Today, almost all current nutritional advice includes fish as a cornerstone of a healthful diet. But my recommendations are slightly different from those of other respected health authorities. While the differences may seem minor, they are significant, and I contend that they will make it possible for you to achieve extraordinarily good health and an extraordinarily long life span.
Fish: a mixed bag
Fish and shellfish contain high concentrations of protein and other essential nutrients, are low in saturated fat, and contain the valuable omega-3 fatty acids, EPA and DHA. These food factors are thought to contribute to heart health and to children's proper growth and development (there is overwhelming evidence confirming the health benefits of omega-3 fatty acids), which is why fish and shellfish are considered to be an important part of a well-balanced diet. Unfortunately, in addition to EPA and DHA, nearly all fish and shellfish contain mercury and other pollutants. Since these toxins in fish have potential health risks, wouldn't it make sense to look for a cleaner, safer source for our omega-3 fats?
Fish polluted with mercury
Nearly all fish and shellfish contain traces of methylmercury. Mercury accumulates in fish when polluted water is filtered through their gills. The longer a fish lives, the more the mercury accumulates. Large fish eat small fish and accumulate all of the mercury that was in the small fish. Over a lifetime, this mounts up exponentially. Likewise, our tissues accumulate the mercury of all of the fish we eat throughout our lifetimes.
Authorities could warn us not to eat species of fish that contain high amounts of mercury. Instead, they warn us not to eat them too often, based on the misguided notion that the benefits of eating fish outweigh the potential harm from the exposure to mercury.
It has been demonstrated conclusively that fish contain enough mercury to harm an unborn baby or harm a young child's developing nervous system. Since the risks from mercury in fish and shellfish depend on the levels of mercury in the fish and shellfish and the amount of fish and shellfish eaten, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) advise pregnant women, women who may become pregnant, nursing mothers, and young children to avoid some types offish and only eat fish and shellfish that are lower in mercury.
The advice given by governmental authorities includes:
1. Never eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury.
2. Check local advisories about the safety of eating local fish caught by family and friends in local rivers and coastal waterways. If unsure, don't eat more than six ounces at a meal, and do not eat any other fish during that week.
EPA makes recommendations for what it considers an acceptable level of mercury in a pregnant woman's body. As the recognition that mercury damages the brains of our children has increased in the last two decades, EPA has had to lower the "acceptable" level more than once.
I have been telling patients for years that if something can damage a fetus and result in childhood learning abnormalities, it can't be a practice that promotes long-term health and wellness in adults. You can't have it both ways. The developing fetus may be seen as a sensitive indicator of the potential of toxins to cause cellular damage.
This potential damage is a risk to adult cells as well. We just may not see the damage in adults in as short a period of time. Subtle cellular damage from mercury can be a contributory factor in combination with other negative influences that lead to the development of diseases seen later in life. So it is not just youngsters who are at risk of brain damage.
Safe levels a myth
No fish is completely free of mercury and other pollutants. If you eat fish regularly, your body is undoubtedly high in mercury. You cannot remove the mercury from the fish by trimming the fat or by cooking because it is deposited throughout the fish's tissues. I've observed that a person's mercury level correlates exceptionally well with the amount of fish consumed, and medical studies back up this observation. Individuals eating fish a few times a week have been found to have blood mercury levels exceeding the maximum level recommended by the National Academy of Sciences, which is a blood level of below 5 micrograms. Women eating seafood more than twice per week have been found to have 7 times the blood mercury levels compared with women who rarely eat fish, and children eating fish regularly were found to have mercury levels 40 times higher than the national mean.1,2
Fish: no brain food
Mercury is poisonous to the brain. Every year, more than 300,000 newborns are thought to develop adverse neurodevelopmental effects because of mercury exposure in utero. Because of their continual exposure to mercury, dentists also are at risk for later life dementia. Female dentists have been shown to have a higher incidence of malformations and aborted pregnancies in their offspring, and male dentists have higher levels of hypospermia (low sperm production) and decreased sperm motility.
Although the FDA wants us to think that eating a variety of fish with different amounts of mercury assures us we will not be harmed by acute mercury poisoning, they do not guarantee we won't suffer from dementia or other diseases of brain aging from the continual accumulation of mercury over the years. High body stores of mercury cause brain damage and memory impairment, leading to dementia in later life.
The risk of brain damage from mercury increases with age and, besides neurological disease, includes hypertension, heart disease, mental disorders, and endocrine diseases.3
Mercury accumulates in one's bloodstream over time. It can be removed from the body naturally (the kidney does continually excrete mercury into our urine), but even after mercury-containing fish are eliminated from the diet,it may take years for the levels to drop significantly.
For women of childbearing age, it is not sufficient to avoid eating fish after becoming pregnant. Fish must be avoided for a few years before conception to guarantee the baby is not harmed by mercury. For the same reason, it is not a good idea to remove amalgam dental fillings during pregnancy because mercury exposure can increase during removal. It is worth noting that fish consumption dwarfs mercury-containing dental fillings as the primary source of mercury in body tissues and breast milk.
Other pollutants in fish
Like mercury, other pollutants, including PCBs, accumulate in fish and in the body tissues of people who eat fish regularly. These pollutants can remain in your body for decades, creating a higher risk of serious diseases such as cancer. These chemicals also can increase the damage to the brain from mercury. People who would be disgusted at the thought of drinking polluted water don't think twice about eating polluted fish with 1,000 times more pollution in it.
Not wild about salmon
Studies published last year showed that dangerous chemicals were ten times higher in farm-raised salmon compared with wild salmon. I commented on this in a prior newsletter, stating that those who eat fish once a week should eat only the wild variety. As concerns have risen about the high levels of pollution and the artificial colors used to turn farm-raised salmon pink, the price and desirability of wild salmon have risen with it.Wild salmon are suddenly appearing in restaurants and food stores everywhere.
Where is all of this wild salmon coming from? A recent article in The New York Times confirmed my suspicions. They reported that most so called "wild Pacific" or "Alaskan" salmon is just farm-raised salmon with a misleading label. In March 2005, the Times tested salmon sold in eight New York City stores, going for as much as $29 a pound, and found that most of the fish was farm raised, not wild (only one sample tested wild).4
They were able to tell the farm raised salmon from the wild salmon because of the presence of the artificial pink food dye, canthaxanthin, manufactured by Hoffman-La Roche. This pharmaceutical company distributes its trademarked SalmoFan (which is a color chart similar to paint store swatches), so fish farmers can choose among various shades used to make the salmon look their pink-orange color. Salmon in the wild have that color naturally from eating pink crustaceans, but those commercially raised have a gray flesh from eating fish meal. Europeans are suspicious of canthaxanthin, which was linked to retinal damage in people when taken as a sunless tanning pill. The British banned its use as a tanning agent, but it currently is still available in the United States.
1. Hightower JM, Moore D. Mercury levels in highend consumers of fish. Environmental Health Perspectives 2003;111(4):604-608.
2. Mahaffey KR, Clickner RP, Bodurow CC. Blood organic mercury and dietary mercury intake. National Health and Nutrition Examination Survey 1999 and 2000. Environmental Health
3. Diakovich MP, Efimova NV. Assessment of health risks upon exposure to mentholated mercury. Gig Sanit 2001;2:49-51.
4. Burros, M. Stores say wild salmon, but tests say farm the risk of myocardial infarction and coronary cardiovascular, and any death in Eastern Finnish Men. Circulation 1995;91:645-655.