26 May 2003
catch to eating a lot of fish
As more people turn to seafood as a source of lean protein, the
risk of mercury poisoning rises. Choosing the right varieties could
Jane E. Allen, Times Staff Writer
Fish, Bad Fish
Flynn thought she had a healthy lifestyle. She was thin and active
and she ate well — with lunches of tuna and fresh vegetables
and dinners of halibut, sea bass or swordfish.
she spent over a decade plagued by fatigue, stomachaches and headaches,
as if she had "a wicked hangover." Her hair started falling
out. Memory lapses made her think she was losing her mind.
really felt something was poisoning me, but I couldn't find the
source," said Flynn, 59.
Sausalito anthropologist and documentary filmmaker eventually ended
up in the office of Dr. Jane Hightower, a San Francisco internist.
When Hightower heard that Flynn was eating fish nine times a week,
she immediately ordered a blood test for mercury. A heavy metal
that accumulates in the flesh of fish, especially the popular predatory
varieties, mercury can also accumulate in people who eat those fish.
a detailed description of Hightower's research...
test's stunning result: Flynn's mercury level was 20.6 micrograms
per liter of blood. A safe level is about 5, according to the federal
Environmental Protection Agency.
Flynn, many adults and children may be unwittingly overdosing on
mercury, say Hightower and some public health activists, and it's
likely that most of them are going undiagnosed.
recent years, fish has become the food of choice for millions of
Americans trying to eat more healthfully, with per capita consumption
at about 15 pounds, a 20% increase since 1980.
on weight-loss diets turn to fish as a lean alternative to beef.
Bodybuilders go for the protein; it's not unusual for them to polish
off entire cans of tuna. Others are drawn to the cardiovascular
benefits of Omega-3 fatty acids in fish. Restaurants, meanwhile,
are expanding their portions, often serving as much as a pound at
a time (a normal portion is 3 or 4 ounces).
health benefits are undeniable -- and some people may suspect the
warnings are overblown. This past week, researchers at the American
Psychiatric Assn. meeting announced that fish rich in omega-3s may
prevent depression late in pregnancy and after childbirth. A study
a week earlier in the Lancet found that children in the Seychelles
Islands whose mothers ate a lot of fish during pregnancy showed
no signs of health problems.
though California supermarkets recently began posting warnings about
mercury in fish and the federal government has advised pregnant
women to limit their fish intake, some people still don't get the
message — or don't understand the cumulative effects. Furthermore,
physicians aren't trained to "think fish" when patients
complain of mental fuzziness, fatigue, hair loss and tingling hands
and feet. All can point to thyroid problems, multiple sclerosis,
chronic fatigue syndrome or menopause.
November, Hightower published a report in the online journal Environmental
Health Perspectives, a publication of the National Institutes of
Health, on 123 patients, 89% of whom had excessive mercury she traced
to fish. The study was one of the first to document mercury levels
in people eating more than two servings of fish a week. To date,
Hightower has documented 300 cases of elevated mercury levels in
her patients, mostly upper-income professionals, including a 4-year-old
girl practically living on canned tuna.
is a known poison," Hightower says. "By definition, this
means it is harmful and can make one ill or even kill."
occurs naturally, but is mostly a byproduct of coal-burning, mining
and other industries. Once in the water supply, it forms methyl
mercury, which lingers in fish flesh. As big fish eat smaller fish,
they absorb more of the heavy metal, making predators like swordfish,
shark, tuna and halibut the most toxic; smaller fish like salmon
and shellfish the least. Although fresh tuna tends to have more
mercury than canned varieties, levels in canned tuna can vary from
nearly undetectable to 1 part per million, the level beyond which
the Food and Drug Administration prohibits its sale.
mercury is especially damaging to the developing brains of fetuses
and children. The FDA advises pregnant women to eliminate shark,
tilefish, king mackerel and swordfish, and limit eating of other
fish to 12 ounces a week.
high mercury levels don't always produce symptoms.
Lee, a 30-year-old pre-school teacher from San Francisco, was eating
lots of swordfish, sea bass and halibut last summer while visiting
Boston, Martha's Vineyard and the Hamptons. In August, she told
her gynecologist that she and her husband wanted to have a baby.
The doctor heard about all the fish and ran a mercury test. Lee's
level was 37. Lee gave up fish for a while, got her mercury levels
down and now indulges in the occasional salmon. As for Flynn, she
gave up fish for almost two years. She now eats fish a couple of
times a month, but never touches the predators. Her mercury levels
are normal, her memory is back and she feels good.
anything to excess," Lee says, "and that's when you get