(James McGregar)
Ocean fish are almost an ideal nutrient package for
pregnancy and breast-feeding. (Emily Oken)
Women who ate more fish
during pregnancy had babies that had better
scores on tests of development at 6 months
and at 3 years. (Dariush Mozaffarian)
Since seafood is so important
for later health, I think it’s very important
for children and young adults to eat seafood
to establish that healthy
dietary pattern at a young age. (John Kanaeko)
We should not consider fish
as a mercury delivery system. That’s not what it is;
it’s a package of nutrients. We need to look
at those nutrients and see it in its entirety. [synthesizer plays
in bright rhythm] (man) Funding is provided by– The National Oceanic and
Atmospheric Administration; The National Marine Fisheries
Service, Pacific Islands Regional Office; and the members
of Prairie Public (woman)
Is it safe for pregnant
and nursing women to eat fish? (man)
How much fish is safe to eat? (woman)
Is any fish safe to eat? (male narrator)
Fish– what to eat
and how much– has left everyone with
more questions than answers. Is the answer different
for children than for adults? How about women
who are pregnant or nursing? What is the story
when it comes to eating fish? We all know that pregnant women
receive lots of warnings about what to do to protect
their developing babies– exercise, take vitamins,
avoid alcohol and smoking. And mothers want to eat foods
that are good for baby. You’ll get one chance to develop
a brain, and if the brain has not been
developed in an optimal way, then that’s what you’re stuck
with the rest of your life. (narrator)
Medical researchers have learned that omega-3 fatty acids,
particularly DHA, are critical
for brain development. The brain is made of fats
and lipids. and some of these fats and lipids can only be
obtained from the diet, especially DHA, one
of the omega-3 fatty acids. So if you don’t eat enough
omega-3 fatty acids, it has a profound impact
because you literally can’t make a new brain without
adequate amounts of DHA. Sort of like building a house–
you can’t do it without
concrete and 2x4s. If it’s not there, if it’s not
present in the diet, the neurons don’t form correctly, and they
don’t function correctly. Omega-3 fatty acids are found
in minor sources in plants. And so flax seed and walnuts and
soybeans are some sources. But the long-chain omega-3s are only found
in shellfish and fish. And the omega-3 fatty acids can’t be made by humans
to any appreciable extent. So really to get the long-chain
omega-3 fatty acids in the body, you have to eat seafood. (narrator)
Not having enough seafood
in the diet could have major impacts
on the developing brain, both in the womb
and during infancy. DHA is particularly important
for the structure and funcon of the brain and the eye,
the neurologic tissues. And it appears that
the great majority of the DHA that’s in the brain and the eye is taken up in the third
trimester of pregnancy and the first year
or two of life. Some experts recommend women
during pregnancy try to get in about 200 mg of
DHA a day. On average in the U.S.,
pregnant women are getting around 80 mg
of DHA a day. That would be in contrast to
women in Norway, for example, that consume about 300 mg,
in Japan, even higher. And we have one
of the lowest DHA levels in human milk in the world. The Sudan in Africa is below us;
vegan vegetarians are lower. But we are in comparison to some
very severely deprived groups. (woman)
You’re missing something here–
check that out. (narrator)
Such low levels are of concern because the DHA found
in shellfish and fish helps young brains develop
as measured by everything– from their attention span
to IQ scores. The story that is well developed
for the last 30 years on omega-3 fatty acids,
and DHA in particular, is related to neural development,
to visual development. But even recently we’re
finding that DHA is affecting the developing
autonomic nervous system, the developing immune system. So far the story is
if you eat more DHA, there’s benefits
for all the systems. (narrator)
But this story isn’t
reaching the public. Instead of DHA and other
critical nutrients that fish provide, people are
hearing about mercury. (Emily Oken)
We just finished
some focus groups among women about
their fish consumption. Most of the women,
who were all pregnant, had received some information about
the federal mercury advisory that mercury is bad
for the brain, and they should avoid fish
containing mercury, and they got a list. None of them got any advice about the fact that fish
contains beneficial nutrients. Some of them knew that, but none
of them received advice and none of them were told to
eat fish during pregnancy. (narrator)
Pregnant women aren’t
the only group who are missing the message that eating
ocean fish is good for health. Many people
don’t recognize that the current
health advisory from the federal
government over fish
consumption is directed towards
pregnant women. So we’ll have an 80-year-old man
raise his hand and say, “Well, do I really
have to limit my sashimi
consumption because of mercury? That’s crazy! I’ve been eating
fish for all my life.” I say, “Sir, the likelihood
of you getting pregnant at this point is
about like this.” Many analyses have shown that if the general population
lowered their fish intake by even a small amount because
of concern, we’d have many thousands of more
heart disease deaths. And so we don’t want
that focused advisory, which is really
for a focused population, to scare everyone else
away from eating fish. (narrator)
Concern about mercury
in our diet stems from mercury poisonings that
devastated local populations. Fish from the waters
of Minamata Bay had fed local residents
for centuries. But in the 1950s, industrial contamination
of the fish led to tragedy. (Phil Davidson) The Minamata
experience was a poisoning. This was a result of a chemical
manufacturing plant pouring effluent into
the Minamata Bay. The fish were poisoned, and the people who ate the fish
were also poisoned. Levels of mercury in the fish and in the hair of the humans that were poisoned were
extremely high and have never been seen again,
ever, anywhere. (Gary Myers) One of the issues
was the fact that mothers who consumed the
contaminated fish could have minimal
or no symptoms and the infants could be damaged rather severely
with cerebral palsy. (narrator)
These tragic poisonings showed that brain damage in children
could occur with high mercury exposure– hundreds of times higher
than in a normal diet. Fish naturally contain
some mercury which they get
from the aquatic environment. This is because the mercury has
been converted to a form that is easily digested and
absorbed by living tissue– from tiny plankton
to great white sharks. As larger fish eat smaller fish the mercury accumulates
in their muscle tissues. When we eat fish, we take in
the mercury from the fish, and pregnant women pass it along
to their babies. Concerned that pregnant women
eat enough fish to provide DHA but still protect
developing brains, the U.S. Food & Drug
Administration and the U.S. Environmental
Protection Agency issued a joint
fish consumption advisory in 2004 for commercial fish. (Michael Bolger)
Our advisory is specifically
addressed to women who are pregnant
and to children. The focus
of our advisory was on the consumption
of fish, but primarily
on 4 species of fish we were
concerned about. And that is shark, swordfish,
tilefish, and king mackerel. And on the basis of our
assessment, we concluded that pregnant women
should not eat these species. As a matter of prudence,
we also recommended that children
not eat these species. And then we gave some further
advice about the fact that fish is
an important part of the diet, that there are benefits
associated with eating fish, and that for women who are
pregnant we recommended the inclusion of about 12 ounces
of fish on a weekly basis. It does not address
the issue of exposure to the rest of the population. The reason
is because of what we know from
the scientific literature in terms of
human health effects. (narrator)
Studies have been documenting
diet and child development in fish-eating populations
for many years. These studies have
an interesting and sometimes puzzling story. If you look around the world, the people who consume the
largest amounts of fish are in Japan, and the Seychelles
is very high too. In fact, there are
more than 1 billion people who depend on fish
for nutrition every day. (narrator)
In the 1980s,
teams of researchers set out to find out what level
of mercury exposure from normal seafood
could cause harm to children. One team traveled
to the Indian Ocean to the fish-eating population
of the Seychelles Islands. (Phil Davidson) People in the
Seychelles eat a lot of fish. At the time we started the main
study in 1989, the average consumption was 11 fish meals per week. That’s roughly 10 times higher
than the U.S. (narrator)
During this same period,
another team of researchers headed to the Northern Atlantic
Ocean to the Faroe Islands. It’s a unique community where they eat from the very, very top of the marine food chain. Some people just eat
cod and salmon and have relatively low
mercury exposures and some people would eat
a lot of pilot whale along with fish and have
much higher mercury exposures. When we looked at the results
at age 7, we saw very clear deficits that
were associated with their prenatal mercury exposure,
that is, from the mother’s diet during
pregnancy. What determines
the child’s deficits is the mother’s mercury exposure
during pregnancy. Our research in the Faroes has
had a very clear impact because the authorities have
recommended that the population abstain from eating pilot whale. And we have seen mercury
concentrations plummeting, especially in pregnant women. They essentially
don’t eat pilot whale anymore. (narrator)
In the Seychelles Islands, the story wasn’t so clear. When we first started the study, we did not know what to expect. Most of us thought that we were
going to immediately discover an adverse association between prenatal mercury levels
in the maternal hair and the very first measures
of child development. At 6 months,
we didn’t find any association at all. So we kept
looking, thinking that it might
emerge over time. At 66 months of age, we started
seeing evidence of “beneficial,” in quotes, associations between maternal hair mercury
and development outcomes. And we have continued
to find them. This is probably linked to
nutrients in the fish that are ingested at
the same time as the mercury is. (Gary Myers) As we looked
at our data, it became increasingly apparent
to us that although we were not
finding anything directly adverse with
the mercury exposure, fish consumption itself proposed
a lot of benefits. Essentially what we found was
that there were beneficial effects on the
children’s developmental testing from the long-chain fatty acids,
specifically omega-3s, and that there were slightly adverse effects
from the methylmercury, but they more than
balanced each other out. (narrator)
So, developmentally speaking, eating ocean fish
is good for babies. In fact, medical research
indicates that ocean fish is
good for everyone. (Dariush Mozaffarian)
Coronary heart disease is the
leading killer of men and women in this country and in almost
every country in the world. Nutrition has
such an important effect on cardiovascular disease,
and among nutritional factors, omega-3 fatty acids EPA and DHA have among the most powerful
beneficial effects for prevention
of cardiovascular disease. (James McGregar) In populations
where more fish is eaten, and that includes northern
Europe, that includes the Mediterranean area, Japan,
and the shoreline of Asia, there are different positive
trends. Higher omega-3s, things that go
along with the fish consumption, there’s less diabetes,
there’s less depression, there’s less heart attacks,
there’s less stroke. (John Kanaeko)
The national average might be 16 pounds mixed seafood
per year per person. The best
estimate is the state
of Hawaii consumes, per capita,
on average at least 3 times
the national average. (narrator)
People in the United States eat far fewer fish meals than the
medical community recommends. And it’s having an impact. In Boston, Massachusetts,
Project Viva followed
2000 women through pregnancy and assessed the development
of their children. (Emily Oken)
The women in Project Viva were eating on average about one
fish meal a week or less. The women who ate more fish
during pregnancy had babies that had
better scores on tests
of development at 6 months
and at 3 years. The women who ate more fish
during pregnancy also had higher mercury levels
in their blood and hair. But despite that,
the overall effect of fish
consumption was that of benefit. (narrator)
These findings were backed up by a much larger study
in Great Britain. One of the
biggest studies was the study in a population
of mothers and children in the UK called
the ALSPAC study in which
they looked at maternal fish
consumption during pregnancy and child development
though the school years. The ALSPAC study had data on 14,500 pregnancies and the amounts
of seafood intake that the mothers ate
during pregnancy. So we decided
to evaluate the data to test the letter of the 2004
EPA and FDA advisory. That advisory advises women
to eat no more than 12 ounces of seafood per week
and to avoid certain species. So we divided
the group of women in ALSPAC into those that ate no seafood, those that ate some seafood
but didn’t cross the limit, and those who ate more
than 12 ounces per week. We asked
which of those 3 groups had children that did the best? Does a diet deficient in seafood
during pregnancy in the mom have long-term results of harm
for the children when they were 8 years of age? And they found that in several
of the outcomes they tested, including components of IQ
and school performance, that the kids of mothers
who ate more than 2 weekly fish servings,
which is the limit currently recommended by the
federal government, those kids had better developmental
outcomes in school the years. (Joseph Hibbeln) When they ate
less than 12 ounces a week, it was associated with nearly
a doubling of the risk that the children would have
low verbal IQ. We also found that children
had greater social problems and peer problems when their
mothers did not eat sufficient seafood, that is,
they followed the advisory. And the children also had
problems with fine motor control and other indicators
of neural development. So the reviewers and the editors
of the “Lancet” when we published the paper
made us add the words that “following the seafood advisory
was detrimental.” (Emily Oken)
The study in the Faroe Islands
subsequently went back and looked at fish consumption
in their cohort, they found
the mothers who ate more fish had higher
mercury levels, but the fish
consumption was beneficial for
the child outcomes. (narrator)
Researchers were seeing the
importance of eating fish for the healthy development
of children. Women in the Seychelles ate 12 ocean fish meals per week
on average. But the trace amounts
of mercury in the fish didn’t seem to be
harming their children. Children in the Faroe Islands did seem to have effects
from mercury. And most of the mercury
in their mothers’ diets came from eating the mammal
pilot whale– not fish. Why would that matter? Biochemists and biologists think
it might be the presence of another beneficial nutrient
in fish– the element selenium. It was first recognized that
selenium protected against mercury
toxicity. This was back in 1967 when they
did an animal study where they found
that feeding animals an amount of mercury
that would kill them could be completely prevented if they were just given
a similar amount of selenium. (narrator)
Many important processes in the body need selenium
to work properly. We know selenium is important for
brain development from studies
in which the deletion of selium
transport to the brain results in severe neurological
developmental problems. Selenium proteins sequester
the heavy metals such as mercury, cadmium,
and lead. But it takes selenium away
from where it’s needed. (Nick Ralston)
Selenium is the essential
molecule that the body needs. Mercury binds the selenium, taking it
out of place, so it can’t
perform its essential
functions. All of the characteristic signs
and symptoms of mercury toxicity line up exactly
with what we would expect in an organism
with selenium deficiency. (narrator)
Where do we get selenium
in our diet? The USDA
found that 17 of the top 25
sources of selenium in the American
diet are ocean fish. (narrator)
The researchers hypothesized that fish containing more
selenium than mercury could provide enough selenium
to bind with the mercury and still meet the body’s needs. Researchers tested this idea
in laboratory studies. (Nick Ralston)
We gave the selenium
in the form of ocean fish. So we had to get rid of any
excess omega-3s or vitamin D. So it’s only
going to be the protein, which is where
the selenium resides. We were still feeding huge
amounts of mercury, amounts that would otherwise eventually
be lethal to the animals. The animals
that we gave fish protein, the selenium from the protein
offset the mercury binding. And the animals maintained
health, normal growth, and no neural functional
consequences. So we are feeling fairly
confident now that ocean fish
consumption prevents, rather than
contributes, to causing
mercury toxicity. Some see people say
oh yes, but an animal model is not the same as a human. However, it’s very important
for everyone to recognize that all forms of life
that have brains have selenium dependent enzymes
that protect their brains. (narrator)
But what about the studies
that suggested harm from mercury from eating normal amounts
of seafood? Does the selenium explanation
fit the findings of the Faroe Islands study that
showed harm from eating seafood? The studies on which the original
recommendations are based are studies
in which the primary source of mercury in the diet
was from pilot whale, which has
very low levels of selenium. (Nick Ralston)
They contain far more mercury
than selenium. Ocean fish are completely
different than that. Most varieties
of ocean fish that people
consider seafoods contain many
times more selenium
than mercury. (narrator)
Ocean fish are enriched in
selenium because the oceans have been accumulating it
for millions of years. But what about freshwater fish
from lakes and rivers? Selenium is not present
in all freshwater fish. It’s actually a function
of the local geography and what’s in the minerals
in the land. The biggest difference that
I see from the literature and our results is that the
marine fish have a much higher selenium
concentration relative to mercury than do the
freshwater fish. (narrator)
A U.S. Environmental Protection
Agency research team looked at how safe the fish were
based on 2 methods. One method looks only at the
levels of mercury in fish. The second method compares the level of mercury
to the level of selenium. So if we use only
the mercury criterion to evaluate
the condition of the fish
that we’ve caught, we see 12% of those fish that
exceed that mercury criterion. This would result in most cases in states issuing warnings
against eating these fish. On the other hand if we use the selenium-to-mercury
assessment approach, only 2.5% of the fish would fall
into a concern for consumption. The takeaway message
from this is that there’s
a vast difference between evaluating the fish
based on mercury alone versus using the selenium-
mercury assessment approach. And then the freshwater fish may
be susceptible to getting increased amounts of
different kinds of toxicants. That would certainly include
mercury. So you need to be aware
of your local fish advisories in terms of nutrition
during pregnancy. (narrator)
Every state publishes
local advisories for the fish
you can catch yourself. So what does the average
consumer need to know when they go to the store
or restaurant? (Emily Oken)
The average fish consumer who’s
buying fish in the grocery store just wants to know what’s safe. When we conducted these focus
groups of pregnant women, they followed the cautionary
principle often, if there’s any risk, I’d rather
be safe than sorry, but not recognizing because
no one had told them that there is risk to eating
no fish as well. Fish should be a part
of a varied diet because there are essential
nutrients in fish, but make sure that the fish
is low in mercury. (narrator)
Fish low in mercury are perfect
for pregnant and nursing moms. As long as pregnant women stay
away from the 4 fish listed
in the advisory they can safely eat 12 ounces per week
of any fish from the store for the benefit
of their developing baby. For everyone else . . . It’s very important to be very
clear that for adults, there are actually no
recommendations to avoid fish that contain moderate amounts of
mercury or other contaminants. So if somebody eats commercially
purchased fish in the store and just eats a variety of fish,
they don’t need to worry about the very low levels
of toxins in those fish. Generally, dark and oily fish are the richest in omega-3
fatty acids. And as a total nutrient package,
fish like sardines are lovely, containing vitamin D and calcium
and other nutrients. But also salmon and tuna are very rich sources
of omega-3 fatty acids. Whitefish are also useful. Shellfish and other shrimp are
also useful. The critical issue is to eat
that 2 to 3 times a week. (narrator)
Over a billion people
around the world benefit from eating
a diet rich in fish. Ocean fish are almost an ideal
nutrient package for pregnancy and breast-feeding
because it contains high-quality protein,
omega-3 fatty acids. It contains micronutrients as
well as minerals and vitamins. (Susan Carlson)
Women in the United States who choose not to consume fish
during pregnancy or who are not consuming
some kind of supplement of DHA are taking
a risk for the development
of their infant. They may be creating a risk
for themselves as well. During adult life seafood is probably the single most
important food you can eat for cardiovascular health,
just gram for gram, calorie for calorie,
because it reduces the risk of dying from heart disease
by about a third. (Gary Myers)
At this point in time we don’t have
any very good evidence that the levels that you get
from consuming fish actually cause adverse effects
from mercury exposure. And we have really quite good
evidence these days that fish consumption
is important to the development
of the brain in children. (man) Funding is provided by– The National Oceanic and
Atmospheric Administration; The National Marine Fisheries
Service, Pacific Islands Regional Office; and the members
of Prairie Public