I've reviewed this research quickly - and actually spoke (via email) with one of the lead researchers a few weeks ago who participated in this research - and its increasingly looking like prenatal choline has a number of benefits in addition to enhancing brain function. In this new research it is suggested that prenatal choline will prevent, or lower the risk of aggressive breast cancer in the babies of mothers that took higher levels of choline (in eggs) during their pregnancy. Here is the full report from the researcher's press release:
Eating eggs when pregnant Reduces Risk of Aggressive breast cancer in offspring
New research shows that the 'genetic impact' of a pregnant woman's diet has a profound effect on her child
A
stunning discovery based on epigenetics (the inheritance of
propensities acquired in the womb) reveals that consuming choline--a
nutrient found in eggs and other foods--during pregnancy may
significantly affect breast cancer outcomes for a mother's offspring.
This finding by a team of biologists at Boston University is the first
to link choline consumption during pregnancy to breast cancer. It also
is the first to identify possible choline-related genetic changes that
affect breast cancer survival rates.
"We've known for a long
time that some agents taken by pregnant women, such as
diethylstibesterol, have adverse consequences for their daughters,"
said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal.
"But there's an upside. The emerging science of epigenetics has yielded
a breakthrough. For the first time, we've learned that we might be able
to prevent breast cancer as early as a mother's pregnancy."
The
researchers made the discovery in rats by studying females whose
mothers were fed varying amounts of choline during pregnancy. Different
groups of pregnant rats received diets containing standard amounts of
choline, no choline at all, or extra choline. Then the researchers
treated the female offspring with a chemical that causes cancer of the
mammary gland (breast cancer). Although animals in all groups developed
mammary cancer, the daughters of mothers that had received extra
choline during pregnancy had slow growing tumors while daughters of
mothers that had no choline during pregnancy had fast growing tumors.
"Our
study provides additional support for the notion that choline is an
important nutrient that has to be considered when dietary guidelines
are developed," said Krzysztof Blusztajn, Ph.D., Professor of Pathology
at Boston University and the study's senior researcher. "We hope it
will be possible to develop nutritional guidelines for pregnant women
that ensure the good health of their offspring well into old age."
The
researchers also found multiple genetic and molecular changes in the
rats' tumors that correlated with survival outcomes. For example, the
slow growing tumors in rats had a genetic pattern similar to those seen
in breast cancers of women who are considered to have a good prognosis.
The fast growing tumors in mice had a pattern of genetic changes
similar to those seen in women with a more aggressive disease. The
researchers also found evidence that these genetic changes may result
from the way that choline affects modifications of the DNA within the
mammary gland of fetuses as they develop in the womb.
The
National Cancer Institute estimates that there will be more than
184,000 new cases of breast cancer in 2008 and more than 40,000 deaths.
Treatments for women suffering from breat cancer range from hormone
therapy to surgery.
A new study by researchers from three of America's top
universities suggests U.S. women aren't getting adequate amounts of a nutrient
thought to promote normal fetal brain development.
Sponsored by the National Institute of Health, researchers
found the average American consumes just 314 milligrams of choline
each day -- much less than the 425 milligrams (women) and 550 milligrams (men)
recommended by government health officials.
Choline is a nutrient essential for
human brain development, normal memory function and fertility, and is thought
to be particularly important during pregnancy. Foods
rich in choline include soy lecithin, beef liver and egg
yolks, although soy lecithin delivers one of the most bioactive and natural
sources of the nutrient without cholesterol or saturated fat.
Accurately estimating per capita choline
intake has been difficult because a food composition database was only recently
made available to the research community. In this analysis, researchers studied
the diets of some 2,000 subjects by comparing data from a food frequency
questionnaire against a new U.S. Department of Agriculture choline database.
"Our research suggests the typical American diet is
lower in choline than recommended," said Steven H.
Zeisel, M.D., one of the study's researchers. "When corrected for energy
intake, daily choline levels were significantly below
the recommended daily intake for both men and women. Although we cannot be sure
from this study, Americans may not understand the importance of choline in their diets, or may not know which foods are rich
in the nutrient."
- New Poll Finds a Public Confused about Choline
-
Most Americans can't say how much choline
they consume each day and don't understand its role in the human diet,
according to an August poll of U.S. adults.
Nearly three-quarters of respondents don't understand or
don't know if they understand what function choline
plays in a person's diet, and only 14 percent said they knew how much of the
nutrient they consume in a day. Respondents over the age of 65 and between the
ages of 25 and 34 were least able to estimate their daily intake.
Nutritionist Greg Paul, Ph.D., thinks choline
consumption would improve if more food manufacturers used a recent Food and
Drug Administration ruling to advertise "Good" or
"Excellent" sources of choline on package
labels.
"The small amount of choline
found in most of today's processed foods makes it difficult for the average
consumer to meet the nutrient's recommended daily intake," Paul said.
"In 2001, the FDA ruled that food manufacturers could make certain claims
about choline on product packages. Increasing the amount
of choline in processed foods and better promoting those
products that are good or excellent sources of choline
are positive steps to help address this public health issue."
Paul said one of the easiest and cost-effective ways to
boost choline
levels in processed foods is to add extra amounts of soybean lecithin, a
naturally occurring emulsifier long used as a functional food ingredient.
The study, "Choline Awareness in America," was conducted by Opinion
Research Corporation's CARAVAN(R) among a nationally representative sample of
1,020 adults 18 years of age and older between August 24 and 27, 2006. Findings
have a margin of error of plus or minus three percentage points at the 95
percent confidence level.
Folic acid is essential for pregnant women to combat neural tube defects in the brains of their children, but so are
other nutrients like choline,
betaine, and methionine.
"Periconceptional intake of folic acid prevents some neural tube defects
(NTDs). Other nutrients may also contribute to NTD etiologies; a likely
candidate is choline," said
G.M. Shaw and associates at the March of Dimes Birth Defects Foundation.
"Similar to folic acid, choline
is involved in one-carbon metabolism for methylation of homocysteine to
methionine."
Shaw and team "investigated whether maternal periconceptional dietary
intakes of choline and its
metabolite betaine influence NTD risk."
They obtained their data "from a case-control study of fetuses and infants
with NTDs among 1989-1991 California births. In-person interviews were
conducted with mothers of 424 NTD cases and with mothers of 440 non-malformed
controls. A standard 100-item food frequency questionnaire was used to assess
nutrient intake," the scientists said.
Their analysis revealed that "[d]ietary intakes of choline were associated with reduced NTD risks. Controlling for
intake of supplemental folic acid, dietary folate, dietary methionine, and
other covariates did not substantially influence risk estimates for choline."
Additionally, Shaw and colleagues reported, "NTD risk estimates were
lowest for women whose diets were rich in choline, betaine, and methionine. That is, for women whose intake
was above the 75th percentile compared with below the 25th percentile for all
three nutrients, the odds ratio was 0.17
"Study findings for dietary components other than folic acid offer
additional clues about the complex etiologies of NTDs," they concluded.
Shaw and colleagues published their study in the American Journal of
Epidemiology (Periconceptional dietary intake of choline and betaine and neural tube defects in offspring. Am J
Epidemiol, 2004;160(2):102-109).
Source: March of Dimes Birth Defects
Foundation, California Birth Defects Monitoring Program, 1917 5th Street., Berkeley, CA94710USA.
Two compounds found in some shampoos, diethanolamine (DEA) and
triethanolamine (TEA), may seep through the skin, into the brain, and block the
ability of neurons to take up choline. Steven H. Zeisel, M.D., Ph.D and
colleagues at University
of North Carolina at Chapel Hill believe the reduction in choline update may reduce neural cell replication.
The research in animals centers around diethanolamine (DEA), a
chemical used in shampoos, lotions, creams and other cosmetics. DEA is used
widely because it provides a rich lather in shampoos and keeps a favorable
consistency in lotions and creams, but there's also some research that shows it
may rob the brain of its ability to make memory cells.
"Depending on the treatment, some mice are stupid, some are
not," said researcher Dr. Steven Zeisel.
In the modern scientific telling of the ancient story Samson was
shampooed by Delilah and he became so dumb she was able to manipulate him to do
her bidding without cutting off his hair.
The risk from this effect is much greater for fetuses and babies than for adult humans.
Dr. Zeisel says if the dea-hypothesis holds true, the memory
impact would probably be minimal in adults. But it could have a bigger effect
on the developing brain, during pregnancy and the first few years of life.
Dr. Zeisel is investigating whether choline supplementation can
counteract the effect of DEA and TEA.
The US National Institutes of Health National Library of Medicine
happens to have an online database of household products and their ingredients.
Check out the lists of Shampoo/Conditioner
and Shampoo products and
what each contains. It doesn't appear that all products are listed. Also, the
ingredient lists look like what you find by reading the side of the bottle
anyway. Still, if you want to check a number of different products while still
remembering the names of these chemicals it is pretty quick to do.
Now, working with nerve tissue derived from a human cancer known
as a neuroblastoma, the UNC researchers have discovered why more choline causes
stem cells -- the parents of brain cells -- to reproduce more than they would
if insufficient choline were available.
A report on the findings will appear in the April issue of the
Journal of Neurochemistry. Authors are doctoral student Mihai D. Niculescu and
Dr. Steven H. Zeisel, professor and chair of nutrition at the UNC schools of
public health and medicine. Dr. Yutaka Yamamuro, a former postdoctoral fellow
in Zeisel's laboratory now with NihonUniversity in Japan, was a
key contributor.
"We found that if we provided them with less choline, those
nerve cells divided less and multiplied less," Zeisel said. "We then
went on to try to explain why by looking at genes known to regulate cell
division."
Scientists focused on cyclin-dependent kinase inhibitor 3 genes,
which keep cells from dividing until a biochemical message turns the genes off,
he said. They found exactly what they expected.
"We showed that choline donates a piece of its molecule
called a methyl group and that gets put on the DNA
for those genes," Zeisel said. "When the gene is methylated, its
expression is shut down."
But when the gene is under-methylated -- such as when there's not
enough choline in the diet -- then it's turned on -- halting or slowing nerve
cell division, he said.
"Nature has built a remarkable switch into these genes
something like the switches we have on the walls at home and at work,"
Zeisel said. "In this very complicated study, we've discovered that the
diet during pregnancy turns on or turns off division of stem cells that form the
memory areas of the brain. Once you have changed formation of the memory areas,
we can see it later in how the babies perform on memory testing once they are
born. And the deficits can last a lifetime."
The next step, Zeisel said, will be confirm that the same things
happen in living mouse fetuses when the mothers receive either high or low
doses of choline.
Five years ago, University of North Carolina (UNC) at Chapel Hill researchers first reported finding that the
nutrient choline played a
critical role in memory and brain
function by positively affecting the brain's
physical development.
Differences in development influenced action, the scientists and their
colleagues found. In animal experiments conducted at DukeUniversity,
both young and old rats performed significantly better on memory tasks if they
received enough choline before
birth compared with same-age rats whose mothers were fed choline-deficient diets. The latter
showed deficits in the hippocampus and septums of their brains.
Because humans and rodents are so similar biologically, something comparable
probably happens in humans, the investigators believe.
Now, working with nerve tissue derived from a human cancer known as a
neuroblastoma, the UNC researchers have discovered why more choline causes stem cells - the
parents of brain cells - to
reproduce more than they would if insufficient choline were available.
A report on the findings appears in the April 2004 issue of the Journal of
Neurochemistry. Authors are doctoral student Mihai D. Niculescu and Dr. Steven
H. Zeisel, professor and chair of nutrition at the UNC schools of public health
and medicine. Dr. Yutaka Yamamuro, a former postdoctoral fellow in Zeisel's
laboratory now with NihonUniversity in Japan, was a key contributor.
"We found that if we provided them with less choline, those nerve cells divided less and multiplied less,"
Zeisel said. "We then went on to try to explain why by looking at genes
known to regulate cell division."
Scientists focused on cyclin-dependent kinase inhibitor 3 genes, which keep
cells from dividing until a biochemical message turns the genes off, he said.
They found exactly what they expected.
"We showed that choline
donates a piece of its molecule called a methyl group and that gets put on the
DNA for those genes," Zeisel said. "When the gene is methylated, its
expression is shut down."
But when the gene is under-methylated - such as when there's not enough choline in the diet - then it's turned
on, halting or slowing nerve cell division, he said.
"Nature has built a remarkable switch into these genes something like the
switches we have on the walls at home and at work," Zeisel said. "In
this very complicated study, we've discovered that the diet during pregnancy
turns on or turns off division of stem cells that form the memory areas of the brain. Once you have changed formation
of the memory areas, we can see it later in how the babies perform on memory
testing once they are born. And the deficits can last a lifetime."
The next step, Zeisel said, will be confirm that the same things happen in
living mouse fetuses when the mothers receive either high or low doses of choline.
Developing babies get choline
from their mothers during pregnancy and from breast milk after they are born,
he said. Other foods rich in choline
include eggs, meat, peanuts and dietary supplements. Breast milk contains much
more of this nutrient than many infant formulas.
Pregnancy and nursing make female rats - and presumably women - especially
susceptible to becoming choline
deficient, the scientist said. The months before and immediately after
childbirth appear to be special times when women need more in their diets.
Choline is a vitamin-like
substance that is sometimes treated like B vitamins and folic acid in dietary
recommendations. The body uses it in making the nerve messenger chemical known
as acetylcholine and in building cell membrane - the biological "wrapper"
that keeps cells from leaking.
A paper Zeisel's laboratory published in January in the Journal of Nutrition
also showed that the nutrient folic acid is not just critical for brain development in embryos during
the earliest stages of pregnancy, but it's a key to healthy brain growth and function late in
pregnancy too.
Humans and other mammals lacking sufficient folic acid shortly before they are
born can suffer lifelong brain
impairment, the earlier UNC animal studies indicated. Such research can never be
done directly in growing human fetuses for obvious reasons.
"In the past few years, folic acid has been the single greatest success
story in nutrition and in preventing birth defects," Zeisel said.
"Spina bifida, the early birth defect in which the spinal cord doesn't
close, and anencephaly, a condition in which the brain doesn't form normally, can be eliminated between 50% and 85%
of the time if women get sufficient folic acid before they become
pregnant."
A new study by Scott Swartzwelder and other researchers at DukeUniversityMedicalCenter
suggests that choline taken during pregnancy can result in "supercharged" brains for the infant. The new study shows this is due to having bigger brain cells in key segments of the brain.
Choline,
is found in egg yolks, liver and other meats
- "exactly the kind of things people were told not to eat" due to
their high cholesterol content, says Swartzwelder.
Dr. Shartzwelder believes their results in the rats could translate to humans, and indeed the US
Institute of Medicine added choline to the list of essential nutrients,
particularly for pregnant women, in its 2003 recommendations.
The
implications of the study's findings are "potentially huge"
Swartzwelder believes: "If it turns out that it's true in humans and can
make people smarter their whole lives and forestall age-related memory decline
- that's potentially a very exciting prospect."
Hannah
Theobald, a nutrition scientist at the British Nutrition Foundation, calls the
study "really interesting" but cautions that more research needs to
be done before any recommendations can be made in humans.
Anatomy
and physiology - Behavioural studies have shown giving choline to pregnant rats
improves learning and memory in their offspring. The pups also suffer
significantly less from failing memories as they get old.
However,
it was not known whether choline's effects were on the general brain
environment or whether it fundamentally changed the brain's cells.
"Our
study is the first time anyone has shown that prenatal choline supplementation
actually changes the anatomy and physiology of single brain cells,"
Swartzwelder told New Scientist.
No adverse effects could be seen in the rats, he adds.
The team
gave pregnant rats three to four times their normal intake of choline for six
days. Gestation lasts about 21 days in rats, and the period during which the
rats were fed extra choline roughly corresponds to the start of the third
trimester in women.
Electrical
signals- The pups born were
raised to adulthood and then their brains were examined, in particular the
hippocampus - the area of the brain critical for learning.
This part
of the brain was sliced in a way that preserved its internal circuitry and kept
it alive. A tiny electrode was then used to recording the behaviour of each
cell. The neurons of rats born to mothers given extra choline fired electrical
signals more rapidly and for longer periods, indicating a capacity to
communicate more easily.
The team
then injected a biological dye into the neurons to look at their shape and
structure. The cells from rats receiving prenatal choline supplements were
substantially bigger than those from rats that did not.
"We
are looking at consistent changes in the range of 20 to 25 per cent," says
Swartzwelder. "These are bigger cells with more dendrites, the areas of
the cell specific to receiving incoming signals." He says the combined
changes induced by choline in the physiology and anatomy of the brain cells
would "hotwire" the system.
Better
membranesThe team does not know
exactly how choline boosts brains, but it is known to contribute to the
building of cell membranes during the embryo stage of development. "My bet
is it has something to do this," Swartzwelder says.
Previous
work by Steven Zeiser at the University
of North Carolina has
shown choline alters a crucial gene by adding a methyl group on to it. This
switches off the gene, CDKN-3, which usually inhibits cell division in the
memory regions of the brain.
There is
little information on how much choline women currently take. "But don't be
afraid of eggs," Swartzwelder suggests. "I used to eat a low fat diet
- I've started eating eggs and I'm not even pregnant!"
However,
Theobald warns that some foods rich in choline should be avoided during
pregnancy. For example, liver is also high in retinol which can cause birth
defects. And certain choline-rich fish like swordfish and tuna can also have a
high mercury content, which is harmful to fetuses.
Original Source of Research Study Information: Journal of Neurophysiology (vol 91 April issue)
Biomedical researchers are exploring the
effects of choline in various
arenas. In fact, for several years there has been clear evidence that lack of choline can harm an individual's
liver.
But more recent experiments in animals suggest that the compound can have more
subtle benefits. A few scientists are, for example, investigating hints that
extra choline in the adult diet
boosts brainpower.
Generating far more excitement is evidence that supplemental choline given to a pregnant female can
offer her offspring a wealth of life-long benefits. A growing number of rat studies indicate that choline enrichment in the womb can
alter brain development in ways that facilitate learning later in life.
Prenatal choline may even guard
the brain against toxic assaults and disease, not to mention senility and other
neurodegenerative changes, notes Christina L. Williams, who heads the
department of psychological and brain sciences at DukeUniversity in Durham, North Carolina.
This may explain why the National Institute on Aging has been a major sponsor
of studies investigating effects of prenatal choline enrichment. "After all," quips neuropsychologist
H. Scott Swartzwelder of the DurhamVeteransAffairsMedicalCenter,
"aging begins at conception."
A chemical building block of every cell, choline plays an integral role throughout the body and throughout
life. It's an ingredient of the membranes surrounding cells. It also transports
a cholesterol carrier out of the liver and helps rid the blood of homocysteine,
an amino acid that at high concentrations increases the risk of heart disease.
Furthermore, choline is a
precursor to molecules that relay signals between nerve cells, including those
in the brain.
Though the liver synthesizes choline,
it may not produce adequate amounts, at least from the food that some people in
the United States
eat. Recognizing that a shortage of choline
in the diet causes liver damage, the Institute of Medicine (IOM) in Washington, D.C.,
established the first choline
recommendations three years ago. This organization, which develops daily intake
guidelines for vitamins and other nutrients, advocates eating about 0.5 grams
per day.
Meeting the IOM's dietary-intake goals, however, can be a hit-or-miss
proposition since there is a dearth of data on how much choline most foods contain. Steven H. Zeisel's laboratory at the University of North Carolina
in Chapel Hill has just begun a systematic assay to quantify the choline in commonly eaten U.S. foods.
Performed for the Agriculture Department, the tests should yield data on 300 of
the most popular items by January 2002 and 2,700 more over the following year.
New studies show, too, that prenatal nutrition may influence how much of the
nutrient an individual requires. Moreover, the IOM's nutrition guidelines were
developed to prevent liver damage, whereas optimum health may require more choline.
More than a decade ago, Williams and her husband, Warren H. Meck, also at Duke,
began their studies of choline's
impacts on rat brains.
Meck, a neuroscientist, had been enriching the diets of adult rats with choline in hopes that it
might improve their performance in certain memory tests. He knew that choline was a building block of
acetylcholine. A chemical that nerve cells use in signaling, it plays an
important role in memory.
Recalls Williams, "I asked if he had considered administering choline early in development,"
when the brain structures central to memory were forming. He hadn't.
So, Meck and Williams launched a study in which they gave pregnant female rats water laced with choline. This supplementation roughly
quadrupled the animals' normal choline
intake. For a few weeks after birth, the pups received injections of additional
choline.
The scientists then tested these offspring throughout their short lives on
their recall of locations in a maze where the researchers had hidden food. The
experiment measured whether the rats
could remember--and not revisit--sites they had already emptied as they sought
out the remaining food during the day.
"We found that the prenatally supplemented animals clearly outperformed
the others," Williams says. With repeated testing, scores improved for
many of the animals in both the supplemented group and an unsupplemented group
that served as a control. Yet even after 16 weeks of daily testing, she notes,
the supplemented rats continued
to make fewer errors than the others did.
One aspect of the results was even more startling, Williams notes. The more
difficult the tests of memory and learning became, the bigger the apparent
benefit of that prenatal enrichment. The best explanation is that the choline-supplemented offspring could
"hold more information," Williams told Science News. "We know of
no other treatment that increases memory size."
Her group and others have repeatedly confirmed the findings. "What's so
amazing," Williams contends, is that the aptitude for learning in
prenatally supplemented animals "is as good in old age as it was when they
were young. They show no decline." In contrast, animals not supplemented
prenatally with choline show
signs of senility in old age. It appears that, with supplementation,
"we're building a better brain," she says.
Nuances in choline action are
showing up. By narrowing the window of prenatal supplementation, Williams and
others have identified only two small periods during which extra choline boosts a rat's intelligence. The first is from
days 12 to 17 in gestation. This correlates roughly with the second half of a
human pregnancy. The other window runs from two to four weeks after birth--a
period that corresponds loosely with human infancy and toddlerhood.
Recently, scientists have begun delving into what underlies that first
malleable period. It coincides with the formation of a complex network of choline-sensitive nerve cells that
sends information to a region of the brain known as the hippocampus, Williams
notes. This area is active in learning and memory.
Five years ago or so, Williams and other researchers asked Swartzwelder to look
for signs that early choline
exposure somehow changes the brain. Dubious that a week of prenatal enrichment
could smarten animals, much less trigger detectable physiological changes, he
nonetheless agreed to a pilot study.
The results changed his perspective.
In a hippocampal neuron, certain patterns of incoming chemical signals can
trigger a response called long-term potentiation. During this response, newly
arriving signals are more effective than under other conditions. The process
helps cement memories by "promoting the encoding and consolidation of new
information. It's the first step in learning," Swartzwelder explains.
Compared with hippocampal tissue from unsupplemented animals, brains primed
with prenatal choline showed
long-term potentiation more readily, Swartzwelder found. When he then turned to
brains from animals whose mothers had been choline-deficient, he found hippocampal circuits unusually
resistant to the effect.
It appeared that choline is
"powerful stuff," Swartzwelder recalls. But to make sure of his
results, he repeated the analyses, using rats reared and treated by a different group of researchers.
Again, he saw the same effect. Overall, the greater the prenatal exposure to choline, the larger the effect on the
brain.
That was two years ago. Now, Swartzwelder is focusing on glutamate, a primary
chemical messenger responsible for triggering long-term potentiation. Brain
cells have specialized protein complexes, called NMDA receptors, that respond
to glutamate. They don't promote long-term potentiation unless they receive
closely timed signals from other brain cells.
Swartzwelder's team has now shown that NMDA receptors in the brains of animals
that received prenatal choline
enrichment are unusually responsive to signals. This finding suggests that
these animals might make memories more readily than others do.
Prenatal supplementation with choline
can also protect the brain later in life. That finding, to be published soon in
the Journal of Neuroscience, is "the wildest thing of all,"
Swartzwelder says.
His group and its collaborators find evidence that choline can influence the effects of a toxic drug. Prenatal
supplementation protects neurons in the brains of adolescent rats from the cell death ordinarily
associated with high doses of a drug that blocks the NMDA receptors.
Last year, prenatal choline
supplementation in another study prevented memory defects following
drug-triggered brain lesions. The researchers used a drug that induces
convulsive epileptic seizures in rodents. Epileptic seizures not only damage
the brain, but they also tend to impair memory and learning.
Gregory L. Holmes of Harvard Medical School's Center for Research in Pediatric
Epilepsy in Boston and his colleagues administered the neurotoxic drug to
rodents--some of which had received prenatal choline supplementation--and then monitored the animals' learning
skills.
Using a standard test of spatial memory, the researchers daily released each rat into a pool of milky water and
waited for the animal to find a stationary platform just beneath the surface.
Animals that had not experienced seizures oriented themselves more quickly
every day. This learning showed up in rats
whether or not they had received prenatal choline supplementation.
After the experienced rats
developed epilepsy, however, the pattern changed. When tested a week after
seizures, prenatally supplemented animals remembered where the platform was and
in succeeding days continued to improve their performance. But rats that had received no prenatal choline supplementation acted as if
they had no memory of where the platform had been and showed less improvement
in finding it during the following days.
If studies of people confirm an effect of prenatal choline on the brain's response to assaults after birth, Holmes'
team wrote in the November 15, 2000 Journal of Neuroscience, these findings
"could lead to nutrition-based preventive strategies." The authors
liken the possibility to the use of folate vitamins now routinely prescribed to
pregnant women to prevent neural tube defects in the fetus.
Jan Krzysztof Blusztajn of BostonUniversity, a co-author
on that paper, has been probing biochemical differences that arise from
prenatal choline
supplementation.
Three years ago, he showed that extra choline
available during hippocampal development permanently modifies that area's
efficiency in using the nutrient. When choline
concentrations in the womb are low, the brain becomes "very frugal"
with this nutrient, Blusztajn says, whereas the choline metabolism of animals that encounter an abundance in the
womb "becomes quite wasteful." Prenatal conditions probably determine
how much choline an adult
requires.
His studies indicate that an overly frugal hippocampus may lead to problems.
Its parsimony may leave little choline
free to perform mentally demanding activities
With a low stockpile of choline,
production of the neurotransmitter acetylcholine may prove insufficient to
carry sustained high-throughput communications between memory neurons. They
just poop out and learning slows. However, Blusztajn reports that prenatally
supplemented rats "have
some sort of cognitive reserve--which is probably also a biochemical reserve.
It lets them sustain longer [choline-fueled]
neurotransmission."
Evidence is emerging that choline
supplementation in adulthood, too, may sometimes improve memory. This result
comes from a study of people who, because of gastrointestinal problems, receive
virtually all of their nutrition intravenously. Manufacturers don't regularly
fortify with choline most
nourishment that's administered intravenously.
"We now know that between 20% and 50% of patients receiving [intravenous]
nutrition long-term develop liver disease," notes Alan L. Buchman of NorthwesternUniversityMedicalSchool
in Chicago.
Some die; others may survive with transplants. In the September-October Journal
of Parenteral and Enteral Nutrition his team reports on a pilot study of 15
volunteers with gastrointestinal problems who were receiving intravenous
nutrition. Signs of liver damage disappeared in those seven who had been
randomly assigned to receive supplemental choline for 24 weeks.
The researchers also administered IQ and other tests to 11 participants. These
initially scored below normal on verbal, memory and visual memory tests. In the
January-February Journal of Parenteral and Enteral Nutrition, the scientists
reported that those scores improved "significantly" in the men and
women receiving supplemental choline.
This suggests, they said, that severe choline
deficiency in adulthood may impair memory reversibly.
Zeisel is beginning several more human trials. In one, resembling the animal
experiments, 80 pregnant women will be given specially prepared waffles and
asked to eat one with each meal from about 15 weeks into their pregnancy until
a month after their baby is born. Some of the women will get normal waffles,
the rest will get ones fortified with either one egg or its choline equivalent in the form of soy
lecithin.
When the women's babies are 10 and 12 months old, psychologists will test the infants'
visual memory--the child's recall of where Mom's picture last appeared.
Zeisel has also just launched the first detailed analysis of how much choline people need for basic health.
Eighty volunteers will be held, Zeisel says, for 71 days in a university
metabolic ward. Everything they eat and excrete will be measured. The
food--resembling heavily fortified milk shakes--will initially carry a normal
range of recommended nutrients. Then, all the participants will be switched to
a choline-free version.
They'll remain on that diet until enzymes indicative of liver damage begin
appearing in their blood. At that point, Zeisel says, "we'll begin adding
back increasing amounts of choline
until we discover how much it takes to return each to normal."
Because the test will include men and women, blacks and whites, and
premenopausal and postmenopausal women, it should determine whether particular
groups differ in their needs.
Today, few people exhibit overt choline
deficiency. Zeisel suspects, however, that at least some teeter on the brink of
insufficiency. Because the best-known choline-rich
foods tend to be animal products, especially ones high in fat, he worries that
vegans and those who have successfully pared most fat from their diet may be
vulnerable.
Don't be afraid of eating eggs despite their cholesterol, he chides. Their
yolks are among the richest known natural sources of choline. A tall glass of skim milk offers as much choline as an egg does. And coming
soon, predicts Gregory Paul, director of nutrition for Central Soya of Fort
Wayne, Indiana, will be a host of foods--orange juice, baked goods, and
pasta--fortified with choline-rich
soy lecithin.
So, keep an eye out for those new choline
labels, Williams says; they'll help identify "what we call food for
thought."
New research is increasingly identifying Choline as a key nutrient for the brain and liver. In the past research has shown that while the liver synthesizes choline, it may
not produce adequate amounts, at least from the food that some people in the United States
eat. Recognizing that a shortage of choline in the diet causes liver damage,
the Institute of Medicine (IOM) in Washington,
D.C., established its first
choline recommendations 3 years ago. This organization, which develops daily
intake guidelines for vitamins and other nutrients, advocates eating about 0.5
gram per day.
Meeting IOM's dietary-intake goals, however,
can be a hit-or-miss proposition since there is a dearth of data on how much
choline most foods contain. Steven H. Zeisel's laboratory at the University of North Carolina
in Chapel Hill has just begun a systematic assay to quantify the choline in
commonly eaten U.S.
foods. Performed for the Agriculture Department, the tests should yield data on
300 of the most popular items by January 2002 and 2,700 more over the following
year.
New studies show, too, that prenatal
nutrition may influence how much of the nutrient an individual requires.
Moreover, IOM's nutrition guidelines were developed to prevent liver damage,
whereas optimum health may require more choline.
Enriched diet
Meck, a neuroscientist, had been enriching
the diets of adult rats with choline in hopes that it might improve their
performance in certain memory tests. He knew that choline is a building block
of acetylcholine. A chemical that nerve cells use in signaling, it plays an important
role in memory.
Recalls Christina L. Williams, who heads the Department
of Psychological and Brain Sciences at DukeUniversity, "I asked if he had
considered administering choline early in development," when the brain
structures central to memory were forming. He hadn't.
So, Meck and Williams launched a study in
which they gave pregnant female rats water laced with choline. This
supplementation roughly quadrupled the animals' normal choline intake. For a
few weeks after birth, the pups received injections of additional choline.
The scientists then tested these offspring
throughout their short lives on their recall of locations in a maze where the
researchers had hidden food. The experiment measured whether the rats could
remember and not revisit sites they had already emptied as they sought out the
remaining food during the day.
"We found that the prenatally
supplemented animals clearly outperformed the others," Williams says. With
repeated testing, scores improved for many of the animals in both the
supplemented group and an unsupplemented group that served as a control. Yet
even after 16 weeks of daily testing, she notes, the supplemented rats
continued to make fewer errors than the others did.
One aspect of the results was even more
startling, Williams notes. The more difficult the tests of memory and learning
became, the bigger the apparent benefit of that prenatal enrichment. The best
explanation is that the choline-supplemented offspring could "hold more
information," Williams told Science News. "We know of no other
treatment that increases memory size."
Her group and others have repeatedly
confirmed the findings. "What's so amazing," Williams contends, is
that the aptitude for learning in prenatally supplemented animals "is as
good in old age as it was when they were young. They show no decline." In
contrast, animals not supplemented prenatally with choline show signs of
senility in old age. It appears that with supplementation, "we're building
a better brain," she says.
Narrow window
Nuances
in choline action are showing up. By narrowing the window of prenatal
supplementation, Williams and others have identified only two small periods
during which extra choline boosts a rat's intelligence. The first is from days
12 to 17 in gestation. This correlates roughly with the second half of a human
pregnancy. The other window runs from 2 to 4 weeks after birth - a period that
corresponds loosely with human infancy and toddlerhood.
Recently, scientists have begun delving into
what underlies that first malleable period. It coincides with the formation of
a complex network of choline-sensitive nerve cells that sends information to a
region of the brain known as the hippocampus, Williams notes. This area is
active in learning and memory.
Five years ago or so, Williams and other
researchers asked Swartzwelder to look for signs that early choline exposure
somehow changes the brain. Dubious that a week of prenatal enrichment could
smarten animals, much less trigger detectable physiological changes, he
nonetheless agreed to a pilot study.
The results changed his perspective.
In a hippocampal neuron, certain patterns of
incoming chemical signals can trigger a response called long-term potentiation.
During this response, newly arriving signals are more effective than under
other conditions. The process helps cement memories by "promoting the encoding
and consolidation of new information. It's the first step in learning,"
Swartzwelder explains.
Compared with hippocampal tissue from
unsupplemented animals, brains primed with prenatal choline showed long-term
potentiation more readily, Swartzwelder found. When he then turned to brains
from animals whose mothers had been choline deficient, he found hippocampal
circuits unusually resistant to the effect.
It appeared that choline is "powerful
stuff," Swartzwelder recalls. But to make sure of his results, he repeated
the analyses, using rats reared and treated by a different group of
researchers. Again, he saw the same effect. Overall, the greater the prenatal
exposure to choline, the larger the effect on the brain.
That was 2 years ago. Now, Swartzwelder is
focusing on glutamate, a primary chemical messenger responsible for triggering
long-term potentiation. Brain cells have specialized protein complexes, called
NMDA receptors, that respond to glutamate. They don't promote long-term
potentiation unless they receive closely timed signals from other brain cells
(SN: 9/4/99, p. 149: http://www.sciencenews.org/sn_arc99/9_4_99/fob3.htm).
Swartzwelder's team has now shown that NMDA
receptors in the brains of animals that received prenatal choline enrichment
are unusually responsive to signals. This finding suggests that these animals
might make memories more readily than others do.
Protecting neurons
Prenatal supplementation with choline can also
protect the brain later in life. That finding, to be published soon in the Journal
of Neuroscience, is "the wildest thing of all," Swartzwelder
says.
His group and its collaborators find evidence
that choline can influence the effects of a toxic drug. Prenatal
supplementation protects neurons in the brains of adolescent rats from the cell
death ordinarily associated with high doses of a drug that blocks the NMDA
receptors.
Last year, prenatal choline supplementation
in another study prevented memory defects following drug-triggered brain
lesions. The researchers used a drug that induces convulsive epileptic seizures
in rodents. Epileptic seizures not only damage the brain, but they also tend to
impair memory and learning.
Gregory L. Holmes of Harvard Medical School's
Center for Research in Pediatric Epilepsy in Boston and his colleagues
administered the neurotoxic drug to rodents?some of which had received prenatal
choline supplementation?and then monitored the animals' learning skills.
Using a standard test of spatial memory, the
researchers daily released each rat into a pool of milky water and waited for
the animal to find a stationary platform just beneath the surface. Animals that
had not experienced seizures oriented themselves more quickly every day. This
learning showed up in rats whether or not they had received prenatal choline
supplementation.
After the experienced rats developed
epilepsy, however, the pattern changed. When tested a week after seizures,
prenatally supplemented animals remembered where the platform was and in
succeeding days continued to improve their performance. But rats that had
received no prenatal choline supplementation acted as if they had no memory of
where the platform had been and showed less improvement in finding it during
the following days.
If studies of people confirm an effect of
prenatal choline on the brain's response to assaults after birth, Holmes' team
wrote in the Nov. 15, 2000 Journal of Neuroscience, these findings
"could lead to nutrition-based preventive strategies." The authors
liken the possibility to the use of folate vitamins now routinely prescribed to
pregnant women to prevent neural tube defects in the fetus.
Jan Krzysztof Blusztajn of BostonUniversity,
a coauthor on that paper, has been probing biochemical differences that arise
from prenatal choline supplementation.
Three years ago, he showed that extra choline
available during hippocampal development permanently modifies that area's
efficiency in using the nutrient. When choline concentrations in the womb are
low, the brain becomes "very frugal" with this nutrient, Blusztajn
says, whereas the choline metabolism of animals that encounter an abundance in
the womb "becomes quite wasteful." Prenatal conditions probably determine
how much choline an adult requires.
His studies indicate that an overly frugal
hippocampus may lead to problems. Its parsimony may leave little choline free
to perform mentally demanding activities.
With a low stockpile of choline, production
of the neurotransmitter acetylcholine may prove insufficient to carry out
sustained, high-throughput communications between memory neurons. They just
poop out and learning slows. However, Blusztajn reports that prenatally
supplemented rats "have some sort of cognitive reserve?which is probably
also a biochemical reserve. It lets them sustain longer [choline-fueled]
neurotransmission."
Improving memory
Evidence is emerging that choline
supplementation in adulthood, too, may sometimes improve memory. This result
comes from a study of people who, because of gastrointestinal problems, receive
virtually all of their nutrition intravenously. Manufacturers don't regularly
fortify with choline most nourishment that's administered intravenously.
"We now know that between 20 and 50
percent of patients receiving [intravenous] nutrition long-term develop liver
disease," notes Alan L. Buchman of NorthwesternUniversityMedicalSchool in Chicago. Some die; others may survive with
transplants. In the September-October Journal of Parenteral and Enteral
Nutrition, his team reports on a pilot study of 15 volunteers with
gastrointestinal problems who were receiving intravenous nutrition. Signs of
liver damage disappeared in those seven who had been randomly assigned to
receive supplemental choline for 24 weeks.
The researchers also administered IQ and
other tests to 11 participants. They initially scored below normal on verbal
memory and visual memory tests. In the January-February Journal of
Parenteral and Enteral Nutrition, the scientists reported that those scores
improved "significantly" in the men and women receiving supplemental
choline. This suggests, they said, that severe choline deficiency in adulthood
may impair memory reversibly.
Zeisel is beginning several more human
trials. In one, resembling the animal experiments, 80 pregnant women will be
given specially prepared waffles and asked to eat one with each meal from about
15 weeks into their pregnancy until a month after their baby is born. Some of
the women will get normal waffles, the rest will get ones fortified with either
one egg or its choline equivalent in the form of soy lecithin.
When the women's babies are 10 and 12 months
old, psychologists will test the infants' visual memory?the child's recall of
where Mom's picture last appeared.
Minimum requirements
Zeisel has also just launched the first
detailed analysis of how much choline people need for basic health. Eighty
volunteers will be held "captive, " Zeisel says, for 71 days in a
university metabolic ward. Everything they eat and excrete will be measured.
The food"resembling heavily fortified milk shakes" will initially carry a
normal range of recommended nutrients. Then, all the participants will be
switched to a cholinefree version.
They'll remain on that diet until enzymes indicative
of liver damage begin appearing in their blood. At that point, Zeisel says,
"we'll begin adding back increasing amounts of choline until we discover
how much it takes to return each to normal."
Because the test will include men and women,
blacks and whites, and premenopausal and postmenopausal women, it should
determine whether particular groups differ in their needs.
Today, few people exhibit overt choline
deficiency. Zeisel suspects, however, that at least some teeter on the brink of
insufficiency. Because the best-known choline-rich foods tend to be animal
products, especially ones high in fat, he worries that vegans and those who
have successfully pared most fat from their diet may be vulnerable.
Don't be afraid of eating eggs despite their
cholesterol, he chides. Their yolks are among the richest known natural sources
of choline. A tall glass of skim milk offers as much choline as an egg does.
And coming soon, predicts Gregory Paul, director of nutrition for Central Soya
of Ft. Wayne, Ind., will be a host of foods?orange juice, baked goods, and
pasta?fortified with choline-rich soy lecithin.
So, keep an eye out for those new choline
labels, Williams says; they'll help identify "what we call food for
thought."
A new study out of Duke University suggests some important benefits of supplementation during pregnancy with choline.
Pregnant rats fed
extra doses of an essential nutrient called choline produced offspring whose
brain circuits were "wired" to learn and remember far more
efficiently than offspring without the supplement, according to a study at Duke
University Medical Center.
Conversely, analysis of brain slices of the offspring of rats deprived of
choline indicated a decrease in memory capability.
The researchers said it is the first time that a common food nutrient has
been shown to cause permanent brain changes in regions responsible for learning
and memory. The findings could have important implications -- especially for
pregnant women and their children -- if choline proves to have the same
memory-enhancing effect in humans, a theory for which considerable evidence
already exists, the researchers said.
Choline is a naturally occurring amino acid found in egg yolks, milk, nuts,
liver and other meats as well as in human breast milk. It is the essential
building block for a memory-forming brain chemical called acetylcholine, and it
plays a vital role in the formation of cell membranes throughout the body.
The Duke researchers found that brain circuits of choline-supplemented rats
were built to accept and retain new information more efficiently than rats that
received normal or substandard amounts of choline prenatally. And that memory
enhancement endured until the rats were 4 months old -- the equivalent of early
adulthood in humans.
Specifically, the research showed that choline enhanced a brain function
called long-term potentiation (LTP), in which the act of receiving an
electrical stimulus or "message" actually paves a pathway allowing
future messages to reach the nerve cell more easily -- similar to the way that
rain water creates a furrow through soil upon repeated downpours, enabling even
a small trickle to find its way more easily.
If further research confirms the findings in humans, then choline could
potentially be used to ensure normal memory function in the population at large
through a modest change in diet, said Scott Swartzwelder, a neuropsychologist
at Duke and the Durham VA Medical Center and lead author of the study. Results
of his study, funded by the National Institute on Aging, will be published in
the April issue of the journal of Neurophysiology.
"The ramifications of this research could be profound, because we've
found that manipulating one single nutrient for a few days during gestation has
a lifelong effect on brain function," Swartzwelder said. "In theory,
we could develop ways to significantly reduce age-related memory deficits."
Swartzwelder said the amount of choline the pregnant rats received was well
within normal limits -- about three times more than the control group received.
The only time they received additional choline was during a five-day period --
days 12 through 17 -- of their 22-day gestation period. The control group
received a normal dietary amount of choline, and a third group was virtually
deprived of choline.
Not surprisingly, Swartzwelder said, the brains of choline-deprived rats
were slower to engage the process of LTP and required a much larger stimulus to
initiate LTP than the other rats.
While Swartzwelder's research is not the first to demonstrate choline's
effects on memory, his is the first study reported to pinpoint the specific
brain process that choline enhances.
In previous choline studies conducted at Duke, researchers showed that rats
exposed to choline prenatally were better able to learn and remember the
location of food in a maze, as well as to locate and swim to safety on a hidden
platform in a water-filled maze. And, their memory abilities lasted well into
old age. That research, conducted by Christina Williams and Warren Meck of Duke
-- both co-authors of the current study -- was among the first to show that
choline has a behavioral effect on memory in animals.
But until now, there has never been a physiologic explanation as to why
these behavior changes occurred, said Williams, chair of the department of
psychology at Duke. So, based on her behavioral studies, Swartzwelder set out
to explain how choline alters memory function. By analyzing brain slices from
the offspring of rats in each group, Swartzwelder showed that rats deprived of
choline prenatally did not respond to even the largest electrical stimulus
applied to their brain's hippocampus -- the region where LTP occurs. But the
offspring of choline-supplemented animals responded very quickly and easily to
the smallest electrical stimulus, indicating their hippocampus was primed to
learn.
"What this suggests is an actual change in brain circuitry brought
about by added choline during a critical window of prenatal development,"
Swartzwelder said. "The brains of choline-supplemented rats have a greater
plasticity, or an ability to change and react to stimuli more readily than
other rats."
Precisely why LTP occurs more readily in the choline-supplemented rats is
unclear, Swartzwelder said. But there are several likely scenarios. One
hypothesis is that extra choline permanently alters the developing brain
circuits so they are built with either more acetylcholine receptors, or they
have a greater capacity to produce acetylcholine.
A second possibility is that something inside individual nerve cells is
altered to respond to acetylcholine more readily, regardless of the amount of
acetylcholine present. In yet a third scenario, researchers hypothesize that
there is no significant change in acetylcholine brain circuitry. Rather,
choline affects a completely different neurotransmitter system, such as
glutamate.
Swartzwelder said the next step is to examine the biochemistry within the
various brain circuits to see which neurotransmitter systems are likely to play
a role in enhancing LTP.