Hi all,
I'm a newbie public health researcher planning to get my PhD in health
psychology to explore motivation for breastfeeding (also a LLL leader, WIC
peer educator, and currently tri/tandem nursing mom of four). This is my
first post. I avidly read your discussions and learn so much from you all. I
just had to share this article from the New York Times on breast milk
sugars. I'm a bit concerned about the discussion of harvesting these sugars
from whey, but I just love the end quote!

-Keleigh Lee
Ann Arbor, Michigan, USA


http://www.nytimes.com/2010/08/03/science/03milk.html?nl=health&emc=healthupdateema6

Breast Milk Sugars Give Infants a Protective Coat

A large part of human
milk<http://health.nytimes.com/health/guides/nutrition/breast-milk/overview.html?inline=nyt-classifier>cannot
be digested by babies and seems to have a purpose quite different
from infant nutrition — that of influencing the composition of the bacteria
in the infant’s gut.

The details of this three-way relationship between mother, child and gut
microbes are being worked out by three researchers at the University of
California, Davis<http://topics.nytimes.com/topics/reference/timestopics/organizations/u/university_of_california/index.html?inline=nyt-org>—
Bruce German, Carlito Lebrilla and David Mills. They and colleagues
have
found that a particular strain of bacterium, a subspecies of Bifidobacterium
longum, possesses a special suite of genes that enable it to thrive on the
indigestible component of milk.

This subspecies is commonly found in the feces of breast-fed infants. It
coats the lining of the infant’s intestine, protecting it from noxious
bacteria.

Infants presumably acquire the special strain of bifido from their mothers,
but strangely, it has not yet been detected in adults. “We’re all wondering
where it hides out,” Dr. Mills said.

The indigestible substance that favors the bifido bacterium is a slew of
complex sugars derived from lactose, the principal component of milk. The
complex sugars consist of a lactose molecule on to which chains of other
sugar units have been added. The human genome does not contain the necessary
genes to break down the complex sugars, but the bifido subspecies does, the
researchers say in a review of their progress in today’s Proceedings of the
National Academy of
Sciences<http://topics.nytimes.com/top/reference/timestopics/organizations/p/proceedings_of_the_national_academy_of_sciences/index.html?inline=nyt-org>.


The complex sugars were long thought to have no biological significance,
even though they constitute up to 21 percent of milk. Besides promoting
growth of the bifido strain, they also serve as decoys for noxious bacteria
that might attack the infant’s intestines. The sugars are very similar to
those found on the surface of human cells, and are constructed in the breast
by the same enzymes. Many toxic bacteria and viruses bind to human cells by
docking with the surface sugars. But they will bind to the complex sugars in
milk instead. “We think mothers have evolved to let this stuff flush through
the infant,” Dr. Mills said.

Dr. German sees milk as “an astonishing product of evolution,” one which has
been vigorously shaped by natural selection because it is so critical to the
survival of both mother and child. “Everything in milk costs the mother —
she is literally dissolving her own tissues to make it,” he said. From the
infant’s perspective, it is born into a world full of hostile microbes, with
an untrained immune system and lacking the caustic stomach acid which in
adults kills most bacteria. Any element in milk that protects the infant
will be heavily favored by natural selection.

“We were astonished that milk had so much material that the infant couldn’t
digest,” Dr. German said. “Finding that it selectively stimulates the growth
of specific bacteria, which are in turn protective of the infant, let us see
the genius of the strategy — mothers are recruiting another life-form to
baby-sit their baby.”

Dr. German and his colleagues are trying to “deconstruct” milk, on the
theory that the fluid has been shaped by 200 million years of mammalian
evolution and holds a wealth of information about how best to feed and
defend the human body. Though milk itself is designed for infants, its
lessons may apply to adults.

The complex sugars, for instance, are evidently a way of influencing the gut
microflora, so they might in principle be used to help premature
babies<http://health.nytimes.com/health/guides/disease/premature-infant/overview.html?inline=nyt-classifier>,
or those born by caesarean, who do not immediately acquire the bifido
strain. It has long been thought there was no source of the sugars other
than human milk, but they have recently been detected in whey, a waste
byproduct of cheesemaking. The three researchers plan to test the complex
sugars for benefit in premature infants and in the elderly.

The proteins in milk also have special roles. One, called Alpha-lactalbumin,
can attack tumor<http://health.nytimes.com/health/guides/disease/tumor/overview.html?inline=nyt-classifier>cells
and those infected by viruses by restoring their lost ability to
commit cell suicide<http://health.nytimes.com/health/guides/disease/suicide-and-suicidal-behavior/overview.html?inline=nyt-classifier>.
The protein, which accumulates when an infant is weaned, is also the signal
for the breast to remodel itself back to normal state.

Such findings have made the three researchers keenly aware that every
component of milk probably has a special role. “It’s all there for a
purpose, though we’re still figuring out what that purpose is,” Dr. Mills
said. “So for God’s sake, please breast-feed.”

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