The three most abundant ingredients in
breast milk are fat, lactose, and human
milk oligosaccharides (or HMOs). The
fat and lactose provide calories to
nourish the baby's growing brain and
body, but HMOs are not digestible by
humans. That's correct; one of the main
ingredients in human milk can't be
digested by her baby. Why would
mother's milk be so replete in
something that her baby can't even
digest? Because HMOs aren't for feeding
the baby, they're for feeding the baby's
growing community of gut microbes.
Infants are born with no bacteria in
their gut. The womb is, for the most
part, a sterile environment. But once the
infant leaves this bacteria-free incubator
there is a land rush by microbes to
colonize this fresh landscape. The first
several months of a baby's life are a
chaotic time in the gut. Particular
species of bacteria will suddenly bloom
in abundance and then, for unknown
reasons, subsequently crash. So far
attempts by scientists to uncover a set
of guiding principles, a road map, to
describe how the infant microbiota
develops has been futile. To our eyes the
microbiota seems to form almost
randomly and is individual for each
child. This seemingly disorganized
assembly process may reflect our poor
understanding of the complex
interactions that occur among different
bacteria as they try to create a stable
ecosystem from scratch. But this
apparent randomness does not mean
that nature has left this process
completely to chance. There is a guiding
force ensuring that an infant forms a
robust and stable gut microbiota. This
force is breast milk and specifically the
HMOs that feed this developing
community.
The infant's microbiota, with its
collection of 25 million genes (our
human genome only contains about
20,000 genes) has the capacity to digest
the complex chemical structures found
in HMOs and extract energy from them.
It appears that by no accident of nature,
the bacteria that are the best nourished
by HMOs, such as the Bifidobacteria,
also seem to be those most likely found
in the guts of healthy babies. But HMOs
do more than just feed beneficial
bacteria the baby needs while nursing,
they also help to seed another type of
beneficial bacteria, the Bacteroides. This
group of bacteria has an amazing
capacity to thrive off of plant material.
By giving the Bacteroides an early
advantage, HMOs prepare the baby for
life on solid food. In many ways, HMOs
serve as a conductor, orchestrating the
major transition in microbiota
development that occurs with the
introduction of solid food.
So far formula companies have
not been able to reproduce the
complex chemical structures found
in HMOs. HMOs can only be found
in human breast milk. Infants fed
formula have a different microbiota composition than
breast-fed infants, likely a reflection of the lack of HMOs in formula. Many formula manufacturers are working hard to try
to compensate for their product's
deficiency in terms of microbiota food.
But the fact remains that formula is the
product of about 50 years of research,
whereas human milk, is the result of
thousands of years of human evolution.
This time has allowed the optimization
of human milk for both the health of the
child and their developing microbial
community.
Mothers work hard to guide their
children in making wise choices to
succeed in a world where so many
events are out of her control. HMOs
illustrate, on a molecular level, how a
mother guides yet another process in
her child's life, one that is impacted by
external forces—microbiota assembly.
So the next time a breast-feeding mom
says she's tired, remember she is not
only providing for her baby, she is also
whipping up dinner for about 100
trillion bacteria. And in the form of a
diaper change, she has to clean up after
these dinner guests as well!
References:
Palmer, C., et al. "Development of the
Human Infant Intestinal Microbiota."
PLoS Biol 5.7 (2007): e177. Print.
De Filippo, C., et al. "Impact of Diet in
Shaping Gut Microbiota Revealed by a
Comparative Study in Children from
Europe and Rural Africa." Proc Natl
Acad Sci U S A 107.33 (2010): 14691–6.
Print.
Marcobal A, et al. "Bacteroides in the
infant gut consume milk
oligosaccharides via mucus-utilization
pathways." Cell Host Microbe. 10.5
(2011): 507-14. Print.
Marcobal A, Sonnenburg JL. "Human
milk oligosaccharide consumption by
intestinal microbiota." Clin Microbiol
Infect. Suppl 4 (2012): 12-5. Print.
www.josiahdele.blogspot.com
breast milk are fat, lactose, and human
milk oligosaccharides (or HMOs). The
fat and lactose provide calories to
nourish the baby's growing brain and
body, but HMOs are not digestible by
humans. That's correct; one of the main
ingredients in human milk can't be
digested by her baby. Why would
mother's milk be so replete in
something that her baby can't even
digest? Because HMOs aren't for feeding
the baby, they're for feeding the baby's
growing community of gut microbes.
Infants are born with no bacteria in
their gut. The womb is, for the most
part, a sterile environment. But once the
infant leaves this bacteria-free incubator
there is a land rush by microbes to
colonize this fresh landscape. The first
several months of a baby's life are a
chaotic time in the gut. Particular
species of bacteria will suddenly bloom
in abundance and then, for unknown
reasons, subsequently crash. So far
attempts by scientists to uncover a set
of guiding principles, a road map, to
describe how the infant microbiota
develops has been futile. To our eyes the
microbiota seems to form almost
randomly and is individual for each
child. This seemingly disorganized
assembly process may reflect our poor
understanding of the complex
interactions that occur among different
bacteria as they try to create a stable
ecosystem from scratch. But this
apparent randomness does not mean
that nature has left this process
completely to chance. There is a guiding
force ensuring that an infant forms a
robust and stable gut microbiota. This
force is breast milk and specifically the
HMOs that feed this developing
community.
The infant's microbiota, with its
collection of 25 million genes (our
human genome only contains about
20,000 genes) has the capacity to digest
the complex chemical structures found
in HMOs and extract energy from them.
It appears that by no accident of nature,
the bacteria that are the best nourished
by HMOs, such as the Bifidobacteria,
also seem to be those most likely found
in the guts of healthy babies. But HMOs
do more than just feed beneficial
bacteria the baby needs while nursing,
they also help to seed another type of
beneficial bacteria, the Bacteroides. This
group of bacteria has an amazing
capacity to thrive off of plant material.
By giving the Bacteroides an early
advantage, HMOs prepare the baby for
life on solid food. In many ways, HMOs
serve as a conductor, orchestrating the
major transition in microbiota
development that occurs with the
introduction of solid food.
So far formula companies have
not been able to reproduce the
complex chemical structures found
in HMOs. HMOs can only be found
in human breast milk. Infants fed
formula have a different microbiota composition than
breast-fed infants, likely a reflection of the lack of HMOs in formula. Many formula manufacturers are working hard to try
to compensate for their product's
deficiency in terms of microbiota food.
But the fact remains that formula is the
product of about 50 years of research,
whereas human milk, is the result of
thousands of years of human evolution.
This time has allowed the optimization
of human milk for both the health of the
child and their developing microbial
community.
Mothers work hard to guide their
children in making wise choices to
succeed in a world where so many
events are out of her control. HMOs
illustrate, on a molecular level, how a
mother guides yet another process in
her child's life, one that is impacted by
external forces—microbiota assembly.
So the next time a breast-feeding mom
says she's tired, remember she is not
only providing for her baby, she is also
whipping up dinner for about 100
trillion bacteria. And in the form of a
diaper change, she has to clean up after
these dinner guests as well!
References:
Palmer, C., et al. "Development of the
Human Infant Intestinal Microbiota."
PLoS Biol 5.7 (2007): e177. Print.
De Filippo, C., et al. "Impact of Diet in
Shaping Gut Microbiota Revealed by a
Comparative Study in Children from
Europe and Rural Africa." Proc Natl
Acad Sci U S A 107.33 (2010): 14691–6.
Print.
Marcobal A, et al. "Bacteroides in the
infant gut consume milk
oligosaccharides via mucus-utilization
pathways." Cell Host Microbe. 10.5
(2011): 507-14. Print.
Marcobal A, Sonnenburg JL. "Human
milk oligosaccharide consumption by
intestinal microbiota." Clin Microbiol
Infect. Suppl 4 (2012): 12-5. Print.
www.josiahdele.blogspot.com
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