From the August issue of Discover Magazine:
Bottle-Fed Eyes
While many of us seek to cut fat from our diet, some babies
may not be getting enough to stay healthy. Over the last
decade, scientists have found that babies born prematurely need
supplements of certain fats--in particular a group of
polyunsaturated fats called omega-threes, in order for their
vision to develop normally. Infants usually get these fats in
their last months in the womb, so premature babies don't get a
full dose. Now vision researcher Eileen Birch and her
colleagues at the Retina Foundation of the Southwest in Dallas
have found that all babies apparently need the fats even a few
months after birth. And, says Birch, not just any fatty acid in
this group will do. She thinks all babies need one called DHA.
Without it, their vision suffers.
Human milk contains DHA, says Birch, but at least a third of
American babies drink only formula from birth, and formula
lacks this fat. DHA is a crucial building block of the
membranes of nerve cells in the retina and brain (and also of
red blood cell membranes)--crucial because it is believed to
keep those membranes fluid and permeable. This is important
because nerve cells depend on the efficient passage of
molecules across their membranes to generate the signals that
transmit visual information from the retina to the brain. Those
membranes develop rapidly from the final three months of
pregnancy to six months after birth, after which they're
essentially set for life. If babies don't get enough dha during
this critical period, another fatty acid takes its place, one
that makes the cell membranes less fluid--and one that may
therefore impair the transmission of nerve signals.
Birch and her colleagues studied 162 infants, none of whom
were born prematurely, for one year. The researchers found that
babies fed formula without DHA had poorer vision than babies
who were given a DHA supplement. The difference between the two
groups, Birch says, is equivalent to about one line on an eye
chart. "It's not as though it's putting them in a poorly
performing group," Birch says. "They're just slightly below
average, and the kids with the supplement are slightly above
average."
Birch says the Food and Drug Administration will decide by next
spring if DHA is necessary for infant development. She expects
the FDA will indeed mandate that DHA be added to infant formula.
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