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.