Fish oil sharpens young preemies' focus.

Babies born quite prematurely enter the world almost fat free. And that poses a double liability: They lack not only a valuable reserve of stored energy, but also the high levels of one fatty acid essential for normal visual development. Researchers now report they can improve the early visual acuity of preemies by fortifying their formula with this nutrient, one of the primary bioactire constituents of fish oil.

In the July AMERICAN JOURNAL OF CLINICAL NUTRITION, Susan E. Carlson and her co-workers at the University of Tennessee in Memphis report a year's worth of visual-acuity measurements for 67 infants, each born about two months early, Though docosahexaenoic acid (DHA) normally accounts for more than one-third of all fatty acids in the brains gray matter and the eye's retina, a fetus begins to acquire large amounts of it only during the last trimester of pregnancy.. Compared to preemies receiving standard preterm infant formula, those drinking fish-oil-fortified formula registered visual-acuity gains for about four months.

In a study published last October, Eileen E. Birch and her colleagues at the University of Texas Southwestern Medical Center in Dallas, also observed early visual benefits among fish-oil-supplemented preemies. Though a more limited investigation than Carlson's, it showed that preemies on a fish-oil-fortifled formula had visual acuity similar to that of term and preterm infants receiving breastmilk. This was true at 57 weeks after conception (17 weeks alter birth for term babies and up to 30 weeks after birth for preemies). Preterm infants on standard, DHA-free preemie formula exhibited notably poorer acuity.

Because early restrictions in visual inputs can permanently alter the development and organization of the brains visual cortex, even temporary decreases in visual function may warrant correcting, maintains vision expert Martha Neuringer of the Oregon Regional Primate Research Center in Beaverton. Moreover, she notes, such impairments may not show up in acuity tests.

Humans can make DHA from another fatty acid in the diet. However, because this system operates inefficiently in infants, it may take preemies months to make up their initial deficit. That's why Carlson now argues that DHA should be considered "a conditionally essential nutrient for the preterm baby?

However, her data also indicate preemies might need another fatty acid (arachidonic acid). And unless the ratio between the two nutrients is balanced, she warns, a baby might encounter subtle, unnecessary side effects.