In fact, it's about as low as that of children who were fed mother's milk, European researchers report.

It is the latest claim to be made for such supplementation, which has been said to improve either vision or intelligence or both. And the new claim is made on the basis of a carefully controlled study backed by a scientific theory. Nevertheless, it is drawing a wary response from at least one pediatrician.

The study was done at four European centers. A report in the May 3 issue of the British Medical Journal says that at 6 years of age, the 71 children given the supplemented formula had blood pressure readings 3 millimeters lower than those of the 76 children in the unsupplemented group. And the supplemented group's readings were about the same as that of 88 children who were breast-fed.

The result is important because "blood pressure does appear to track from childhood into adulthood," says study author Dr. J. Stewart Forsyth, a consultant pediatrician at the Tayside Institute of Child Health in Dundee, Scotland. Adult high blood pressure is one the strongest risk factors for heart disease and stroke.

The theory is that the long chain polyunsaturated acids are absorbed in the cells of the endothelium, the delicate tissue that lines the blood vessels, Forsyth says, making them less vulnerable to the fatty deposits that eventually can block a blood vessel.

Until recently, it was assumed that "infants were able to make these long chain fatty acids from short-chain fatty acids in formula," Forsyth says. Newer research shows that is not so, he says.

But the study results may not be as convincing as they seem, says Dr. Michael Wasserman, a pediatrician at Ochsner for Children, a New Orleans branch of the Ochsner Clinic.

There was a high dropout rate in the study, with only about 40 percent of the children who enrolled at the start completing it, he says, and there were differences between the groups that might cloud the results.

But the main reason for skepticism is that high blood pressure is "a multidimensional condition influenced by many factors," Wasserman says. "You can't look at development of high blood pressure so simplistically. It is multidimensional in ways we don't understand."

Diet is one dimension, Wasserman says, but "you are looking at a big pie. We don't know how big a slice of the pie this is."

The question of using a supplemented formula comes up constantly in his pediatric practice, Wasserman says, because some formula makers advertise the benefits of the supplements. When he is asked, he says, "it probably does no harm and probably does some good."

The gold standard of nutrition early in life is breast-feeding, says the American Academy of Pediatrics, and Forsyth and Wasserman agree.

"I am a great supporter of breast-feeding," Forsyth says. "It is especially important in the first months of life."

More information

Advice on feeding your baby is offered by the American Academy of Pediatrics. The academy also offers A Woman's Guide to Breastfeeding.