TUESDAY, Aug. 14, 2001 (HealthDayNews) -- Break out the sippy cups. A look at the long-term effects of soy formula on child development shows that people who drank the milk substitute as babies are as healthy as those who nursed on cow's milk.
The finding, reported in the latest issue of the Journal of the American Medical Association, is based on research conducted in Iowa during the 1960s and 1970s that looked at the impact of soy formula and cow's milk on hundreds of infants.
Soy formulas have long been a valuable alternative for babies who have trouble digesting or are allergic to cow's milk.
Soybeans contain high levels of compounds called isoflavones, which are plant versions of the female hormone estrogen. Also called "phytoestrogens," they may guard against a variety of cancers, vessel disease, weak bones and other health problems, experts say.
But since estrogen is an important sex hormone, some researchers have speculated that infants exposed to isoflavones in soy milk may be getting an unhealthy dose of the plant hormone that could affect their reproductive development down the road.
In the latest work, led by University of Pennsylvania epidemiologist Brian Strom, the researchers surveyed 811 subjects, now adults, about their puberty, menstruation and reproduction, as well as their height, weight and dozens of other health outcomes. Nearly 250 had nursed on soy formula; the rest were fed cow's milk.
The groups were similar in all but two categories: women fed soy formula as infants said they had slightly longer menstrual periods -- about eight hours, on average -- and a greater risk of extremely painful periods.
"Exposure to soy formula does not appear to lead to different general health or reproductive outcomes than exposure to cow-milk formula," the researchers write. "Although the few positive findings should be explored in future studies, our findings are reassuring about the safety of infant soy formula." The differences that did turn up were likely due to chance, the researchers say.
"Breast milk is the ideal and recommended source of nutrition for infant feeding," says a statement by the International Formula Council, which helped fund the latest research. "However, if parents choose or need to formula-feed their infant, physicians and other health-care professionals are best qualified to help parents decide when a soy formula may be appropriate for their infant."
Mardi Mountford, executive director of the council, says soy beverages make up about 20 percent of the $3 billion annual formula market.
The American Academy of Pediatrics in 1998 endorsed soy formula. "In term infants whose nutritional needs are not being met from maternal breast milk or cow-milk-based formulas, isolated soy-protein-based formulas are safe and effective alternatives to provide appropriate nutrition for normal growth and development," the group says. But soy formula "has no advantage over cow-milk protein-based formula as a supplement for the breast-fed infant," nor is it recommended for very low-weight preemie babies, the academy says.
Dr. Norman Carvalho, an Atlanta pediatrician, says parents shouldn't worry about giving their infants soy-based formulas. But he says they should be wary of feeding their children unfortified soy milk, which doesn't always contain the calcium and vitamin D vital for healthy bone growth.
What To Do
To learn more about infant formulas, check Parenthood.com. For more on soy products in particular, try the U.S. Food and Drug Administration or the University of Illinois.
For general information, and even some recipes, try Soyfoods.com.
