Concerns regarding the safety of soy formula were raised after two studies revealed that the amounts of soy isoflavone genistein, a chemical found in commercial soy formulas, might inhibit the intestinal growth in babies.
There is a great deal of merit surrounding this concern, particularly because nearly 25 percent of formula-fed babies in the United States consume soy formula.
Commercial soy formulas contain anywhere from 32 to 45 milligrams of genistein. These concentration levels exceed the amount found to affect menstrual cycles in women. Since formula is the only source of nutrition for infants during their first four to six months of life, a period in which several critical organ systems are developing, researchers were motivated to study the possible effects of genistein.
Two Soy Studies Show Same Results -- Slowing of Cell Reproduction
The first study involving the treatment of intestinal cells in culture with genistein that included the same amount found in soy formula showed that the cells ceased to grow. One researcher did point out that the actions observed in cells in culture might not be the same as those in infants.
The second study was made up of two groups of piglets: one group was fed cow's milk-based formula and the other was given formula supplemented with genistein at the amount it is found in soy formula.
It was discovered that the piglets given the genisten formula displayed 50 percent less proliferating cells in the intestine over the group that was fed solely the cow's milk formula. Because the metabolism and physiology of newborn pigs is so similar to human infants, researchers believe these results could be applied to infants.
Researchers of the study cautioned that although the soy formulas might appear to be safe based on some clinical data, these above studies show that it might not come without side effects.
Pediatric Research December 7, 2004. DOI: 10.1203/01.PDR.0000150723.87976.32
Science Daily December 27, 2004