Posted on 01/12/2005 11:05:18 PM PST by Coleus
| Soy Formula May Stunt the Intestinal Growth in Your Baby |
| 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 |
Received March 25, 2004
Accepted November 4, 2004
Division of Nutritional Sciences [A.-C.C., K.A.T., S.M.D.], University of Illinois at Urbana-Champaign, Urbana, IL 61801; and United States Department of Agriculture [M.A.B.], Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL 61604
* To whom correspondence should be addressed. E-mail: sdonovan@uiuc.edu.
Currently 15% of U.S. infants are fed soy formulas that contain up to 14 mg of genistein equivalents/L. Our goal was to investigate the impact of dietary genistein on intestinal development. Piglets (n = 8/group) were fed sow milk replacer (MR), MR + 1 mg/L of genistein (LG), or MR + 14 mg/L of genistein (HG) for 10 d. Formula intake, weight gain, and intestinal length and weight were similar in all groups. Average serum genistein concentration in the HG group was similar to that of soy formula-fed infants. No significant effects of genistein on enterocyte apoptosis, lactase, and sucrase activities or electrophysiologic measures were observed in jejunum or ileum. Jejunal and ileal villus heights were not significantly different, but the percentage of proliferating cell nuclear antigen-positive jejunal crypt cells in the HG was reduced 50% compared with that in MR and LG (p = 0.001), indicating decreased proliferation. Enterocyte migration distance in the HG group tended to be 20% less (p = 0.1) than LG or MR. Jejunal estrogen receptor 
mRNA expression in HG was half of that in LG (p = 0.05), but neither was significantly different from MR. In conclusion, genistein at the level present in soy infant formula is bioactive in the small intestine and results in reduced enterocyte proliferation and migration. The lack of effect of genistein on nutrient transport and enzyme activity suggests that the impact of genistein is greater on proliferating versus differentiated intestinal cells.Abbreviations: BrdU, 5'-bromodeoxyuridine • ER, estrogen receptor • HG, high genistein • ITF, intestinal trefoil factor • LC-MS, liquid chromatography-mass spectrometry • LG, low genistein • LPH, lactase phlorizin hydrolase • MR, milk-replacer • PCNA, proliferating cell nuclear antigen • SP, spasmolytic polypeptide • TFF, trefoil factor
URBANA, Ill. -- Two studies by University of Illinois food science and human nutrition professor Sharon Donovan show that the soy isoflavone genistein, in amounts present in commercial soy infant formulas, may inhibit intestinal cell growth in babies. So what are we to think about soy in a baby's diet?
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Donovan said it's an important question to ask because almost 25 percent of formula-fed babies in the United States consume soy formula. Although babies on soy formula appear to grow normally, these formulas contain very high concentrations of genistein, from 32 to 45 milligrams, which is higher than the amount found to affect menstrual cycles in women, she said.
"I'm struck by the fact that these babies are receiving isoflavones at such high concentrations," Donovan said. "Formula is the sole source of nutrition for these infants for the first four to six months of life, when so many important organ systems are developing."
In the first study, published in the Journal of Nutrition in June 2004, Donovan treated intestinal cells in culture with genistein in the amount present in soy infant formula and found that the cells "basically stopped proliferating." However, actions seen in cells in culture may not be seen in infants, Donovan said.
In a second study, she fed one group of newborn piglets a cow's milk-based formula, while feeding other piglets formula supplemented with genistein at the level found in soy formula. This study will be published in the February 2005 issue of Pediatric Research, but an electronic version was released on line on Dec. 7.
Newborn pigs are an excellent model for human infants because they have a similar metabolism and physiology, Donovan said.
In the piglets fed genistein, the number of proliferating cells in the intestine was 50 percent lower than piglets fed the cow's milk formula alone. Concentrations of genistein in the piglets' blood were similar to those of babies fed soy formula, so these data may be applicable to human infants, the researcher said.
No differences in the activities of digestive enzymes or uptake of nutrients were observed, which suggests that genistein had little effect on mature intestinal cells that were no longer proliferating.
Although these data are the first to show that genistein is bioactive in the neonatal intestine, Donovan said these results do not mean soy formulas should not be fed to babies. "Clinical data suggest that soy formulas are safe," she said, "but even though they appear to be safe, they may not be without effect."
So far, Donovan has studied genistein alone, but soy formulas contain other soy isoflavones that likely affect genistein's actions in the intestine. The researcher plans to study those interactions. "Soy isoflavones may have both positive and negative effects that need to be better understood," she said.
Donovan pointed to recent research that showed adding long-chain polyunsaturated fatty acids to infant formula improves brain and retinal development and even IQ scores. Recent research has also shown that adding nucleotides to baby formula causes babies to react better to vaccinations and make more antibodies, she said.
"And although that research showed differences that were measurable, the babies fed formula with added fatty acids or nucleotides appeared to grow the same as other babies do," she said. "So I don't think you can use growth as the sole parameter for normal development."
An-Chian Chen contributed to the cell-culture study. Other researchers contributing to the piglet study were An-Chian Chen, a doctoral student in nutritional sciences; Mark A. Berhow, an adjunct professor of biochemistry in the UI department of crop sciences and researcher for the USDA-ARS Bioactive Agents Research Unit in Peoria, Ill.; and Kelly A. Tappenden, professor of food science.
Both studies were funded by the Illinois Council on Food and Agricultural Research and the USDA.
I gotta call this place and ask them how they flavor their Soylent Green ice cream. I'm curious what they used as a base. The most revolting choice I could think of would be Spumoni - imagine eating something called "Soylent Green" and having all those chewy things in there...
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