From ABC radio (australia) http://www.abc.net.au/rn/talks/8.30/helthrpt/ Exposure to Soy-Based Formula in Infancy Broadcast Monday 3 September 2001  with Norman Swan Summary: Over the years soy-based formulae have been criticised because of concerns that the phyto oestrogens in them might affect the reproductive capacity of infants. Researchers at the University of Pennsylvania found that exposure to soy formula does not appear to lead to different general health or reproductive outcomes than exposure to cow milk formula. Transcript: Norman Swan: Letís stay with diet and move to what has been from time to time a rather controversial infant food: soy milk formula. These are artificial milk formulae for babies, made from soy protein rather than cowsí milk. Theyíre often used for cowsí milk allergy and sometimes, perhaps unnecessarily, for babies who are a bit fussy and colicky. Anyway, over the years, soy formulae have been criticised because of concerns that the phyto oestrogens in them might affect the reproductive capacity of infants at a vulnerable stage of their lives. Dr Brian Strom and his colleagues at the University of Pennsylvania School of Medicine in Philadelphia, wanted to find out if that was true. Brian Strom: We studied young adults ages 20 to 34, who as infants had been part of infantsí feeding studies conducted at the University of Iowa, between 1965 and 1978, so these were the first infants first fed soy formula decades ago. Norman Swan: So when companies started producing soy formula, these were the kids that they tested them on? Brian Strom: Exactly. Norman Swan: So you knew exactly what theyíd taken, because theyíd been part of a scientific trial? Brian Strom: Thatís exactly right. Norman Swan: And before you go on, what were they taking the soy for, was this just random studies of healthy children, or was it children with allergies or whatever? Brian Strom: This was just random studies of healthy children. Norman Swan: So now you looked at them 20 or 30 years later. Brian Strom: Right. We compared 248 subjects who received as infants, soy formula to 563 who had received cow milk formula, and then we conducted telephone interviews inquiring for women about adult height, weight, number of days between periods and so on, and many different outcomes that primarily focused on effects that oestrogens might have later in their lives and we asked analogous questions of men as well. And when they reported an abnormality in telephone interview, the physician who was treating them went back to the medical record of that physician to confirm them. Norman Swan: And essentially what did you find? Brian Strom: Essentially we found the groups were identical. The soy formula kids and the cowsí milk formula kids were virtually the same, neither better nor worse. Norman Swan: And you only found menstrual abnormalities in the women? Brian Strom: Yes, we made a large number of comparisons, over 30 comparisons, and the groups were essentially indistinguishable. Menstrual bleeding was slightly longer, about a third of a day per cycle in the women, although without heavier bleeding. Discomfort with menstruation was slightly more common, but given the fact that the other 28 variables were not abnormal, we thought that these minor and borderline differences were probably due to chance. If you do a scientific study with conventional criteria, one out of 20 things you study will be positive just by chance. We studies 30 outcomes, so one would expect one or two outcomes to be positive just purely by random variation. Norman Swan: Presumably this study is too early to look at outcomes such as bone density and the instance of breast cancer. Brian Strom: Absolutely. We asked about such things, but it is too early. Norman Swan: So what you can say here is that soy formula grossly looks safe, that you didnít find an epidemic of cancer, short stature or early breast cancer or anything like that in these kids, but nor was it any better than cowsí milk formula. Brian Strom: Thatís correct. It was just grossly, when it came to things like cancer and so on itís only grossly. When it came to issues of height, weight, puberty, length of periods, fertility, breast size, reproductive outcomes, pregnancy outcomes, homosexual orientation, a lot of the sexually related outcomes that soy has been accused of as a problem, we had adequate sample sizes. Those are things that are apparent in 20 to 34 year olds. I guess thereís really two take-home messages: one is that exposure to soy formula does not appear to lead to any of many different general health or reproductive outcomes, that itís been accused of, any more than exposure to cow milk formula. And the second is that the public needs to be careful about believing accusations of possibly harmful effects of exposures when theyíre based just on theory and case reports rather than good science. Norman Swan: Youíre talking about exposures to synthetic oestrogens in the environment. Brian Strom: This is an example of that, certainly, but my conclusion goes way beyond that in terms of whether youíre talking about electromagnetic fields, whether youíre talking about fluoride in water, or whether youíre talking about use of cell phones. The public gets very scared about many different exposures and possibly harmful effects, and in most cases those accusations are not based on good science. Norman Swan: Brian Strom is Professor of Biostatistics and Epidemiology at the University of Pennsylvania School of Medicine in Philadelphia. And you should just be aware that some of the people involved in this research have received funding from the infant formula industry. Reference: Strom Sister BL et al. Journal of the American Medical Association 2001;286:807-814 Guests: Dr. Brian Strom Professor of Biostatistics and Epidemioloogy University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania email: bstrom@cceb.med.upenn.edu