Taken from BJU International January 2000;85:107-113
In 1998, investigators reported that the daily exposure of infants to isoflavones in soy infant formula is 6 to 11 times higher on a body-weight basis than the dose that has hormonal effects in adults consuming soy foods. Circulating concentrations of isoflavones in infants fed soy-based formula were 13,000 to 22,000 times higher than plasma oestradiol concentrations in infants on cow’s milk formula. Approximately 25 per cent of bottle-fed children in the US receive soy-based formula – a much higher percentage than in other parts of the Western world. Fitzpatrick estimated that an infant exclusively fed soy formula receives the oestrogenic equivalent (based on body weight) of at least five birth control pills per day. By contrast, almost no phytoestrogens have been detected in dairy-based infant formula or in human milk, even when the mother consumes soy products.
THYROID PROBLEMS IN BABIES
Scientists have known for years that soy-based formula can cause thyroid problems in babies. But what are the effects of soy products on the hormonal development of the infant, both male and female? Male infants undergo a “testosterone surge” during the first few months of life, when testosterone levels may be as high as those of an adult male. During this period, the infant is programmed to express male characteristics after puberty, not only in the development of his sexual organs and other masculine physical traits, but also in setting patterns in the brain characteristic of male behaviour.
In monkeys, deficiency of male hormones impairs the development of spatial perception (which, in humans, is normally more acute in men than in women), of learning ability and of visual discrimination tasks (such as would be required for reading). It goes without saying that future patterns of sexual orientation may also be influenced by the early hormonal environment. Male children exposed during gestation to diethylstilbestrol (DES), a synthetic oestrogen that has effects on animals similar to those of phytoestrogens from soy, had testes smaller than normal on maturation. Learning disabilities, especially in male children, have reached epidemic proportions.
Soy infant feeding – which began in earnest in the early 1970s – cannot be ignored as a probable cause for these tragic developments. As for girls, an alarming number are entering puberty much earlier than normal, according to a recent study reported in the journal Pediatrics. Investigators found that one per cent of all girls now show signs of puberty, such as breast development or pubic hair, before the age of three; by age eight, 14.7 per cent of white girls and almost 50 per cent of African-American girls have one or both of these characteristics.
EARLY SEXUAL DEVELOPMENT
New data indicate that environmental oestrogens such as PCBs and DDE (a breakdown product of DDT) may cause early sexual development in girls. In the 1986 Puerto Rico Premature Thelarche study, the most significant dietary association with premature sexual development was not chicken – as reported in the press – but soy infant formula. The consequences of this truncated childhood are tragic. Young girls with mature bodies must cope with feelings and urges that most children are not well-equipped to handle. And early maturation in girls is frequently a harbinger for problems with the reproductive system later in life, including failure to menstruate, infertility and breast cancer.
VEGETARIAN DIET IN PREGNANCY LINKED TO BIRTH DEFECT
Mothers who ate a vegetarian diet during pregnancy had a five-time greater risk of delivering a boy with hypospadias, a birth defect of the penis. The research team suggests that phytoestrogens, hormone-like compounds found in soy, may be responsible for the link.
Interestingly, the researchers also found that mothers who took iron supplements and those who had influenza in the first 3 months of pregnancy also had a higher risk of having a baby boy with hypospadias. The authors suggest that more research is needed to see if any of the associations found in the study actually cause the birth defect.
It is important to note that there is biological evidence that vegetarians have a greater exposure to phytoestrogens and thus a causal link is biologically feasible.
Hypospadias is a birth defect where the opening of the penis is found on the underside of the penis rather than at the tip. It is a common congenital defect, affecting about 1 in 300 newborn males. The condition requires surgery to correct it, where the foreskin is used to repair the problem. Untreated, it can interfere with urination and sexual function.
The investigators asked mothers to fill out questionnaires during pregnancy regarding obstetric history, lifestyle, and dietary practices. Of 7,928 boys born to mothers participating in the study, 51 cases of hypospadias were identified.
Mothers with a vegetarian diet in the first half of pregnancy had a 4.99 times greater risk of having a boy with hypospadias compared with mothers who included meat in their diets, the researchers report. In addition, mothers who took iron supplements had double the normal risk of having a boy with hypospadias, and influenza during the first 3 months of pregnancy increased the risk of by just over three times.