[ RadSafe ] Causes of neural tube defects and their possible prevention

[Steven Dapra]

Jan. 28

         James Salsman wrote:  "Presumably the U.S. and U.K. troops whose 
children are suffering from sharply increasing incidences of birth defects 
are getting enough folate in their diet."

         Yes:  "presumably".  This qualifier undercuts everything else you 
said, James.  It is common knowledge that at least in the United States 
people in general do not eat a proper diet, and in particular they do not 
eat enough fruits and vegetables.

         "The exact cause of spina bifida remains a mystery.   No one knows 
what disrupts complete closure of the neural tube, causing a malformation 
to develop.  Scientists suspect genetic, nutritional, and environmental 
factors play a role.  Research studies indicate that insufficient intake of 
folic acid - a common B vitamin - in the mother's diet is a key factor in 
causing spina bifida and other neural tube defects.   Prenatal vitamins 
that are prescribed for the pregnant mother typically contain folic acid as 
well as other vitamins."   This is from a Spina Bifida Fact Sheet available 
at 
<http://www.ninds.nih.gov/disorders/spina_bifida/detail_spina_bifida.htm>. 
The fact sheet recommends foods high in folic acid such as dark green 
vegetables, egg yolks, and some fruits.  It does not specify which 
fruits.  In a culture (the US) where most people seem to survive on fast 
food, TV dinners, and steak and french fries, how likely are women to get 
their folic acid?  (NINDS is National Institute of Neurological Disorders 
and Strokes.)

         According to another website, "Anencephaly is the single most 
common neural tube defect. The incidence of anencephaly is 1 per 1500 
births in North America, with a higher incidence in the United 
Kingdom."  Also:  "The causes of neural tube defects are multiple. They may 
be part of a syndrome resulting from a single gene defect (Meckel-Grueber 
syndrome), or occur with a chromosomal abnormality, or by a teratogenic 
insult, or by maternal diabetes mellitus. Other causes include the amniotic 
band syndrome, dietary deficiencies, teratogenic levels of zinc, and 
hyperthermia, which affects the closure of the neural tube.

         "Anencephaly, for instance, is a neural tube defect usually 
considered to result from multifactorial influences. Anencephaly may occur 
as part of a monogenic syndrome, chromosome anomaly, teratogenic insult 
(e.g., hyperthermia, folate deficiency), or secondary to amniotic bands."

         Note the listing of diabetes, an increasingly serious public 
health problem, as a possible cause.  This is from 
<http://www.gehealthcare.com/inen/rad/us/education/msucmefh.html>.

         According to <http://vm.cfsan.fda.gov/~lrd/cf101-79.html>, some 
FDA regulations about food labeling,:

         "Prevalence rates for neural tube defects have been reported to 
vary with a wide range of factors including genetics, geography, 
socioeconomic status, maternal birth cohort, month of conception, race, 
nutrition, and maternal health, including maternal age and reproductive 
history. Women with a close relative (i.e., sibling, niece, nephew) with a 
neural tube defect, those with insulin- dependent diabetes mellitus, and 
women with seizure disorders who are being treated with valproic acid or 
carbamazepine are at significantly increased risk compared with women 
without these characteristics. Rates for neural tube defects vary within 
the United States, with lower rates observed on the west coast than on the 
east coast."

         Also:  "It is expected that consumption of adequate folate will 
avert some, but not all, neural tube defects. The underlying causes of 
neural tube defects are not known."

         And: "Adequate amounts of folate can be obtained from diets rich 
in fruits, including citrus fruits and juices, vegetables, including dark 
green leafy vegetables, legumes, whole grain products, including breads, 
rice, and pasta, fortified cereals, or a dietary supplement."

         In summary, neural tube defects (NTDs) have many apparent causes 
but the specific causes are not known.  Folic acid and a better diet may 
help prevent NTDs.  The anti-DU partisans have invoked DU as the cause of 
NTDs and birth defects in general in Iraq.  What is the typical Iraqi 
diet?  I don't know, however my guess is it is not rich in citrus fruits 
and dark green leafy vegetables, especially in the rural areas and in the 
smaller towns.

Steven Dapra
sjd at swcp.com