http://www.thelancet.com/newlancet/sub/discuss/TOP119/msg00001.html
Re: Aspartame toxicity
From russell@misnet.com
Date Thu, 29 Jul 1999 23:07:04 +0100 (BST)
In reviewing the available literature on aspartame toxicity I have
developed several concerns. First, is the results of the GD Searle study
itself in 1977 which indicated a significant increase in brain tumor
induction in the aspartame fed animals. This appeared to be secondary to
a breakdown product, DKP. Follow up studies with DKP were seriously
flawed, as demonstrated by the Bressler report. It should also be noted
that other tumors appeared in the NutraSweet group including breast
tumors, pancreatic tumors, testicular tumors, ovarian tumors and other
tissues. Aspartame has been reported in association with a cutaneous
panniculitis as well in human cases.
The recent study using radiolabeled aspartame that indicated attachment
of the formaldehyde breakdown product to DNA and that the formaldehyde
was cumulative with each dose should cause all of us concern. This is
especially so in relation to oncogene activation and in disorders
associated with elevated rates of DNA damage, such as lupus and the
neurodegenerative disorders. I have found no studies relating to
possible elevation of free radicals with aspartame exposure, but this
certainly deserves review.
Shephard, et al found that aspartame was nitrosated in the GI tract and
that in this form was significantly mutagenic. Such nitrosation,
according to their findings, could also occur in endothelial cells and
stimulated macrophages. This would raise concern not only of
carcinogenic potential but also the stimulation of free radical
generation in blood vessels associated with atherosclerosis. Related to
this finding is another report by Hardcastle and Bruch, in which they
found that macrophages treated with aspartame produced an excess of
leukotrienes and other arachidonic acid metabolites. Yamada, et al found
that aspartic acid inhibited melatonin secretion from the pineal gland.
It has been shown that aspartame consumption does increase aspartic acid
blood levels, especially when consumed with MSG.
Another concern is the formation of stereoisomer when aspartame is
heated. Jeffry Bada has shown that when aspartame is heated there is a
significant conversion of the L-phenylalanine and aspartate to the D-
form. In addition, he found 6 to 10 decomposition products, some of
which are known to have deleterious neurological effects. Elevated
levels of D-aspartate have been described in several of the
neurodegenerative diseases.
The effect of aspartame feeding on blood phenylalanine is of concern to
the pregnant mother and those with newborns as well, since phenylalanine
has been associated with abnormal neural connectivity in the immature
brain. It has been established that PKU carriers develop phenylalanine
blood levels double that of normals. Further, it has been shown that the
placenta concentrates phenylalanine on the fetal side of the
circulation. Matalon, et al demonstrated that in the human a loading
dose of 34mg/kg increased phenylalanine levels greater than 6mg/dl in
14% of normals and 35% of PKU carriers. Of even more concern 5% of
normals and 12% of carriers had blood Phe levels exceeding 10mg/dl. The
National Collaborative Study for Maternal PKU has recommended that
during pregnancy blood Phe should not exceed 6mg/dl. This means that 14%
of the general public could exceed this level when consuming high
intakes of aspartame and that 5% of normal people could exceed 10mg/dl.
One in fifty persons carries a heterozygous gene for PKU. Up to 35% of
such unfortunate individuals, and their babies, would be at risk without
knowing it. Especially, since the babies brain levels would even exceed
that of the mother.
With the complexity of the central nervous system it would be
irresponsible for the FDA to allow the widespread selling of aspartame
without further independent study of the neurophysiological,
neurobehavioral and neurochemical effects of high intakes of this drug
at all ages using chronic studies. I think it is foolish to ignore the
complaints of millions of individuals reporting difficulties with this
substance.
Russell L. Blaylock
Neurosurgeon
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