Arabinose
It is not clear whether elevated urinary levels of arabinose detected
in by the
Organic Acid Test
are simply a marker for yeast dysbiosis, or are pathogenic in their own
right.
It has been hypothesized that arabinose, being an aldol (reducing)
sugar which contains an aldehyde functional group, may contribute to
pathology by reacting with the terminal ammonia group of the amino acid
lysine, which is found in many proteins of the body, to form a
pentosidine, which may further react with an arginine in an adjoining
protein strand to form a pentosidine link [Shaw2008, pg 36].
The pentosidine link alters the structure and function of the affected
proteins, which may be enzymes.
Dr. Weyrich notes that this is similar
to the mechanisms underlying protein glycosylation, which is measured
by the HbA1c test [Sell1989]. Both protein
glycosylation and formation of pentosidine links are associated with aging -
once these links are formed, they persist until the cell they are associated
with dies and is replaced. Note that neurons are not replaced when they die.
The concentration of pentosidines has been reported to increase linearly
with age [Sell1989].
Elevated urine arabinose has also been found in an autistic child in whom
a brain MRI showed diffuse demyelization [Shaw2008].