Vitamin B6 deficiency

Vitamin B6 is widely distributed in foods, and any diet
so poor as to be insuffi cient in this vitamin would
most likely lack adequate amounts of other B-group
vitamins. For this reason, a primary clinical defi ciency
of B6 in the adult human is rarely encountered under
normal circumstances.
In a well-controlled study conducted by Hodges et
al. (1962), six healthy male volunteers were divided
into pairs and given a basic formulated diet administered
by nasogastric tube twice daily. The fi rst pair of
men received a complete formula including pyridoxine;
the second pair received the same diet without
pyridoxine; and the third pair were given the anti-vitamin
deoxypyridoxine in addition to the pyridoxinefree
diet. The men receiving pyridoxine-free diets, but
not those receiving complete diets, developed adverse
symptoms and signs of illness, which were more
severe in the men given the anti-vitamin. The most
obvious symptoms were gastrointestinal disturbances
and epithelial changes. Both men in the anti-vitamin
group had scaling of the skin, foul breath, severe gingivitis,
soreness and discoloration of the tongue and
dry cracked lips. No objective neurological changes
could be demonstrated. After vitamin B6 was restored
to their diet and the anti-vitamin discontinued, one
man recovered promptly and the other recovered
gradually.
Vitamin B6 deprivation imposed at certain stages of
brain development interferes with the orderly process
of neuronal development (Kirksey et al., 1990). In the
1950s, an occurrence of convulsions in infants was
traced to an unfortifi ed liquid milk-based canned formula
that had undergone autoclaving in manufacture
(Coursin, 1954). There is some circumstantial evidence
that convulsions resulting from vitamin B6 defi
ciency may be caused by an insuffi cient production
of γ-aminobutyric acid, the major neurotransmitter
in the brain (Ebadi, 1978). However, a meaningful
correlation among vitamin B6 defi ciency, concentration
of γ-aminobutyric acid and convulsion has not
been established.