Abstract:
The effect of oral contraceptives on urinary and plasma vitamin
B₆ as well as erythrocyte transaminase activities was investigated in
women. Five women who were taking oral contraceptives and four
who were not using these drugs served as subjects. They were
apparently healthy and free from any known metabolic disorder. The
subjects, who consumed normal diets, recorded their dietary intake for
three days. Twenty-four hour urine specimens were collected on two
consecutive days by the subjects. On the morning of the second day
blood for the various biochemical measurements was drawn from
fasting subjects. Following the blood drawing the women were given
an oral dose of 3 g of L-methionine. Results of the methionine load
test are reported elsewhere.
The subjects consumed diets that supplied at least two-thirds or
more of their National Academy of Science-National Research Council
(1974) Recommended Dietary Allowances (RDA) for most nutrients except iron and vitamin B₆. The mean dietary intake of vitamin B₆ was 1.57 mg per day for the untreated women and 1.52 for the oral
contraceptive users.
On both days the mean levels of free and total vitamin B₆ in
urine were less in the oral contraceptive users than that in the
untreated controls, but the differences were not statistically significant.
There appeared to be some relationship between dietary intake
of vitamin B₆ and urinary excretion of the vitamin. The methionine
loading dose did not affect the excretion of vitamin B₆
The mean plasma level of vitamin B₆ was lower for the oral
contraceptive users than for the untreated controls although the difference
is not statistically significant. There was, however, a large
variation in values among the subjects taking oral contraceptives.
Two of them had extremely low plasma vitamin B₆ levels. Vitamin
B₆ in the plasma did not appear to be related to dietary intake or
urinary excretion of the vitamin.
Erythrocyte glutamic oxaloacetic transaminase (EGOT) and
erythrocyte glutamic pyruvic transaminase (EGPT) activities with
and without in vitro stimulation with pyridoxal phosphate (PALPO)
were also measured. There were no significant differences between
the two groups in EGOT and EGPT activities with and without in vitro
stimulation. According to the activity indexes (PALPO stimulated
activity/activity without added PALPO) for EGOT and EGPT (Sauberlich et al., 1972), all subjects had adequate vitamin B₆ nutritional status. Activity indexes for EGOT and EGPT did not
appear to be related to urinary or plasma levels of vitamin B₆
Urinary and plasma vitamin B₆ levels and erythrocyte trans-
aminase activities were not related to the length of time the women
had been taking oral contraceptives or the estrogen content of their
oral contraceptive agent.
