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To evaluate the effect of oral contraceptive usage on the nutritional requirement for vitamin B6, control women and oral contraceptive users were depleted of vitamin B6 for 1 month followed by a month of repletion with 0.8, 2.0, or 20.0 mg of pyridoxine hydrochloride per day. At weekly intervals a number of indices of vitamin B6 nutrition were measured. Marked elevation in excretion of tryptophan metabolites occurred in oral contraceptive users after tryptophan loads. However, other indices of vitamin B6 nutritional state, including urinary 4-pyridoxic acid excretion, urinary cystathionine excretion, plasma pyridoxal phosphate concentrations, and erythrocyte aspartate and alanine aminotransferases were not different between controls and oral contraceptive users. The excretion of metabolites after oral loading doses of L-kynurenine (which bypasses tryptophan oxygenase) was elevated in oral contraceptive users indicating that abnormal metabolism of tryptophan was not due only to induced tryptophan oxygenase. The data indicate that use of oral contraceptives does not generally change the requirement for vitamin B6 but rather produces a specific change in activity of enzymes beyond kynurenine in the pathway of tryptophan metabolism.
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
August 1974,
The American journal of clinical nutrition,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
April 1976,
Lancet (London, England),
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
March 1971,
The American journal of clinical nutrition,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
April 1978,
The American journal of clinical nutrition,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
January 1980,
International journal for vitamin and nutrition research. Internationale Zeitschrift fur Vitamin- und Ernahrungsforschung. Journal international de vitaminologie et de nutrition,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
August 1975,
The American journal of clinical nutrition,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
October 1972,
Contraception,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
January 1976,
Advances in clinical chemistry,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
May 1976,
The Journal of laboratory and clinical medicine,
R R Brown, and
D P Rose, and
J E Leklem, and
H M Linkswiler
April 1972,
Clinical science,
