Vitamin B6 Effects for Women Taking Birth Control Pills
Condition: Vitamin B6 Deficiency
MeSH terms: Vitamin B 6 Deficiency
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      Chronically inadequate B6 nutritional status is associated with aberrant one-carbon (1C)
      metabolism and health. Plasma pyridoxal phosphate (PLP) >30 nmol/L often has been considered
      to be the cutoff indicative of nutritional adequacy, with 20-30 nmol/L considered marginal
      deficiency; however, the current Recommended Dietary Allowance (RDA) value was based on a
      more conservative cutoff of 20 nmol/L plasma PLP. As shown by in the investigators
      preliminary data, biochemical perturbations occur when humans have marginal B6 deficiency
      consistent with plasma PLP of 20-30 nmol/L. A prospective study also showed that plasma PLP
      <23.3 nmol/L is associated with 1.8-times higher risk of recurrent venous thromboembolism
      than those with PLP >23.3 nmol/L. The mechanism by which low B6 intake is associated with
      risk of vascular disease is not known. Since B6-deficiency has little tendency to raise
      fasting plasma total homocysteine (tHcy) but yields an elevated tHcy response following a
      methionine load, low B6 nutriture may lead to repeated transient mild hyperhomocysteinemia
      following meal consumption. Several reports of associations between elevated plasma
      C-reactive protein (CRP) and low B6 status have raised the hypothesis that systemic
      inflammation is prone to occur during B6 deficiency or contributes to low B6 status. The
      investigators previously found that healthy humans in low B6 status caused by dietary
      restriction exhibited normal plasma CRP levels. The investigators also postulate that
      oxidative stress associated with low B6 status, coupled with impaired glutathione synthesis,
      contributes to such risk. These questions indicate the need for a more thorough understanding
      of the metabolic changes occurring in low B6 status from marginal B6 intake and from drug
      interactions such as in women using oral contraceptives.
    

Detailed description: 
      Potential subjects will undergo a prescreening visit to meet the inclusion criteria, have a
      history, physical exam and routine labs drawn. The labs will verify the nutritional
      eligibility of folate, vitamin B12 and vitamin B6. If the inclusion criteria is met then the
      following will take place.

      The subjects will come to the University of Florida (UF) Clinical and Translational Science
      Institute (CTSI) Clinical Research Center (CRC) for a 9 hour infusion (with stable isotope
      labeled serine, methionine and leucine) twice during the research study. Once at the start of
      the study and again at day 29. Blood samples will be taken for metabolite analysis. The
      infusion of nonradioactive, stable isotope labeled amino acids allows determination of the
      rate of metabolic reactions in one-carbon metabolism. The results from all subjects' blood
      analyses will provide us with information about rates of several parts of metabolism and
      vitamin B6 status.

      During the 2-days prior to the infusion a controlled diet will be required. The subjects will
      be fed at the CTSI CRC. Dietary calculations and formulations will be conducted by using
      Minnesota Nutrition Data Systems software. Subjects will come to the CRC twice per day where
      they will meet with staff, consume morning and evening meals, and will be provided a sack
      lunch and snacks (including weekends). Protein intake will be kept constant.

      After the first infusion, all subjects will consume their self-selected usual diets for 28
      days along with a commercial B6 supplement providing 10 mg/day. Weekly measurement of blood
      will be used to verify compliance. All subjects will then consume a 2-day controlled diet at
      the UF CRC to normalize protein intake, followed by an infusion procedure identical to the
      first.

      During the 4-week supplementation period, all subjects will come to the CRC weekly for
      weighing, blood samples, and consultation with staff. Careful screening, close monitoring and
      education of subjects, along with weekly monitoring of blood levels, all contribute to a high
      degree of compliance.
    

Intervention name(s): Vitamin B6; Infusion of labeled serine, methionine and leucine
Intervention type(s): Dietary Supplement; Procedure
Intervention description(s): Subjects will receive vitamin B6 supplementation.; Subjects will be given an infusion of the stable isotope labeled amino acids, serine, methionine and leucine prior to vitamin B6 supplementation and after 28 days of B6 treatment. In addition, they will receive a special diet 2 days prior to the infusion and will have weekly weight, blood, and visits to the clinic.
Other intervention name(s): pyridoxine HCl supplement; USP pyridoxine HCL
Intervention MeSH terms: Pyridoxine; Pyridoxal; Vitamin B 6
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: oral contraceptives; Vitamin B6; birth control pills; amino acids; Vitamin B6 deficiency; Vitamin B6 deficiency in women on oral contraceptives