Vitamin B6 Effects for Women Taking Birth Control Pills

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.

Conditions

• Vitamin B6 Deficiency

Interventions

DIETARY_SUPPLEMENT

Vitamin B6

Subjects will receive vitamin B6 supplementation.

PROCEDURE

Infusion of labeled serine, methionine and leucine

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.

Sponsors & Collaborators

• University of Florida

  lead OTHER

Principal Investigators

• Jesse Gregory, PhD · University of Florida

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

20 Years

Max Age

40 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2010-04-30

Primary Completion

2014-06-30

Completion

2014-06-30

Countries

• United States

Study Locations