Vitamin B6 Effects for Women Taking Birth Control Pills
| Status: | Completed |
|---|---|
| Conditions: | Food Studies |
| Therapuetic Areas: | Pharmacology / Toxicology |
| Healthy: | No |
| Age Range: | 20 - 40 |
| Updated: | 2/7/2015 |
| Start Date: | April 2010 |
| End Date: | June 2015 |
| Contact: | Candy Caputo |
| Email: | Candace.caputo@medicine.ufl.edu |
| Phone: | (352) 273-9023 |
Vitamin B6 Effects on One-Carbon Metabolism
Chronically inadequate B6 nutritional status is associated with aberrant one-carbon (1C)
metabolism and health. Plasma 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 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 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.
metabolism and health. Plasma 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 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 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.
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 CTSI Shands Clinical Research Unit (CRU) for a 9 hour infusion
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.
During the 2-days prior to the infusion a controlled diet will be required. The subjects
will be fed at the CTSI Shands CRU. Dietary calculations and formulations will be conducted
by using Minnesota Nutrition Data Systems software. Subjects will come to the CRU 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, 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. The 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, subjects will come to the CRU 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.
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 CTSI Shands Clinical Research Unit (CRU) for a 9 hour infusion
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.
During the 2-days prior to the infusion a controlled diet will be required. The subjects
will be fed at the CTSI Shands CRU. Dietary calculations and formulations will be conducted
by using Minnesota Nutrition Data Systems software. Subjects will come to the CRU 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, 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. The 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, subjects will come to the CRU 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.
Inclusion Criteria:
- healthy female subjects
- normal screening labs
- normal body weight
- nonpregnant
- Plasma PLP<30nmol/L
Exclusion Criteria:
- history of gastrointestinal surgery
- chronic disease
- vitamin supplementation
- high protein diet
- progesterone
- no smoking
- chronic drug use
- alcoholism
- no vitamin supplementation
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