Disorder of Vitamin B12
Conditions
Keywords
Vitamin B12 absorption, Holo-transcobalamin
Brief summary
Vitamin B12 is an essential nutrient that the body needs for cells to divide and function normally. Individuals may develop a deficiency of vitamin B12 by either limiting the amount in the diet or by decreased vitamin B12 intake into the body (absorption). Keeping adequate B12 blood levels is important for health. Vitamin B12 deficiency may increase one's risk for developing anemia and can even lead to neurological problems and paralysis if the deficiency is severe and lasts a long time. It is very important for doctors to have accurate tests to determine if people are absorbing vitamin B12 normally so that treatment can be started before severe clinical problems occur. The purpose of this research is to provide new information that may help scientists develop a better method to test for problems with absorbing vitamin B12. In this study, changes in the amounts of vitamin B12 bound to protein (transcobalamin) in the blood will be measured after doses of vitamin B12 are taken. If the amounts of this vitamin B12-protein complex (called holo-transcobalamin) change in response to taking a vitamin B12 supplement in normal individuals, it may be possible to use this information to develop a new sensitive test to identify individuals who have problems absorbing vitamin B12. This new vitamin B12 absorption test may be a better clinical test for vitamin B12 absorption than those now available for doctors to use.
Detailed description
Part I Screening: Individuals who meet initial screening criteria will be scheduled to have fasting blood samples drawn in the General Clinical Research Center (GCRC). All participants will sign informed consent forms approved by the UF Institutional Review Board prior to the initiation of this part of the study. Subjects' heights and weights will be measured and subjects will be asked to complete a medical history questionnaire. Blood analyses will include serum B12, blood chemistry, and hematological indices. Females will be given a pregnancy test. Subjects eligible for Part II of the study (Intervention) will have serum B12 concentrations that are ≥444 pmol/L; will be non-anemic; and will have normal general blood chemistry (all values within or near the normal range), and no history of chronic disease (e.g., pernicious anemia, cancer, diabetes, renal disease, hypertension, neurological abnormalities, gastrointestinal disorders). Any subject with deficient (\<148 pmol/L) serum B12 concentration \[18\] will not be eligible for participation and will be instructed to see their personal physician for complete follow-up and treatment. Part II Intervention: Changes in B12 status assessment indicators in response to B12 supplementation will be evaluated. Subjects will come to the GCRC the night before (Day 1) the intervention protocol. The next morning (Day 1) following an overnight fast, an indwelling catheter will be inserted from which repeated blood samples will be drawn throughout Day 1. A baseline fasting blood sample (#1) will be drawn. Subjects will then consume a light breakfast (including 1 piece of bread and 8 oz of orange juice) and will take a 9 ug dose of B12 (Dose 1). Thirty minutes after completion of the meal and consumption of the B12 supplement, a second blood sample (#2) will be drawn. Five subsequent hourly blood samples (# 3-7) will be drawn. After the 7th blood sample the subjects will consume one piece of bread and 8 ounces of orange juice and will take a second 9 ug dose of B12 (Dose 2) and have a blood sample (#8) drawn 30 minutes after consumption of the meal and the B12 dose. Five subsequent hourly blood samples (#9-13) will be drawn. The subjects will then consume one piece of bread and 8 ounces of orange juice and take a 9 ug dose of B12 (Dose 3). Another blood sample (#14) will be drawn 30 minutes after the meal and the B12 dose. One hour later, a final (Day 1) blood sample (#15) will be drawn followed by removal of the catheter. In addition to the bread and juice consumed with each B12 supplement, subjects will receive a mid-morning snack 2 hours after Dose 1 of the B12 supplement, lunch 3.5 hrs after Dose 1 of the B12 supplement, dinner at 4 hours after Dose 2 of the B12 supplement, and an evening snack at 3 hours after Dose 3. Low B12-containing foods will be provided in the GCRC. Water and non-caffeinated, non-caloric beverages will be allowed ad libitum. The subjects will remain in the GCRC overnight and a fasting blood sample (#16) will be drawn in the morning on Day 2. On Day 2 participants will be provided breakfast following the blood draw, after which they will be free to leave the GCRC. Subjects will be provided with take-away meals and snacks (lunch, dinner, snacks) consisting of low-B12 containing foods. Subjects will be instructed to return on the morning of Day 3 at which time they will have one am fasting blood sample (#17) drawn and will be provided with breakfast before they leave the GCRC. All overnight fasts will be from 10 pm the previous night. The following B12 indicators will be measured at each blood draw (a) holo-TC; (b) total-TC; (c) holo-HC and total HC; (d) serum B12; and (e) plasma albumin. Additional B12 status indicators (e.g. homocysteine, methylmalonic acid, RBC B12) will be measured at select blood draw intervals. A baseline folate analysis will be done.
Interventions
DIETARY_SUPPLEMENTVitamin B12
After taking a fasting blood sample, all subjects were given a light breakfast plus 9 micrograms of vitamin B12. Two more doses of vitamin B12, 9 micrograms each, were administered 6 hours apart.
Sponsors
National Center for Research Resources (NCRR)
University of Florida
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 49 Years
Healthy volunteers
Yes
Inclusion criteria
* No vitamin B12-containing supplement use within past year * No vitamin B12 injections within past year * No use of tobacco products * No chronic use of prescription medications except oral contraceptives * No history of chronic disease (e.g., pernicious anemia, cancer, diabetes, renal disease, hypertension, neurological abnormalities, gastrointestinal disorders) * BMI between 18.5-29.9 * General Chemistry Blood Tests (all values within or near normal range; hemoglobin if female ≥ 11.0 g/dL; if male ≥ 12 g/dL) * B12 status (Serum B12 ≥ 444 pmol/L) * Capable of understanding the informed consent form * Agrees to comply with protocol requirements
Exclusion criteria
* History of pernicious anemia, cancer, diabetes, renal disease, hypertension, heart disease, neurological abnormalities, gastrointestinal disorders, lung disease, hepatic disease, hematologic, or other metabolic diseases that, in the opinion of the Co-Principal Investigators, would affect safety or compliance * Vitamin B12 supplement use or injections within past year * Pregnant or breast feeding * Has BMI \<18.5 or \>29.9 * Has donated or lost a significant volume (\>450 mL) of blood or plasma within 30 days of the study * General chemistry lab values outside of ranges * Serum B12 outside of range listed above * Use of tobacco products * Chronic use of prescription medications except oral contraceptives * Does not understand the informed consent form * Does not agree to comply with protocol requirements
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Holo-transcobalamin | Holo-transcobalamin measured at 24 hours after baseline | Holo-TC is a vitamin B12 carrier protein. Only vitamin B12 bound to holo-TC can be taken up by cells. Changes in holo-TC after an oral dose of vitamin B12 may provide a clinical test to assess vitamin B12 absorption. The change in holo-transcobalamin (holo-TC) from baseline was measured at timed intervals in response to supplemental vitamin B12 and compared to baseline. The purpose was to ascertain the time point at which holo-TC reaches the maximum concentration in the blood following a dose of vitamin B12 in subjects without defects in vitamin B12 absorption. |
Secondary
| Measure | Time frame |
|---|---|
| Total Transcobalamin Measured at Intervals From Baseline to 48 Hours. | Baseline through 48 hours at intervals of 0, 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6, 7, 8, 9, 10, 11, 11.5, 12.5, 24, 48 |
Countries
United States
Participant flow
Recruitment details
Subjects were recruited from the Gainesville/Alachua county area through newspaper ads, email, and flyers posted on the UF campus. Flyers also were given to individuals or groups. Respondents were interviewed by telephone and asked questions to ascertain if they met inclusion criteria. Individuals meeting criteria were screened for B12 status.
Pre-assignment details
Individuals with a normal general blood chemistry profile, no history of chronic disease and normal CBC and vitamin B12 status were eligible to participate in the study. Those with deficient serum B12 levels were instructed to follow up with their personal physician. Subjects who met all inclusion criteria received the same treatment.
Participants by arm
| Arm | Count |
|---|---|
| All Study Participants All study participants received the same treatment of 3 doses of 9 micrograms of vitamin B12 at 6 hour intervals on day 1. | 21 |
| Total | 21 |
Baseline characteristics
| Characteristic | All Study Participants |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 21 Participants |
| Region of Enrollment United States | 21 participants |
| Sex: Female, Male Female | 8 Participants |
| Sex: Female, Male Male | 13 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 21 |
| serious Total, serious adverse events | 0 / 21 |
Outcome results
Primary
Change in Holo-transcobalamin
Holo-TC is a vitamin B12 carrier protein. Only vitamin B12 bound to holo-TC can be taken up by cells. Changes in holo-TC after an oral dose of vitamin B12 may provide a clinical test to assess vitamin B12 absorption. The change in holo-transcobalamin (holo-TC) from baseline was measured at timed intervals in response to supplemental vitamin B12 and compared to baseline. The purpose was to ascertain the time point at which holo-TC reaches the maximum concentration in the blood following a dose of vitamin B12 in subjects without defects in vitamin B12 absorption.
Time frame: Holo-transcobalamin measured at 24 hours after baseline
Population: The number of participants for analysis was per protocol.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Vitamin B12 Group | Change in Holo-transcobalamin | 124 pmol/L | Standard Deviation 46 |
Secondary
Total Transcobalamin Measured at Intervals From Baseline to 48 Hours.
Time frame: Baseline through 48 hours at intervals of 0, 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6, 7, 8, 9, 10, 11, 11.5, 12.5, 24, 48