VN: Vitamin B-12 (2011)
Miller DR, Specker BL, Ho ML, Norman EJ. Vitamin B-12 status in a macrobiotic community. Am J Clin Nutr. 1991; 53: 524-529.
PubMed ID: 1989421
To determine the vitamin B12 status in members of a macrobiotic community and to determine whether vitamin B12 status correlates with the intake of certain foods in a vegetarian diet that may contain vitamin B12.
Adults and children following a macrobiotic diet in two macrobiotic communities; one in Boston, MA and the other in Middletown, CT.
None reported.
Recruitment
Adults and children following a macrobiotic diet recruited in Boston, MA and Middletown, CT; no further details were provided.
Design
Cross-sectional.
Statistical Analysis
- Analyses performed:
- Student's T-test
- Regression analysis
- Chi-square analysis
- Values of urinary MMA and serum vitamin B12 concentrations were log transformed
- Means of log values were obtained; log value and ranges reported
- Statistical significance value were not specifically indicated.
Timing of Measurements
- Blood samples were drawn from only adults
- Urine samples were obtained from adults and children
- Dietary information was obtained from adults and children
- Weight and height information of the children was obtained when urine was collected
- Details of the collection methods were not clearly specified.
Dependent Variables
- Primary variables:
- Urinary MMA concentration (mmol per mol)
- Serum vitamin B12 concentration (pmol per L) in adults
- Secondary variables
- Dietary vitamin B12 intake score
- Determined from reported consumption of 49 food items
- Calculated by using the average vitamin B12 content of each food item and multiplying that by a coefficient of daily frequency of consumption
- Products of all food items (except tempeh, miso and sea vegetables) were then summed
- Length and weight indices based on age- and sex-specific growth curves (percentile) for children.
- Dietary vitamin B12 intake score
Independent Variables
Macrobiotic diet:
- Duration of this dietary practice
- Frequency of consumption of certain foods:
- Eggs
- Dairy products
- Seafood
- Tempeh
- Miso
- Sea vegetables.
Control Variables
Dietary variables were controlled for statistically using regression analysis of results.
Note: Vitamin supplements are generally not consumed by this diet group, though this was not measured in this study.
Initial N
N=153.
- 110 adults (46 males, 64 females)
- 42 children
Attrition (Final N)
N=153.
Age
- Adults: 21 to 70 years (median = 33 years)
- Children: 1.5 to 11.7 years (median = 3.9 years).
Other Relevant Demographics
Dietary information obtained from adults and children:
- Frequency of consumption was stated as being examined but instrument was not specified
- Frequency of consumption examined for:
- Dairy products
- Eggs
- Seafood
- Various foods common to macrobiotic diet:
- Tempeh
- Miso
- Sea vegetables, categorized according to vitamin B12 content:
- High (wakame, kombu)
- Low (hijiki)
- Unknown (arame, nori, dulse and non-specified)
- Frequency of consumption for eggs, dairy and seafood categories:
- Never (zero)
- Less than one per week (one)
- More than one per week (two)
- Frequency of consumption for tempeh, miso and sea vegetables categories:
- Never (0)
- One or less per month (one)
- Two to three per month (two)
- One per week (three)
- Two to four per week (four)
- Five to six per week (five)
- One per day (six)
- Four to six per day (seven)
- More than six per day (eight).
Anthropometrics
- Weight and height information recorded for children; it was not specified whether this information was self-reported or actually measured
- Blood samples obtained only from adults
- Urine samples obtained from adults and children
- Length of time reported for practicing macrobiotic diet obtained:
- Adults: One to 379 months (median = 41 months)
- Children:
- All children had been fed human milk
- 30 children (71%) followed macrobiotic diet since weaning
- Remaining 12 children:
- Started macrobiotic diet at ages 1.1 to 8.8 years
- Had consumed macrobiotic diet for eight to 48 months (median = 27 months).
Location
- Boston, MA
- Middletown, CT.
Key Findings
- Adults:
- 51% of adults had low serum vitamin B12 concentration (less than 148pmol per L), with mean serum concentration = 150pmol per L (range 18 to 583pmol per L)
- 30% of adults had high urinary MMA concentration (4.3mmol per mol creatinine or more). Mean urinary MMA concentration = 4.0mmol per mol (range 1.6 to 20mmol per mol)urinary MMA was inversely correlated with serum vitamin B12 concentration (R=-0.494, P=0.01)
- significant inverse correlation between serum vitamin B12 concentration and duration of macrobiotic dietary practice (R=-0.210, P=0.03)
- Children:
- MMA concentrations:
- 55% of children had high urinary MMA concentrations (more than 4.3μmol per mmol creatinine); mean = 4.9mmol per mol (range 0.5 to 35mmol per mol)
- Urinary MMA concentrations were higher in those children who had consumed a vegetarian diet during their entire lifetime (x = 6.0mmol per mol creatinine, range 0.7 to 35) compared with children who had not (3.0mmol per mol creatinine, 0.5 to 12)
- Length:
- 32% of children (11 of 34) for whom length information was obtained were in the 5th or less percentile for length
- 73% of these children had high MMA concentrations compared with 39% (9 of 23) children whose length measured higher than the 5th percentile (Χ2=3.36, P=0.07)
- Weight: 15% of children (6 of 41) for whom weight information was obtained were in the 5th or less percentile for weight (Χ2=7.61, P<0.01).
- MMA concentrations:
Serum Vitamin B12 and Urinary MMA by Consumption of Major Foods*
Consumption of Food | ||||
Never | One per Week or Less | More than One per Week | P** | |
Adult serum vitamin B12 (pmol per L) |
||||
Dairy | 122 (18 to 583) N=57 | 183 (76 to 485) N= 4 | 179 (93 to 392) N=12 | 0.004 |
Eggs | 139 (18 to 583) N=71 | 167 (18 to 485) N=25 | 157 (93 to 358) N=7 | 0.27 |
Seafood | 111 (18 to 429) N=14 | 145 (18 to 485) N=45 | 161 (45 to 583) N=44 | 0.07 |
Adult urinary MMA (mmol per mol creatinine) | ||||
Dairy | 5.3 (2.0 to 20.1) N=15 | 2.8 (1.6 to 5.3) N=8 | 2.1 N=1 | 0.02 |
Eggs | 4.8 (1.6 to 20.1) N=18 | 3.1 (1.6 to 5.0) N=4 | 2.2 (2.1 to 2.3) N=2 | 0.08 |
Seafood | 4.4 (1.6 to 20.1) N=5 | 5.3 (2.0 to 14.1) N=12 | 2.6 (1.6 to 5.0) N=7 | 0.14 |
Child urinary MMA (mmol per mol creatinine) | ||||
Dairy | 7.0 (1.4 to 35.1) N=23 | 4.4 (0.7 to 18.0) N=11 | 2.1 (0.5 to 5.1) N=8 | 0.001 |
Eggs |
6.3 (1.0 to 35.1) N=23 |
3.6 (0.5 to 17.1) N=15 | 3.9 (2.2 to 12.0) N=4 | 0.10 |
Seafood |
7.3 (2.8 to 12.0) N=7 |
4.3 (0.7 to 35.1) N=18 | 4.8 (0.5 to 18.0) N=17 | 0.50 |
* Geometric mean (range).
** By regression analyses; similar results were obtained when never vs. ever groups were compared by student's T-test.
Serum vitamin B12 and Uinary MMA by Tertile of Vitamin B12 Intake Score*
Vitamin B12 Intake Score | ||||
Low | Medium | High | P** | |
Serum vitiman B12 | ||||
Adults (pmol per L) |
128 (18 to 508) N=30 |
139 (18 to 583) N=28 |
184 (45 to 399) N=28 |
0.03 |
Adults' intake score | 0 |
0.01 to 0.15 |
0.16 to 1.7 |
|
Urinary MMA | ||||
Children (mmol per mol creatinine) |
6.7 (1.4 to 35.1) N=13 |
5.9 (1.7 to 25) n=12 |
2.6 (0.5 to 10) N=12 |
0.005 |
Children's intake score |
0-0.02 |
0.02-0.19 |
0.20 to 0.77 |
* Geometric mean (range).
** By regression analyses; similar results were obtained when never vs. ever groups were compared by student's T-test.
Other Findings
- Adults:
- Vitamin B12 concentration was not correlated with age (R=-0.091, P=0.3) and did not differ by sex
- Mean serum vitamin B12 concentrations tended to be lower and mean MMA concentrations tended to be higher for adults who consumed no dairy, eggs or seafood; this was statistically significant only for dairy (P<0.05)
- Children:
- Urinary MMA was not related to child's age (R=-0.252, P=0.11)
- Mean MMA concentrations tended to be higher for children who consumed no dairy, eggs or seafood
- Statistically significant only for dairy (P<0.05)
- 70% of children not consuming dairy had high urinary MMA compared to 37% who consumed dairy (chi-square test, P=0.03)
- Urinary MMA was higher with lower tertile of vitamin B12 intake
- For both Adults and Children: Urinary MMA concentration was not correlated with consumption of tempeh, miso or sea vegetables.
Individuals consuming a vegetarian diet for long periods of time may be at risk of vitamin B12 deficiency.
Not-for-profit |
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Quality Criteria Checklist: Primary Research
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Relevance Questions | |||
1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | N/A | |
2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | Yes | |
Validity Questions | |||
1. | Was the research question clearly stated? | Yes | |
1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | No | |
2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | No | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
2.3. | Were health, demographics, and other characteristics of subjects described? | ??? | |
2.4. | Were the subjects/patients a representative sample of the relevant population? | No | |
3. | Were study groups comparable? | Yes | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | Yes | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | Yes | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | Yes | |
3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | Yes | |
3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | Yes | |
3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
4. | Was method of handling withdrawals described? | No | |
4.1. | Were follow-up methods described and the same for all groups? | N/A | |
4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | No | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | Yes | |
4.4. | Were reasons for withdrawals similar across groups? | N/A | |
4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | N/A | |
5. | Was blinding used to prevent introduction of bias? | No | |
5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | N/A | |
5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | Yes | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | No | |
5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | No | |
6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | N/A | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | No | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | No | |
6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | No | |
6.6. | Were extra or unplanned treatments described? | N/A | |
6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | Yes | |
6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | ??? | |
7.7. | Were the measurements conducted consistently across groups? | Yes | |
8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | N/A | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | Yes | |
8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
8.7. | If negative findings, was a power calculation reported to address type 2 error? | N/A | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | Yes | |
10. | Is bias due to study's funding or sponsorship unlikely? | ??? | |
10.1. | Were sources of funding and investigators' affiliations described? | Yes | |
10.2. | Was the study free from apparent conflict of interest? | No | |