VN: Vitamin B-12 (2011)

Study Design:
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Quality Rating:
Research Purpose:

To determine the relationship between bone mineral density and cobalamin status in Dutch adolescents who followed a macrobiotic diet and in their counterparts.

Inclusion Criteria:
  • Adolescent, aged nine-15 years old
  • Recruited from an existing study where they followed a macrobiotic diet until age of six years followed by a lacto-ovo vegetarian or omnivorous diet.
  • Caucasian
  • Healthy
  • No medication-interactions affecting bone or calcium metabolism
  • Serum blood samples sufficient for detection of cobalamin status.
Exclusion Criteria:

None reported

Description of Study Protocol:


The macrobiotic adolescents, aged nine-15 years old, were recruited from an existing group of macrobiotic families affiliated with the Division of Human Nutrition, Wageningen University.  

Blinding used

Not applicable


  • Subjects divided in two groups: Macrobiotic Diet vs. Control diet (lacto-ovo vegetarian or omnivorous diet)
  • Biochemical Measurements: Non-fasting blood specimens were taken (90% taken from mid May to mid-June 1995, followed by other 10% in the subsequent month)
  • Food frequency questionnaire to estimate Calcium intake (mg per day) including questions specific to non-dairy sources of calcium that are present in a macrobiotic diet.  
Data Collection Summary:

Timing of Measurements

May-June 1995

Dependent Variables

  • Bone mineral density, bone mineral content
  • MMA
  • Homocysteine.

Independent Variables

Dietary pattern

Control Variables

Bone area

Description of Actual Data Sample:
  • Initial N: 195 adolescents (nine to 15 years)
  • Attrition (final N): 170
    • 76 previously macrobiotic adolescents
    • 94 controls
  • Age: Nine to 15 years
  • Ethnicity: Caucasian
  • Location: Netherlands.


Summary of Results:

Mean B12 and MMA levels by Group and Sex

Mean (5th-95th percentile)
  • Macrobiotic Boys
    • B12 (pmol/L): 212 (103–370)*
    • MMA (μmol/L): 0.30 (0.11–0.94)*
  • Macrobiotic Girls
    • B12 (pmol/L): 286 (115–580)*
    • MMA (μmol/L): 0.25 (0.09–0.76)*
  • Omnivore Boys
    • B12 (pmol/L): 484 (259–813)
    • MMA (μmol/L): 0.15 (0.05–0.34)
  • Omnivore Girls
    • B12 (pmol/L): 458 (219–850)
    • MMA (μmol/L): 0.17 (0.07–0.28).

 *Significantly different than omnivores

Proportions of Comparison Groups Potentially Deficient

  • B12<229 pmol/L
    • Macrobiotic: 41%
    • Omnivores: 5%
  • MMA>0.29 μmol/L
    • Macrobiotic: 41%
    • Omnivores: 5%.

B12 and MMA Levels by Bone Mineral Parameters

  Low Bone Mineral Density (BMD) Normal Bone Mineral Density (BMD) Low Bone Mineral Concentration) (BMC) Bone Mineral Concentration (BMC)
All subjects 60 101 50  111 
Vitamin B12 (pmol, L) 344 (24) 13±1  P<0.001 P<0.001 
MMA (umol,L) 0.31 (0.26, 0.35) 19±1  P<0.001  P<0.001
Only macrobiotic fed adolescents, n 36 20±1  P<0.001  P=0.001
Vitamin B12 (pmol,L) 269 (23) 279 (25)  P<0.001  P=0.003
MMA (umol, l) 0.40 (0.32, 0.49) 0.22 (0.13, 0.32)  0.26 (0.14, 0.39)  P=0.006

Magnesium intake was higher in the ovo-lacto vegetarians and low-meat eaters than in the control group.

Author Conclusion:

"The present study shows that serum cobalamin concentrations were significantly lower and MMA concentrations significantly higher in previously macrobiotic-fed adolescents as compared to the controls.

Funding Source:
Government: Dutch Prevention Fund/Netherlands Organization for Health Research and Development
Dutch Dairy Foundation for Nutrition and Health
Foundation associated with industry:
Reviewer Comments:
Quality Criteria Checklist: Primary Research
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) N/A
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? No
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  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) No
  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? No
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? No
  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? Yes
  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? Yes
  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? N/A
  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? No
  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)? No
  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? No
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes