B12 & EEG

Clinician Name: Miranda Garland

Clinic Name & Location: Biofeedback Associates of Northeast Florida

Professional Status:  Miranda, B.A. is a neurofeedback technician. Chris Branciere, M.S., BCB is a board certified biofeedback therapist, adjunct psychology professor, and PhD student

Abstract

This is a prospective self-report in which vitamin B₁₂ dietary supplements were excluded from a raw, plant-based diet for one year.  Vitamin B₁₂ deficiency may result in prolific intracerebral consequences of demyelination, often reflected as frontal and diffuse slowing in the electroencephalogram (EEG).  The prevalence of vitamin B₁₂ deficiency is common but consensus on precise cutoff points for plasma vitamin B₁₂ deficiency has been inconsistent.  This has raised questions about potential presymptomatic vitamin B₁₂ risks or whether higher vitamin B₁₂ stores could provide additive health benefits.  Vitamin B₁₂ values, symptoms potentially associated, methylcobalamin supplementation, and resting EEG recordings before and after neurofeedback (NF) training were examined.  Eight sessions of NF training at T3, T4, T5, and T6 resulted in 38% EEG normalization with reduced symptoms of irritability, insomnia, fatigue, and memory problems.  Even though blood test results before and after vitamin B₁₂ supplementation readings indicated an increase of 8 mg/mL (from 436 pg/mL to 444 pg/mL), neuroenhancements were not evident without NF training.

Keywords: encephalopathies, methylcobalamin, hematological, individual response specificity, stimulus response specificity, intraindividual variation

 

Literature Review

Neurological symptoms often precede hematological symptoms that are initially diagnosed based on plasma vitamin B₁₂ analysis (Gröber, Kisters, & Schmidt, 2013).  Previous authors have indicated a need to improve diagnostic criteria for vitamin B₁₂ deficiency (Tucker, et al., 2000).  If electroencephalography (EEG) biomarkers associated with low vitamin B₁₂ status could be detected earlier - as part of a combination of screening methods to identify subclinical vitamin B₁₂ symptoms, such neurophysiological biomarkers could be used as non-invasive and cost-effective approaches for additional diagnostic value.  Neurofeedback (NF) training could also provide early management of preclinical vitamin B₁₂ deficiency.  Monitoring EEG activity could serve to identify the degree to which symptoms may be associated with metabolic or psychogenic factors and therefore more or less amenable to change.

Although sample sizes were small in earlier studies that sought to identify signature EEG features related to vitamin B₁₂ deficiency symptoms (Walton, Kiloh, Osselton, & Farrall, 1954; West & Ellis, 1966; Smith, 1962), EEG features among vegan subjects with hypovitaminosis- B₁₂ were interpreted as heterogeneous (vitamin B₁₂ deficiency does generally result in heterogeneous symptoms) and slightly abnormal with diffuse cortical slowing.  Vegetarian serum vitamin B₁₂ values were intermediate between controls and vegans, with less EEG abnormality detected.  Walton, Kiloh, Osselton, and Farrall (1954) examined EEG features related to vitamin B₁₂ deficiency symptoms of pernicious anemia and plant-based diets; they documented improvements in 79% of post-treatment EEG recordings after oral vitamin B₁₂ supplementation.  Slight to moderate excess delta and theta activity were lowered in many subjects and alpha frequency rose within seven days of vitamin B₁₂ treatment.  Continued improvements were noted three years after vitamin B₁₂ supplementation in some cases (p. 55).  Carmel (2008) also verified symptom reductions beginning within a week of vitamin B₁₂ supplementation.

Smith (1962) speculated, "Although most subjects were clinically normal, the electroencephalographic evidence suggests that occult damage to the central nervous system is taking place and that this form of diet may produce subtle cerebral changes that are unrecognizable by normal clinical methods" (p. 1,658).  However, recent studies have not verified this or similar conjectures from Walton, Kiloh, Osselton, and Farrall (1954); and West and Ellis (1966) attributing slight EEG abnormalities to cerebral metabolic adjustments of plant diets (Amodio, et al, 2001; Beezhold, Radnitz & DiMatteo, 2014).

Kaplan and Rosetti (2011) documented diffuse slow EEG activity (5-6 Hz) associated with encephalopathies and they understood much of the research correlating EEG patterns with encephalopathic conditions has been based on case studies so the clinical value of rapidly identifying EEG features associated with encephalopathies has been under-recognized.  However, EEG is increasingly used in hospitals for causal and prognostic data.  Perhaps EEG recordings can be used to identify encephalopathic symptoms early among those with low vitamin B₁₂ status, too.

Palacios, et al. (2013) noted "clinical severity of vitamin B₁₂ deficiency is often unrelated to B₁₂ concentrations" (p. 1451).  The duration of vitamin B₁₂ deficiency is most crucial in determining whether symptoms become irreversible (Healton, 1995).  Pacholok and Stuart (2011) stalwartly advocate for substantially higher serum vitamin B₁₂ lower limit cutoff values for the general population: "Serum B₁₂ must be 550 in order to have a good amount of B₁₂ in the CSF.”  While this introduces the considerably legitimate topic of neurological symptomology preceding hematological symptoms, what constitutes a good amount of vitamin B₁₂ in CSF is even more unformulated than World Health Organization (WHO) serum vitamin B₁₂ deficiency cutoff values of 203 pg/mL (de Benoist, 2008, p. S242).  Klee (2000) revealed that by the same cut-off levels of serum vitamin B₁₂ (>500 pg/mL), there would be inordinately more patients requiring follow-up tests.  Although Travica, Ried, Bujnowski, and Sali (2016) logically recognize vitamin B₁₂ requirements vary with age, the authors caution, "when the serum level drops below 500 or 550 pg/mL the cerebrospinal fluid level can become deficient... Some experts suggested the current recommended range of vitamin B₁₂ is too low and that the optimal range should be at least 500–1300 pg/mL" (p. 5).  However, the reference of these oft-cited experts was a preliminary study of 14 subjects with senile dementia who had normal ranges of serum vitamin B₁₂ levels (500-1300 pg/mL) and CSF vitamin B₁₂ levels were not related to severity of dementia (Mitsuyama & Kogoh, 1988).  Zhang (2016) also noted in a small study that reduced CSF vitamin B12 appeared in subjects with autism and schizophrenia.  Generalizing this limited evidence to support increasing serum vitamin B₁₂ cutoffs by such a great margin for the general population demonstrates markedly conservative bias for inclusion of outliers since exhaustive reviews of intake and plasma status of vitamin B₁₂ in different populations has led to the current estimated average daily intake requirements that are not just adequate but increase bodily vitamin B₁₂ stores in healthy people.  Lindenbaum, Savage, Stabler, and Allen (1990) evaluated the sensitivity of the 200 pg/mL cutoff value for serum vitamin B₁₂ deficiency in two groups of patients with vitamin B₁₂ deficiency symptoms and arrived at an average false negative result of ~4%.  Regland, Abrahamsson, Blennow, Gottfries, and Wallin, (1992) logically furnished rationale for developing a database for different health conditions or populations based not on free serum vitamin B₁₂ levels but ratios of CSF/serum vitamin B₁₂ values.

 

Subject History

Client Gender: Male

Age:  45

Marital Status: Single

Socioeconomic status:  Middle Class

Public or Private School:  Grew up attending public and Catholic Sunday School

Years in School:  Current PhD student

Started Dating at Age: 16

Number of Friends:  4-6 close friends

Current social Groups:  Soccer team

Dating Frequency:  None

Sports Played:  Soccer and Surfing

Exercise Frequency:  2 Days/Week

Parental Status:  Mother recently passed away from heart condition

Sexual or Physical Abuse:  None

Personal substance abuse:  None. No Alcohol, Caffeine, Herbal Remedies, or Medication.

Family Substance Abuse:  Smoking-one parent.

History of Head Trauma:  None.

 

Presenting Symptoms

Insomnia:  Sleep onset

Attention:  Low attention

Reading comprehension: Slow processing speed while reading

Memory:  CPTs show Declarative Memory, Sequential Memory, and Short Term Memory Problems

Headaches:  None

Rumination:  Frequent

Worry:  Low

Suicidal Thoughts:  None

Mood: Irritable, angry, inhibited, and busy after mother passed, particularly following missed meals.  Insomnia, irritability, fatigue, and memory problems were among the symptoms identified in the first qEEG summary report and coincidentally, these are common symptoms known to be associated with vitamin B₁₂ deficiency (Audebert, Gendre, & Le Quintrec, 1978; Dror, & Allen, 2008; Briani, et al., 2013).

 

Metabolic Issues 

 

Metabolic issues were not apparent.

Metabolic Analysis

 

Training

I subscribed to topographic mapping of quantitative electroencephalography (qEEG) using Brainmaster Discovery 24e hardware.  A second brain map was completed for comparison to the baseline eyes open and eyes closed qEEG brain maps, following an 8-session (40 minutes each) massed practice schedule using BrainDX normative database and Brainmaster Atlantis I hardware for four channels of EEG z-score NF training.  The training sites were the four most statistically deviant sites (T3, T4, P4, and O1 using the International 10-20 System for standardized electrode placement) from the eyes closed primary protocol based upon NewMind qEEG analysis.  When the threshold for training criteria was achieved approximately 80% of the time, the threshold level was raised one percent.  After cessation of NF training, eight oral doses of vegan methylcobalim (2.4 µg/day) were consumed in accordance with WHO daily vitamin B₁₂ requirements for adults (FAO, 2001, p. 69; de Benoist, 2008, p. S242).  A final brain map following eight sessions of vitamin B₁₂ supplementation allowed comparisons between the baseline neurometric recordings, the first intervention (NF training), and the second intervention (oral methylcobalim supplementation).

Pre Post Trend Screen Protocol 1 

Figure 1. Z-score training session 1 at T3/T4 and T5/T6 5-minutes and 59 seconds into training.  The threshold of 48% was initially set to meet age and gender-specific criteria within 0.9 standard deviations above and below normative values approximately 70 - 80% of the training time and that was the threshold setting during the training.  For comparison purposes, screenshots for 52% threshold settings are displayed here.

Pre Post Trend Screen Protocol 2 

Figure 2. Z-score training session 8 at T3/T4 and T5/T6 during the 5:59 mark.  The training threshold was gradually increased to 52% by the 5^th training session to meet the age and gender-specific criteria within 0.9 standard deviations above and below normative values approximately 70% or more of the training session.

Pre Post Map

Figure 3. Baseline qEEG compared to qEEG following neurofeedback training

 

Figure 4. Baseline qEEG compared to qEEG following both neurofeedback training and oral vitamin B₁₂ intake interventions.

 

Results

The most dramatic differences were noticed between baseline and post-neurofeedback training in eyes closed maps.  T3 and T4 are the nearest 10/20 cortical sites to the hippocampus and amygdala and training these sites seemed to reduce irritability and memory problems (common vitamin B₁₂ deficiency symptoms) indicated as problems in the baseline brain map.  No evidence was found for neuroenhancements by increasing low normal serum vitamin B₁₂ values 8 pg/mL (from 436 pg/mL to 444 pg/mL) with oral vitamin B₁₂ supplementation.  A slightly disproportionate increase in serum vitamin B₁₂ exceeded what would be proportionately expected for eight consecutive days of 2.4 µg/d oral methylcobalim supplementation.  A spillover effect or delayed changes from NF training could have occurred following cessation of NF training but the overall percent change in the maps between the baseline and post vitamin B₁₂ supplementation was less than would be expected, given the 39% overall change and higher percent of normalization that occurred between the baseline and post NF training.  The fact that the NF training was only eight sessions and was not a spaced practice schedule may have reduced generalization, though.  Higher reorganization relative to normalization between the post NF training and post vitamin B₁₂ supplementation maps was observed.  Subjective awareness of improved reading comprehension and processing speed were also noticed following NF training.

Figure 5. Baseline serum vitamin B₁₂

Figure 6. Post-intervention serum vitamin B₁₂

 

Figure 7. Z-score training sessions (1-8)

Figure 8. Z-score training session #1

Figure 9. Z-score training session #2

 

Figure 10. Z-score training session #3

Figure 11. Z-score training session #4

Figure 12. Z-score training session #5

 

Figure 13. Z-score training session #6

Figure 14. Z-score training session #7

Figure 15. Z-score training session #8

 

Discussion

Vitamin B₁₂ deficiency and demyelination are often reflected as diffuse slowing in the EEG.  Vitamin B₁₂ deficiency is caused by malnutrition, malabsorption, or reabsorption problems and may be comorbid or secondary to digestive disorders such as reduced colonic bacteria from vitamin D or iron deficiency, alcohol intake, diabetes, etc. (Laufer, 2004; Carmel, 2008; Solomon, 2011; Gominak, 2015).  Smoking, medications, and cooking food can also reduce absorption or deplete vitamin B₁₂ (Linnell, Smith, Smith, Wilson, & Matthews, 1968; Nishioka, Kanosue, Yabuta, & Watanabe, 2011; “Nutritional Effects of Food Processing,” 2014).  Increased vitamin A and vitamin C intake will increase vitamin B12 absorption (“Mayo Clinic,” n.d.).  Cyanocobalamin B₁₂ intake can restore serum vitamin B₁₂ values and it is a more common and cost-effective supplement form but less bioavailable than methylcobalim B₁₂, which is premethylated (Adams, 2011).  There is a lack of evidence demonstrating detrimental effects of the small amounts of cyanide in the cyanocobalamin B₁₂, so far (West & Ellis, 1966).

Wide-ranging diagnoses with differential effects such as vitamin B₁₂ deficiency are traditionally categorized as diverse sets of fluctuating and overlapping symptoms, such as fatigue, insomnia, mood, or memory problems.  Such heterogeneous symptoms are not likely to be unambiguously reflected in EEG as distinctly clear categories of metabolic abnormalities, particularly in early stages.  Identifying EEG features potentially associated with individual symptoms instead of signature feature patterns or broad diagnostic categories may be a more fruitful approach to addressing metabolic problems such as vitamin B₁₂ deficiency.  EEG activity reflects numerous intraindividual variations (different individual responses to the same stimuli at different times), stimulus response specificity (products of evoking stimuli), and individual response specificity (unique products of responding individuals, i.e., some subjects show more hematological symptoms while others exhibit more neurological symptoms).  A long-term follow-up self-report is warranted to estimate vitamin B₁₂ absorption and reabsorption rates by monitoring serum vitamin B₁₂ over time and controlling oral vitamin B₁₂ intake with continued exclusion of digestive compromises.  Future studies are necessary to clarify the degree to which EEG activity may correlate with neurological symptoms of B₁₂ hypovitaminosis and to determine whether diffuse slowing or other, as yet unrecognized, neurological biomarkers can be detected before the threshold effect of vitamin B₁₂ deficiency.

 

Conclusions

Spaced NF training sessions, as opposed to mass training, may increase generalization.  NF training could potentially mask chronic deficiencies if it can be used to manage metabolic symptoms.  Diffuse slowing seems to be the most common sign of demyelination and low vitamin B₁₂ status that has been detected in the EEG so far, but the literature on the topic is anemic and the symptoms of vitamin B₁₂ deficiency are diverse.  Oral supplementation (particularly with methylcobalimin) can quickly increase serum vitamin B12 levels if absorption problems are not an issue.

Vitamin B₁₂ is necessary for maintaining myelin sheath and neurotransmitter synthesis (Herrmann & Obeid, 2008).  The prevalence of vitamin B₁₂ deficiency is common and reported to range vastly between 6-40% (Palacios, 2013).  Dietary vitamin B₁₂ has low bioavailability and it becomes more difficult to absorb with age but most of it is reabsorbed by the ileum in healthy adults.  Carmel (2008) documented fractional vitamin B₁₂ absorption decreases with intake but total vitamin B₁₂ absorption increases with vitamin B₁₂ intake.  Oral doses of vitamin B₁₂ ranging from 1 μg – 1000 μg correspond with absorption rates of decreasing efficiency from 56% - 1.3%.  These figures serve as critical reminders that frequent intake of relatively low vitamin B₁₂ doses (as with many other nutrients) is far more efficiently absorbed and the otherwise overworked phrase “eat a balanced diet” becomes meaningfully applicable in light of this ratio data (Carmel, 2008; Tucker, et al., 2000).  Vitamin B₁₂ intake is also more efficient on an empty stomach.  One may exhibit statistically normal serum vitamin B₁₂ and still develop functional vitamin B₁₂ deficiency, particularly among infants who have not had time to build up stores, those with diabetes, and the elderly, in which various types of dementia frequently occur with associated low levels of vitamin B₁₂ in CSF (Dror, & Allen, 2008; Solomon, 2011).   Paradoxically, one may exhibit low serum vitamin B₁₂ without symptoms, depending on how long vitamin B₁₂ was stored in the kidney, liver, and other cells (Bopape, Mbhenyane & Alberts, 2008, p. 334).

Vitamin B₁₂ deficiency symptoms may begin before exhausting bodily stores or by excluding dietary vitamin B₁₂ for an average of 5-6 years, depending on age, digestive cofactors, etc. (Bopape, Mbhenyane & Alberts, 2008, p. 334).  It may be tempting to presume saturation of vitamin B₁₂ stores could provide incremental life promoting benefits or that monotonic trends of increased vitamin B₁₂ stores could create health protective effects up to or beyond serum vitamin B₁₂ levels of 500 pg/mL.  Prospective studies on vitamin B₁₂ status and diseases of affluence have yielded correlations with breast cancer risk slightly elevated among those with serum vitamin B₁₂ up to 280 pg/mL (Wu, et al., 1999).  Reduced plasma homocysteine levels were also associated with serum vitamin B₁₂ levels up to 300 pmol/l and elevated homocysteine levels may increase cardiovascular disease risk (Fenech, Aitken, & Rinaldi, 1998, p. 1163; Ryan-Harshman, & Aldoori, 2008, p. 536; “Linus Pauling Institute,” 2015).  The most convincing support for raising vitamin B₁₂ lower threshold cutoff levels applies to reduced risks of neural tube defects with serum vitamin B₁₂ levels ≥400 ng/L (Molloy, 2009, p. 918).  But WHO already advised higher vitamin B₁₂ (+40%) intake for pregnancy and the recommended daily dose of 2.4 µg/day for most adults (who have a 50% reabsorption rate) provides 0.4 µg/day beyond daily requirements (Ladipo, 2000, p. 284; Joint, F. A. O., & World Health Organization, 2005).  Unless clinically deficient, there is a paucity of evidence to support increasing vitamin B₁₂ stores for healthy adults who want to enhance cognition or that increased vitamin B₁₂ intake has protective effects for dementia (Malouf & Areosa Sastre, 2003; Health Quality Ontario, 2013, p. 1).

 

References

Amodio, P., Caregaro, L., Pettenó, E., Marcon, M., DelPiccolo, F., & Gatta, A. (2001). Vegetarian diets in hepatic encephalopathy: facts or fantasies? [PDF file]. .Digestive and Liver Disease, 33(6), 492-500. http://ac.els-cdn.com/S1590865801800281/1-s2.0-S1590865801800281-main.pdf?tid=0aea4e30-4c49-11e6-9e6a-00000aab0f26&acdnat=1468778908_5bd3b0835957d1ecd36087bedadb5513

Audebert, M., Gendre, J. P., & Le Quintrec, Y. (1978). [Folate and the nervous system (author's transl)]. La semaine des hopitaux: organe fonde par l'Association d'enseignement medical des hopitaux de Paris, 55(31-32),1383-1387.

Adams, M. (2011). Vitamin B-12 warning: Avoid cyanocobalamin, take only methylcobalamin. Natural News. http://www.naturalnews.com/032766_cyanocobalamin_vitamin_B-12.html#ixzz4EWTZs9XP

Beezhold, B., Radnitz, C., & DiMatteo, J. (2014). Large vegan sample reports less anxiety and stress than omnivores (823.3). The FASEB Journal,28(1 Supplement), 823-3. http://www.fasebj.org/content/28/1_Supplement/823.3.short

Bopape, M. M., Mbhenyane, X. G., & Alberts, M. (2008). The prevalence of anaemia and selectedmicronutrientstatus in pregnant teenagers of Polokwane Municipality in the LimpopoProvince. South African Journal of Clinical Nutrition, 21(4), 332336.http://www.tandfonline.com/doi/abs/10.1080/16070658.2008.11734175

Briani, C., Dalla Torre, C., Citton, V., Manara, R., Pompanin, S., Binotto, G., & Adami, F. (2013). Cobalamindeficiency: clinical picture and radiological findings. Nutrients, 5(11), 4521-4539.http://www.mdpi.com/2072-6643/5/11/4521/htm

Carmel, R. (2008). How I treat cobalamin (vitamin B₁₂) deficiency. Blood,112(6), 2214-2221.http://www.bloodjournal.org/content/112/6/2214 de Benoist, B. (2008). Conclusions of a WHO Technical Consultation on folate and vitamin B12 deficiencies. [PDFfile]. Food and nutrition bulletin, 29(2 Suppl), S238. http://www.who.int/nutrition/publications/micronutrients/FNBvol29N2supjun08.pdf

Dror, D. K. & Allen, L. H. (2008). Effect of vitamin B12 deficiency on neurodevelopment in infants: currentknowledge and possible mechanisms. [PDF file]. Nutrition reviews, 66(5), 250 – 255. http://naldc.nal.usda.gov/download/17955/PDF

FAO, W. (2001). Human Vitamin and Mineral Requirements. Report of a Joint FAO/WHO Expert Consultation, Bangkok, Thailand. [PDF file]. Food and Nutrition Division, FAO Rome. http://www.fao.org/3/a-y2809e.pdf

Fenech M, Aitken C & Rinaldi J (1998): Folate, vitamin B₁₂, homocysteine status and DNA damage in young Australian adults. Carcinogenesis 19, 1163–1171. http://carcin.oxfordjournals.org/content/19/7/1163

Gominak, S. (2015). What does D hormone deficiency look like? Vitamin D Hormone.drgominak.com/vitamin-d-hormone.html

Gröber, U., Kisters, K., & Schmidt, J. (2013). Neuroenhancement with vitamin B12—underestimated neurological significance. Nutrients, 5(12), 5031-5045. http://www.mdpi.com/2072-6643/5/12/5031/htm

Health Quality Ontario. (2013). Vitamin B12 and Cognitive Function: An Evidence-Based Analysis. Ontario Health Technology Assessment Series,13(23), 1–45. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3874776/

Herrmann, W., & Obeid, R. (2008). Causes and early diagnosis of vitamin B12 deficiency. [PDF file]. Dtsch Arztebl  Int, 105(40), 680-5. http://www.homocysteine-panel.org/website_en/pdfdocs/m680.pdf

Joint, F. A. O., & World Health Organization. (2005). Vitamin and mineral requirements in human nutrition. [PDF file]. http://apps.who.int/iris/bitstream/10665/42716/1/9241546123.pdf

Kaplan, P. W., & Rossetti, A. O. (2011). EEG patterns and imaging correlations in encephalopathy: encephalopathy part II. Journal of Clinical Neurophysiology, 28(3), 233-251. https://www.researchgate.net/publication/51184533_EEG_Patterns_and_Imaging_Correlations_in_Encephalopathy_Encephalopathy_Part_II

Klee, G. G. (2000). Cobalamin and folate evaluation: measurement of methylmalonic acid and homocysteine vs vitamin B12 and folate. [PDF file]. Clinical chemistry, 46(8), 1277-1283.http://www.clinchem.org/content/46/8/1277.full.pdf+html

Ladipo, O. A. (2000). Nutrition in pregnancy: mineral and vitamin supplements. The American journal of clinical nutrition, 72(1), 280s-290s. http://ajcn.nutrition.org/content/72/1/280s.full

Laufer, E. M., Hartman, T. J., Baer, D. J., Gunter, E. W., Dorgan, J. F., Campbell, W. S., ... & Taylor, P. R. (2004). Effects of moderate alcohol consumption on folate and vitamin B12 status in postmenopausal women. European journal of clinical nutrition, 58(11), 1518-1524.http://www.nature.com/ejcn/journal/v58/n11/full/1602002a.html

Linnell, J. C., Smith, A. D., Smith, C. L., Wilson, J., Matthews, D. M. (1968). Effects of smoking on metabolism and excretion of vitamin B12. British Medical Journal.;2(5599):215-216.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1985886/

“Linus Pauling Institute.” (2015). Vitamin B12. Micronutrient Information Center.http://lpi.oregonstate.edu/mic/vitamins/vitamin-B12

Malouf, R., & Areosa Sastre, A. (2003). Vitamin B12 for cognition. The Cochrane Library.http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004394/full

“Mayo Clinic.” (n.d.). Mayo Medical Laboratories. Test ID: B12 Vitamin B12 Assay, Serum.http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9154

Mitsuyama, Y., & Kogoh, H. (1988). Serum and Cerebrospinal Fluid Vitamin B12 Levels in Demented

Patients with CH3—B12 Treatment—Preliminary Study—. Psychiatry and Clinical

Neurosciences, 42(1), 65-71. http://onlinelibrary.wiley.com/doi/10.1111/j.1440-1819.1988.tb01957.x/abstract

Molloy, A. M., Kirke, P. N., Troendle, J. F., Burke, H., Sutton, M., Brody, L. C., ... & Mills, J. L. (2009). Maternalvitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic acid fortification. Pediatrics, 123(3), 917-923. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4161975/

Nishioka, M., Kanosue, F., Yabuta, Y., & Watanabe, F. (2011). Loss of vitamin B 12 in fish (round herring)meats during various cooking treatments.Journal of nutritional science and vitaminology, 57(6),432-436. https://www.jstage.jst.go.jp/article/jnsv/57/6/57_6_432/_article

Palacios G, Sola R, Barrios L, Pietrzik K, Castillo MJ, González-Gross M. (2013) Algorithm for early diagnosisof vitamin B12 in elderly people. [PDF file]. Nutr Hosp 2013;28:1447–52.http://www.nutricionhospitalaria.com/pdf/6821.pdf

“Nutritional Effects of Food Processing.” (2014). SelfNutritionData. http://nutritiondata.self.com/topics/processing

Ryan-Harshman, M., & Aldoori, W. (2008). Vitamin B12 and health. Canadian Family Physician, 54(4), 536-541.http://www.cfp.ca/content/54/4/536.full

Regland, B., Abrahamsson, L., Blennow, K., Gottfries, C. G. and Wallin, A. (1992), Vitamin B₁₂ in CSF: reduced CSF/serum B₁₂ratio in demented men. Acta Neurologica Scandinavica, 85: 276–281. doi:10.1111/j.1600-0404.1992.tb04044.x

Smith, A. D. M. (1962). Veganism: a clinical survey with observations on vitamin-B12 metabolism. British medical  journal, 1(5293), 1655. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1958824/

Solomon, L. R. (2011). Diabetes as a cause of clinically significant functional cobalamin deficiency. Diabetes Care,34(5), 1077-1080. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114505/

Travica, N., Ried, K., Bujnowski, R., & Sali, A. (2016). Integrative health check reveals suboptimal levelsin a number of vital biomarkers. Advances in Integrative Medicine. https://scholar.googleusercontent.com/scholarq=cache:e4Bf5cbLHlEJ:scholar.google.com/+Serum+and+cerebrospinal+fluid+vitamin+B12+levels+550&hl=en&as_sdt=0,10&as_ylo=2012

Tucker, K. L., Rich, S., Rosenberg, I., Jacques, P., Dallal, G., Wilson, P. W. F., & Selhub, J. (2000). Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring Study.  Am J Clin Nutr 71 (2). pp 514-522. http://m.ajcn.nutrition.org/content/71/2/514.long

Walton, J. N., Kiloh, L. G., Osselton, J. W., & Farrall, J. (1954). The electroencephalogram in pernicious anaemiaand subacute combined degeneration of the cord. Electroencephalography and clinical neurophysiology, 6, 45-64. http://www.sciencedirect.com/science/article/pii/0013469454900061

Zhang, Y., Hodgson, N. W., Trivedi, M. S., Abdolmaleky, H. M., Fournier, M., Cuenod, M., ... & Deth, R. C.(2016). Decreased brain levels of vitamin B12 in aging, autism and schizophrenia. [PDF file]. PloS one, 11(1), e0146797. http://journals.plos.org/plosone/article/asset?id=10.1371/journal.pone.0146797.PDF

West, E. D. & Ellis, F. R. (1966). The electroencephalogram in veganism, vegetarianism, vitamin B₁₂ deficiency, and in controls. Journal of Neurology, Neurosurgery & Psychiatry, 29(5), 391-397.https://scholar.google.com/scholar?hl=en&q=+The+electroencephalogram+in+veganism%2C+vegetarianism%2C+vitamin+B12+deficiency%2C+and+in+controls&btnG=&as_sdt=1%2C10&as_sdtp=

Wu K, Helzlsouer KJ, Comstock GW, Hoffman SC, Nadeau MR & Selhub J (1999) A prospective study on folate, B12, and pyridoxal 5'-phosphate (B6) and breast cancer. Cancer Epidemiol. Biomarkers Prev. 8, 209–217.http://cebp.aacrjournals.org/content/8/3/209.long