Markers for the functional availability of cobalamin/folate and their association with neuropsychiatric symptoms in the elderly

Mild behavioral impairment domains are longitudinally associated with pTAU and metabolic biomarkers in dementia-free older adults

BACKGROUND

The mechanisms linking mild behavioral impairment (MBI) and Alzheimer's disease (AD) have been insufficiently explored, with conflicting results regarding tau protein and few data on other metabolic markers. We aimed to evaluate the longitudinal association of the MBI domains and a spectrum of plasma biomarkers.

METHODS

Our study is a secondary analysis of data from NOLAN. The longitudinal association of the MBI domains with plasma biomarkers, including pTau181, was tested using adjusted linear mixed-effects models.

RESULTS

The sample comprised 359 participants (60% female, mean age: 78.3, standard deviation: 0.3 years). After 1 year, the MBI domain of abnormal perception was associated with steeper increases in plasma pTau181. Abnormal perception, decreased motivation, and impulse dyscontrol were associated with homocysteine or insulin dysregulation.

DISCUSSION

Apart from the association with plasma pTau181, our results suggest that MBI might also represent metabolic dysregulation, probably contributing to dementia transition among older adults with subjective cognitive decline or mild cognitive impairment.

HIGHLIGHTS

Mild behavioral impairment (MBI) psychosis was associated with steeper increases in plasma p. pTau could be a pharmacological target to treat agitation and psychosis symptoms. MBI domains were linked to metabolic dysregulation involving insulin and homocysteine.

Synthetic biology-driven microbial production of folates: Advances and perspectives

With the development and application of synthetic biology, significant progress has been made in the production of folate by microbial fermentation using cell factories, especially for using generally regarded as safe (GRAS) microorganism as production host. In this review, the physiological functions and applications of folates were firstly discussed. Second, the current advances of folate-producing GRAS strains development were summarized. Third, the applications of synthetic biology-based metabolic regulatory tools in GRAS strains were introduced, and the progress in the application of these tools for folate production were summarized. Finally, the challenges to folates efficient production and corresponding emerging strategies to overcome them by synthetic biology were discussed, including the construction of biosensors using tetrahydrofolate riboswitches to regulate metabolic pathways, adaptive evolution to overcome the flux limitations of the folate pathway. The combination of new strategies and tools of synthetic biology is expected to further improve the efficiency of microbial folate synthesis.

Helicobacter pylori moderates the association between 5-MTHF concentration and cognitive function in older adults

Objective

To explore potential interactions between folate-cycle factors and Helicobacter pylori seropositivity in the prediction of cognitive function.

Methods

We used data obtained from the 1999–2000 continuous National Health and Nutrition Examination Survey produced by the United States’ Centers for Disease Control and Prevention. Using Ordinary Least Squares regression, we tested for associations between multiple folate-cycle factors, Helicobacter pylori seropositivity, and cognitive function assessed by the digit symbol coding subtest of the Wechsler Adult Intelligence Scale-III. We then tested for interactions between each of the folate-cycle factors and Helicobacter pylori in the prediction of cognitive function.

Results

Although Helicobacter pylori seropositivity, 5-methyltetrahydrofolate, vitamin B-12, and homocysteine were not associated with performance on the digit symbol coding task, Helicobacter pylori seropositivity interacted with 5-methyltetrahydrofolate concentration to predict performance on the digit symbol coding task. The Helicobacter pylori seropositive group performed worse on the digit symbol coding task as 5-methyltetrahydrofolate concentration decreased.

Conclusion

The interaction between Helicobacter pylori seropositivity and reduced folate-cycle factor 5-methyltetrahydrofolate might impair aspects of cognitive function.

Deleterious Effects of Chronic Folate Deficiency in the Ts65Dn Mouse Model of Down Syndrome

Folate is an important B vitamin naturally found in the human diet and plays a critical role in methylation of nucleic acids. Indeed, abnormalities in this major epigenetic mechanism play a pivotal role in the pathogenesis of cognitive deficit and intellectual disability in humans. The most common cause of cognitive dysfunction in children is Down syndrome (DS). Since folate deficiency is very common among the pediatric population, we questioned whether chronic folate deficiency (CFD) exacerbates cognitive dysfunction in a mouse model of DS. To test this, adult Ts65Dn mice and their disomic littermates were chronically fed a diet free of folic acid while preventing endogenous production of folate in the digestive tract for a period of 8 weeks. Our results show that the Ts65Dn mouse model of DS was significantly more vulnerable to CFD in terms of plasma homocysteine and N5-methyltetrahydrofolate (5-MTHF) levels. Importantly, these changes were linked to degenerative alterations in hippocampal dendritic morphology and impaired nest building behavior in Ts65Dn mice. Based on our results, a rigorous examination of folate intake and its metabolism in individuals with DS is warranted.

Toxoplasma Gondii Moderates the Association between Multiple Folate-Cycle Factors and Cognitive Function in U.S. Adults

Toxoplasma gondii (T. gondii) is a microscopic, apicomplexan parasite that can infect muscle or neural tissue, including the brain, in humans. While T. gondii infection has been associated with changes in mood, behavior, and cognition, the mechanism remains unclear. Recent evidence suggests that T. gondii may harvest folate from host neural cells. Reduced folate availability is associated with an increased risk of neurodevelopmental disorders, neurodegenerative diseases, and cognitive decline. We hypothesized that impairment in cognitive functioning in subjects seropositive for T. gondii might be associated with a reduction of folate availability in neural cells. We analyzed data from the third National Health and Nutrition Examination Survey to determine the associations between T. gondii infection, multiple folate-cycle factors, and three tests of cognitive functioning in U.S. adults aged 20 to 59 years. In these analyses, T. gondii moderated the associations of folate, vitamin B-12, and homocysteine with performance on the Serial Digit Learning task, a measure of learning and memory, as well as the association of folate with reaction time. The results of this study suggest that T. gondii might affect brain levels of folate and/or vitamin B-12 enough to affect cognitive functioning.

Novel relationships between B12, folate and markers of inflammation, oxidative stress and NAD(H) levels, systemically and in the CNS of a healthy human cohort

OBJECTIVE

To evaluate the relationship between folate, cobalamin (Cbl), and homocysteine (Hcy), and markers of inflammation and oxidative stress within the periphery and central nervous system (CNS) of a healthy human cohort.

METHODS

Thirty-five matched cerebrospinal fluid (CSF) and plasma samples were collected from consenting participants who required a spinal tap for the administration of anaesthetic. Plasma concentrations of Hcy and both plasma and CSF levels of folate, Cbl, nicotinamide adenine dinucleotide (NAD(H)) and markers of inflammation (interleukin-6, IL-6), and oxidative stress (F2-isoprostanes, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and total antioxidant capacity (TAC)) were quantified.

RESULTS

In the peripheral circulation, positive associations were observed between plasma folate and Cbl, and plasma TAC (P ≤ 0.01; P ≤ 0.01) and plasma NAD(H) (P ≤ 0.05; P ≤ 0.05) levels, respectively. Plasma folate was inversely associated with plasma Hcy concentrations (P ≤ 0.05); however, no statistically significant relationships were observed between plasma Hcy and plasma markers of inflammation, oxidative stress, or [NAD(H)]. Within the CNS plasma Hcy correlated positively with CSF IL-6 (P ≤ 0.01) and negatively with CSF NAD(H) (P ≤ 0.05) concentrations. An inverse association was observed between CSF folate and CSF levels of IL-6 (P ≤ 0.05). Unexpectedly, a positive association between CSF Cbl and CSF 8-OHdG levels was also found (P ≤ 0.01).

DISCUSSION

These results indicate that folate and Cbl concentrations may influence the levels of oxidative damage, inflammation, and NAD(H), both systemically and within the CNS.

A study of the prevalence of serum vitamin B12 and folic Acid deficiency in Western maharashtra

Context:

This study summarizes the prevalence of vitamin B12 and folic acid deficiency in the population coming to tertiary care center in Western Maharashtra along with the main presenting symptom routinely misinterpreted in daily practice.

Aims and Objectives:

1. To study the prevalence of vitamin B12 and folic acid deficiency in the population of western Maharashtra. 2. To correlate the symptoms with serum vitamin B12 and folic acid levels.

Materials and Methods:

The present study is a cross-sectional observation study carried out on patients from western Maharashtra seeking medical attention on outpatient and inpatient basis in the medicine department of a teaching institute in Karad. One-hundred patients were selected on basis of below mentioned symptoms viz. tingling and numbness in extremities, dizziness, unsteady gait, early tiredness, forgetfulness, proximal weakness, distal weakness, chronic headache, less interest in work, chronic loose stools, strict vegetarians, alcoholics, intake of medications like anti-tubercular treatment, surgery involving terminal ileum. Serum vitamin B12 and folic acid levels of these patients were observed. Deficiency of vitamin B12 and folic acid was studied in 4 groups: (a) Absolute vitamin B12 deficiency; (b) Absolute folic acid deficiency; (c) Borderline vitamin B12 deficiency; (d) Combined vitamin B12 and folic acid deficiency.

Results:

Of the 100 cases, 33% patients were vegetarian. Folic acid deficiency formed the major chunk of deficiency group. Six percent patients had neuropsychiatric manifestations. Depressive illness in 1% patients, dementia in 0% patients, forgetfulness in 1% patients, mania/hallucination in 0% patients each, and chronic headache in 1% patients. Neuropathy in form of loss of reflexes, decreased touch sensation was present in 9% patients. Posterior column involvement viz. Loss of joint position, vibration, positive Romberg's sign were present in 34% patients of vitamin B12 and folic acid deficiency.

Conclusion:

In a small study, it was found that megaloblastic anemia may have symptoms and signs referable to several systems including hematology, dermatology, gastrointestinal, neurology, and neuropsychiatry.

Is increased red cell distribution width an indicating marker of nonalcoholic steatohepatitis and fibrotic stage?

Red cell distribution width (RDW) may play an important role in predicting steatohepatitis and liver fibrosis. In the original study, it was aimed to determine whether RDW could be used for this purpose or not. There are studies indicating that higher RDW is correlated well with components of metabolic syndrome. Because nonalcoholic fatty liver disease is now recognized as the hepatic manifestation of metabolic syndrome, possible impact of the accompanying confounders on the study findings should have been detailed. There may be a patient selection bias due to use of improper cut-off values for alcohol consumption and inclusion of only subjects with normal aminotransferase levels and normal abdominal ultrasonography. Patients without hepatosteatosis on ultrasonography and with any restriction of aminotransferase levels should have been included in the control group, because isolated aminotransferase elevation is not decisive in the diagnosis of hepatosteatosis. Although iron, vitamin B₁₂ and folic acid deficiencies were included in exclusion criteria, functional forms of these molecules like methylmalonic acid, homocysteine, ferritin levels and total iron binding capacity, which are more sensitive and specific parameters for vitamin B₁₂ and folic acid deficiencies, were not mentioned. Consequently, RDW, an inexpensive, non-invasive, but powerful indicator overlooked on whole blood analysis, itself without other inflammatory markers may not accurately provide information about progression of nonalcoholic steatohepatitis and fibrosis.

Structure of putative 4-amino-4-deoxychorismate lyase from Thermus thermophilus HB8

The pyridoxal 5'-phosphate-dependent enzyme 4-amino-4-deoxychorismate lyase converts 4-amino-4-deoxychorismate to p-aminobenzoate and pyruvate in one of the crucial steps in the folate-biosynthesis pathway. The primary structure of the hypothetical protein TTHA0621 from Thermus thermophilus HB8 suggests that TTHA0621 is a putative 4-amino-4-deoxychorismate lyase. Here, the crystal structure of TTHA0621 is reported at 1.93 A resolution. The asymmetric unit contained four NCS molecules related by 222 noncrystallographic symmetry, in which the formation of intact dimers may be functionally important. The cofactor pyridoxal 5'-phosphate (PLP) binds to the protein in the large cleft formed by the N-terminal and C-terminal domains of TTHA0621. The high structural similarity and the conservation of the functional residues in the catalytic region compared with 4-amino-4-deoxychorismate lyase (PabC; EC 4.1.3.38) from Escherichia coli suggest that the TTHA0621 protein may also possess 4-amino-4-deoxychorismate lyase activity.

Studies of biomarker responses to intervention with vitamin B-12: a systematic review of randomized controlled trials

BACKGROUND

Mild vitamin B-12 deficiency is common among older adults, but evidence for setting dietary recommendations is limited because most studies have administered vitamin B-12 via nonoral routes or at doses several hundred times higher than current recommendations. Furthermore, different biomarkers of vitamin B-12 status have not been systematically reviewed.

OBJECTIVE

The aim was to assess the effectiveness of biomarkers of vitamin B-12 status through a systematic review of published randomized controlled trials of oral vitamin B-12 supplementation.

DESIGN

Methods included a structured search strategy on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction; validity assessment; and meta-analysis.

RESULTS

Eight randomized controlled trials were included, and all studies measured serum and plasma total vitamin B-12, 3 studies measured methylmalonic acid, and 6 studies measured total homocysteine response. All 3 biomarkers were found to be effective measures of altered vitamin B-12 intake in populations with low and borderline baseline vitamin B-12 status (P < 0.00001); however, in the case of total vitamin B-12, substantial heterogeneity that could not be fully explained by subgroup analysis was observed. Insufficient data were available to determine the effectiveness of plasma holotranscobalamin, which was measured in only one randomized controlled trial.

CONCLUSIONS

The available evidence suggests that plasma and serum concentrations of total vitamin B-12, methylmalonic acid, and total homocysteine are all effective biomarkers of a change in vitamin B-12 intake; however, because the available data were limited, it was not possible to examine fully the factors that could explain the substantial heterogeneity in total vitamin B-12. Future trials should include low-dose vitamin B-12 in adults across the entire age spectrum and measure the holotranscobalamin response to supplementation.

Biomarkers of folate and vitamin B(12) status in cerebrospinal fluid

Folate and vitamin B(12) are essential cofactors for the methionine/homocysteine cycle in the brain. These vitamins mediate the remethylation of homocysteine (Hcy), which affects the production of the universal methyl donor, S-adenosylmethionine (SAM), in the brain among other organs. Additionally, increased plasma concentrations of total Hcy (tHcy) are associated with cerebrovascular disease and can compromise the blood-brain barrier. tHcy concentrations in the brain and cerebrospinal fluid become increased in several psychiatric and neurological disorders. Disturbances in the transmethylation pathway indicated by abnormal SAM, S-adenosylhomocysteine or their ratio have been reported in many neurodegenerative diseases, such as dementia, depression or Parkinson's disease. Cobalamin is essential for neuronal generation and its deficiency can cause degeneration of the nervous system. Available data emphasize that deficiency of folate and vitamin B(12) can lead to elevated concentrations of tHcy and disturbed methylation potential in the brain. Therefore, acquired or inherited disorders in these metabolic pathways are associated with brain abnormalities and severe neurological symptoms that are mostly irreversible, even after providing the missing cofactors. This review discusses the relationship between brain and blood levels of key vitamins and metabolites related to one carbon metabolism.

Characterization of the role of para-aminobenzoic acid biosynthesis in folate production by Lactococcus lactis

The pab genes for para-aminobenzoic acid (pABA) biosynthesis in Lactococcus lactis were identified and characterized. In L. lactis NZ9000, only two of the three genes needed for pABA production were initially found. No gene coding for 4-amino-4-deoxychorismate lyase (pabC) was initially annotated, but detailed analysis revealed that pabC was fused with the 3' end of the gene coding for chorismate synthetase component II (pabB). Therefore, we hypothesize that all three enzyme activities needed for pABA production are present in L. lactis, allowing for the production of pABA. Indeed, the overexpression of the pABA gene cluster in L. lactis resulted in elevated pABA pools, demonstrating that the genes are involved in the biosynthesis of pABA. Moreover, a pABA knockout (KO) strain lacking pabA and pabBC was constructed and shown to be unable to produce folate when cultivated in the absence of pABA. This KO strain was unable to grow in chemically defined medium lacking glycine, serine, nucleobases/nucleosides, and pABA. The addition of the purine guanine, adenine, xanthine, or inosine restored growth but not the production of folate. This suggests that, in the presence of purines, folate is not essential for the growth of L. lactis. It also shows that folate is not strictly required for the pyrimidine biosynthesis pathway. L. lactis strain NZ7024, overexpressing both the folate and pABA gene clusters, was found to produce 2.7 mg of folate/liter per optical density unit at 600 nm when the strain was grown on chemically defined medium without pABA. This is in sharp contrast to L. lactis strains overexpressing only one of the two gene clusters. Therefore, we conclude that elevated folate levels can be obtained only by the overexpression of folate combined with the overexpression of the pABA biosynthesis gene cluster, suggesting the need for a balanced carbon flux through the folate and pABA biosynthesis pathway in the wild-type strain.

Biomarkers of folate and vitamin B12 are related in blood and cerebrospinal fluid

BACKGROUND

B-vitamins (folate, B(12)) are important micronutrients for brain function and essential cofactors for homocysteine (HCY) metabolism. Increased HCY has been related to neurological and psychiatric disorders. We studied the role of the B-vitamins in HCY metabolism in the brain.

METHODS

We studied blood and cerebrospinal fluid (CSF) samples from 72 patients who underwent lumbar puncture. We measured HCY, methylmalonic acid (MMA), and cystathionine by gas chromatography-mass spectrometry; S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) by liquid chromatography-tandem mass spectrometry; and the B-vitamins by HPLC or immunoassays.

RESULTS

Concentrations were lower in CSF than serum or plasma for HCY (0.09 vs 9.4 micromol/L), SAH (13.2 vs 16.8 nmol/L), cystathionine (54 vs 329 nmol/L), and holotranscobalamin (16 vs 63 pmol/L), whereas concentrations in CSF were higher for MMA (359 vs 186 nmol/L) and SAM (270 vs 113 nmol/L; all P <0.05). CSF concentrations of HCY correlated significantly with CSF folate (r = -0.46), CSF SAH (r = 0.48), CSF-albumin (r = 0.31), and age (r = 0.32). Aging was also associated with lower concentrations of CSF-folate and higher CSF-SAH. The relationship between serum and CSF folate depended on serum folate: the correlation (r) of serum and CSF-folate was 0.69 at serum folate <15.7 nmol/L. CSF concentrations of MMA and holotranscobalamin were not significantly correlated.

CONCLUSIONS

CSF and serum/plasma concentrations of vitamin biomarkers are significantly correlated. Older age is associated with higher CSF-HCY and CSF-SAH and lower CSF-folate. These metabolic alterations may be important indicators of low folate status, hyperhomocysteinemia, and neurodegenerative diseases.

Acquired and inherited disorders of cobalamin and folate in children

Cobalamin deficiency in the newborn usually results from cobalamin deficiency in the mother. Megaloblastic anaemia, pancytopenia and failure to thrive can be present, accompanied by neurological deficits if the diagnosis is delayed. Most cases of spina bifida and other neural tube defects result from maternal folate and/or cobalamin insufficiency in the periconceptual period. Polymorphisms in a number of genes involved in folate and cobalamin metabolism exacerbate the risk. Inborn errors of cobalamin metabolism affect its absorption, (intrinsic factor deficiency, Imerslund-Gräsbeck syndrome) and transport (transcobalamin deficiency) as well as its intracellular metabolism affecting adenosylcobalamin synthesis (cblA and cblB), methionine synthase function (cblE and cblG) or both (cblC, cblD and cblF). Inborn errors of folate metabolism include congenital folate malabsorption, severe methylenetetrahydrofolate reductase deficiency and formiminotransferase deficiency. The identification of disease-causing mutations in specific genes has improved our ability to diagnose many of these conditions, both before and after birth.

Elderly psychiatric patients at risk of folic acid deficiency: A case controlled study

In the elderly, folic acid deficiency may result in psychiatric symptoms or the increases in severity of other organic and non-organic mental diseases. We aimed to characterize elderly, community-dwelling, newly admitted patients to a large urban psychiatric hospital who are suffering from untreated folic acid deficiency in comparison with elderly inpatients who do not suffer from this deficiency. During a 2-year period, all subjects aged 65 years or older admitted to the large psychiatric center were tested for levels of serum folic acid levels. Subjects suffering from folic acid deficiency were compared (unpaired t-test) with matched patients with normal serum levels. Of the 293 newly admitted elderly patients 45 (15.7%) suffered from folic acid deficiency. Mean age for the folic acid deficient group was 77.3+/-8.1 years, 38% were diagnosed as suffering from dementia, 22% were depressed and 51% were living alone. In the comparison group mean age was 77.3+/-6.3 years, 33% were diagnosed as suffering from dementia, 24% were suffering from depression and 57% were living alone. We conclude that we could not find any "characteristic" of elderly subjects at risk of folic acid deficiency.

Plasma homocysteine concentration and its relation to symptoms of vascular disease in psychogeriatric patients

BACKGROUND

There is a high frequency of elevated plasma total homocysteine (tHcy) concentrations in elderly patients with mental disorders. Psychogeriatric patients with a history of vascular disease exhibit a significantly higher plasma tHcy concentration than patients without vascular disease.

METHOD

The main reason for the present study is to further investigate the association between plasma tHcy concentration and vascular disease in psychogeriatric patients. We therefore investigated 152 psychogeriatric patients and determined plasma tHcy and its most important determinants (serum folate and serum cobalamin, serum cystatin C and serum creatinine). The patients were divided into two groups according to the presence of vascular disease. Eighty-seven patients had concomitant vascular disease. We also analysed the natriuretic peptide N-terminal pro brain natriuretic peptide (NT-proBNP) and protein S-100B in serum. NT-proBNP is a marker for congestive heart failure, whereas protein S-100B is a marker for brain damage.

RESULTS

The plasma tHcy concentration is elevated in the presence of dementia or vascular disease in psychogeriatric patients. The presence of dementia or vascular disease is also associated with higher age, renal impairment and lower serum folate concentration than in patients without dementia or vascular disease. Furthermore, we observed elevated serum concentrations of NT-proBNP in patients with dementia or vascular disease as a sign of poorer cardiovascular status. Likewise, protein S-100B concentrations were elevated in patients with dementia or vascular disease, possibly indicating brain damage in these groups of patients.

CONCLUSION

The high frequency of comorbidity of vascular disease and mental illness indicates a possibility to prevent and treat psychogeriatric disease by actively counteracting vascular disease in patients with psychogeriatric symptoms. Routine determination of NT-proBNP is valuable for obtaining information about cardiovascular status.

Controlled modulation of folate polyglutamyl tail length by metabolic engineering of Lactococcus lactis

The dairy starter bacterium Lactococcus lactis is able to synthesize folate and accumulates >90% of the produced folate intracellularly, predominantly in the polyglutamyl form. Approximately 10% of the produced folate is released into the environment. Overexpression of folC in L. lactis led to an increase in the length of the polyglutamyl tail from the predominant 4, 5, and 6 glutamate residues in wild-type cells to a maximum of 12 glutamate residues in the folate synthetase overproducer and resulted in a complete retention of folate in the cells. Overexpression of folKE, encoding the bifunctional protein 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase and GTP-cyclohydrolase I, resulted in reduction of the average polyglutamyl tail length, leading to enhanced excretion of folate. By simultaneous overexpression of folKE and folC, encoding the enzyme folate synthetase or polyglutamyl folate synthetase, the average polyglutamyl tail length was increased, again resulting in normal wild-type distribution of folate. The production of bioavailable monoglutamyl folate and almost complete release of folate from the bacterium was achieved by expressing the gene for gamma-glutamyl hydrolase from human or rat origin. These engineering studies clearly establish the role of the polyglutamyl tail length in intracellular retention of the folate produced. Also, the potential application of engineered food microbes producing folates with different tail lengths is discussed.

Increased production of folate by metabolic engineering of Lactococcus lactis

The dairy starter bacterium Lactococcus lactis is able to synthesize folate and accumulates large amounts of folate, predominantly in the polyglutamyl form. Only small amounts of the produced folate are released in the extracellular medium. Five genes involved in folate biosynthesis were identified in a folate gene cluster in L. lactis MG1363: folA, folB, folKE, folP, and folC. The gene folKE encodes the biprotein 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase and GTP cyclohydrolase I. The overexpression of folKE in L. lactis was found to increase the extracellular folate production almost 10-fold, while the total folate production increased almost 3-fold. The controlled combined overexpression of folKE and folC, encoding polyglutamyl folate synthetase, increased the retention of folate in the cell. The cloning and overexpression of folA, encoding dihydrofolate reductase, decreased the folate production twofold, suggesting a feedback inhibition of reduced folates on folate biosynthesis.

Serum folate and Vitamin B12 levels in women using modern oral contraceptives (OC) containing 20 microg ethinyl estradiol

OBJECTIVE

The effects of modern oral contraceptives (OC) on serum concentrations of folate and cobalamin are controversial.

STUDY DESIGN

Case-control study on the cobalamin and folate status of 71 healthy female nulligravidae using "low dose" OC for >or=3 months and 170 controls. Factors interfering with vitamin metabolism were thoroughly controlled. Serum concentrations were measured by commercial assays. The results were evaluated using Mann-Whitney's U-test and chi(2) analysis.

RESULTS

OC-users showed significantly lower concentrations of cobalamin than controls. The rates of women with reduced, normal, and elevated levels differed significantly. Nine users but no control had frank cobalamin deficiency without clinical symptoms. Folate levels did not differ between the groups. Vegetarian diet, smoking or obesity did not have a significant influence.

CONCLUSIONS

Routine measurement of cobalamin or folate in women using "low dose" OC is not warranted. Vitamin supplementation or different contraceptive methods should be considered in women with pre-existing cobalamin deficiency or restrictive dietary habits.

Functional Vitamin B12 Deficiency and Determination of Holotranscobalamin in Populations at Risk

BACKGROUND

The prevalence of a sub-clinical functional vitamin B12 deficiency in the general population is higher than previously expected. Total serum vitamin B12 may not reliably indicate vitamin B12 status. To get more specificity and sensitivity in diagnosing vitamin B12 deficiency, the concept of measuring holotranscobalamin II (holoTC), a sub-fraction of vitamin B12, has aroused great interest. HoloTC as a biologically active vitamin B12 fraction promotes a specific uptake of its vitamin B12 by all cells. In this study we investigated the diagnostic value of storage (holoTC) of vitamin B12 and functional markers (methylmalonic acid (MMA)) of vitamin B12 metabolism in populations who are at risk of vitamin B12 deficiency.

SUBJECTS AND METHODS

Our study included 93 omnivorous German controls, 111 German and Dutch vegetarian subjects, 122 Syrian apparently healthy subjects, 127 elderly Germans and finally 92 German pre-dialysis renal patients. Serum concentrations of homocysteine (Hcy) and MMA were measured by gas chromatography-mass spectrometry, folate and vitamin B12 by chemiluminescence immunoassay, and holoTC by utilizing a RIA test.

RESULTS

High Hcy (>12 micromol/l), high MMA (>271 nmol/l) resp. low holoTC (vitamin B12) in serum were detected in 15%, 8% resp. 13% (1%) of German controls, 36%, 60%, resp. 72% (30%) of vegetarians, 42%, 48% resp. 50% (6%) of Syrians, 75%, 42%, resp. 21% (7%) of elderly subjects and 75%, 67% resp. 4% (2%) of renal patients. The lowest median levels of holoTC were observed in vegetarians, followed by the Syrian subjects (23 and 35 pmol/l, respectively). Renal patients had significantly higher levels of holoTC compared to the German controls (74 vs. 54 pmol/l). In the vitamin B12 range between 156 pmol/l (conventional cut-off level) and 241 pmol/l, both mean concentrations of holoTC and MMA were in the pathological range. HoloTC was the earliest marker for vitamin B12 deficiency followed by MMA. Vitamin B12 deficiency causes folate trapping. A higher folate level is required to keep Hcy normal. The relationship between MMA and holoTC seemed dependent on renal function. In renal patients with a glomerular filtration rate below 36 ml/min, a significantly lower mean level of MMA was detected within the highest tertile of holoTC concentration, compared to the lowest tertile. Thus, in renal patients, a higher serum concentration of circulating holoTC is required to deliver sufficient amounts of holoTC into the cells.

CONCLUSION

Our data support the concept that the measurement of holoTC and MMA provides a better index of cobalamin status than the measurement of total vitamin B12. HoloTC is the most sensitive marker, followed by MMA. The use of holoTC and MMA enables us to differentiate between storage depletion and functional vitamin B12 deficiency. Renal patients have a higher requirement of circulating holoTC. In renal dysfunction, holoTC cannot be used as a marker of vitamin B12 status.

Vegetarian lifestyle and monitoring of vitamin B-12 status

Vegetarians are at risk to develop deficiencies of some essential nutrients, especially vitamin B-12 (cobalamin). Cobalamin occurs in substantial amounts only in foods derived from animals and is essential for one-carbon metabolism and cell division. Low nutritional intake of vitamin B-12 may lead to negative balance and, finally, to functional deficiency when tissue stores of vitamin B-12 are depleted. Early diagnosis of vitamin B-12 deficiency seems to be useful because irreversible neurological damages may be prevented by cobalamin substitution. The search for a specific and sensitive test to diagnose vitamin B-12 deficiency is ongoing. Serum vitamin B-12 measurement is a widely applied standard method. However, the test has poor predictive value. Optimal monitoring of cobalamin status in vegetarians should include the measurement of homocysteine (HCY), methylmalonic acid (MMA), and holotranscobalamin II. Vitamin B-12 deficiency can be divided into four stages. In stages I and II, indicated by a low plasma level of holotranscobalamin II, the plasma and cell stores become depleted. Stage III is characterized by increased levels of HCY and MMA in addition to lowered holotranscobalamin II. In stage IV, clinical signs become recognizable like macroovalocytosis, elevated MCV of erythrocytes or lowered haemoglobin. In our investigations, we have found stage III of vitamin B-12 deficiency in over 60% of vegetarians, thus underlining the importance of cobalamin monitoring in this dietary group.

Optimal use of markers for cobalamin and folate status in a psychogeriatric population

BACKGROUND

Cobalamin/folate deficiency is common in elderly subjects and may lead to psychiatric symptoms, but even more often it increases the severity of other organic and non-organic mental diseases. It is therefore of importance to evaluate the optimal use of different markers of cobalamin/folate status in a psychogeriatric population.

METHODS

We measured serum cobalamin, blood folate, plasma homocysteine (tHcy) and serum methylmalonic acid (MMA) in 475 well-defined psychogeriatric patients.

RESULTS

The findings in the present study showed that many (41%) of the patients with normal levels of serum MMA (< 0.41 micromol/l) had pathological values of at least one of the other markers for cobalamin/folate status, whereas only 17% of patients with normal plasma tHcy (< 19.9 micromol/l) had pathological levels of other markers. If patients with decreased levels of serum cobalamin and/or blood folate were also excluded from these patients, only nine patients with slightly elevated levels of serum MMA remained. In the present study different upper reference limits were also tested for both serum MMA and plasma tHcy. However, the use of these limits did not cause any diagnostic improvement in the evaluation of cobalamin-folate status. Plasma tHcy was increased in almost all diagnosis groups of the psychogeriatric patients, whereas serum MMA was increased in only some groups. The distribution of the two common polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) was similar in patients with elevated and normal plasma tHcy.

CONCLUSIONS

The findings in the present study suggest the use of plasma tHcy, serum cobalamin and blood folate to evaluate cobalamin-folate status in psychogeriatric patients and to omit the use of serum MMA.