Vitamin B12 status and the risk of developing sepsis in patients with bacterial infection: a prospective observational cohort study.

BACKGROUND: Data have shown that vitamin B12 has immunomodulatory effects via different pathways, which could influence the pathophysiology of sepsis. The objective of this study was to investigate whether vitamin B12 levels, assessed by the measurement of holotranscobalamin (HTC), total vitamin B12 (B12), and methylmalonic acid (MMA, which accumulates in case of B12 deficiency), are associated with the development of sepsis in patients with onset of bacterial infection. METHODS: This was a single-center, prospective observational pilot study. Adult patients who presented to the emergency department with bacterial infection confirmed by a positive microbiological culture result were included in the study and followed up for 6 days to assess whether they developed sepsis or not. The primary objective was to compare HTC concentration in patients who developed sepsis to those who did not develop sepsis. Secondary objectives were the evaluation of B12 and MMA concentrations in those two groups. Multiple logistic regression models were used, with presence of sepsis as the outcome variable, and HTC, B12, and MMA concentrations as predictor variables, separately, and adjusted for potential confounders. RESULTS: From 2019 to 2022, 2131 patients were assessed for eligibility, of whom 100 met the inclusion criteria. One patient was excluded from the analysis due to missing data. Of the 99 patients, 29 developed sepsis. There was no evidence for an association between HTC or B12 concentration and the development of sepsis (OR 0.65, 95% CI 0.31-1.29, p = 0.232, OR 0.84, 95% CI 0.44-1.54, p = 0.584, respectively). There was an association between MMA concentration and the development of sepsis, with a positive effect, i.e. with increasing MMA, the odds for sepsis increased (OR 2.36, 95% CI 1.21-4.87, p = 0.014). This association remained significant when adjusted for confounders (OR 2.72, 95% CI 1.23-6.60, p = 0.018). CONCLUSIONS: Our study found an association between elevated MMA concentration and the development of sepsis. We did not find an association between HTC and B12 concentrations and the development of sepsis. Further, larger studies are warranted, as it could lead to interventional trials investigating whether B12 supplementation provides a clinical benefit to patients with infection or sepsis. TRIAL REGISTRATION: The study was registered on ClinicalTrials.gov under the identifier NCT04008446 on June 17, 2019.

Simultaneous determination of total homocysteine, methionine, methylmalonic acid and 2-methylcitric acid in dried blood spots by ultra-performance liquid chromatography-tandem mass spectrometry.

Homocysteine, methionine, methylmalonic acid and 2-methylcitric acid are clinically relevant markers in the methionine, propionate, and cobalamin metabolism. This study aimed to develop and validate an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for simultaneously determining total homocysteine, methionine, methylmalonic acid and 2-methylcitric acid in dried blood spots. Three 3.2 mm discs were punched from each calibrator, quality control, and sample dried blood spot into a 96-well U-plate. Each sample was spiked with internal standards and extracted. Then the supernatant was transferred to another 96-well U-plate. After nitrogen drying, the dried residues were reconstituted, centrifuged, and the resulting supernatant was transferred to another 96-well plate for analysis. The method was performed using UPLC-MS/MS within 3 min, validated according to guidance documents, and applied to 72 samples from confirmed patients with methionine, propionate, and cobalamin metabolism disorders. The UPLC-MS/MS method provided satisfactory separation of the four analytes. The R2 values were ≥ 0.9937 for all analytes. The recoveries ranged from 94.17 to 114.29 %, and the coefficients of variation for intraday and interday precision were 0.19 % to 5.23 % and 1.02 % to 6.89 %, respectively. No significant carry-over was detected for the four analytes, and most of confirmed samples exhibited biomarker patterns characteristic of the relevant disorders. A simple and fast UPLC-MS/MS method was successfully developed, validated, and applied to clinical samples for the simultaneous determination of total homocysteine, methionine, methylmalonic acid, and 2-methylcitric acid in dried blood spots.

Association between serum methylmalonic acid and chronic kidney disease in adults: a cross-sectional study from NHANES 2013-2014.

Introduction: Chronic kidney disease(CKD) is a global medical problem. Serum methylmalonic acid(MMA) is a serum marker associated with many diseases. This study aimed to investigate the association between MMA and CKD. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 were downloaded and analyzed. The association between MMA and CKD was confirmed by using multiple logistic regression modeling. The smooth curve fitting method was used to investigate the nonlinear relationship between them. Subgroup analyses and interaction tests were used to verify the stability of the association between different subgroups. Threshold effect analysis was used to determine the optimal control point for MMA. Results: There was a unique W-shaped nonlinear relationship between MMA and the risk of CKD, with a positive correlation between them (OR=1.66,95% CI:1.27, 2.17; P=0.0002). As the stage of CKD progressed, MMA levels increased. Age, hypertension, and serum vitamin B12 had significant influences on the association between MMA and the risk of CKD. Conclusion: Our findings revealed that serum MMA accumulation was positively associated with the risk of CKD. Serum MMA level may be a novel index to predict the development and course of CKD. This study may help in the early identification of people at risk for chronic kidney disease and provide new ideas and approaches for prevention and treatment.

Healthy Plasma Exosomes Exert Potential Neuroprotective Effects against Methylmalonic Acid-Induced Hippocampal Neuron Injury.

Exosomes have shown good potential for alleviating neurological deficits and delaying memory deterioration, but the neuroprotective effects of exosomes remain unknown. Methylmalonic acidemia is a metabolic disorder characterized by the accumulation of methylmalonic acid (MMA) in various tissues that inhibits neuronal survival and function, leading to accelerated neurological deterioration. Effective therapies to mitigate these symptoms are lacking. The purpose of this study was to explore the neuroprotective effects of plasma exosomes on cells and a mouse model of MMA-induced injury. We evaluated the ability of plasma exosomes to reduce the neuronal apoptosis, cross the blood-brain barrier, and affect various parameters related to neuronal function. MMA promoted cell apoptosis, disrupted the metabolic balance, and altered the expression of B-cell lymphoma-2 (Bcl-2), Bcl2-associated X (Bax), and synaptophysin-1 (Syp-1), and these changes may be involved in MMA-induced neuronal apoptosis. Additionally, plasma exosomes normalized learning and memory and protected against MMA-induced neuronal apoptosis. Our findings indicate that neurological deficits are linked to the pathogenesis of methylmalonic acidemia, and healthy plasma exosomes may exert neuroprotective and therapeutic effects by altering the expression of exosomal microRNAs, facilitating neuronal functional recovery in the context of this inherited metabolic disease. Intravenous plasma-derived exosome treatment may be a novel clinical therapeutic strategy for methylmalonic acidemia.

Long-Term Proton Pump Inhibitor-Acid Suppressive Treatment Can Cause Vitamin B12 Deficiency in Zollinger-Ellison Syndrome (ZES) Patients.

Whether the long-term treatment of patients with proton pump inhibitors (PPIs) with different diseases [GERD, Zollinger-Ellison syndrome (ZES), etc.] can result in vitamin B12 (VB12) deficiency is controversial. In this study, in 175 patients undergoing long-term ZES treatment with anti-acid therapies, drug-induced control acid secretory rates were correlated with the presence/absence of VB12 deficiency, determined by assessing serum VB12 levels, measurements of VB12 body stores (blood methylmalonic acid (MMA) and total homocysteine[tHYC]), and other features of ZES. After a mean of 10.2 yrs. of any acid treatment (5.6 yrs. with PPIs), 21% had VB12 deficiency with significantly lower serum and body VB12 levels (p < 0.0001). The presence of VB12 deficiency did not correlate with any feature of ZES but was associated with a 12-fold lower acid control rate, a 2-fold higher acid control pH (6.4 vs. 3.7), and acid control secretory rates below those required for the activation of pepsin (pH > 3.5). Over a 5-yr period, the patients with VB12 deficiency had a higher rate of achlorhydria (73% vs. 24%) and a lower rate of normal acid secretion (0% vs. 49%). In conclusion, in ZES patients, chronic long-term PPI treatment results in marked acid hyposecretion, resulting in decreased serum VB12 levels and decreased VB12-body stores, which can result in VB12 deficiency.

Vitamin B12-Related Biomarkers.

BACKGROUND: Adult vitamin B12 (B12) deficiency may present itself with nonspecific mainly neurological symptoms, and thus plasma biomarkers are often judged to be of major importance in the further diagnostic process. Four biomarkers are of special relevance: total B12, holotranscobalamin (the part of B12 bound to the active transport protein, transcobalamin, also named holoTC or active B12) and the 2 so-called metabolic markers that accumulate if B12 is lacking, methylmalonic acid (MMA) and homocysteine. OBJECTIVE: This article briefly reviews the inherent limitation of biomarkers, discusses its use in establishing the diagnosis and cause of B12 deficiency, and when following or discontinuing treatment with B12. METHODS: The review is based on published papers, but also on knowledge gained from working within the area. CONCLUSION: It is concluded that a combination of a B12 and a metabolic marker, for example, total B12 and MMA, may prove most useful in daily practice. An unexpectedly high level of total B12 is most often of no clinical importance, though sometimes related to the presence of underlying cancer. Measurement of total B12 is of limited value in patients on treatment with pharmacological doses of B12 but may be helpful if B12 treatment is discontinued.

Plain language titleVitamin B12-Related Blood TestsPlain language summaryBlood-testing is considered an important part of the diagnostic procedure in patients suspected to suffer from B12 deficiency. A deficiency is supported by a low level of plasma B12, and confirmed by a high level of methylmalonic acid, judged according to age and kidney function. Alternatively, a high level of homocysteine may support the diagnosis. Treatment of B12 deficiency is mainly guided by improvement of symptoms, with a very limited need for further blood testing. If B12-treatment is discontinued, B12 status should be judged every 6 months for approximately 2 years to detect a possible reoccurrence of a deficient state. An unexpected high level of plasma B12 is most often of no clinical implication.

Vitamin B12 Deficiency-Induced Neuropathy and Cognitive and Motor Impairment in the Elderly: A Case Study.

Vitamin B12 deficiency can present with a variety of neurological and cognitive symptoms. Especially in elderly patients, vitamin B12 deficiency can be easily overlooked because symptoms may be attributed to comorbid conditions or solely to the aging process. In this case study, we present two patients, a 71-year-old man and a 74-year-old female, with vitamin B12 deficiency. The male patient had a history of (partial) resection of the ileum/jejunum/colon because of intestinal ischemia. The female patient had a history of hypothyroidism, type 2 diabetes with complications (including peripheral neuropathy), mitochondrial myopathy, and chronic lymphocytic leukemia. Both patients presented with severe fatigue, cognitive impairment, and impaired walking. Next to this, the male patient suffered from depressive symptoms and mild disorientation, and the female patient experienced neuropathic pain. She also mentioned a positive family history for B12 deficiency. The first patient had normal to high B12 levels because he was already on B12 injections (once every three weeks) because of an earlier diagnosed B12 deficiency. The female patient had B12 levels within normal range (holotranscobalamin 54 pmol/L) and her diagnosis was confirmed by elevated homocysteine and methylmalonic acid levels. Treatment with frequent hydroxocobalamin injections and other supplements significantly improved their cognitive, emotional, and motor functions. These cases underscore the need for a high level of clinical suspicion in elderly patients, also in cases of normal B12 levels but with clinical signs of deficiency and a positive risk factor, such as stomach or small bowel surgery or positive family history.

Plain language titleA case study of two elderly patients with vitamin B12 deficiency and neurological and cognitive complaintsPlain language summaryVitamin B12 deficiency in elderly patients can be easily overlooked as symptoms can also be caused by other age-related diseases or the aging process. In our article we present two elderly patients, a 71-year-old male and a 74-year-old female, with neurological complaints, such as severe fatigue, cognitive decline, and walking impairment. The male patient had a history of small bowel surgery, and the female patient mentioned that she had several siblings with B12 deficiency. Additionally, the male patient suffered from depressive symptoms and mild disorientation, and the female had severe pain in her legs. The male patient already received B12 injections because of an earlier B12 diagnosis, but with a relatively low frequency. The B12 levels of the female patients were within the normal range. However, her diagnoses could be confirmed with additional laboratory measurements, such as homocysteine and methylmalonic acid. Treatment with frequent B12 injections and other supplements significantly improved their cognitive, emotional, and motor functions. Our study shows that clinicians should carefully consider the possibility of B12 deficiency in elderly patients with cognitive and neurological complaints, also in patients with B12 levels within the normal range, but with risk factors such as family members with B12 deficiency or conditions that may impair the vitamin B12 uptake, such as previous stomach or small bowel surgery.

A Brief Overview of the Diagnosis and Treatment of Cobalamin (B12) Deficiency.

BACKGROUND: An increasing number of adult individuals are at risk of vitamin B12 deficiency, either from reduced nutritional intake or impaired gastrointestinal B12 absorption. OBJECTIVE: This study aims to review the current best practices for the diagnosis and treatment of individuals with vitamin B12 deficiency. METHODS: A narrative literature review of the diagnosis and treatment of vitamin B12 deficiency. RESULTS: Prevention and early treatment of B12 deficiency is essential to avoid irreversible neurological consequences. Diagnosis is often difficult due to diverse symptoms, marked differences in diagnostic assays' performance and the unreliability of second-line biomarkers, including holo-transcobalamin, methylmalonic acid and total homocysteine. Reduced dietary intake of B12 requires oral supplementation. In B12 malabsorption, oral supplementation is likely insufficient, and parenteral (i.e. intramuscular) supplementation is preferred. There is no consensus on the optimal long-term management of B12 deficiency with intramuscular therapy. According to the British National Formulary guidelines, many individuals with B12 deficiency due to malabsorption can be managed with 1000 µg intramuscular hydroxocobalamin once every two months after the initial loading. Long-term B12 supplementation is effective and safe, but responses to treatment may vary considerably. Clinical and patient experience strongly suggests that up to 50% of individuals require individualized injection regimens with more frequent administration, ranging from daily or twice weekly to every 2-4 weeks, to remain symptom-free and maintain a normal quality of life. 'Titration' of injection frequency based on measuring biomarkers such as serum B12 or MMA should not be practiced. There is currently no evidence to support that oral/sublingual supplementation can safely and effectively replace injections. CONCLUSIONS: This study highlights the interindividual differences in symptomatology and treatment of people with B12 deficiency. Treatment follows an individualized approach, based on the cause of the deficiency, and tailored to help someone to become and remain symptom-free.

Plain language titleDiagnosis and Treatment of Vitamin B12 DeficiencyPlain language summaryThe number of people who are at risk of developing a deficiency of vitamin B12 is steadily increasing. B12 deficiency can develop when people consume too few B12-containing foods of animal origin, or when they develop a form of B12 malabsorption. B12 deficiency can lead to serious complications so prevention and early treatment are essential. Diagnosing B12 deficiency can be challenging: the symptoms vary from patient to patient, and the methods used to measure B12 in the blood, or certain biomarkers associated with B12 metabolism, such as holo-transcobalamin, methylmalonic acid, and total homocysteine are unreliable. When people do not consume enough B12-containing foods, supplementation with B12 tablets is needed. In the case of B12 malabsorption, intramuscular injections of B12 are mandatory. The usual treatment with B12 is starting with injections of 1000 µg hydroxocobalamin twice weekly or on every other day for a period of up to 5 weeks or longer, until all symptoms have disappeared, and thereafter, the frequency of injections is gradually reduced. There is, however, a large group of people who require more frequent administration to become and remain symptom-free: this may range from daily or twice weekly to every 2 to 4 weeks.

Excess Folic Acid and Vitamin B12 Deficiency: Clinical Implications?

BACKGROUND: In the 1940s to 1950s, high-dose folic acid supplements (>5 mg/d) were used clinically to reverse the megaloblastic anemia of vitamin B12 deficiency caused by pernicious anemia. However, this treatment strategy masked the underlying B12 deficiency and possibly exacerbated its neuropathological progression. The issue of masking and exacerbating B12 deficiency has recently been rekindled with the institution of folic acid fortification and the wide-spread use of folic acid supplements. OBJECTIVES: The objectives of this review are to describe clinical and epidemiological evidence that excess folic acid exacerbates B12 deficiency, to summarize a hypothesis to explain this phenomenon, and to provide guidance for clinicians. RESULTS: Cognitive function test scores are lower and blood homocysteine and methylmalonic acid concentrations are higher in people with low B12 and elevated folate than in those with low B12 and nonelevated folate. High-dose folic acid supplementation in patients with pernicious anemia or epilepsy cause significant reductions in serum B12. It is hypothesized that high-dose folic acid supplements cause depletion of serum holotranscobalamin and thus exacerbate B12 deficiency. CONCLUSION: The evidence for excess folic acid exacerbating B12 deficiency is primarily correlative or from uncontrolled clinical observations, and the hypothesis to explain the phenomenon has not yet been tested. Nonetheless, the evidence is sufficiently compelling to warrant increased vigilance for identifying B12 deficiency in at risk individuals, including older adults and others with low B12 intake or conditions that are associated with B12 malabsorption, who also ingest excessive folic acid or are prescribed folic acid in high doses.

Plain language titleExcess Folic Acid and Vitamin B12 Deficiency: Clinical Implications?Plain language summaryIt has been known for many decades that high doses of the B vitamin supplement, folic acid, can alleviate the anemia of vitamin B12 deficiency, at least temporarily. However, by alleviating the anemia, such folic acid supplements were said to "mask" the underlying vitamin B12 deficiency, thus allowing neurological damage to continue or possibly be exacerbated. Consequently, treating vitamin B12 deficiency with high dose folic acid was discontinued in the 1970s. The issue of whether folic acid supplements can exacerbate vitamin B12 deficiency reemerged in the 1990s with folic acid fortification of cereals and grains in the United States and Canada (and now in over 80 countries around the world) to prevent spina bifida and other birth defects. This narrative review summarizes the results of studies that have assessed the relationships between folic acid and folate and vitamin B12 status in patients and in populations. A recent hypothesis on how folic acid might exacerbate vitamin B12 deficiency is summarized, and recommendations to clinicians are made for increased vigilance in assessing vitamin B12 status in certain groups at risk of vitamin B12 deficiency, including older adults, people with gastrointestinal issues and other factors that cause vitamin B12 malabsorption, people with unexplained neurological problems, and people who follow vegan or vegetarian diets which are naturally low in vitamin B12.

Associations of methylmalonic acid and depressive symptoms with mortality: a population-based study.

Methylmalonic acid (MMA), a biomarker of mitochondrial dysfunction, has been reported to be associated with depression in specific populations (i.e., older adults and postpartum women). Our study aimed to investigate to what extent MMA was associated with depressive symptoms and mortality in the general population, and assess whether depressive symptoms mediate the relationship between MMA and mortality. We analyzed cross-sectional data from 8343 participants from the US National Health and Nutrition Examination Survey. MMA was measured by liquid chromatography-tandem mass spectrometry, while depressive symptoms were measured by the Patient Health Questionnaire-9. Mortality data were obtained through linkage with National Death Index records. Linear regression models were performed to assess the association between MMA and depressive symptoms. The Cox proportional hazard regression model was utilized to assess the association of MMA and depressive symptoms with mortality. Mediation analysis was conducted within the counterfactual framework. In this general population, each SD (around 0.49 µmol/L) increase in MMA was associated with a 0.03 SD (approximately 0.15 score) increase in depressive symptoms (ß = 0.033, 95% CI: 0.010, 0.055, p = 0.005). Notably, this association was more pronounced in men and participants over 60 years old. Higher levels of MMA and having more depressive symptoms were associated with a higher risk of mortality. However, depressive symptoms do not mediate the relationship between MMA and mortality. Elevated MMA levels were associated with depressive symptoms and an increased risk of mortality. These findings suggest that mitochondrial dysfunction may contribute to the multifactorial etiology of depression.

Aging-Associated Metabolite Methylmalonic Acid Increases Susceptibility to Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by pulmonary fibroblast overactivation, resulting in the accumulation of abnormal extracellular matrix and lung parenchymal damage. Although the pathogenesis of IPF remains unclear, aging was proposed as the most prominent nongenetic risk factor. Propionate metabolism undergoes reprogramming in the aging population, leading to the accumulation of the by-product methylmalonic acid (MMA). This study aimed to explore alterations in propionate metabolism in IPF and the impact of the by-product MMA on pulmonary fibrosis. It revealed alterations in the expression of enzymes involved in propionate metabolism within IPF lung tissues, characterized by an increase in propionyl-CoA carboxylase and methylmalonyl-CoA epimerase expression, and a decrease in methylmalonyl-CoA mutase expression. Knockdown of methylmalonyl-CoA mutase, the key enzyme in propionate metabolism, induced a profibrotic phenotype and activated co-cultured fibroblasts in A549 cells. MMA exacerbated bleomycin-induced mouse lung fibrosis and induced a profibrotic phenotype in both epithelial cells and fibroblasts through activation of the canonical transforming growth factor-ß/Smad pathway. Overall, these findings unveil an alteration of propionate metabolism in IPF, leading to MMA accumulation, thus exacerbating lung fibrosis through promoting profibrotic phenotypic transitions via the canonical transforming growth factor-ß/Smad signaling pathway.

Associations of serum vitamin B12 and its biomarkers with musculoskeletal health in middle-aged and older adults.

Introduction: The effects of vitamin B12 metabolism on musculoskeletal health and the exact mechanism have not been fully determined. Our study aimed to assess the association of vitamin B12 and its biomarkers with musculoskeletal health in middle-aged and older adults. Methods: The data from the National Health and Nutrition Examination Survey 2001-2002 were used to investigate the effects of serum vitamin B12 and its biomarkers (homocysteine and methylmalonic acid) on skeletal muscle health. Bone mineral density (BMD), lean mass, gait speed and knee extensor strength were used as indicators for musculoskeletal health. Results: Serum vitamin B12 level was positively correlated with the total and appendicular lean mass (ß = 584.83, P = 0.044; ß = 291.65, P = 0.043) in older adults over 65 years of age. In the full population, plasma homocysteine was associated with total lean mass, appendicular lean mass, gait speed, and knee extensor strength (all P < 0.05). Among older adults over 65 years of age, homocysteine level was significantly negatively correlated with gait speed and knee extensor strength (ß = -12.75, P = 0.019; ß = -0.06, P <0.001). Plasma methylmalonic acid was negatively associated with total BMD and femur BMD in the full population (ß = -0.01, P = 0.018; ß = -0.01, P = 0.004). In older adults, methylmalonic acid significantly affected total BMD, femur BMD and knee extensor strength (ß = -0.01, P = 0.048; ß = -0.01, P = 0.025; ß = -7.53, P = 0.015). Conclusions: Vitamin B12 and its biomarkers are closely related to BMD, body composition, muscle strength and physical function in middle-aged and older adults. Vitamin B12 may be an important indicator of musculoskeletal health in the elderly.

Decreased cobalamin sensitivity and biological aging acceleration in the general population.

BACKGROUND: The evidence on the association between cobalamin (Cbl) and aging or relevant outcomes is limited and controversial. We aimed to investigate the relationships between cobalamin intake- and function-related biomarkers and biological aging. METHODS: The study encompassed 22,812 participants aged 20 years and older from the National Health and Nutrition Examination Survey. A panel of biomarkers or algorithms was used to assess biological aging, including Klemera-Doubal Age Acceleration (KDMAccel), Phenotypic age acceleration (PhenoAgeAccel), telomere length, α-Klotho, and PhenoAge advancement. Weighted generalized linear regression analysis was used to assess the associations between cobalamin-intake biomarkers (serum cobalamin, cobalamin intake from food, cobalamin supplement use, serum methylmalonic acid [MMA], and homocysteine [Hcy]) and function-related biomarkers (functional cobalamin deficiency and cobalamin insensitivity index). RESULTS: Among the 22,812 individuals, the weighted mean (SE) age was 48.3 (0.2) years and 48.0% were males. Unexpectedly, serum and dietary cobalamin as well as serum MMA and Hcy levels were positively associated with most indicators of biological aging. Cobalamin sensitivity was assessed by the combination of binary Cbllow/high and MMAlow/high or Hcylow/high (cutoff values: 400 pg/mL for cobalamin, 250 nmol/L for MMA, and 12.1 µmol/l for Hcy) and a newly constructed cobalamin insensitivity index (based on the multiplicative term of serum cobalamin and serum MMA or Hcy). The multivariable-adjusted ß (95%CIs) of KDMAccel in the MMAlowCbllow, MMAlowCblhigh, MMAhighCbllow, and MMAhighCblhigh groups were reference, 0.27 (0.03 to 0.51), 0.85 (0.41 to 1.29), and 7.97 years (5.77 to 10.17) respectively, which were consistent for the combination of serum Hcy and cobalamin. Both cobalamin insensitivity indices were robustly associated with biological aging acceleration in a dose-response pattern (each p < 0.001). CONCLUSIONS: Decreased cobalamin sensitivity but not cobalamin insufficiency might be associated with biological aging acceleration. Further studies would improve understanding of the underlying mechanisms between decreased cobalamin sensitivity and biological aging acceleration.

NMR Spectroscopy in Diagnosis and Monitoring of Methylmalonic and Propionic Acidemias.

Although both localized nuclear magnetic resonance spectroscopy (MRS) and non-localized nuclear magnetic resonance spectroscopy (NMR) generate the same information, i.e., spectra generated by various groups from the structure of metabolites, they are rarely employed in the same study or by the same research group. As our review reveals, these techniques have never been applied in the same study of methylmalonic acidemia (MMA), propionic acidemia (PA) or vitamin B12 deficiency patients. On the other hand, MRS and NMR provide complementary information which is very valuable in the assessment of the severity of disease and efficiency of its treatment. Thus, MRS provides intracellular metabolic information from localized regions of the brain, while NMR provides extracellular metabolic information from biological fluids like urine, blood or cerebrospinal fluid. This paper presents an up-to-date review of the NMR and MRS studies reported to date for methylmalonic and propionic acidemias. Vitamin B12 deficiency, although in most of its cases not inherited, shares similarities in its metabolic effects with MMA and it is also covered in this review.

[Clinical features and follow-up study on 55 patients with adolescence-onset methylmalonic acidemia].

Objective: To investigate the clinical features and outcomes of adolescence-onset methylmalonic acidemia (MMA) and explore preventive strategies. Methods: This was a retrospective case analysis of the phenotypes, genotypes and prognoses of adolescence-onset MMA patients. There were 55 patients diagnosed in Peking University First Hospital from January 2002 to June 2023, the data of symptoms, signs, laboratory results, gene variations, and outcomes was collected. The follow-ups were done through WeChat, telephone, or clinic visits every 3 to 6 months. Results: Among the 55 patients, 31 were males and 24 were females. The age of onset was 12 years old (range 10-18 years old). They visited clinics at Tanner stages 2 to 5 with typical secondary sexual characteristics. Nine cases (16%) were trigged by infection and 5 cases (9%) were triggered by insidious exercises. The period from onset to diagnosis was between 2 months and 6 years. Forty-five cases (82%) had neuropsychiatric symptoms as the main symptoms, followed by cardiovascular symptoms in 12 cases (22%), kidney damage in 7 cases (13%), and eye disease in 12 cases (22%). Fifty-four cases (98%) had the biochemical characteristics of methylmalonic acidemia combined with homocysteinemia, and 1 case (2%) had the isolated methylmalonic acidemia. Genetic diagnosis was obtained in 54 cases, with 20 variants identified in MMACHC gene and 2 in MMUT gene. In 53 children with MMACHC gene mutation,1 case had dual gene variants of PRDX1 and MMACHC, with 105 alleles. The top 5 frequent variants in MMACHC were c.482G>A in 39 alleles (37%), c.609G>A in 17 alleles (16%), c.658_660delAAG in 11 alleles (10%), c.80A>G in 10 alleles (10%), c.567dupT and c.394C>T both are 4 alleles (4%). All patients recovered using cobalamin, L-carnitine, betaine, and symptomatic therapy, and 54 patients (98%) returned to school or work. Conclusions: Patients with adolescence-onset MMA may triggered by fatigue or infection. The diagnosis is often delayed due to non-specific symptoms. Metabolic and genetic tests are crucial for a definite diagnosis. Treatment with cobalamin, L-carnitine, and betaine can effectively reverse the prognosis of MMA in adolescence-onset patients.

Intranasal vitamin B12 administration in elderly patients: A randomized controlled comparison of two dosage regimens.

AIM: Vitamin B12 deficiency is common in the elderly population. Standard treatment via intramuscular injections, however, has several disadvantages. Safer and more convenient dosage forms such as intranasal are therefore being explored. This study compares the effects of two intranasal vitamin B12 dosage regimens in elderly vitamin B12-deficient patients. METHODS: Sixty patients ≥65 years were randomly assigned to either a loading dose (daily administration for 14 days followed by weekly administration) or a no loading dose (administration every 3 days) regimen for 90 days. Each dose contained 1000 µg cobalamin. Total vitamin B12, holotranscoblamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy) levels in serum were measured on days 0, 7, 14, 30, 60 and 90. RESULTS: Both dosage regimens resulted in a rapid increase of vitamin B12 and holoTC concentrations and normalization of initial high, MMA and tHcy concentrations. The loading dose regimen resulted in the fastest and greatest increase to a median vitamin B12 of 1090 pmol/L (reference 350-650 pmol/L) concentration after 14 days. Following weekly administration, B12 rapidly decreased to a median concentration of 530 pmol/L after 90 days. The no loading dose regimen resulted in a steady increase to a median vitamin B12 of 717 pmol/L after 90 days. CONCLUSIONS: Intranasal vitamin B12 administration is an effective and suitable way to replenish and sustain vitamin B12 levels in elderly patients.

Oral vitamin B12 supplementation in pernicious anemia: a prospective cohort study.

BACKGROUND: The absorption of vitamin B12 is hindered in pernicious anemia (PA) owing to intrinsic factor deficiency. Traditionally, intramuscular vitamin B12 injections were the standard treatment, bypassing the impaired absorption. Although there is potential for oral vitamin B12 supplementation through passive enteral absorption, it is not commonly prescribed in PA owing to limited studies assessing its efficacy. OBJECTIVES: We aimed to assess the efficacy of oral vitamin B12 supplementation in PA. METHODS: We enrolled participants diagnosed with incident vitamin B12 deficiency related to PA. The diagnosis of PA was based on the presence of classical immune gastritis and of anti-intrinsic factor and/or antiparietal cell antibodies. To evaluate the vitamin B12 status, we measured total plasma vitamin B12, plasma homocysteine, and plasma methylmalonic acid (pMMA) concentration and urinary methylmalonic acid-to-creatinine ratio. Participants were treated with oral cyanocobalamin at a dosage of 1000 µg/d throughout the study duration. Clinical and biological vitamin B12 deficiency related features were prospectively and systematically assessed over the 1-y study duration. RESULTS: We included 26 patients with vitamin B12 deficiency revealing PA. Following 1 mo of oral vitamin B12 supplementation, 88.5% of patients were no longer deficient in vitamin B12, with significant improvement of plasma vitamin B12 [407 (297-485) compared with 148 (116-213) pmol/L; P < 0.0001], plasma homocysteine [13.5 (10.9-29.8) compared with 18.6 (13.7-46.8) µmol/L; P < 0.0001], and pMMA [0.24 (0.16-0.38) compared with 0.56 (0.28-1.09) pmol/L; P < 0.0001] concentrations than those at baseline. The enhancement of these biological parameters persisted throughout the 12-month follow-up, with no patients showing vitamin B12 deficiency by the end of the follow-up period. The median time to reverse initial vitamin B12 deficiency abnormalities ranged from 1 mo for hemolysis to 4 mo for mucosal symptoms. CONCLUSIONS: Oral supplementation with 1000 µg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in PA.

The association between serum methylmalonic acid, cobalamin-related biomarkers, and long-term mortality risk in cancer survivors: a prospective cohort study.

BACKGROUND: Elevated serum methylmalonic acid (MMA), a marker of cobalamin (vitamin B12) deficiency, has been linked to cancer progression. However, the impact of MMA or cobalamin on mortality risk in cancer survivors remains unknown. OBJECTIVES: To explore the relationship between MMA, serum, dietary, and supplement of cobalamin, MMA metabolism-related genes, and poor prognosis in adult cancer survivors. METHODS: We analyzed data from 1988 cancer survivors aged ≥20 y. Patients were selected from the National Health and Nutrition Examination Survey and followed up until December 31, 2019. Weighted Cox proportional hazard regression was used to estimate hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) for mortality risk assessment. Genomic analysis identified MMA metabolism-related genes linked to early death in a 33-cancer-type cohort from The Cancer Genome Atlas. RESULTS: Among 1988 participants, 872 deaths occurred over a 10-year follow-up. Higher serum MMA levels were significantly linked to increased long-term mortality risk (tertile 3 compared with tertile 1: adjusted HR: 1.37; 95% CI: 1.11, 1.70; P-trend < 0.001). No associations were found between serum, dietary, and supplement of cobalamin and cancer survivor mortality (each P-trend > 0.143). However, MMA-associated mortality was notable in patients without deficiency. When combining cobalamin and MMA categories, multivariate-adjusted HR (95% CI) for all-cause mortality was 2.06 (95% CI: 1.60, 2.65) in participants with >250 nmol/L and cobalamin >295.1 pmol/L compared with those with MMA ≤250 nmol/L and cobalamin >295.1 pmol/L. Moreover, reduced transcriptional levels of MMA metabolism-related genes, indicating decreased mitochondrial MMA metabolism capability, are linked to an unfavorable prognosis in certain cancer types. CONCLUSIONS: Serum MMA was associated with long-term mortality risk in adult cancer survivors, which was more significant among individuals with higher levels of serum cobalamin. These findings suggest that mortality related to MMA was attributed to the insufficient flux of MMA metabolism, not cobalamin deficiency.

On the Relationship between MMA Levels in Blood Products and Donor Sex, Age, and Donation Frequency.

As the aging process accelerates, the age structure of blood donors turns to older and even aged groups. Methylmalonic acid (MMA), a byproduct of propionate metabolism, may be upregulated in the serum of older adults. As a mediator of chronic disease and tumor progression, the MMA content in blood products has become the focus of research. Absolute concentrations of MMA in blood products were determined based on the liquid chromatography-tandem mass spectrometry, so as to analyze how they were affected by donors' age, sex, and frequency of blood donation. The MMA content in leukocyte-depleted suspended red blood cell (lds-RBC) was significantly higher than that in fresh plasma (p<0.0001). The MMA content among five age groups showed no difference in either fresh plasma or lds-RBCs. The MMA content in fresh plasma was similar in the parameters of the sex, whereas that in lds-RBCs was higher in males than that in females (p=0.035). There were no significant differences in MMA content when it comes to different frequencies of blood donors in either fresh plasma or lds-RBCs. Additionally, there was no significant difference or clear trend in the rate of elevated plasma MMA levels among different sexes, age groups, and blood donation frequency groups. MMA in the blood products from donors in China does not compromise the safety of blood transfusions for cancer patients. Nevertheless, there is a need to focus on MMA levels in Chinese and to develop race-specific and age-specific normal reference ranges.