Review: State of the knowledge on the importance of folates and cobalamin for dairy cow metabolism.

Synthesis of B vitamins by the rumen microbiota is usually sufficient to avoid the appearance of clinical deficiency symptoms in dairy cows under normal feeding conditions. Nevertheless, it is now generally accepted that vitamin deficiency is much more than the appearance of major functional and morphological symptoms. Subclinical deficiency, which is present as soon as the supply is lower than the need, causes cellular metabolic changes leading to a loss of metabolic efficiency. Folates and cobalamin, two B vitamins, share close metabolic relationships. Folates act as co-substrates in one-carbon metabolism, providing one-carbon unit for DNA synthesis and de novo synthesis of methyl groups for the methylation cycle. Cobalamin acts as a coenzyme for reactions in the metabolism of amino acids, odd-numbered chain fatty acids including propionate and de novo synthesis of methyl groups. Both vitamins are involved in reactions to support lipid and protein metabolism, nucleotide synthesis, methylation reactions and possibly, maintenance of redox status. Over the last decades, several studies have reported the beneficial effects of folic acid and vitamin B12 supplements on lactation performance of dairy cows. These observations indicate that, even when cows are fed diets adequately balanced for energy and major nutrients, B-vitamin subclinical deficiency could be present. This condition reduces casein synthesis in the mammary gland and milk and milk component yields. Folic acid and vitamin B12 supplements, especially when given together, may alter energy partitioning in dairy cows during early and mid-lactation as indicated by increased milk, energy-corrected milk, or milk component yields without affecting DM intake and BW or even with reductions in BW or body condition loss. Folate and cobalamin subclinical deficiency interferes with efficiency of gluconeogenesis and fatty acid oxidation and possibly alters responses to oxidative conditions. The present review aims to describe the metabolic pathways affected by folate and cobalamin supply and the consequences of a suboptimal supply on metabolic efficiency. The state of knowledge on the estimation of folate and cobalamin supply is also briefly mentioned.

Production and characterization of cyanocobalamin-enriched tomato (Solanum lycopersicum) fruits grown using hydroponics.

BACKGROUND: Vitamin B12 is an essential vitamin that is absent in plant-derived foods such as fruits and vegetables. This can result in an increased risk of developing vitamin B12 deficiency in strict vegetarians (vegans). There are several studies that have aimed to enhance nutrients in food crops. The purpose of the present study was to fortify tomato fruits with vitamin B12 (or cyanocobalamin). RESULTS: Tomato plants were grown for 70 days in hydroponic culture pots and treated with 5 µm of cyanocobalamin on days 1-24 after the fruiting, and then harvested for tomato fruits. The ripened tomato fruits contained 4.0 × 10-7  g of cyanocobalamin per 100 g of dry weight and showed a significant increase in glucose and lycopene levels. CONCLUSION: The present study highlights the use of a cyanocobalamin-supplementation system for the production of B12 fortified tomato fruits that can help prevent B12 deficiency in vegetarians. © 2022 Society of Chemical Industry.

Effects of dietary supplementation of different levels of vitamin B12 on the liver metabolism of laying hens.

BACKGROUND: Vitamin B12 plays an important role in lipid, protein, carbohydrate and nucleic acid metabolism. We investigated the effect of supplementing layers' diets with different vitamin B12 levels on liver metabolism using a liquid chromatography-mass spectrometry-based metabolomic approach to observe and analyse wide-target metabolomics in the liver. RESULTS: We assigned hens to three groups, namely blank control group without vitamin B12 diet (BCG), normal control group with 25 µg kg-1 vitamin B12 (NCG) and vitamin B12 supplement group I with 100 µg kg-1 vitamin (VBSG I). The VBSG I group layers had higher (P < 0.05) vitamin B12 concentration than those from other groups. The egg yolk vitamin B12 concentration increased (P < 0.01) with the increasing vitamin B12 dietary supplemental level. Between the NCG versus BCG, VBSG I versus BCG, and VBSG I versus NCG groups, 11, 20 and 11 metabolites were significantly changed, respectively. The KEGG pathway of vitamin B6 metabolism was significantly impacted in the NCG layers than those from BCG; seven and five pathways were significantly impacted in the VBSG I layers compared with those from BCG and NCG, including pyrimidine metabolism, vitamin B6 metabolism, glycerophospholipid metabolism, etc. CONCLUSION: We concluded that 25 µg kg-1 vitamin B12 supplementation in corn-soybean meal-based layer diet increased the egg yolk vitamin B12 concentration and impacted the vitamin B6 metabolic pathway, and 100 µg kg-1 of it increased the egg yolk and liver vitamin B12 concentrations and impacted vitamin B6 , lipid, nucleic acid and amino acid metabolic pathways. © 2022 Society of Chemical Industry.

Nicotinamide-Functionalized Carbon Quantum Dot as New Sensing Platform for Portable Quantification of Vitamin B12 in Fluorescence, UV-Vis and Smartphone Triple Mode.

Development of an efficient, portable and simple nanosensor-based systems with reliable analytical performance for on-site monitoring of vitamin B12 (VB12) are still major problems and a challenging work for quality control of manufacturers. Herein, a new fluorescence, UV-Vis and smartphone triple mode nanosensors were designed for the simultaneous detection of VB12 with high sensitivity and accuracy. A novel nanosensor was synthesized through nicotinamide-functionalizing of carbon quantum dot (NA-CQDs) by an one-step microwave-assisted method with green approach. The NA-CQDs sensor showed excellent fluorescence properties and wide linear ranges from 0.1-60 µM with the detection limits of 31.7 nM. Moreover, color changes of NA-CQDs induced by the VB12 could also be detected by UV-Vis spectrophotometer and inhouse-developed application installed on smartphone as a signal reader, simultanusly. The Red, Green and Blue (RGB) intensities of the colorimetric images of NA-CQDs/VB12 system which taken by smartphone's camera converted into quantitative values by the application. A smartphone-integrated with NA-CQDs as colorimetric sensing platform displays good linear ranges (4.16 to 66.6 µM) for on-site determination of VB12 with detection limit of 1.40 µM. The method was successfully applied in the determination of VB12 in complex pharmaceutical supplement formulations without any sample pre-treatment and matrix interfering effects. The recovery results (96.52% to 105.10%) which were in agreement with the reference methods, demonstrating the capability of the smartphone-assisted colorimetric sensing platform in many on-site practical applications of quality controls.

[Determination of cobalt in plasma blood samples by the ICP-MS method after oral intake of dietary supplements containing low doses of cobalt].

Salts of inorganic cobalt (Со) prevent the degradation of the alpha subunit of the hypoxia-inducible factor (HIF), imitating the state of hypoxia in the body and increasing the production of the endogenous hormone erythropoietin (EPO), and are used as doping substances that increase blood oxygen capacity and endurance, which give competitive advantages in sports. Currently, a large number of dietary supplements, including Co-containing ones, are offered on free sale. Their uncontrolled intake can affect not only the professional career of athletes, but also their health, due to the fact that this trace element and its salts are the strongest inorganic poisons and carcinogens. Despite this, their availability on the pharmaceutical market, a noticeable effect of erythropoiesis stimulation and a convenient oral form of administration lead to the need for their detection in modern doping control. The purpose of this research was to develop an approach to differentiate cobalt from vitamin B12, present in the body in its natural state, from the intake of cobalt salts by quantifying and comparing blood levels of vitamin B12 and total cobalt. Methods. The study involved 9 healthy volunteers (women and men) aged 25 to 45 years, leading an active lifestyle. Three of them took 2500 µg/day of cobalamin for 20 days (comparison group), three - dietary supplement containing cobalt asparaginate (100 µg/day in terms of pure cobalt), and the rest - dietary supplements with cobalt sulfate heptahydrate (100 µg/day in terms of pure cobalt) (administration groups) at the same time after meals. Blood samples were taken at baseline and on days 5, 9, 14 and 20. The concentrations of total cobalt in blood plasma samples of volunteers were measured by inductively coupled plasma mass-spectrometry (ICP-MS), the levels of cobalamin were determined on a Cobas 6000 immunochemical analyzer using the Elecsys Vitamin B12 II Assay ELISA kits. Results. It was found that oral intake of of cobalamin at a therapeutic dose significantly exceeding the recommended daily intake (3 µg), there was a regular slight increase in the blood concentration of total cobalt (1.1 times). At the same time intake of dietary supplements containing cobalt in the form of sulfate or asparaginate (about 100 µg per day in terms of pure cobalt) was accompanied by 4-6.7 fold increase in the concentration of total cobalt while unchanged vitamin B12 plasma concentration was observed. The detection of such changes can reliably indicate the use of prohibited salts and, of course, will be in demand for anti-doping control. Conclusion. Long-term monitoring of vitamin B12 and total cobalt levels, similar to hematological module of the Athlete Biological Passport program, will unambiguously detect possible abuse of cobalt salts and can be an additional evidence of the presence of these doping substances to other analytical methods, such as a combination of liquid chromatography and ICP-MS (LC-ICP-MS).

Vitamin B12 quantification in human milk - Beyond current limitations using liquid chromatography and inductively coupled plasma - Mass spectrometry.

Vitamin B12 plays a key role in human biological functions and is vital in the neurological development of infants. The assessment of the vitamin B12 intake in exclusively breastfed babies depends on the reliability of its determination in milk. In this report, we present a new accurate and robust method for quantification of vitamin B12 in human milk. A highly specific sample preparation is applied, associated with chromatographic separation and detection by ICP-MS. Excellent sensitivity and accuracy are reported, with recovery values well within acceptability limits (80-120%), within- and between-day variability are lower than 10% and 15% respectively. Strong correlation with a microbiological assay was observed (r2 = 0.9) within the validation range (40-1000 pmol/L, corresponding to 54 to 1355 ng/L). The method can be used to routinely monitor vitamin B12 in clinical or population observational studies, determine infant's intake or assess efficacy of mother's supplementation.

International Analysis of the Nutritional Content and a Review of Health Benefits of Non-Dairy Plant-Based Beverages.

Concerns about environmental impact and sustainability, animal welfare, and personal health issues have fueled consumer demand for dairy alternatives. The aim of this study was to conduct a cross-sectional survey of plant-based non-dairy beverages from three different continents (USA, Australia, and Western Europe) to assess their nutritional content and health profile. A total of 148 non-dairy beverages were analyzed from the nutrition label and ingredients listed on the commercial package or from the information located on the website of the manufacturer or retailer. The different types of beverages were extracts of nuts or seeds (n = 49), grains (n = 38), legumes (n = 36), coconut (n = 10), and mixed blends (n = 15). On average, the plant-based beverages generally scored well in terms of not containing high levels of sodium, saturated fat, or calories. Over half of the beverages were fortified with calcium to levels equal to or greater than that of dairy milk. The protein content varied from 0 to 10 g/serving. Levels of vitamin D and B12 fortification were quite low. Consumers should be informed of the nutritional profile and potential health benefits of plant-based dairy alternatives as the nutritional content can vary greatly between the different types of beverages.

Energy, Sugars, Iron, and Vitamin B12 Content of Commercial Infant Food Pouches and Other Commercial Infant Foods on the New Zealand Market.

There has been an important shift in the New Zealand infant food market over the past decade, with the majority of complementary foods now sold in "pouches". Along with the increasing market share of commercial infant food pouches internationally, there have been growing concerns about their nutritional quality. However, research examining the nutritional quality of these pouches compared to other forms of commercial infant foods in New Zealand has not been undertaken. Nor have any studies reported the free sugars or added sugars content of these foods. To address this knowledge gap, a cross-sectional survey of infant foods sold in New Zealand supermarkets was conducted in 2019-2020. Recipes and nutrient lines were developed for the 266 foods identified (133 food pouches). The energy, iron, vitamin B12, total sugars, free sugars, and added sugars content of infant food pouches and other forms of commercial infant foods per 100 g were compared, both within food groups and by age group. Infant food pouches contained similar median amounts of energy, iron, and vitamin B12 to other forms of commercial infant foods but contained considerably more total sugars (8.4 g/100 g vs. 2.3 g/100 g). However, median free sugars and added sugars content was very low across all food groups except for "dairy" and "sweet snacks". All "dry cereals" were fortified with iron whereas none of the infant food pouches were. Therefore, consuming food pouches to the exclusion of other commercial infant foods may place infants at risk of iron deficiency if they do not receive sufficient iron from other sources.

Nutritional Content and Health Profile of Single-Serve Non-Dairy Plant-Based Beverages.

A growing number of people are seeking a non-dairy plant-based beverage both for their personal health, and for the health of the planet. The aim of this study was to conduct a cross-sectional survey of single-serve plant-based beverages to assess their nutritional content and health profile. A total of 51 non-dairy plant-based beverages were analyzed from the nutrition label listed on the commercial package. The various beverages contained extracts of soy (n = 14), almonds (n = 13), oats (n = 12), peas (n = 7), banana (n = 2), coconut (n = 2), and rice (n = 1). Almost one-half (45%) of the single-serve beverages had 5 g or more of protein/serving. A total of 75% and 65% of the single-serve beverages had calcium and vitamin B12 levels, respectively, fortified to at least 20% of the Daily Value (DV), while only 28% had vitamin D fortification at the 20% DV level. Two-thirds of the single-serve beverages had high sugar levels, while 39% were low in sodium, 63% were low in fat, and 96% were low in saturated fat. The single-serve plant-based beverages had more protein, calcium, vitamin B12, and sugar but less fat than the non-dairy, multi-serve plant-based beverages/ serving. A limited number of single-serve beverages met the requirements of school meal programs.

Multiple Micronutrients, Lutein, and Docosahexaenoic Acid Supplementation during Lactation: A Randomized Controlled Trial.

Breastfed infants require an adequate supply of critical nutrients for growth, tissue functions, and health. Recommended intakes for several nutrients are considerably higher in lactating than non-lactating women but are not always met with habitual diets. We report a randomized, double-blind clinical trial in 70 healthy lactating women in Germany evaluating the effects of supplementation with multiple micronutrients, lutein, and docosahexaenoic acid (DHA) compared to placebo on maternal nutrient status and milk composition. The primary endpoint was the effect on the change of human milk DHA content (as a proportion of total milk fatty acids) during 12 weeks of supplementation. Maternal blood and milk biomarkers were measured as secondary endpoints. Supplementation increased maternal milk DHA by 30% compared to a decline in the placebo group. Supplementation also increased maternal blood DHA (17%), eicosapentaenoic acid (4%), 25-OH-vitamin D (24%), vitamin B12 (12%), lutein (4%), and beta carotene (49%), while homocysteine decreased. No significant difference in the number of adverse events was observed between supplementation and placebo groups. In conclusion, multi-micronutrient supplementation was safe and increased maternal blood and milk concentrations of selected nutrients in healthy women.

Analysis of cobalt for human sports drug testing purposes using ICP- and LC-ICP-MS.

Due to the current demands in the fight against manipulation of blood and blood components, commonly referred to as "blood doping" in sports drug testing, specific and sensitive detection methods enabling the detection of prohibited substances and methods of doping are required. Similar to illicit blood transfusions, erythropoiesis stimulating agents have been shown to be misused in sport, aiming at improving an athlete's aerobic capacity and endurance performance. Amongst other strategies, the administration of ionic cobalt (Co2+ ) can increase the number of erythrocytes by stimulating the endogenous erythropoietin (EPO) biosynthesis. Conversely, several organic Co-containing compounds such as cyanocobalamin (vitamin B12) are not prohibited in sports, and thus, an analytical differentiation of permitted and banned contributions to urinary Co-concentrations is desirable. An excretion study with daily applications of either 1 mg of CoCl2 or 1 mg of cyanocobalamin was conducted with 20 volunteers over a period of 14 consecutive days. Urine, plasma, and concentrated red blood cells were analyzed for their cobalt content. The samples were collected starting 7 days before the administration until 7 days after. Total Co concentrations were analyzed by using inductively coupled plasma mass spectrometry (ICP-MS), which yielded significantly elevated levels exclusively after inorganic cobalt intake. Furthermore, a liquid chromatography (LC)-ICP-MS approach was established and employed for the simultaneous determination of organically bound and inorganic cobalt by chromatographic separation within one single run. The analytical approach offers the option to further develop detection methods of illegal Co2+ supplementation in sport.

Wolffia globosa-Mankai Plant-Based Protein Contains Bioactive Vitamin B12 and Is Well Absorbed in Humans.

BACKGROUND: Rare plants that contain corrinoid compounds mostly comprise cobalamin analogues, which may compete with cobalamin (vitamin B12 (B12)) metabolism. We examined the presence of B12 in a cultivated strain of an aquatic plant: Wolffia globosa (Mankai), and predicted functional pathways using gut-bioreactor, and the effects of long-term Mankai consumption as a partial meat substitute, on serum B12 concentrations. METHODS: We used microbiological assay, liquid-chromatography/electrospray-ionization-tandem-mass-spectrometry (LC-MS/MS), and anoxic bioreactors for the B12 experiments. We explored the effect of a green Mediterranean/low-meat diet, containing 100 g of frozen Mankai shake/day, on serum B12 levels during the 18-month DIRECT-PLUS (ID:NCT03020186) weight-loss trial, compared with control and Mediterranean diet groups. RESULTS: The B12 content of Mankai was consistent at different seasons (p = 0.76). Several cobalamin congeners (Hydroxocobalamin(OH-B12); 5-deoxyadenosylcobalamin(Ado-B12); methylcobalamin(Me-B12); cyanocobalamin(CN-B12)) were identified in Mankai extracts, whereas no pseudo B12 was detected. A higher abundance of 16S-rRNA gene amplicon sequences associated with a genome containing a KEGG ortholog involved in microbial B12 metabolism were observed, compared with control bioreactors that lacked Mankai. Following the DIRECT-PLUS intervention (n = 294 participants; retention-rate = 89%; baseline B12 = 420.5 ± 187.8 pg/mL), serum B12 increased by 5.2% in control, 9.9% in Mediterranean, and 15.4% in Mankai-containing green Mediterranean/low-meat diets (p = 0.025 between extreme groups). CONCLUSIONS: Mankai plant contains bioactive B12 compounds and could serve as a B12 plant-based food source.

Vitamin B12 is Low in Milk of Early Postpartum Women in Urban Tanzania, and was not Significantly Increased by High dose Supplementation.

The effect of maternal multivitamin supplementation on breast milk vitamin B12 concentrations has not been examined in Tanzania, where the prevalence of maternal plasma B12 insufficiency is 25.6%. Multivitamins (containing 50 µg vitamin B12) or placebo were provided during pregnancy and in the postpartum period. Breast milk samples were collected at or around six weeks postpartum from 491 participants in a trial of multivitamins (NCT00197548). Linear and logistic regression models were used to examine the effect of supplements on vitamin B12 concentration in milk and its associations with other variables including potential confounders. Median vitamin B12 concentration in breast milk was 206 pmol/L and 70% of women had levels indicating inadequacy (<310 pmol/L). Multivitamin supplements did not significantly reduce the odds of inadequate vitamin B12 in breast milk, suggesting suboptimal absorption. A single unit increase in maternal hemoglobin at six weeks was associated with 18% lower odds of inadequate vitamin B12 in breast milk. Participants with higher BMI at baseline had double the odds of having inadequate vitamin B12 than the reference group (<22 kg/m2). Trials to determine the optimal dose, route, and duration of supplementation to improve maternal B12 status in Sub-Saharan Africa are of utmost importance.

Vitamin B12 concentrations in milk from Norwegian women during the six first months of lactation.

BACKGROUND: Human milk vitamin B12 (B12) concentrations depend on maternal status and intake; only few data are available in high-income countries. OBJECTIVE: We assessed human milk B12 concentrations during the first 6 months postpartum in Norwegian women and its association with maternal dietary B12 intake and maternal urinary methylmalonic acid (MMA) concentration. METHODS: In this cross-sectional study, 175 mothers, exclusively (80%) or partially (20%) breastfeeding, were included. Milk B12 was measured by IMMULITE®/IMMULITE® 1000 B12 competitive protein binding assay and urinary MMA relative to creatinine (MMA/Cr) by liquid chromatography-tandem-mass spectrometry. Maternal habitual B12 intake and supplement use were estimated using a food frequency questionnaire. RESULTS: Mean human milk B12 concentration was 327 pmol/L (range 140-1089), with 402 pmol/L at 1 month (n = 21), 333 pmol/L at four months (n = 32), and 299 pmol/L at 6 months (n = 21). Maternal B12 intake was 5 µg/d, 89% met the Estimated Average Requirement, and supplement use did not affect milk B12 concentrations. MMA/Cr was low in all women compared with published data. In exclusively breastfeeding women, MMA/Cr (beta (95% CI) -42.5 (-82.5, -2.5) and time since birth (-4.9 (-9.6, -0.3)) were significant predictors of human milk B12 concentrations. There was no association between total B12 intake and milk B12 concentration or between total B12 intake and MMA/Cr. CONCLUSIONS: Maternal B12 status and human milk B12 concentrations are likely sufficient, based on adequate maternal B12 dietary intake combined with low urinary MMA concentrations. Nevertheless, milk B12 concentration fell during 6 months postpartum while maternal B12 status did not change.

An accurate determination method for cobalt in sage tea and cobalamin: Slotted quartz tube-flame atomic absorption spectrometry after preconcentration with switchable liquid-liquid microextraction using a Schiff base.

This study reports a stepwise optimization of switchable liquid-liquid microextraction (SLLME) for cobalt determination by flame atomic absorption spectrometry (FAAS) coupled with a slotted quartz tube (SQT). The main purpose of this study was to develop an accurate and sensitive analytical method for cobalt. Extraction method was used to separate and preconcentrate cobalt from sage tea and vitamin B12 samples after complexing with a Schiff base ligand. 107.7 folds enhancement in detection power under the optimum conditions was recorded with respect to direct FAAS. This enhancement correlated to 3.1 µg/L limit of detection and 10 µg/L limit of quantification. The SLLME-SQT-FAAS method was linear over a broad concentration range and low %RSD values established high precision for the method. Appreciable percent recovery results (94-108%) obtained from spiked sage sample and from cobalamin also validated the accuracy of the method.

Determination of active vitamin B12 (cobalamin) in dietary supplements and ingredients by reversed-phase liquid chromatography: Single-laboratory validation.

Vitamin B12 dietary supplement can be critical to the alleviation strategies against micronutrient malnutrition and food insecurity. An HPLC-DAD method has been developed and validated, per AOAC SMPR 2016.017 (Standard Method Performance Requirements), for the quantitation of four bioactive forms of vitamin B12 (adenosylcobalamin, cyanocobalamin, hydroxocobalamin, methylcobalamin) from dietary ingredients and supplements. The method achieves chromatographic baseline resolution of vitamin B12 forms on a modern column platform without the expensive requirement of an ultra-high pressure liquid chromatography and/or mass spectrometry. The method has a wide analytical range (0.0005%w/w-85%w/w), high precision (reproducibility relative standard deviations ranged from 1.43% to 4.67%), and high accuracy (>96% spike recovery rate for 11 out of 12 accuracy testing data points). The method detection and quantification limits are less than 0.16 and 0.52 µg/mL, respectively. To our best knowledge, it is simpler, less time-consuming, and more economical than other published methods for its intended uses.

Micronutrients Dietary Supplementation Advices for Celiac Patients on Long-Term Gluten-Free Diet with Good Compliance: A Review.

Background and objective: Often micronutrient deficiencies cannot be detected when patient is already following a long-term gluten-free diet with good compliance (LTGFDWGC). The aim of this narrative review is to evaluate the most recent literature that considers blood micronutrient deficiencies in LTGFDWGC subjects, in order to prepare dietary supplementation advice (DSA). Materials and methods: A research strategy was planned on PubMed by defining the following keywords: celiac disease, vitamin B12, iron, folic acid, and vitamin D. Results: This review included 73 studies. The few studies on micronutrient circulating levels in long-term gluten-free diet (LTGFD) patients over 2 years with good compliance demonstrated that deficiency was detected in up to: 30% of subjects for vitamin B12 (DSA: 1000 mcg/day until level is normal, then 500 mcg), 40% for iron (325 mg/day), 20% for folic acid (1 mg/day for 3 months, followed by 400-800 mcg/day), 25% for vitamin D (1000 UI/day or more-based serum level or 50,000 UI/week if level is <20 ng/mL), 40% for zinc (25-40 mg/day), 3.6% of children for calcium (1000-1500 mg/day), 20% for magnesium (200-300 mg/day); no data is available in adults for magnesium. Conclusions: If integration with diet is not enough, starting with supplements may be the correct way, after evaluating the initial blood level to determine the right dosage of supplementation.

Carbon quantum dots doped with phosphorus and nitrogen are a viable fluorescent nanoprobe for determination and cellular imaging of vitamin B12 and cobalt(II).

Phosphorus and nitrogen dually-doped carbon quantum dots (PN-CQDs) were prepared from sucrose, 85% phosphoric acid and 1,2-ethylenediamine as the sources for carbon, phosphorus and nitrogen, respectively. The PN-CQDs possess good water solubility and favorable biocompatibility. The excitation/emission peaks are at 365/451 nm, but bright blue, green, or red emissions are found depending on whether the excitation wavelengths of the laser are set to 408 nm, 488 nm, or 543 nm, respectively. Fluorescence is quenched by both vitamin B12 (VB12) and Co(II) by a combination of inner filter effect and static quenching. The PN-CQDs are shown to be useful nanoprobes for determination of VB12 and Co(II). Response to VB12 is linear in the range of 2.0-31 µM. The response to Co(II) is linear in two ranges, viz. from 1.7-12 µM and from 28 to 141 µM. The limit of detection of VB12 and Co(II) are 3.0 nM and 29.4 nM, respectively. The nanoprobe was successfully applied to the analyses of VB12 in drug samples and of Co(II) in spiked water samples, and it gave satisfactory results. The nanoprobe was also applied to the determination of VB12 and Co(II) in human hepatocarcinoma cells (type SMMC7721), human pulmonary epithelial cells (type BEAS-2B), human adenocarcinoma cells (type A549), and human pheochromocytoma cells (type PC12), respectively. Graphical abstract Schematic presentation of the quenching of the fluorescence of phosphorus and nitrogen dually-doped carbon quantum dots (PN-CQDs) by vitamin B12 (VB12) and Co(II).

Vitamin B-12 and liver activity and expression of methionine synthase are decreased in fetuses with neural tube defects.

BACKGROUND: The risk of neural tube defects (NTDs) is influenced by nutritional factors and genetic determinants of one-carbon metabolism. A key pathway of this metabolism is the vitamin B-12- and folate-dependent remethylation of homocysteine, which depends on methionine synthase (MS, encoded by MTR), methionine synthase reductase, and methylenetetrahydrofolate reductase. Methionine, the product of this pathway, is the direct precursor of S-adenosylmethionine (SAM), the universal methyl donor needed for epigenetic mechanisms. OBJECTIVES: This study aimed to evaluate whether the availability of vitamin B-12 and folate and the expression or activity of the target enzymes of the remethylation pathway are involved in NTD risk. METHODS: We studied folate and vitamin B-12 concentrations and activity, expression, and gene variants of the 3 enzymes in liver from 14 NTD and 16 non-NTD fetuses. We replicated the main findings in cord blood from pregnancies of 41 NTD fetuses compared with 21 fetuses with polymalformations (metabolic and genetic findings) and 375 control pregnancies (genetic findings). RESULTS: The tissue concentration of vitamin B-12 (P = 0.003), but not folate, and the activity (P = 0.001), transcriptional level (P = 0.016), and protein expression (P = 0.003) of MS were decreased and the truncated inactive isoforms of MS were increased in NTD livers. SAM was significantly correlated with MS activity and vitamin B-12. A gene variant in exon 1 of GIF (Gastric Intrinsic Factor gene) was associated with a dramatic decrease of liver vitamin B-12 in 2 cases. We confirmed the decreased vitamin B-12 in cord blood from NTD pregnancies. A gene variant of GIF exon 3 was associated with NTD risk. CONCLUSIONS: The decreased vitamin B-12 in liver and cord blood and decreased expression and activity of MS in liver point out the impaired remethylation pathway as hallmarks associated with NTD risk. We suggest evaluating vitamin B-12 in the nutritional recommendations for prevention of NTD risk beside folate fortification or supplementation.

Impact of diet management and composition on vitamin B12 concentration in milk of Holstein cows.

As vitamin B12 is only synthesized by bacteria, ruminant products, especially dairy products, are excellent sources of this vitamin. This study aims to identify if diet and cow characteristics could affect vitamin B12 concentration in milk of dairy cows. Information on 1484 first, 1093 second and 1763 third and greater parity Holstein cows in 100 herds was collected during three consecutive milkings. During the first morning milking, all dietary ingredients given to cows were sampled and quantities offered were recorded throughout the day. Nutrient composition of ingredients was obtained by wet chemistry to reconstitute nutrient composition of the ration. Milk samples were taken with in-line milk meters during the evening milking of the 1st day and the morning milking of the 2nd day and were analyzed for vitamin B12 concentration. Milk yields were recorded and milk components were separately analyzed for each milking. Daily vitamin B12 concentration in milk was obtained using morning and evening vitamin B12 concentrations weighted with respective milk yield, then divided by daily yield. To decrease the number of interdependent variables to include in the multivariable model, a principal component analysis was carried out. Daily milk concentration of vitamin B12 averaged 3809±80 pg/ml, 4178±79 pg/ml and 4399±77 pg/ml for first, second and third, and greater lactation cows. Out of 11 principal components, six were significantly related to daily milk concentration of vitamin B12 when entered in the multivariable model. Results suggested that vitamin B12 concentration in milk was positively related to percentage of fiber and negatively related to starch as well as energy of the diet. Negative relationships were noted between vitamin B12 concentration in milk and milk yield as well as milk lactose concentration and positive relationships were observed between vitamin B12 concentration in milk and milk fat as well as protein concentrations. The percentages of chopped mixed silage and commercial energy supplement in the diet as well as cow BW were positively related to vitamin B12 in milk and percentages of baled mixed silage, corn and commercial protein supplement in the ration were negatively related to vitamin B12 concentration in milk. The pseudo-R2 of the model was low (52%) suggesting that diet and cow characteristics have moderate impact on vitamin B12 concentration in milk. Moreover, when entering solely the principal component related to milk production in the model, the pseudo-R2 was 46%. In conclusion, it suggests that studied diet characteristics have a marginal impact on vitamin B12 concentration in milk variation.