Rate Of Ethanol Oxidation Research Articles

Insight into the mechanism of CO2 to initiate and regulate ethanol-driven chain elongation by microbial community and metabolic analysis

The present study investigated the impact of CO2 on ethanol-driven chain elongation and its related mechanism. The findings showed that CO2 acts as the initiator of chain elongation. Specifically, the effect of different CO2 dosages (0.5, 1.0, and 2.0 LCO2·L-1·d-1) on chain elongation was examined, revealing that the lower dosage of CO2 (0.5 LCO2·L-1·d-1) favored caproate biosynthesis, as evidenced by higher caproate yield and selectivity compared to the higher dosages (1.0 and 2.0 LCO2·L-1·d-1). A higher dosage of CO2 resulted in the acceleration of ethanol oxidation rate and excessive oxidation of ethanol. The isotopic experiment using 13CO2 indicated that CO2-C is incorporated into microbial biomass and extracellular products, providing direct evidence of CO2 fixation in bacteria involved in the chain elongation process. Furthermore, analysis of 16 S rRNA genes revealed that CO2 dosages have effects on microbial community structure. The relative abundance of chain elongators, such as Clostridium kluyveri and Oscillibacter valericigenes, was significantly increased after the addition of CO2 at 0.5 LCO2·L-1·d-1. Metagenomic analysis showed that the relative abundance of key functional genes related to reverse β-oxidization pathway and fatty acid biosynthesis pathway was upgraded more than 30% under the addition of 0.5 LCO2·L-1·d-1. Overall, this research provides a systematic investigation of the effect of CO2 on chain elongation and offers a research basis for optimizing the chain elongation system.

Development of a detailed kinetic model for high-pressure ethanol oxidation in gas phase and supercritical water

The present study aims to develop a detailed chemical kinetic model for high-pressure ethanol oxidation in the gas phase and supercritical water (SCW). Kinetic parameters for key elementary reactions involving HO2 and CH3OO radicals were updated, deriving from a careful analysis of ignition delay data or analogy. The model performance is validated comprehensively by comparison to a wide variety of recent experimental data from both gas-phase and SCW conditions. The model predicted ignition delay times and speciation measurements (15–60 bar) in the gas phase fairly well. Additionally, the model showed satisfactory performance in reproducing the species concentration profiles at SCW conditions. A comparative kinetic analysis was further conducted to investigate the characteristic differences and similarities of ethanol oxidation at the two conditions. The results indicated SCW lowered the onset temperature for ethanol ignition and facilitated the ethanol oxidation rate, but did not introduce additional oxidation pathways.

Improving the Acetic Acid Fermentation of Acetobacter pasteurianus by Enhancing the Energy Metabolism.

Energy metabolism is important for cell growth and tolerance against environment stress. In acetic acid fermentation by Acetobacter pasteurianus, the correlation coefficients of acid production rate with energy charge and ATP content were 0.9981 and 0.9826, respectively. The main energy metabolism pathway, including glycolysis pathway, TCA cycle, ethanol oxidation, pentose phosphate pathway, and ATP production, was constructed by transcriptome analysis. The effects of fermentation conditions, including dissolved oxygen, initial acetic acid concentration, and total concentration, on acetic acid fermentation and energy metabolism of A. pasteurianus were analyzed by using the RT-PCR method. The results showed the high energy charge inhibited glucose catabolism, and associated with the high ethanol oxidation rate. Consequently, a virtuous circle of increased ethanol oxidation, increased energy generation, and acetic acid tolerance was important for improving acetic acid fermentation.

Specific ion effects on the enzymatic activity of alcohol dehydrogenase from Saccharomyces cerevisiae.

The enzymatic activity of alcohol dehydrogenase (ADH) in the presence of a range of electrolytes is investigated. In the presence of 150 and 200 mM cations a substantial increase in activity following the series GnCl < CsCl < KCl ∼ NaCl < LiCl was observed with a 69% increase in the presence of KCl 200 mM with respect to the salt-free solution. In the presence of 150 and 200 mM anions the increase in activity followed an ion specific trend NaF ∼ NaCl ∼ NaBr > no salt > NaClO4 > NaSCN with a peak in activity increase of 75% in the presence of NaBr. The values of the Michaelis-Menten constant (Km) did not show any significant ion specific effect, while the maximum rate (Vmax) of ethanol oxidation to acetaldehyde was strongly ion specific. The changes in specific activity and Vmax in the presence of anions likely arises from ion specific interactions with charged residues in the active site of ADH. The data indicate that the enzymatic activity of alcohol dehydrogenase can be modulated by the nature of electrolytes at physiological concentration.

Lactate-stimulated ethanol oxidation: Revisiting an old hypothesis

Liver slices from starved rats and incubated without other substrates oxidized ethanol at a rate of 4.1 µmols • h−1 • g−1. Addition of 10 mmols • L−1 lactate increased this rate 2-fold. 4-methylpyrazole (4-MP), an alcohol dehydrogenase (ADH) inhibitor, drastically decreased the rate of ethanol oxidation, but did not inhibit the stimulation due to lactate. In the same context, liver acetaldehyde production, as the main by-product of ethanol oxidation, appeared to be much less inhibited by 4-MP in the presence of lactate. Aminotriazole (a catalase inhibitor), however, completely inhibited the stimulation. Furthermore, 2-hydroxybut-3-ynoate, an alpha-hydroxy acid oxidase inhibitor, completely abolished the stimulated ethanol oxidation promoted by lactate. Moreover, to determine the origin of the H2O2 produced, we did liver subcellular fractionation and then analyzed their content in peroxisomes, mitochondria and catalase. We observed that cytoplasm and peroxisomes appears to be the main producers of H2O2, and that the acceleration of ethanol oxidation by lactate is completely dependent on catalase. In conclusion, the H2O2 necessary to boost the catalase-dependent oxidation of ethanol appears to come from cytoplasm and peroxisomes, and is produced by the enzyme lactate oxidase.

Ethanol oxidation with high water content: A reactive molecular dynamics simulation study

Ethanol is a potential alternative to conventional fossil fuels. However, the required dewatering process to produce anhydrous ethanol is extremely energy-intensive and expensive. A promising solution is the direct use of hydrous ethanol for combustion applications, which can dramatically reduce the production cost. Many researchers have undertaken experiments demonstrating the feasibility and advantages of burning hydrous ethanol solely as a fuel. In this study, molecular dynamics (MD) simulation with the reactive force field (ReaxFF) is employed to investigate the fundamental reaction mechanisms of hydrous ethanol oxidation in comparison with the ethanol oxidation under fuel-air condition in order to understand the effects of water addition on ethanol oxidation. The results show that the reaction rate of ethanol oxidation is faster in water than in nitrogen environment and the presence of water advances the ionisation process and accelerates the radical production rate thereby enhancing the oxidation reaction. Additionally, it is suggested that the water content plays a vital role in reactions at low temperatures but that effect can be ignored at high temperatures. The detailed reaction pathways and time evolution of relevant key species indicate that H2O promotes many reactions involving OH generation and these OH radicals also facilitate its reactions with C1 & C2 intermediates as well as the dehydrogenation of C1 & C2 intermediates. Similarly, CO production is reduced in hydrous ethanol oxidation as a result of CO reaction with OH converting the CO to CO2 ultimately. Therefore, it is the addition of water that promotes the OH production due to the chemical effect of H2O leading to the enhancement of ethanol oxidation and reduction of CO production. In summary, this research provides the scientific base for the direct use of hydrous ethanol as a fuel for combustion systems with a low cost.

Synthetic strategies for the encapsulation of nanoparticles of Ni, Co, and Fe oxides within crystalline microporous aluminosilicates

A synthetic strategy is reported here for the selective containment of oxide nanoparticles of base metals within zeolitic voids of molecular dimensions. The technique, though generally applicable, is specifically illustrated to encapsulate Ni, Co, and Fe oxides within LTA, MFI, and FAU zeolites through hydrothermal framework crystallization in the presence of ligand-protected metal cations. Such ligands contain bidentate amine groups that preclude the precipitation of metal precursors in alkaline synthesis gels, and alkoxysilane moieties that form covalent linkages with nucleating zeolite precursors to enforce metal uptake into crystallized solids. These ligands are removed by subsequent oxidative treatments that nucleate oxide nanoparticles without structural degradation of the zeolites. The clusters are small (<2.5 nm) and uniformly distributed in size, reflecting their constrained growth within zeolite crystals. In contrast with exchange strategies for encapsulation, which lead to grafted cations and dense metal aluminosilicates, these methods form oxide nanoparticles, evident from infrared spectra of samples exposed to CO. Oxide nanoparticles undergo more facile redox cycles than grafted cations or dense aluminosilicates, thus rendering oxide domains more effective oxidation catalysts. The dynamics and stoichiometry of nanoparticle reduction in H2 confirmed the presence of NiO, Co3O4, and Fe2O3 clusters and their more facile reducibility relative to metal aluminosilicates. Ethanol oxidation rates on these clusters were essentially unaffected by exposure to bulky thiol poisons that titrate metal oxide surfaces, reflecting the selective placement of the oxide nanoparticles within the confines of microporous voids, where they are protected from contact by large molecules. These synthetic strategies and guiding principles circumvent long-standing hurdles in the selective encapsulation of base metals, and provide enabling routes for the synthesis of the many metal-zeolite systems that confront similar hurdles.

Synthesis of highly dispersed cobalt oxide clusters encapsulated within LTA zeolites

Small Co3O4 nanoparticles uniformly distributed in size were encapsulated within LTA zeolite crystals in a one-step process through hydrothermal self-assembly of crystalline frameworks around ligated Co2+ precursors. The use of bifunctional ligands containing a chelating bidentate amine functionality and an alkoxysilane moiety prevented the precipitation of Co2+ species as colloidal hydroxides in the highly alkaline synthesis gels, while also allowing the formation of linkages between precursors and the framework during the nucleation and growth of LTA crystals. Oxidative treatments of ligated compounds occluded within zeolite crystals removed ligand residues and formed small Co3O4 nanoparticles visible in transmission electron micrographs. These nanoparticles retained their small size (average diameter 1.5 nm) after oxidative treatment at 620–870 K, a reflection of their stabilization by confinement within zeolite voids. The infrared spectra of adsorbed CO on Co-LTA samples confirmed the absence of Co2+ as exchanged cations or aluminosilicates, indicating the presence of Co oxide clusters, with dynamics and stoichiometry of reduction in H2 corresponding to small Co3O4 clusters. Ethanol oxidation rates on Co-LTA samples, exchanged with K+ or Ca2+ cations to vary the diffusive properties of LTA crystals, indicated that more than 97% of the active surfaces on these Co3O4 clusters resided within zeolite crystals, where ethanol and O2 concentrations depend on the diffusive properties of the LTA framework. The Co3O4 clusters prepared by these methods, in contrast with Co2+ in exchanged or aluminosilicate forms, exhibit reactivity in CO and NO oxidation. Their turnover rates (per exposed Co atom), however, were lower than on bulk Co3O4 powders, because of the combined effects of diffusional constraints imposed by the confining framework and the small size of these clusters, which leads to lower intrinsic reactivities as a result of their more difficult reduction during catalytic redox cycles. These clusters would be attractive in catalytic applications requiring stability against sintering during reaction or regeneration, reactant or product shape selectivity, or protection from contact with large molecules that block active surfaces. Such oxide clusters cannot be formed by sequential ion exchange, detachment by reduction to Co0, and re-oxidation because the extremely high temperatures required for reduction destroy the aluminosilicate frameworks. The synthesis protocols and their mechanistic interpretations described herein represent a conceptual and practical platform for the encapsulation of nanoparticles of base elements within a broad range of confining crystalline environments through one-step hydrothermal self-assembly.

Acetobacter pasteurianus metabolic change induced by initial acetic acid to adapt to acetic acid fermentation conditions.

Initial acetic acid can improve the ethanol oxidation rate of acetic acid bacteria for acetic acid fermentation. In this work, Acetobacter pasteurianus was cultured in ethanol-free medium, and energy production was found to increase by 150% through glucose consumption induced by initial acetic acid. However, oxidation of ethanol, instead of glucose, became the main energy production pathway when upon culturing ethanol containing medium. Proteome assay was used to analyze the metabolism change induced by initial acetic acid, which provided insight into carbon metabolic and energy regulation of A. pasteurianus to adapt to acetic acid fermentation conditions. Results were further confirmed by quantitative real-time PCR. In summary, decreased intracellular ATP as a result of initial acetic acid inhibition improved the energy metabolism to produce more energy and thus adapt to the acetic acid fermentation conditions. A. pasteurianus upregulated the expression of enzymes related to TCA and ethanol oxidation to improve the energy metabolism pathway upon the addition of initial acetic acid. However, enzymes involved in the pentose phosphate pathway, the main pathway of glucose metabolism, were downregulated to induce a change in carbon metabolism. Additionally, the enhancement of alcohol dehydrogenase expression promoted ethanol oxidation and strengthened the acetification rate, thereby producing a strong proton motive force that was necessary for energy production and cell tolerance to acetic acid.

Cobalt Oxides Supported Over Ceria–Zirconia Coated Cordierite Monoliths as Catalysts for Deep Oxidation of Ethanol and N2O Decomposition

Cordierite monoliths coated with ceria–zirconia supporting cobalt oxide were prepared, examined in the deep oxidation of ethanol and N2O decomposition, and compared with pelletized commercial cobalt oxide catalyst. Interaction of Co3O4 with ceria–zirconia washcoat led to formation of Co3O4 particles with slightly worse structure ordering resulting in better reducibility than that observed for the commercial Co3O4 catalyst. In oxidation of ethanol, activity of the Co3O4-containing monoliths was comparable with that of pelletized cobalt oxide catalyst with nearly seven times higher content of active components. However, conversions of N2O over the monolith catalysts were lower. Nevertheless, incorporation of Co3O4 onto ZrO2–CeO2 washcoat increased rate of both catalytic reactions, i.e., N2O decomposition and deep ethanol oxidation.

Silica-supported silver-containing OMS-2 catalysts for ethanol oxidative dehydrogenation

The silver-modified cryptomelane-type crystalline and silica-supported OMS-2 catalysts (Ag/OMS-2 and Ag/OMS-2/SiO2, respectively) were prepared by impregnation, co-precipitation, and consecutive impregnation methods and tested in selective oxidation of ethanol to acetaldehyde. Modifying OMS-2 and OMS-2/SiO2 catalysts by silver was shown to improve the redox properties of the catalysts and increase the ethanol oxidation rate. However, selectivity to acetaldehyde decreased with increased reaction temperature due to intensification of total oxidation on the Ag-MnOx sites. Preparation method of the catalyst affected the Ag localization and catalytic activity. Introducing silver into the OMS-2 channels provided a higher ethanol oxidation rate. The use of silica support for Ag/OMS-2 composites improved the selectivity towards acetaldehyde at higher temperatures and, therefore, increased the acetaldehyde yield in comparison with crystalline samples.

Development of RuO2-Coated Sintered Nickel Electrode as Ethanol Sensor

RuO2 -coated sintered nickel electrodes were developed by thermal decomposition of RuCl on sintered nickel pellet. The surface and compositional features of the developed sintered nickel electrodes were optimized based on their performance. The sensing behavior of the electrodes was studied in 0.4 M NaOH containing ethanol solution using cyclic voltammetry and chronoamperometry. The maximum rate of ethanol oxidation was observed at its sensing potential. The modified electrodes exhibited good linear response of ethanol concentration from 100 to 500 ppm. The response time of the sensor was 6 sec, and the sensitivity of the sensor was 1.26 mA/ppm cm2. The RuO2 -coating on the large surface area sintered nickel electrode further enhanced the large electrochemically active surface area causing high performance of the electrode.

Enhancing ethanol oxidation rate at PtRu electro-catalysts using metal-oxide additives

Metal oxides are investigated, as additives of a PtRu/C catalyst, for enhancing the electro-oxidation of ethanol in acidic solution. High surface area TiO2 and SnO2 additives are synthesized and physico-chemically characterized. These oxides are added to PtRu/C during the catalytic ink preparation to obtain tri-metallic composite electrodes. These composite electro-catalysts are investigated for the ethanol electro-oxidation in half-cell configuration in comparison with additive-free PtRu/C and Pt/C catalysts. The PtRu-based composite catalyst containing SnO2 promoter shows a lower onset potential and larger current density for ethanol oxidation than the additive-free catalyst and that containing TiO2 promoter. The composite catalysts (PtRu/C+metal oxide) are also used in a direct ethanol fuel cell under practical operating conditions and assessed against the benchmark PtRu catalyst. An increase in performance is recorded with the composite tri-metallic electrodes. The analysis of electro-catalytic activity towards ethanol oxidation reaction and ethanolic residues coverage indicates an enhanced capability to activate ethanol chemisorption or a larger electroactive surface area, together with a faster intrinsic activity at lower overpotential, as the reasons for the improved performance with the use of metal oxide additives.

Steady-state metabolism of ethanol in perfused rat livers treated with cyanamide: quantitative analysis of acetaldehyde effects on the metabolic flux rates.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are principal enzymes responsible for metabolism of ethanol in mammals. The steady-state metabolic flux of ethanol has been poorly understood. We investigated flux rates of the individual steps of ethanol metabolism in perfused rat livers treated with ALDH inactivator cyanamide as an attempt to mimic human ALDH2 deficiency commonly seen in East Asians. The net rates of ethanol oxidation, acetaldehyde oxidation, and acetate activation were determined with a set of defined equations, based on the set influx rates of ethanol and the measured efflux rates of ethanol, acetaldehyde, and acetate. After intraperitoneal injections of 0.2 and 1.5mg/kg cyanamide, hepatic activities of mitochondrial ALDH2 and cytoplasmic ALDH1A1 decreased to a similar degree, that is, 51 to 57% and 69 to 74%, compared with the corresponding controls, respectively, whereas cytoplasmic ADH1 activity remained unchanged. At infusing 2mM ethanol, acetaldehyde oxidation rate well matched (99%) the net ethanol oxidation rate in control liver. Both the ethanol and acetaldehyde oxidation rates were significantly decreased after cyanamide treatments. At 10mM ethanol, the efflux acetaldehyde was significantly higher than that infusing 2mM ethanol in both control and cyanamide groups. Seventy-eight percent of the oxidized ethanol released as efflux acetate. At 2mM ethanol, the apparent flux control coefficients of ADH1 were assessed to be 0.78, 0.54, and 0.39, respectively, in control, low, and high cyanamide-treated livers. Kinetic simulations revealed that inhibition by acetaldehyde may largely account for the observed reduction of ADH1 oxidation rates after cyanamide treatment. Our results provide the first flux evidence that ADH and ALDH are steps influencing steady-state metabolism of ethanol in rat livers with inactivated ALDHs.

Increased Electrochemical Oxidation Rate of Alcohols in Alkaline Media on Palladium Surfaces Electrochemically Modified by Antimony, Lead, and Tin

Several adatoms (M=Sb, Sn, or Pb) were added to Pd nanoparticles and examined for the electrochemical oxidation of ethanol, 1-propanol, 2-propanol, ethylene glycol, propylene glycol, and glycerol. We observed a significant increase in oxidation rate on Pd-M for each of the adatoms in each of the fuels. For example, the oxidation rate of ethanol was 1.5 times greater on Pd-Pb and Pd-Sn as compared with the oxidation rate on Pd after 10minutes of oxidation. However, even more notable is the behavior observed by the polyhydric alcohols that exhibit sluggish reaction kinetics even in alkaline media. For example, the oxidation rate of propylene glycol on Pd-Pb was observed to be 21 times greater than the oxidation rate on Pd after 10minutes, and it was still 7.1 times greater after 12hours. These results show particular promise for the potential of efficiently oxidizing bulkier and higher energy density alcohols in the alkaline direct liquid fuel cell. All three bimetallic surfaces induced an increase in oxidation rate with all alcohols as compared to the monometallic Pd. Based on analysis of our results, we attribute a significant amount of the increase in oxidation rate to the bifunctional effect and suggest a lesser role is played by the electronic effect.

Electrocatalysis and pH (a review)

The factors determining pH effects on principal catalytic reactions in low-temperature fuel cells (oxygen reduction, hydrogen oxidation, and primary alcohols oxidation) are analyzed. The decreasing of hydrogen oxidation rate when passing from acidic electrolytes to basic ones was shown to be due to the electrode surface blocking by oxygen-containing species and changes in the adsorbed hydrogen energy state. In the case of oxygen reduction, the key factors determining the process’ kinetics and mechanism are: the O2 adsorption energy, the adsorbed molecule protonation, and the oxygen reaction thermodynamics. The process’ high selectivity in acidic electrolytes at platinum electrodes is caused by rather high Pt-O2 bond energy and its protonation. The passing from acidic electrolytes to basic ones involves a decrease in the oxygen adsorption energy, both at platinum and nonplatinum catalysts, hence, in the selectivity of the oxygen-to-water reduction reaction. The increase in the methanol and ethanol oxidation rate in basic media, as compared with acidic ones, is due to changes in the reacting species’ structure (because of the alcohol molecules dissociation) on the one hand, and active OHads species inflow to the reaction zone, on the other hand. In the case of ethanol, the above-listed factors determine the process’ increased selectivity with respect to CO2 at higher pHs. Based on the survey and valuation, priority guidelines in the electrocatalysis of commercially important reactions are formulated, in particular, concepts of electrocatalysis at nonplatinum electrode materials that are stable in basic electrolytes, and approaches to the practical control of the rate and selectivity of oxygen reduction and primary alcohols oxidation over wide pH range.

Ethanol vapor photocatalytic oxidation with uranyl modified titania under visible light: Comparison with silica and alumina

Gas-phase photocatalytic oxidation (PCO) of ethanol vapor in a batch reactor using UO2(NO3)2-modified titania, alumina and silica as photocatalysts was studied. The uranyl nitrate content was varied from 0.2 to 10 wt.%. Special optical glass filters were placed between the light source and reactor to cutoff the UV light. Photooxidation experiments under the visible light irradiation demonstrated that UO2(NO3)2 loading on TiO2 improves its activity in the ethanol photooxidation and CO2 formation. The influence of support and uranyl nitrate content on the ethanol vapor PCO was investigated. The rate of ethanol oxidation increased with the increase of uranyl content. Alumina and silica based photocatalysts demonstrated almost the same photoactivity whereas the titania based photocatalyst had at least a five times higher rate of the acetaldehyde accumulation. All the synthesized photocatalysts oxidize ethanol even under light with wavelength higher than 470 nm.

Measurement of carbon dioxide yields for ethanol oxidation by operation of a direct ethanol fuel cell in crossover mode

Faradaic yields of carbon dioxide from ethanol oxidation were measured with a non-dispersive CO2 detector for a direct ethanol fuel cell (DEFC) operating in crossover mode with aqueous ethanol delivered to the cathode and N2 passing through the anode compartment. Under these conditions, the rate of ethanol oxidation is limited by its rate of diffusion though the Nafion membrane (crossover). It is shown, by comparison with results obtained with methanol and by running the cell normally, that this experimental configuration provides more accurate results by minimizing the effects of CO2 crossover. The faradaic yield of CO2 was found to increase significantly with decreasing ethanol concentration, reaching 64% for oxidation of 0.1M ethanol at 80°C. However, the highest yield (>68%) was obtained by operating the cell normally.

Selective Autooxidation of Ethanol over Titania-Supported Molybdenum Oxide Catalysts: Structure and Reactivity.

We study the selective catalytic oxidation of ethanol with air as a sustainable alternative route to acetaldehyde. The reaction is catalysed by molybdenum oxide supported on titania, in a flow reactor under ambient pressure. High selectivity to acetaldehyde (70%–89%, depending on the Mo loading) is obtained at 150 °C. Subsequently, we investigate the structure/performance relationship for various molybdenum oxide species using a combination of techniques including diffuse reflectance UV-visible, infrared, X-ray photoelectron spectroscopies, X-ray diffraction and temperature programmed reduction. As their surface density increases, the monomeric molybdenum oxide species undergo two-dimensional and three-dimensional oligomerisation. This results in polymolybdates and molybdenum oxide crystallites. Importantly, the ethanol oxidation rate depends not only on the overall molybdenum loading and dispersion, but also on the type of molybdenum oxide species prevalent at each surface density and on the domain size. As the molybdenum oxide oligomerisation increases, electron delocalisation becomes easier. This lowers the absorption edge energy and increases the reaction rate.

Alcohol Consumption, Genetic Variants in Alcohol Deydrogenases, and Risk of Cardiovascular Diseases: A Prospective Study and Meta-Analysis

ObjectiveFirst, to investigate and compare associations between alcohol consumption and variants in alcohol dehydrogenase (ADH) genes with incidence of cardiovascular diseases (CVD) in a large German cohort. Second, to quantitatively summarize available evidence of prospective studies on polymorphisms in ADH1B and ADH1C and CVD-risk.MethodsWe conducted a case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort including a randomly drawn subcohort (n = 2175) and incident cases of myocardial infarction (MI; n = 230) or stroke (n = 208). Mean follow-up time was 8.2±2.2 years. The association between alcohol consumption, ADH1B or ADH1C genotypes, and CVD-risk was assessed using Cox proportional hazards regression. Additionally, we report results on associations of variants in ADH1B and ADH1C with ischemic heart disease and stroke in the context of a meta-analysis of previously published prospective studies published up to November 2011.ResultsCompared to individuals who drank >0 to 6 g alcohol/d, we observed a reduced risk of MI among females consuming >12 g alcohol/d (HR = 0.31; 95% CI: 0.10–0.97) and among males consuming >24 to 60 g/d (HR = 0.57; 95% CI: 0.33–0.98) or >60 g alcohol/d (HR = 0.30; 95% CI: 0.12–0.78). Stroke risk was not significantly related to alcohol consumption >6 g/d, but we observed an increased risk of stroke in men reporting no alcohol consumption. Individuals with the slow-coding ADH1B*1/1 genotype reported higher median alcohol consumption. Yet, polymorphisms in ADH1B or ADH1C were not significantly associated with risk of CVD in our data and after pooling results of eligible prospective studies [ADH1B*1/1: RR = 1.35 (95% CI: 0.98–1.88; p for heterogeneity: 0.364); ADH1C*2/2: RR = 1.07 (95% CI: 0.90–1.27; p for heterogeneity: 0.098)].ConclusionThe well described association between alcohol consumption and CVD-risk is not reflected by ADH polymorphisms, which modify the rate of ethanol oxidation.