RESUMEN
There is an increasing prevalence of poor health behaviors during childhood, particularly in terms of physical activity and nutrition. This trend has occurred alongside a growing body of evidence linking these behaviors to cognitive function. B-vitamins are thought to be particularly important in the neural development that occurs during pregnancy, as well as in healthy cognitive aging. However, much less is known regarding the role of B-vitamins during childhood. Given that preadolescent childhood is a critical period for cognitive development, this study investigated the relationship between specific aspects of nutrition, particularly B-vitamins, and related health factors (e.g., body mass, fitness) on selective attention in children. Children (n = 85; 8-11 years) completed a selective attention task to assess inhibition. Participant's dietary intake was collected using the Automated Self-Administered 24-h dietary assessment tool. Correlations between specific nutrients, BMI, fitness, and task performance were investigated. After accounting for demographic variables and total caloric intake, increased B-vitamin intake (i.e., thiamin and folic acid) was associated with shorter reaction times (p's < 0.05), fitness was associated with greater response accuracy (p < 0.05), and increased BMI was related to increased variability in reaction times (p < 0.05). Together, these findings suggest that aspects of health may have unique contributions on cognitive performance. Proper physical health and nutrition are imperative for effective cognitive functioning in preadolescent children. Targeted efforts aimed at health education amongst this population could ensure proper cognitive development during school-age years, providing a strong foundation throughout life.
Asunto(s)
Atención/fisiología , Peso Corporal/fisiología , Aptitud Física/fisiología , Complejo Vitamínico B/fisiología , Índice de Masa Corporal , Niño , Cognición/fisiología , Dieta , Femenino , Conductas Relacionadas con la Salud/fisiología , Humanos , Masculino , Consumo de Oxígeno/fisiología , Tiempo de Reacción , Análisis y Desempeño de Tareas , Complejo Vitamínico B/administración & dosificaciónRESUMEN
The gut microbiota produce hundreds of bioactive compounds, including B-vitamins, which play significant physiological roles in hosts by supporting the fitness of symbiotic species and suppressing the growth of competitive species. B-vitamins are also essential to the host and certain gut bacterium. Although dietary B-vitamins are mainly absorbed from the small intestine, excess B-vitamins unable to be absorbed in the small intestine are supplied to the distal gut. In addition, B-vitamins are supplied from biosynthesis by distal gut microbiota. B-vitamins in the distal colon may perform many important functions in the body. They act as 1) nutrients for a host and their microbiota, 2) regulators of immune cell activity, 3) mediators of drug efficacy, 4) supporters of survival, or the fitness of certain bacterium, 5) suppressors of colonization by pathogenic bacteria, and 6) modulators of colitis. Insights into basic biophysical principles, including the bioavailability of B-vitamins and their derivatives in the distal gut are still not fully elucidated. Here, the function of single B-vitamin in the distal gut including their roles in relation to bacteria are briefly reviewed. The prospect of extending analytical methods to better understand the role of B-vitamins in the gut is also explored.
Asunto(s)
Microbioma Gastrointestinal/fisiología , Complejo Vitamínico B/fisiología , Animales , Tracto Gastrointestinal/fisiología , Humanos , Complejo Vitamínico B/farmacocinética , Complejo Vitamínico B/farmacologíaRESUMEN
BACKGROUND: Neurotropic B vitamins play crucial roles as coenzymes and beyond in the nervous system. Particularly vitamin B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) contribute essentially to the maintenance of a healthy nervous system. Their importance is highlighted by many neurological diseases related to deficiencies in one or more of these vitamins, but they can improve certain neurological conditions even without a (proven) deficiency. AIM: This review focuses on the most important biochemical mechanisms, how they are linked with neurological functions and what deficits arise from malfunctioning of these pathways. DISCUSSION: We discussed the main role of B Vitamins on several functions in the peripheral and central nervous system (PNS and CNS) including cellular energetic processes, antioxidative and neuroprotective effects, and both myelin and neurotransmitter synthesis. We also provide an overview of possible biochemical synergies between thiamine, pyridoxine, and cobalamin and discuss by which major roles each of them may contribute to the synergy and how these functions are inter-related and complement each other. CONCLUSION: Taking into account the current knowledge on the neurotropic vitamins B1, B6, and B12, we conclude that a biochemical synergy becomes apparent in many different pathways in the nervous system, particularly in the PNS as exemplified by their combined use in the treatment of peripheral neuropathy.
Asunto(s)
Fenómenos Fisiológicos del Sistema Nervioso , Piridoxina/fisiología , Tiamina/fisiología , Vitamina B 12/fisiología , Complejo Vitamínico B/fisiología , Animales , Sistema Nervioso Central/fisiología , Humanos , Enfermedades del Sistema Nervioso , Sistema Nervioso Periférico/fisiologíaRESUMEN
Most B vitamins and vitamin C are among the nutrients in milk most strongly affected by maternal status and/or dietary intake. Recent analytical methods are more efficient and valid, revealing major differences in water-soluble vitamins across population groups. An inadequate supply in milk can be detrimental to the breastfed infant's health and development although cutoff points below which risk is increased are often uncertain, and little attention has been paid to adverse effects of low milk water-soluble vitamins on infant health and function. Concentrations change during lactation: thiamine, niacin, and pantothenic acid increase; B6, B12, and ascorbic acid gradually decrease; while riboflavin concentrations are stable, as is choline after an initial increase. Folate fluctuates until stabilizing in late lactation. Water-soluble vitamin concentrations in milk are also influenced by maternal supplementation, and, for some, by parity, preterm delivery, smoking, and maternal illness. However, there is relatively little change in concentrations during a feed nor is diurnal variation a major influence. Reported concentrations are used to set adequate intakes for infants and incremental requirements for lactation. However, the status of available data is poor due to the small number of participants in most studies, uncertainties about maternal nutritional status, and variable times of milk collection postpartum.
Asunto(s)
Leche Humana/química , Leche Humana/fisiología , Vitaminas/análisis , Vitaminas/fisiología , Ácido Ascórbico/análisis , Ácido Ascórbico/fisiología , Lactancia Materna , Dieta , Suplementos Dietéticos , Femenino , Alimentos Fortificados , Humanos , Lactante , Recién Nacido , Lactancia/fisiología , Salud Materna , Necesidades Nutricionales , Estado Nutricional , Complejo Vitamínico B/análisis , Complejo Vitamínico B/fisiologíaRESUMEN
BACKGROUND: Birth defects remain a significant source of worldwide morbidity and mortality. Strong scientific evidence shows that folic acid fortification of a region's food supply leads to a decrease in spina bifida (a birth defect of the spine). Still, many countries around the world have yet to approve mandatory fortification through government legislation. OBJECTIVES: We sought to perform a systematic review and meta-analysis of period prevalence of spina bifida by folic acid fortification status, geographic region, and study population. SEARCH METHODS: An expert research librarian used terms related to neural tube defects and epidemiology from primary research from 1985 to 2010 to search in EMBASE and MEDLINE. We searched the reference lists of included articles and key review articles identified by experts. SELECTION CRITERIA: Inclusion criteria included studies in English or French reporting on prevalence published between January 1985 and December 2010 that (1) were primary research, (2) were population-based, and (3) reported a point or period prevalence estimate of spina bifida (i.e., prevalence estimate with confidence intervals or case numerator and population denominator). Two independent reviewers screened titles and abstracts for eligible articles, then 2 authors screened full texts in duplicate for final inclusion. Disagreements were resolved through consensus or a third party. DATA COLLECTION AND ANALYSIS: We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses, or PRISMA, abstracting data related to case ascertainment, study population, folic acid fortification status, geographic region, and prevalence estimate independently and in duplicate. We extracted overall data and any subgroups reported by age, gender, time period, or type of spina bifida. We classified each period prevalence estimate as "mandatory" or "voluntary" folic acid fortification according to each country's folic acid fortification status at the time data were collected (as determined by a well-recognized fortification monitoring body, Food Fortification Initiative). We determined study quality on the basis of sample representativeness, standardization of data collection and birth defect assessment, and statistical analyses. We analyzed study-level period prevalence estimates by using a random effects model (α level of < 0.05) for all meta-analyses. We stratified pooled period prevalence estimates by birth population, fortification status, and continent. RESULTS: Of 4078 studies identified, we included 179 studies in the systematic review and 123 in a meta-analysis. In studies of live births (LBs) alone, period prevalences of spina bifida were (1) lower in geographical regions with mandatory (33.86 per 100,000 LBs) versus voluntary (48.35 per 100,000 LBs) folic acid fortification, and (2) lower in studies of LBs, stillbirths, and terminations of pregnancy in regions with mandatory (35.22 per 100,000 LBs) versus voluntary (52.29 per 100,000 LBs) fortification. In LBs, stillbirths, and terminations of pregnancy studies, the lowest pooled prevalence estimate was in North America (38.70 per 100,000). Case ascertainment, surveillance methods, and reporting varied across these population-based studies. CONCLUSIONS: Mandatory legislation enforcing folic acid fortification of the food supply lags behind the evidence, particularly in Asian and European countries. This extensive literature review shows that spina bifida is significantly more common in world regions without government legislation regulating full-coverage folic acid fortification of the food supply (i.e., Asia, Europe) and that mandatory folic acid fortification resulted in a lower prevalence of spina bifida regardless of the type of birth cohort. African data were scarce, but needed, as many African nations are beginning to adopt folic acid legislation.
Asunto(s)
Ácido Fólico/administración & dosificación , Alimentos Fortificados/normas , Salud Global/estadística & datos numéricos , Disrafia Espinal/epidemiología , Femenino , Ácido Fólico/fisiología , Salud Global/legislación & jurisprudencia , Humanos , Embarazo , Prevalencia , Disrafia Espinal/prevención & control , Complejo Vitamínico B/administración & dosificación , Complejo Vitamínico B/fisiologíaRESUMEN
Vitamin B1 (thiamin) is considered to be the oldest vitamin and in 1936 R.R. Williams and colleagues determined its chemical structure and were able to synthesize this vitamin. Vitamin B1 influences pro-apoptotic proteins, mitochondrial membrane potential, cytochrome C release, protein kinases, p38-MAPK, suppresses oxidative stress-induced NF-kappaB and has anti-inflammatory properties. Deficiency of vitamin B1 may cause beriberi, dysfunction of the nervous system, neuroinflammation, T cell infiltration, chemokine CCL2 activation, over expression of proinflammatory cytokines, such as IL-1, TNF, IL-6, and arachidonic acid products, and induces expression of CD40 by the microglia and CD40L by astrocytes which provoke the death of neurons. Here we report the relationship between vitamin B complex and immunity.
Asunto(s)
Sistema Inmunológico/fisiología , Complejo Vitamínico B/fisiología , Deficiencia de Vitamina B/inmunología , Animales , Citocinas/biosíntesis , Citocinas/fisiología , Insuficiencia Cardíaca/etiología , Humanos , Inflamación/fisiopatología , Modelos Animales , Enfermedades del Sistema Nervioso/etiología , Enfermedades del Sistema Nervioso/inmunología , Enfermedades Neuromusculares/etiología , Enfermedades Neuromusculares/inmunología , Complejo Vitamínico B/uso terapéutico , Deficiencia de Vitamina B/complicacionesRESUMEN
The risk of osteoporosis and bone fractures increases with age. Several other factors are also related to bone disease including gender, race/ethnicity, physical activity, alcohol, smoking, estrogen, and calcium and vitamin D. B-vitamins (folate, B12, and B6) are also emerging dietary factors related to bone health, both individually and through their action on influencing total plasma homocysteine concentrations (tHcy). The primary objective of this review is to summarize the available data on B-vitamins and bone health, highlighting clinical trials and observational data. In populations without folic acid fortification, the totality of evidence suggests that elevated tHcy has a small but significant association with bone fracture risk and bone quality but not on bone mineral density (BMD) or bone turnover biomarkers. Very little supportive evidence exists for a direct role of folate for either BMD or fracture risk; however, the data available are quite limited. Meta-analyses and some cross-sectional and cohort studies suggest a small but significant role of vitamin B12 status on risk of fracture but not on BMD. The mechanism by which tHcy and B12 may influence bone health is not well characterized but may be through modulation of collagen cross-linking or through altering osteoclasts or osteoblasts. Much more data are needed-particularly the role that each vitamin directly has on bone, or whether the vitamins only exert their effect though tHcy concentrations. Nevertheless, consistent findings across different populations with different study designs suggest a role for tHcy and B12 in reducing fracture risk.
Asunto(s)
Huesos/metabolismo , Osteoporosis/prevención & control , Complejo Vitamínico B/fisiología , Anciano , Anciano de 80 o más Años , Densidad Ósea/fisiología , Fracturas Óseas/prevención & control , Humanos , Persona de Mediana EdadRESUMEN
Many different environmental factors (nutrients, pollutants, chemicals, physical activity, lifestyle, physical and mental stress) can modulate epigenetic markers in the developing and adult organism. Epigenetics, in turn, can cause and is associated with several neurodegenerative and aging-dependent human diseases. Alzheimer's disease certainly represents one of the most relevant neurodegenerative disorders due to its incidence and its huge socio-economic impact. Therefore, it is easy to understand why recent literature focuses on the epigenetic modifications associated with Alzheimer's disease and other neurodegenerative disorders. One of the most intriguing and, at the same time, worrying evidence is that even "mild" environmental factors (such as behavioral or physical stress) as well as the under-threshold exposure to pollutants and chemicals, can be effective. Finally, even mild nutrients disequilibria can result in long-lasting and functional alterations of many epigenetic markers, although they don't have an immediate acute effect. Therefore, we will probably have to re-define the current risk threshold for many factors, molecules and stresses. Among the many different environmental factors affecting the epigenome, nutrition represents one of the most investigated fields; the reasons are probably that each person interacts with nutrients and that, in turn, nutrients can modulate at molecular level the epigenetic biochemical pathways. The role that nutrition can exert in modulating epigenetic modifications in Alzheimer's disease will be discussed with particular emphasis on the role of B vitamins and DNA methylation.
Asunto(s)
Enfermedad de Alzheimer/genética , Epigénesis Genética/genética , Interacción Gen-Ambiente , Estado Nutricional/genética , Adulto , Factores de Edad , Metilación de ADN/genética , Predisposición Genética a la Enfermedad/genética , Humanos , Enfermedades Neurodegenerativas/genética , Complejo Vitamínico B/genética , Complejo Vitamínico B/fisiologíaRESUMEN
The potential contributions of B vitamins by a yeast associate to the nutrition of the carpenter ant Camponotus vicinus Mayr was examined as part of an effort to develop a chemically defined diet. This diet was used to test the effects of individual B vitamin and other nutrient deletions on larval development. The chemically defined diet contained amino acids, vitamins, minerals, and other growth factors in a liquid sucrose matrix. C. vicinus worker colonies with third- and fourth-instar larvae were fed a complete artificial diet or that diet with a component deleted for a 12-wk period. There was a significant effect of diet on larval growth and number of adult worker ants produced in the overall nutrient deletion test, but ant development was often better on incomplete diets with one B vitamin deleted compared with the complete holidic basal diet. Thiamine deletion resulted in significantly higher brood weights compared with the complete diet. Diets of sugar water plus all B vitamins, sugar water only, or a diet minus all B vitamins and cholesterol were associated with significantly lower brood weights. Significantly more adult worker ants were produced by worker colonies fed diets minus cholesterol, choline, thiamine, or riboflavin compared with the complete basal diet. The results suggest that the diet, while suitable for rearing, could benefit from further study to better define component levels. The potential relationship of C. vicinus with yeast associates is discussed in relation to further studies.
Asunto(s)
Hormigas/crecimiento & desarrollo , Complejo Vitamínico B/fisiología , Deficiencia de Vitamina B/fisiopatología , Animales , Peso Corporal , Dieta , Larva/crecimiento & desarrolloRESUMEN
The US diet has been fortified with folic acid to prevent neural tube defects since 1998. The Physician Data Queries from the National Cancer Institute describe folate as protective against prostate cancer, whereas its synthetic analog, folic acid, is considered to increase prostate cancer risk when taken at levels easily achievable by eating fortified food or taking over-the-counter supplements. We review the present literature to examine the effects of folate and folic acid on prostate cancer, help interpret previous epidemiologic data, and provide clarification regarding the apparently opposing roles of folate for patients with prostate cancer. A literature search was conducted in Medline to identify studies investigating the effect of nutrition and specifically folate and folic acid on prostate carcinogenesis and progression. In addition, the National Health and Nutrition Examination Survey database was analyzed for trends in serum folate levels before and after mandatory fortification. Folate likely plays a dual role in prostate carcinogenesis. There remains conflicting epidemiologic evidence regarding folate and prostate cancer risk; however, there is growing experimental evidence that higher circulating folate levels can contribute to prostate cancer progression. Further research is needed to clarify these complex relationships.
Asunto(s)
Neoplasias de la Próstata/fisiopatología , Animales , Carcinogénesis/genética , Carcinogénesis/metabolismo , Línea Celular Tumoral/metabolismo , Progresión de la Enfermedad , Ácido Fólico/sangre , Ácido Fólico/fisiología , Deficiencia de Ácido Fólico/epidemiología , Humanos , Inmunohistoquímica , Calicreínas/metabolismo , Calicreínas/fisiología , Masculino , Encuestas Nutricionales , Antígeno Prostático Específico/metabolismo , Antígeno Prostático Específico/fisiología , Neoplasias de la Próstata/epidemiología , Neoplasias de la Próstata/metabolismo , Complejo Vitamínico B/fisiologíaRESUMEN
Increasing evidence suggests that dietary vitamin B6 is linked to the prevention of cancer and cardiovascular disease. However, the molecular mechanisms involved in this process are not yet understood. Preliminary results in the current study indicated, following DNA microarray analysis and quantitative PCR, that insulinlike growth factorbinding protein 1 (IGFBP1) mRNA is upregulated in HT29 colon carcinoma cells exposed to pyridoxal (PL, 500 µM). IGFBP1 is secreted from the liver and is hypothesized to exert a protective role in the development of cancer and cardiovascular disease. Thus, further experiments were performed to investigate the effect of PL on the expression of IGFBP1 in HepG2 hepatocellular carcinoma cells. The addition of PL (500 µM) markedly increased the expression of IGFBP1 mRNA in HepG2 cells at 6, 12 and 24 h (P<0.01), whereas other vitamers (500 µM), including pyridoxal 5'phosphate (PLP), pyridoxine (PN) and pyridoxamine (PM), caused no such effect. The expression of the IGFBP1 protein in the cell lysate and culture medium was elevated in the presence of PL. PL elevated expression of the active form of ERK1 protein, pERK1, and the pcJun protein, a downstream factor of ERK. Furthermore, IGFBP1 expression, elevated by PL, was suppressed by PD98059, an ERK inhibitor. Higher expression of IGFBP1 protein by PL was suppressed by cycloheximide. These results suggest that PL may induce the expression of IGFBP1 in hepatoma cells via a mechanism involving the ERK/cJun pathway.
Asunto(s)
Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Sistema de Señalización de MAP Quinasas , Piridoxal/farmacología , Complejo Vitamínico B/farmacología , Proliferación Celular/efectos de los fármacos , Cicloheximida/farmacología , Células HT29 , Células Hep G2 , Humanos , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Biosíntesis de Proteínas/efectos de los fármacos , Inhibidores de la Síntesis de la Proteína/farmacología , Piridoxal/fisiología , Activación Transcripcional/efectos de los fármacos , Regulación hacia Arriba , Complejo Vitamínico B/fisiologíaAsunto(s)
Ácido Pantoténico/efectos adversos , Ácido Pantoténico/fisiología , Esquizofrenia/inducido químicamente , Complejo Vitamínico B/efectos adversos , Complejo Vitamínico B/fisiología , Coenzima A/biosíntesis , Coenzima A/metabolismo , Humanos , Mutación/efectos de los fármacos , Mutación/genética , Esquizofrenia/genética , Esquizofrenia/metabolismoRESUMEN
The water-soluble group B3 vitamin nicotinamide (NAM) is involved in a wide range of physical processes through biosynthetically converted to nicotinamide adenine dinucleotide (NAD(+)). In addition to its pivotal role in energy metabolism, NAD(+) is also the indispensable substrate of poly (ADP-ribose) polymerase-1 (PARP-1) and sirtuin 1 (SIRT1). PARP-1 and SIRT1 may catalyze the posttranslational poly(ADP-ribosyl)ation and acetylation of histones as well as non-histone proteins, such as nuclear factor kappa B and activator protein 1, which play crucial roles in transcriptional regulation of inflammatory genes. The NAD(+)-dependent modifications catalyzed by PARP-1 and SIRT1 liberate NAM, and NAM acts as feedback inhibitor of PARP-1 and SIRT1 through interacting with the enzymes at the binding site for NAD(+). There is increasing evidence that NAM effectively suppresses the expression of inflammatory genes and provides therapeutic benefits in various inflammation-based diseases. The mechanisms underlie the anti-inflammatory properties of NAM might involve the inhibition of PARP-1 and SIRT1.
Asunto(s)
Regulación de la Expresión Génica , Mediadores de Inflamación/fisiología , Inflamación/genética , Niacinamida/fisiología , Transcripción Genética , Animales , Humanos , Inflamación/metabolismo , Poli(ADP-Ribosa) Polimerasa-1 , Poli(ADP-Ribosa) Polimerasas/genética , Poli(ADP-Ribosa) Polimerasas/metabolismo , Sirtuina 1/genética , Sirtuina 1/metabolismo , Complejo Vitamínico B/fisiologíaRESUMEN
Dietary compounds as well as commensal microbiota contribute to the generation of a unique gut environment. In this study, we report that dietary folic acid (FA) is required for the maintenance of Foxp3+ regulatory T cells (Tregs) in the colon. Deficiency of FA in the diet resulted in marked reduction of Foxp3+ Tregs selectively in the colon. Blockade of folate receptor 4 and treatment with methotrexate, which inhibits folate metabolic pathways, decreased colonic Foxp3+ Tregs. Compared with splenic Tregs, colonic Tregs were more activated to proliferate vigorously and were highly sensitive to apoptosis. In colonic Tregs derived from mice fed with a FA-deficient diet, expression of anti-apoptotic molecules Bcl-2 and Bcl-xL was severely decreased. A general reduction of peripheral Tregs was induced by a neutralizing Ab against IL-2, but a further decrease by additional FA deficiency was observed exclusively in the colon. Mice fed with an FA-deficient diet exhibited higher susceptibility to intestinal inflammation. These findings reveal the previously unappreciated role of dietary FA in promotion of survival of Foxp3+ Tregs that are in a highly activated state in the colon.
Asunto(s)
Alimentación Animal , Colon/inmunología , Colon/metabolismo , Ácido Fólico/administración & dosificación , Ácido Fólico/fisiología , Factores de Transcripción Forkhead/biosíntesis , Linfocitos T Reguladores/inmunología , Animales , Supervivencia Celular/inmunología , Colon/citología , Factores de Transcripción Forkhead/fisiología , Técnicas de Sustitución del Gen , Ratones , Ratones Endogámicos BALB C , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/metabolismo , Complejo Vitamínico B/administración & dosificación , Complejo Vitamínico B/fisiologíaRESUMEN
Heart failure (HF) is the leading cause of morbidity and mortality in industrialized countries, creating a significant burden on both the healthcare system and quality of life. Research efforts continue to explore new pharmaceutical or surgically based approaches to HF management, but the role of nutrition as an adjunct therapy has been largely ignored. Elderly age, anorexia, malabsorption, premature satiety, and disease severity are among the factors identified as contributing to reduced nutrient intakes in patients with HF. These factors suggest that patients with HF are at increased risk of multiple-nutrient deficiencies, including B vitamins. B vitamins may be of particular therapeutic interest because of their key roles as cofactors in energy-producing pathways. Recently, impaired stores of high-energy compounds have been linked with myocardial dysfunction and prognosis in patients with HF. Therefore, deficiencies of B vitamins might contribute to reduced energy stores and disease progression. This review summarizes the existing literature both with respect to the prevalence of B vitamin deficiency as well as evidence from supplementation trials in patients with HF. The findings suggest that most of the literature in this area has focused on thiamin deficiency in patients with HF, whereas other B vitamins remain largely unstudied. Although few sporadic trials suggest a role for B vitamins in the management of HF, none are conclusive. Therefore, there is a need for larger, more robust trials to assist in defining the B vitamin requirements as well as the impact of supplementation on both morbidity and mortality in patients with HF.
Asunto(s)
Insuficiencia Cardíaca/terapia , Complejo Vitamínico B/administración & dosificación , Suplementos Dietéticos , Insuficiencia Cardíaca/complicaciones , Humanos , Necesidades Nutricionales , Factores de Riesgo , Tiamina/administración & dosificación , Tiamina/fisiología , Deficiencia de Tiamina/complicaciones , Deficiencia de Tiamina/tratamiento farmacológico , Complejo Vitamínico B/fisiología , Deficiencia de Vitamina B/complicaciones , Deficiencia de Vitamina B/tratamiento farmacológicoRESUMEN
Moderately elevated homocysteine levels have been associated with a higher risk of cardiovascular disease in observational studies, but whether these associations are causal is uncertain. Randomized trials of dietary supplementation with B vitamins were set up to assess whether lowering homocysteine levels could reduce the risk of vascular disease. This review is based on a meta-analysis of published results of eight homocysteine-lowering trials for preventing vascular disease. The eight trials comprised a total of 37,485 individuals and provided comparisons of the effects of B vitamins on 5,074 coronary heart disease (CHD) events, 1,483 stroke events, 2,692 incident cancer events, and 5,128 deaths. Our meta-analysis assessed the effects of lowering homocysteine levels by about 25% for about 5 years. Allocation to B vitamins had no beneficial effects on any cardiovascular events, with hazard ratios (95% confidence intervals) of 1.01 (0.96-1.07) for CHD and 0.96 (0.87-1.07) for stroke. Moreover, allocation to B vitamins had no significant adverse effects on cancer [1.08 (0.99-1.17)], or for death from any cause [1.02 (0.97-1.07)]. Thus, supplementation with B vitamins had no statistically significant effects on the risks of cardiovascular events, total mortality rates, or cancer. A meta-analysis based on individual participant data from all available trials will assess the effects of lowering homocysteine levels on a broader range of outcomes, overall and in all relevant subgroups. However, available evidence does not support the routine use of B vitamins to prevent cardiovascular disease.
Asunto(s)
Ensayos Clínicos como Asunto/métodos , Homocisteína/fisiología , Enfermedades Vasculares/etiología , Causas de Muerte , Suplementos Dietéticos , Regulación hacia Abajo , Ácido Fólico/metabolismo , Ácido Fólico/fisiología , Homocisteína/efectos adversos , Homocisteína/sangre , Homocisteína/metabolismo , Humanos , Neoplasias/etiología , Neoplasias/metabolismo , Neoplasias/mortalidad , Enfermedades Vasculares/metabolismo , Enfermedades Vasculares/mortalidad , Complejo Vitamínico B/administración & dosificación , Complejo Vitamínico B/metabolismo , Complejo Vitamínico B/fisiologíaRESUMEN
Deficiencies of the vitamins folate, B(12) , and B(6) are associated with neurological and psychological dysfunction and with congenital defects. In the elderly, cognitive impairment and incident dementia may be related to the high prevalence of inadequate B vitamin status and to elevations of plasma homocysteine. Plausible mechanisms include homocysteine neurotoxicity, vasotoxicity, and impaired S-adenosylmethionine-dependent methylation reactions vital to central nervous system function. In light of this, it is imperative to find safe ways of improving vitamin B status in the elderly without exposing some individuals to undue risk.
Asunto(s)
Envejecimiento/fisiología , Encéfalo/fisiología , Trastornos del Conocimiento/etiología , Deficiencia de Vitamina B 12/complicaciones , Deficiencia de Vitamina B 6/complicaciones , Anciano , Encéfalo/efectos de los fármacos , Trastornos del Conocimiento/prevención & control , Homocisteína/sangre , Humanos , Estado Nutricional , Vitamina B 12/administración & dosificación , Vitamina B 12/fisiología , Deficiencia de Vitamina B 12/metabolismo , Vitamina B 6/administración & dosificación , Vitamina B 6/fisiología , Deficiencia de Vitamina B 6/metabolismo , Complejo Vitamínico B/administración & dosificación , Complejo Vitamínico B/fisiologíaRESUMEN
Predators influence the phenotype of prey through both natural selection and induction. We investigated the effects of grazers and nutrients on chain formation in a dinoflagellate, Cochlodinium polykrikoides, which forms dense blooms and has deleterious effects on marine ecosystems around the world. Field populations of C. polykrikoides formed longer chains than laboratory cultures without grazers. In the field, chain length of C. polykrikoides was positively correlated with the abundance of the copepod Acartia tonsa. Chain length of C. polykrikoides increased when exposed to live females of A. tonsa or its fresh (<24 h post-isolation) exudates for 48 h. These results suggest that dissolved chemical cues released by A. tonsa induce chain formation in C. polykrikoides. Ingestion rate of A. tonsa on four-cell chains of C. polykrikoides was lower than on single cells, suggesting that chain formation may be an effective anti-grazing defense. Finally, nutrient amendment experiments demonstrated that vitamins (B(1), B(7), and B(12)) increased the chain length of C. polykrikoides both singly and collectively, while trace metals and inorganic nutrients did not, showing that vitamins may also influence chain formation in this species.
Asunto(s)
Copépodos/fisiología , Dinoflagelados/fisiología , Cadena Alimentaria , Complejo Vitamínico B/fisiología , Adaptación Fisiológica , Animales , Femenino , Fenotipo , Conducta Predatoria , Tiamina/fisiología , Vitamina B 12/fisiologíaRESUMEN
Esmond E. Snell (1914-2003) was a giant of B-vitamin and enzyme research. His early research in bacterial nutrition had lead to the discovery of vitamins such as lipoic acid and folic acid, and an anti-vitamin avidin. He developed microbiological assay methods for riboflavin and other vitamins and amino acids, which are still used today. He also investigated the metabolism of vitamins, discovered pyridoxal and pyridoxamine as the active forms of vitamin B(6) and revealed the mechanism of transamination and other reactions catalysed by vitamin B(6) enzymes. His research in later years on pyruvoyl-dependent histidine decarboxylase unveiled the biogenesis mechanism of this first built-in cofactor. Throughout his career, he was a great mentor of many people, all of whom are inspired by his philosophy of science.
Asunto(s)
Coenzimas/historia , Complejo Vitamínico B/historia , Animales , Arthrobacter/enzimología , Arthrobacter/metabolismo , Bioquímica/historia , Coenzimas/aislamiento & purificación , Coenzimas/fisiología , Historia del Siglo XX , Humanos , Lactobacillus/enzimología , Lactobacillus/crecimiento & desarrollo , Lactobacillus/metabolismo , Técnicas Microbiológicas/historia , Ácido Pantoténico/aislamiento & purificación , Ácido Pantoténico/fisiología , Pseudomonas/enzimología , Pseudomonas/metabolismo , Saccharomyces/enzimología , Saccharomyces/crecimiento & desarrollo , Saccharomyces/metabolismo , Vitamina B 6/historia , Vitamina B 6/aislamiento & purificación , Vitamina B 6/fisiología , Complejo Vitamínico B/aislamiento & purificación , Complejo Vitamínico B/fisiologíaRESUMEN
Vitamin C and a vitamin B are essential nutrients to maintain bone density and bone quality. Recent literature clearly shows that vitamin C and B affect bone quality determinant "collagen cross-link formation" . Mildly elevated plasma homocysteine levels induced by vitamin B insufficiency and methylenetetrahydrofolate reductase (MTHFR) deteriorate normal collagen cross-link formation (Saito M, Osteoporos Int 2009 May 30. [Epub ahead of print] , Shiraki M and Saito M, J Bone Miner Metab [6] 2008) . In this review, we describe the effects of vitamin C and vitamin B insufficiency and hyperhomocysteinemia on bone quality in terms of collagen cross-link formation in bone that have been reported in the literature.