***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Context Disruption of gut microbiota may exacerbate severity of cystic fibrosis ( CF ) . Vitamin D deficiency is a common comorbidity in patients with CF that may influence composition of the gut microbiota . Objectives Compare microbiota of vitamin D-sufficient and -insufficient CF patients and assess impact of a weekly high-dose vitamin D3 bolus regimen on gut and airway microbiome in adults with CF and vitamin D insufficiency ( 25-hydroxyvitamin D < 30 ng/mL ) . Design Forty-one subjects with CF were classified into two groups : vitamin D insufficient ( n = 23 ) and vitamin D sufficient ( n = 18 ) . Subjects with vitamin D insufficiency were r and omized to receive 50,000 IU of oral vitamin D3 or placebo weekly for 12 weeks . Sputum and stool sample s were obtained pre- and postintervention and 16S ribosomal RNA genes sequenced using Illumina MiSeq technology . Results Gut microbiota differed significantly based on vitamin D status with Gammaproteobacteria , which contain numerous , potentially pathogenic species enriched in the vitamin D-insufficient group . Principal coordinates analysis showed differential gut microbiota composition within the vitamin D-insufficient patients following 12 weeks treatment with placebo or vitamin D3 ( permutation multivariate analysis of variance = 0.024 ) , with Lactococcus significantly enriched in subjects treated with vitamin D3 , whereas Veillonella and Erysipelotrichaceae were significantly enriched in patients treated with placebo . Conclusion This exploratory study suggests that vitamin D insufficiency is associated with alterations in microbiota composition that may promote inflammation and that supplementation with vitamin D has the potential to impact microbiota composition . Additional studies to determine the impact of vitamin D on microbiota benefit clinical outcomes in CF are warranted The importance of gut microbiota in pathogenesis of diabetes remains unknown . This study investigated the relationship between microbiota and metabolic markers in African American men ( AAM ) with prediabetes and hypovitaminosis D. The study was ancillary to a r and omized trial of vitamin D supplementation with weekly ergocalciferol ( 50,000 IU ) conducted in AAM veterans over 12 months ( D Intervention in Veterans Affairs ) . Glycemic groups ( Gr ) were characterized based on changes in oral glucose tolerance between baseline and exit . Subjects with stable normal glucose tolerance were assigned to Gr-1 and those with stable prediabetes ( impaired glucose tolerance and impaired fasting glucose ) to Gr-2 . Microbiota composition was analyzed in stool collected at the exit ( n = 115 ) and compared between Gr-1 and Gr-2 , as well as between the lowest and highest quartiles of dietary intake of energy and fat , hemoglobin A1c , and serum 25-hydroxyvitamin D ( 25[OH]D ) level . Differences between Gr-1 and Gr-2 included the Bacteroidetes/Firmicutes and Bacteroidales/Clostridia ratios and differences in genera such as Ruminococcus and Dialister . Changes in specific taxa associated with the lowest and highest quartiles of 25(OH)D ( eg , Ruminococcus , Roseburia , Blautia , Dorea ) were clearly distinct from those of dietary intake ( eg , Bacteroides , Bacteroides/Prevotella ratio ) or A1c ( eg , Faecalibacterium , Catenibacterium , Streptococcus ) . These findings suggest a novel interaction between microbiota and vitamin D and a role for microbiota in early stages of diabetes development . Although results suggest that specific taxa are associated with glycemic stability over time , a causative relationship between microbiota makeup and dysglycemia is still to be demonstrated Vitamin D has immunomodulatory properties giving it the potential to affect microbial colonization of the intestinal tract . We investigated whether maternal vitamin D supplemention , maternal plasma 25-hydroxyvitamin D concentration , or direct supplementation of the infant influences key bacterial taxa within microbiota of one month old infants . Infant and maternal vitamin D supplement  use was ascertained via question naires . Maternal plasma 25-hydroxyvitamin D was determined at approximately the 36th week of pregnancy . In 913 one month old infants in the prospect i ve KOALA Birth Cohort Study , fecal Bifidobacterium spp . , Escherichia coli , Clostridium difficile , Bacteroides fragilis group , Lactobacillus spp . and total bacteria were quantified with real-time polymerase chain reaction assays targeting 16S rRNA gene sequences . The association between vitamin D exposure and prevalence or abundance of a specific bacterial group or species was analyzed using logistic or linear regression , respectively . There was a statistically significant negative linear trend between counts of Bifidobacterium spp . and levels of maternal vitamin D supplementation and maternal 25-hydroxyvitamin D quintiles , respectively . In addition , a positive linear trend between quintile groups and B. fragilis group counts was observed . Lower counts of C. difficile were associated with vitamin D supplementation of breast fed infants whose mothers were more likely to adhere to an alternative lifestyle in terms of , e.g. , dietary habits . These data suggest that vitamin D influences the abundance of several key bacterial taxa within the infant microbiota . Given that intestinal microbiotic homeostasis may be an important factor in the prevention of immune mediated diseases and that vitamin D status is a modifiable factor , further investigation of the impact of postnatal vitamin D supplementation should be conducted in older infants Background : The gut microbiome in infancy influences immune system maturation , and may have an important impact on allergic disease risk . Objective : We sought to determine how prenatal and early life factors impact the gut microbiome in a relatively large , ethnically diverse study population of infants at age 3 to 6 months , who were enrolled in Vitamin D Antenatal Asthma Reduction Trial , a clinical trial of vitamin D supplementation in pregnancy to prevent asthma and allergies in offspring . Methods : We performed 16S rRNA gene sequencing on 333 infants ' stool sample s. Microbial diversity was computed using the Shannon index . Factor analysis applied to the top 25 most abundant taxa revealed 4 underlying bacterial coabundance groups ; the first dominated by Firmicutes ( Lachnospiraceae/Clostridiales ) , the second by Proteobacteria ( Klebsiella/Enterobacter ) , the third by Bacteriodetes , and the fourth by Veillonella . Scores for coabundance groups were used as outcomes in regression models , with prenatal/birth and demographic characteristics as independent predictors . Multivariate analysis , using all microbial community members , was also conducted . Results : White race/ethnicity was associated with lower diversity but higher Bacteroidetes coabundance scores . C‐section birth was associated with higher diversity , but decreased Bacteroidetes coabundance scores . Firmicutes scores were higher for infants born by C‐section . Breast‐fed infants had lower proportions of Clostridiales . Cord blood vitamin D was linked to increased Lachnobacterium , but decreased Lactococcus . Conclusions : The findings presented here suggest that race , mode of delivery , breast‐feeding , and cord blood vitamin D levels are associated with infant gut microbiome composition , with possible long‐term implication s for immune system modulation and asthma/allergic disease incidence 
    Output:
    
Conclusions Despite substantial heterogeneity , we found evidence to support the hypothesis that vitamin D influences the composition of the gastrointestinal microbiome .