UGT1A1 polymorphism is associated with serum bilirubin concentrations in a randomized, controlled, fruit and vegetable feeding trial

The beneficial effect of sulforaphane on platelet responsiveness during caloric load: a single-intake, double-blind, placebo-controlled, crossover trial in healthy participants

Background and aims

As our understanding of platelet activation in response to infections and/or inflammatory conditions is growing, it is becoming clearer that safe, yet efficacious, platelet-targeted phytochemicals could improve public health beyond the field of cardiovascular diseases. The phytonutrient sulforaphane shows promise for clinical use due to its effect on inflammatory pathways, favorable pharmacokinetic profile, and high bioavailability. The potential of sulforaphane to improve platelet functionality in impaired metabolic processes has however hardly been studied in humans. This study investigated the effects of broccoli sprout consumption, as a source of sulforaphane, on urinary 11-dehydro-thromboxane B₂ (TXB₂), a stable thromboxane metabolite used to monitor eicosanoid biosynthesis and response to antithrombotic therapy, in healthy participants exposed to caloric overload.

Methods

In this double-blind, placebo-controlled, crossover trial 12 healthy participants were administered 16g of broccoli sprouts, or pea sprouts (placebo) followed by the standardized high-caloric drink PhenFlex given to challenge healthy homeostasis. Urine samples were collected during the study visits and analyzed for 11-dehydro-TXB₂, sulforaphane and its metabolites. Genotyping was performed using Illumina GSA v3.0 DTCBooster.

Results

Administration of broccoli sprouts before the caloric load reduced urinary 11-dehydro-TXB₂ levels by 50% (p = 0.018). The amount of sulforaphane excreted in the urine during the study visits correlated negatively with 11-dehydro-TXB₂ (r_s = -0.377, p = 0.025). Participants carrying the polymorphic variant NAD(P)H dehydrogenase quinone 1 (NQO1*2) showed decreased excretion of sulforaphane (p = 0.035).

Conclusion

Sulforaphane was shown to be effective in targeting platelet responsiveness after a single intake. Our results indicate an inverse causal relationship between sulforaphane and 11-dehydro-TXB₂, which is unaffected by the concomitant intake of the metabolic challenge. 11-Dehydro-TXB₂ shows promise as a non-invasive, sensitive, and suitable biomarker to investigate the effects of phytonutrients on platelet aggregation within hours.

Clinical trial registration

[https://clinicaltrials.gov/], identifier [NCT05146804].

The Effects of Cruciferous Vegetable-Enriched Diets on Drug Metabolism: A Systematic Review and Meta-Analysis of Dietary Intervention Trials in Humans

Relatively few studies exist in the literature that discuss the effects of diet on drug metabolism and how this can affect interindividual differences in systemic drug exposure. Several studies have investigated the effects of cruciferous vegetables (Cruciferae) or their constituents on drug-metabolizing activity, as these vegetables form an important part of many peoples' diets. In general, the ingestion of cruciferous vegetables is associated with induction of cytochrome P450 (CYP) 1A2 activity in vivo; however, there is contention between reports, and the clinical significance of potential diet-drug interactions remains unclear. This study reports a systematic review, critical appraisal, and meta-analysis of the published literature in this area, and discusses the clinical significance of Cruciferae-enriched diets in the context of diet-drug interactions. Twenty-three dietary intervention trials with drug metabolism end points were identified across Embase, Medline, and the Cochrane Controlled Register of Trials (CENTRAL). Cruciferous vegetables represented in the literature included broccoli, Brussels sprout, cabbage, cauliflower, radish, and watercress. A range of phase I and II drug-metabolizing enzymes and phenotyping metrics were represented in the literature. The meta-analyses performed demonstrated a significant effect on CYP1A2 and glutathione S-transferase-alpha (GST-α), with consumption of Cruciferae increasing the activities of these enzymes by 20-40% and 15-35%, respectively. The results herein suggest that patients undergoing pharmacotherapy with CYP1A2 or GST-α substrates could have altered drug exposure profiles if they regularly eat large or variable amounts of cruciferous vegetables. Recommendations regarding the design of future randomized, controlled trials to test hypotheses in this area are included.

Future prospects for dissecting inter-individual variability in the absorption, distribution and elimination of plant bioactives of relevance for cardiometabolic endpoints

PURPOSE

The health-promoting potential of food-derived plant bioactive compounds is evident but not always consistent across studies. Large inter-individual variability may originate from differences in digestion, absorption, distribution, metabolism and excretion (ADME). ADME can be modulated by age, sex, dietary habits, microbiome composition, genetic variation, drug exposure and many other factors. Within the recent COST Action POSITIVe, large-scale literature surveys were undertaken to identify the reasons and extent of inter-individual variability in ADME of selected plant bioactive compounds of importance to cardiometabolic health. The aim of the present review is to summarize the findings and suggest a framework for future studies designed to investigate the etiology of inter-individual variability in plant bioactive ADME and bioefficacy.

RESULTS

Few studies have reported individual data on the ADME of bioactive compounds and on determinants such as age, diet, lifestyle, health status and medication, thereby limiting a mechanistic understanding of the main drivers of variation in ADME processes observed across individuals. Metabolomics represent crucial techniques to decipher inter-individual variability and to stratify individuals according to metabotypes reflecting the intrinsic capacity to absorb and metabolize bioactive compounds.

CONCLUSION

A methodological framework was developed to decipher how the contribution from genetic variants or microbiome variants to ADME of bioactive compounds can be predicted. Future study design should include (1) a larger number of study participants, (2) individual and full profiling of all possible determinants of internal exposure, (3) the presentation of individual ADME data and (4) incorporation of omics platforms, such as genomics, microbiomics and metabolomics in ADME and efficacy studies.

Dose adjustment of irinotecan based on UGT1A1 polymorphisms in patients with colorectal cancer

PURPOSE

Irinotecan is effective for metastatic colorectal cancer (mCRC). SN-38 is an active metabolite of irinotecan, which is formed by carboxylesterase and inactivated by UDP-glucuronyltransferase (UGT) 1A1. The UGT enzyme activity is reduced in patients with homozygous mutation in UGT1A1 genes (*6/*6, *28/*28 and *6/*28); thus dose reduction is required for prevention of severe adverse events associated with irinotecan. The present study was designed to investigate the relationship between UGT1A1 polymorphisms and the incidence of adverse events or the therapeutic effect in mCRC patients who received irinotecan.

METHODS

Sixty-three mCRC patients who received irinotecan during January 2014 and May 2018 were the subjects of this study. The incidence of adverse events, including diarrhea and neutropenia, and the therapeutic effect of irinotecan were compared among homozygous group, heterozygous group and wild-type group. The initial dose of irinotecan was 150 mg/m² in the heterozygous group and wild-type group, while the dose was reduced by 20% (120 mg/m²) in the homozygous group.

RESULTS

The UGT1A1 polymorphisms occurred in 15.9%, 33.3%, and 50.8% for homozygous group, heterozygous group, and wild-type group, respectively. The average dose of irinotecan during overall cycles was not significantly different among three groups, despite the reduction of initial dose in homozygous group. There were no significant differences in the incidence rates of adverse events, tumor response, or time to treatment failure among three groups.

CONCLUSION

The present study demonstrated that dose reduction by 20% ensured safety and efficacy of irinotecan in mCRC patients with homozygous mutation in UGT1A1 genes.

The role of metabolism (and the microbiome) in defining the clinical efficacy of dietary flavonoids

At a population level, there is growing evidence of the beneficial effects of dietary flavonoids on health. However, there is extensive heterogeneity in the response to increased intake, which is likely mediated via wide interindividual variability in flavonoid absorption and metabolism. Flavonoids are extensively metabolized by phase I and phase II metabolism (which occur predominantly in the gastrointestinal tract and liver) and colonic microbial metabolism. A number of factors, including age, sex, and genotype, may affect these metabolic processes. In addition, food composition and flavonoid source are likely to affect bioavailability, and emerging data suggest a critical role for the microbiome. This review will focus on the current knowledge for the main subclasses of flavonoids, including anthocyanins, flavonols, flavan-3-ols, and flavanones, for which there is growing evidence from prospective studies of beneficial effects on health. The identification of key factors that govern metabolism and an understanding of how the differential capacity to metabolize these bioactive compounds affect health outcomes will help establish how to optimize intakes of flavonoids for health benefits and in specific subgroups. We identify research areas that need to be addressed to further understand important determinants of flavonoid bioavailability and metabolism and to advance the knowledge base that is required to move toward the development of dietary guidelines and recommendations for flavonoids and flavonoid-rich foods.

Modulation of Metabolic Detoxification Pathways Using Foods and Food-Derived Components: A Scientific Review with Clinical Application

Research into human biotransformation and elimination systems continues to evolve. Various clinical and in vivo studies have been undertaken to evaluate the effects of foods and food-derived components on the activity of detoxification pathways, including phase I cytochrome P450 enzymes, phase II conjugation enzymes, Nrf2 signaling, and metallothionein. This review summarizes the research in this area to date, highlighting the potential for foods and nutrients to support and/or modulate detoxification functions. Clinical applications to alter detoxification pathway activity and improve patient outcomes are considered, drawing on the growing understanding of the relationship between detoxification functions and different disease states, genetic polymorphisms, and drug-nutrient interactions. Some caution is recommended, however, due to the limitations of current research as well as indications that many nutrients exert biphasic, dose-dependent effects and that genetic polymorphisms may alter outcomes. A whole-foods approach may, therefore, be prudent.

Effect of apple, baobab, red-chicory, and pear extracts on cellular energy expenditure and morphology of a Caco-2 cells using transepithelial electrical resistance (TEER) and scanning electron microscopy (SEM)

The present study investigated the effects of four food extracts on the Caco-2 intestinal cell line using a new transepithelial electrical resistance method (TEER) concurrent with electron microscopy (SEM).

Cruciferous vegetables have variable effects on biomarkers of systemic inflammation in a randomized controlled trial in healthy young adults

BACKGROUND

Isothiocyanates in cruciferous vegetables modulate signaling pathways critical to carcinogenesis, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a central regulator of inflammation. Glutathione S-transferase (GST) M1 and GSTT1 metabolize isothiocyanates; genetic variants may result in differences in biologic response.

OBJECTIVE

The objective of this study was to test whether consumption of cruciferous or cruciferous plus apiaceous vegetables altered serum concentrations of interleukin (IL)-6, IL-8, C-reactive protein (CRP), tumor necrosis factor (TNF) α, and soluble TNF receptor (sTNFR) I and II, and whether this response was GSTM1/GSTT1 genotype dependent.

METHODS

In a randomized crossover trial, healthy men (n = 32) and women (n = 31) aged 20-40 y consumed 4 14-d controlled diets: basal (vegetable-free), single-dose cruciferous (1xC) [7 g vegetables/kg body weight (BW)], double-dose cruciferous (2xC) (14 g/kg BW), and cruciferous plus apiaceous (carrot family) (1xC+A) vegetables (7 and 4 g/kg BW, respectively), with a 21-d washout period between each intervention. Urinary isothiocyanate excretion was also evaluated as a marker of systemic isothiocyanate exposure. Fasting morning blood and urine samples were collected on days 0 and 14 and analyzed.

RESULTS

IL-6 concentrations were significantly lower on day 14 of the 2xC and 1xC+A diets than with the basal diet [-19% (95% CI: -30%, -0.1%) and -20% (95% CI: -31%, -0.7%), respectively]. IL-8 concentrations were higher after the 1xC+A diet (+16%; 95% CI: 4.2%, 35.2%) than after the basal diet. There were no effects of diet on CRP, TNF-α, or sTNFRI or II. There were significant differences between GSTM1-null/GSTT1+ individuals for several biomarkers in response to 1xC+A compared with basal diets (CRP: -37.8%; 95% CI: -58.0%, -7.4%; IL-6: -48.6%; 95% CI: -49.6%, -12.0%; IL-8: 16.3%; 95% CI: 6.7%, 57.7%) and with the 2xC diet compared with the basal diet (IL-8: -33.2%; 95% CI: -43.0%, -1.4%; sTNFRI: -7.5%; 95% CI: -12.7%, -2.3%). There were no significant reductions in biomarker concentrations in response to diet among GSTM1+/GSTT1+ or GSTM1-null/GSTT1-null individuals. Twenty-four-hour urinary isothiocyanate excretion was not associated with any of the inflammation markers overall; however, IL-6 was inversely associated with total isothiocyanate excretion in GSTM1-null/GSTT1-null individuals (β = -0.12; 95% CI: -0.19, -0.05).

CONCLUSIONS

In this young, healthy population, consumption of cruciferous and apiaceous vegetables reduced circulating IL-6; however, results for other biomarkers of inflammation were not consistent.

Association Between Flavonoid-Rich Fruit and Vegetable Consumption and Total Serum Bilirubin

Emerging work demonstrates that serum bilirubin is a novel biomarker implicated in cardiovascular and metabolic diseases. However, we have a limited understanding of the influence of flavonoid-rich fruit and vegetable consumption on bilirubin levels, which was the purpose of this study. Data from the 2003 to 2006 National Health and Nutrition Examination survey were used (n = 1783; 18-85 years of age), with analyses performed in 2014. Total serum bilirubin was measured from a blood sample. Using a food frequency questionnaire (FFQ), a flavonoid index variable was created summing the frequency of consumption of flavonoid-rich foods. After adjustments, greater consumption of flavonoid-rich fruits and vegetables was positively associated with bilirubin levels. Our findings suggest an association between flavonoid-rich fruit and vegetable consumption and bilirubin levels. If confirmed by prospective and experimental studies, then regular consumption of flavonoid-rich fruits and vegetables should be promoted to increase levels of bilirubin.

Metabolomic profiling of urine: response to a randomised, controlled feeding study of select fruits and vegetables, and application to an observational study

Metabolomic profiles were used to characterise the effects of consuming a high-phytochemical diet compared with a diet devoid of fruits and vegetables (F&V) in a randomised trial and cross-sectional study. In the trial, 8 h fasting urine from healthy men (n 5) and women (n 5) was collected after a 2-week randomised, controlled trial of two diet periods: a diet rich in cruciferous vegetables, citrus and soya (F&V), and a fruit- and vegetable-free (basal) diet. Among the ions found to differentiate the diets, 176 were putatively annotated with compound identifications, with forty-six supported by MS/MS fragment evidence. Metabolites more abundant in the F&V diet included markers of the dietary intervention (e.g. crucifers, citrus and soya), fatty acids and niacin metabolites. Ions more abundant in the basal diet included riboflavin, several acylcarnitines and amino acid metabolites. In the cross-sectional study, we compared the participants based on the tertiles of crucifers, citrus and soya from 3 d food records (n 36) and FFQ (n 57); intake was separately divided into the tertiles of total fruit and vegetable intake for FFQ. As a group, ions individually differential between the experimental diets differentiated the observational study participants. However, only four ions were significant individually, differentiating the third v. first tertile of crucifer, citrus and soya intake based on 3 d food records. One of these ions was putatively annotated: proline betaine, a marker of citrus consumption. There were no ions significantly distinguishing tertiles by FFQ. The metabolomic assessment of controlled dietary interventions provides a more accurate and stronger characterisation of the diet than observational data.

Mechanisms underlying food-drug interactions: inhibition of intestinal metabolism and transport

Food-drug interaction studies are critical to evaluate appropriate dosing, timing, and formulation of new drug candidates. These interactions often reflect prandial-associated changes in the extent and/or rate of systemic drug exposure. Physiologic and physicochemical mechanisms underlying food effects on drug disposition are well-characterized. However, biochemical mechanisms involving drug metabolizing enzymes and transport proteins remain underexplored. Several plant-derived beverages have been shown to modulate enzymes and transporters in the intestine, leading to altered pharmacokinetic (PK) and potentially negative pharmacodynamic (PD) outcomes. Commonly consumed fruit juices, teas, and alcoholic drinks contain phytochemicals that inhibit intestinal cytochrome P450 and phase II conjugation enzymes, as well as uptake and efflux transport proteins. Whereas myriad phytochemicals have been shown to inhibit these processes in vitro, translation to the clinic has been deemed insignificant or undetermined. An overlooked prerequisite for elucidating food effects on drug PK is thorough knowledge of causative bioactive ingredients. Substantial variability in bioactive ingredient composition and activity of a given dietary substance poses a challenge in conducting robust food-drug interaction studies. This confounding factor can be addressed by identifying and characterizing specific components, which could be used as marker compounds to improve clinical trial design and quantitatively predict food effects. Interpretation and integration of data from in vitro, in vivo, and in silico studies require collaborative expertise from multiple disciplines, from botany to clinical pharmacology (i.e., plant to patient). Development of more systematic methods and guidelines is needed to address the general lack of information on examining drug-dietary substance interactions prospectively.

UGT1A6 and UGT2B15 polymorphisms and acetaminophen conjugation in response to a randomized, controlled diet of select fruits and vegetables

Acetaminophen (APAP) glucuronidation is thought to occur mainly by UDP-glucuronosyltransferases (UGT) in the UGT1A family. Interindividual variation in APAP glucuronidation is attributed in part to polymorphisms in UGT1As. However, evidence suggests that UGT2B15 may also be important. We evaluated, in a controlled feeding trial, whether APAP conjugation differed by UGT1A6 and UGT2B15 genotypes and whether supplementation of known dietary inducers of UGT (crucifers, soy, and citrus) modulated APAP glucuronidation compared with a diet devoid of fruits and vegetables (F&V). Healthy adults (n = 66) received 1000 mg of APAP orally on days 7 and 14 of each 2-week feeding period and collected saliva and urine over 12 h. Urinary recovery of the percentage of the APAP dose as free APAP was higher (P = 0.02), and the percentage as APAP glucuronide (APAPG) was lower (P = 0.004) in women. The percentage of APAP was higher among UGT1A6*1/*1 genotypes, relative to *1/*2 and *2/*2 genotypes (P = 0.045). For UGT2B15, the percentage of APAPG decreased (P < 0.0001) and that of APAP sulfate increased (P = 0.002) in an allelic dose-dependent manner across genotypes from *1/*1 to *2/*2. There was a significant diet × UGT2B15 genotype interaction for the APAPG ratio (APAPG/total metabolites × 100) (P = 0.03), with *1/*1 genotypes having an approximately 2-fold higher F&V to basal diet difference in response compared with *1/*2 and *2/*2 genotypes. Salivary APAP maximum concentration (C(max)) was significantly higher in women (P = 0.0003), with F&V (P = 0.003), and among UGT1A6*2/*2 and UGT2B15*1/*2 genotypes (P = 0.02 and 0.002, respectively). APAP half-life was longer in UGT2B15*2/*2 genotypes with F&V (P = 0.009). APAP glucuronidation was significantly influenced by the UGT2B15*2 polymorphism, supporting a role in vivo for UGT2B15 in APAP glucuronidation, whereas the contribution of UGT1A6*2 was modest. Selected F&V known to affect UGT activity led to greater glucuronidation and less sulfation.

Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment

Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.

Bilirubin, cardiovascular diseases and cancer: epidemiological perspectives

Owing to a potent antioxidant property of bilirubin, a growing interest has been drawn to the potential protective effects of bilirubin against oxidative stress-related diseases. This article evaluates associations of bilirubin with atherosclerotic diseases and cancer. Serum bilirubin has consistently been shown to be inversely associated with diverse atherosclerotic diseases, mostly among men in different populations. A limited number of prospective studies have shown a U-shaped or reversed J-shaped relationship between bilirubin and coronary heart disease in men and no evident association in women. Few studies have provided evidence supportive of a protective association between bilirubin and cancer risk. The findings on bilirubin-related genetic polymorphisms are inconsistent in relation to coronary heart disease and cancer.

The clinical application of UGT1A1 pharmacogenetic testing: gene-environment interactions

Over the past decade, the number of pharmacogenetic tests has increased considerably, allowing for the development of our knowledge of their clinical application. The uridine diphosphate glucuronosyltransferase 1A1 gene (UGT1A1) assay is an example of a pharmacogenetic test. Numerous variants have been found in UGT1A1, the main conjugating enzyme of bilirubin and drugs such as the anticancer drug irinotecan. Recently, the US Food and Drug Administration (FDA) recommended testing for the presence of UGT1A1*28, an allele correlated with decreased transcriptional activity, to predict patients at risk of irinotecan toxicity. The administration of other drugs -- such as inhibitors of the UGT1A1 enzyme -- can clinically mimic the *28 phenotype, whereas inducers of UGT1A1 can increase the glucuronidation rate of the enzyme. The *28 polymorphism is not present in all ethnicities at a similar frequency, which suggests that it is important to study different populations to determine the clinical relevance of testing for UGT1A1*28 and to identify other clinically relevant UGT1A1 variants. Environmental factors such as lifestyle can also affect UGT1A1 activity. This review is a critical analysis of studies on drugs that can be affected by the presence of UGT1A1*28, the distribution of this polymorphism around the globe, distinct variants that may be clinically significant in African and Asian populations and how lifestyle can affect treatment outcomes that depend on UGT1A1 activity.

DNA damage and repair: fruit and vegetable effects in a feeding trial

Epidemiologic studies have examined the association between fruit and vegetable (F&V) consumption and the risk of cancer. Several cancer-preventive mechanisms have been proposed, such as antioxidant properties and modulation of biotransformation enzyme activities; both may be associated with reducing DNA damage and hence the mutation rate. We investigated, in a randomized, controlled, crossover feeding trial, the effect of 10 servings/day of botanically defined F&V for 2 wk on endogenous DNA damage; resistance to gamma -irradiation damage; and DNA repair capacity in lymphocytes, measured by the Comet assay. We also explored the association between the UGT1A1*28 polymorphism and serum bilirubin concentrations and DNA damage and repair measures. Healthy men (n = 11) and women (n = 17), age 20 to 40 yr, provided blood samples at the end of each feeding period. Overall, F&V did not affect DNA damage and repair measures in lymphocytes. The number of UGT1A1*28 alleles was inversely associated with sensitivity to gamma -irradiation exposure and DNA repair capacity, but a biological mechanism to explain this association is unclear. A larger sample size is needed to investigate the association between bilirubin concentrations and endogenous DNA damage. With inconsistent findings in the literature, additional dietary intervention studies on the effect of F&V on DNA damage and repair are needed.

Dietary and demographic correlates of serum beta-glucuronidase activity

beta-glucuronidase, an acid hydrolase that deconjugates glucuronides, may increase cancer risk; however, little is known about factors associated with human beta -glucuronidase. Our objective was to examine whether dietary and demographic factors were associated with serum beta -glucuronidase activity. We conducted a cross-sectional study among 279 healthy men and women aged 20 to 40 yr. Diet, categorized by botanical families and nutrient intakes, was assessed from 3-day food records and a validated semiquantitative food frequency questionnaire. Demographic factors were directly measured or self-reported. Adjusted mean beta -glucuronidase activity across categories of exposure variables were calculated by multiple linear regression. Higher beta -glucuronidase activity was significantly associated with being male, older age (> or = 30 yr), non-Caucasian, overweight (> or = 25 kg/m(2)), and higher intakes of gamma-tocopherol. Conversely, lower beta -glucuronidase activity was significantly associated with higher intakes of calcium, iron, and magnesium. A suggestive decrease in beta -glucuronidase activity was observed for the botanical families Cruciferae, Rutaceae, Compositae, Roseaceae, and Umbelliferae, but tests for trend were not statistically significant. In conclusion, several dietary and nondietary factors were associated with beta -glucuronidase activity; however, confirmation of these associations are needed.

Human gut bacterial communities are altered by addition of cruciferous vegetables to a controlled fruit- and vegetable-free diet

In the human gut, commensal bacteria metabolize food components that typically serve as energy sources. These components have the potential to influence gut bacterial community composition. Cruciferous vegetables, such as broccoli and cabbage, contain distinctive compounds that can be utilized by gut bacteria. For example, glucosinolates can be hydrolyzed by certain bacteria, and dietary fibers can be fermented by a range of species. We hypothesized that cruciferous vegetable consumption would alter growth of certain bacteria, thereby altering bacterial community composition. We tested this hypothesis in a randomized, crossover, controlled feeding study. Fecal samples were collected from 17 participants at the end of 2 14-d intake periods: a low-phytochemical, low-fiber basal diet (i.e. refined grains without fruits or vegetables) and a high ("double") cruciferous vegetable diet [basal diet + 14 g cruciferous vegetables/(kg body weightd)]. Fecal bacterial composition was analyzed by the terminal restriction fragment length polymorphism (tRFLP) method using the bacterial 16S ribosomal RNA gene and nucleotide sequencing. Using blocked multi-response permutation procedures analysis, we found that overall bacterial community composition differed between the 2 consumption periods (delta = 0.603; P = 0.011). The bacterial community response to cruciferous vegetables was individual-specific, as revealed by nonmetric multidimensional scaling ordination analysis. Specific tRFLP fragments that characterized each of the diets were identified using indicator species analysis. Putative species corresponding to these fragments were identified through gene sequencing as Eubacterium hallii, Phascolarctobacterium faecium, Burkholderiales spp., Alistipes putredinis, and Eggerthella spp. In conclusion, human gut bacterial community composition was altered by cruciferous vegetable consumption, which could ultimately influence gut metabolism of bioactive food components and host exposure to these compounds.

Cruciferous vegetable feeding alters UGT1A1 activity: diet- and genotype-dependent changes in serum bilirubin in a controlled feeding trial

Chemoprevention by isothiocyanates from cruciferous vegetables occurs partly through up-regulation of phase II conjugating enzymes, such as UDP-glucuronosyltransferases (UGT). UGT1A1 glucuronidates bilirubin, estrogens, and several dietary carcinogens. The UGT1A1*28 polymorphism reduces transcription compared with the wild-type, resulting in decreased enzyme activity. Isothiocyanates are metabolized by glutathione S-transferases (GST); variants may alter isothiocyanate clearance such that response to crucifers may vary by genotype. We evaluated, in a randomized, controlled, crossover feeding trial in humans (n = 70), three test diets (single- and double-"dose" cruciferous and cruciferous plus apiaceous) compared with a fruit and vegetable-free basal diet. We measured serum bilirubin concentrations on days 0, 7, 11, and 14 of each 2-week feeding period to monitor UGT1A1 activity and determined effects of UGT1A1*28 and GSTM1/GSTT1-null variants on response. Aggregate bilirubin response to all vegetable-containing diets was statistically significantly lower compared with the basal diet (P < 0.03 for all). Within each UGT1A1 genotype, lower bilirubin concentrations were seen in *1/*1 in both single- and double-dose cruciferous diets compared with basal (P < 0.03 for both); *1/*28 in double-dose cruciferous and cruciferous plus apiaceous compared with basal, and cruciferous plus apiaceous compared with single-dose cruciferous (P < 0.02 for all); and *28/*28 in all vegetable-containing diets compared with basal (P < 0.02 for all). Evaluation of the effects of diet stratified by GST genotype revealed some statistically significant genotypic differences; however, the magnitude was similar and not statistically significant between genotypes. These results may have implications for altering carcinogen metabolism through dietary intervention, particularly among UGT1A1*28/*28 individuals.

Citrus fruit intake is associated with lower serum bilirubin concentration among women with the UGT1A1*28 polymorphism

UDP-glucuronosyltransferase (UGT) 1A1 glucuronidates bilirubin, estrogens, and xenobiotic compounds. The UGT1A1*28 polymorphism results in lower promoter activity due to 7 thymine-adenine (TA) repeats rather than the more common 6 TA repeats. Previously, we showed that serum bilirubin, a marker of UGT1A1 activity, was lower among individuals homozygous for the UGT1A1*28 polymorphism (7/7) when randomized to a high fruit and vegetable (F&V) diet, whereas there was no effect in individuals with the wild-type (6/6) and heterozygous (6/7) genotypes. Our objective here was to determine if we could detect genotype x diet interactions on bilirubin concentrations in an observational study. Healthy nonsmoking men (n = 146) and women (n = 147), recruited from the Seattle area, provided blood samples for genotyping and bilirubin measurements. We used multiple linear regression to assess the relationships among UGT1A1 genotype, bilirubin concentrations, and consumption of specific F&V [cruciferous vegetables, citrus fruits, and soy foods (n = 268)] based on FFQ and F&V from 6 botanical families [Cruciferae, Rosaceae, Rutaceae, Umbelliferae, Solanaceae, and Leguminosae (n = 261)] based on 3-d food records. We observed a significant interaction of UGT1A1 genotype and citrus consumption among women. Women with the 7/7 genotype who consumed > or = 0.5 daily servings of citrus fruit or foods from the Rutaceae botanical family had approximately 30% lower serum bilirubin than those with the same genotype who consumed less, whereas 6/6 and 6/7 genotypes did not differ by consumption (P for interaction = 0.006 and 0.03, respectively). These results suggest that citrus consumption may increase UGT1A1 activity among women with the 7/7 genotype.

Serum beta-glucuronidase activity in response to fruit and vegetable supplementation: a controlled feeding study

BACKGROUND

Fruit and vegetable (F&V) intake may lower the risk of some cancers. One hypothesized, but understudied, chemopreventive mechanism is that plant food constituents inhibit beta-glucuronidase, an acid hydrolase that deconjugates glucuronides.

METHODS

We conducted a crossover feeding trial in 63 healthy women and men ages 20 to 40 years to examine the effect of diet on serum beta-glucuronidase activity. Participants were randomized to two 2-week experimental diets with an intervening washout period: a diet high in selected citrus fruit, crucifers, and soy (F&V) and a diet devoid of fruits, vegetables, and soy (basal). Serum beta-glucuronidase activity was measured during the preintervention, F&V, and basal periods. Linear mixed models were used to obtain effect estimates and 95% confidence intervals (95% CI).

RESULTS

We observed statistically significantly higher beta-glucuronidase activity during the F&V than the basal diet (ratio, F&V versus basal diet, 1.09; 95% CI, 1.05-1.13; P < 0.01). These results were probably due to decreased beta-glucuronidase activity during the basal diet (ratio, basal period versus preintervention, 0.93; 95% CI, 0.87-0.98; P = 0.01) rather than increased enzyme activity during the F&V diet (ratio, F&V period versus preintervention, 1.01; 95% CI, 0.96-1.06; P = 0.64). Response to the experimental diet did not differ by sex (P(interaction) = 0.30), but there was a suggestion of a short-term diet effect at 8 versus 15 days (P(interaction) = 0.06).

CONCLUSION

This intervention of selected F&V did not lower beta-glucuronidase activity. Further investigation is needed regarding what other foods and phytochemicals may influence beta-glucuronidase activity and effect modifiers of this relation.

Antioxidant status of bilirubin and uric acid in patients diagnosed with Plasmodium falciparum malaria in Douala

Oxidative stress and changes in antioxidant status have been implicated in the pathogenesis of malaria. To assess the antioxidant level ofbilirubin and uric acid associated with falciparum malaria infection, 60 untreated patients (30 men and 30 women) in Douala, Cameroon were screened for the study. Sixty five healthy individuals (29 men and 36 women) were used as controls. Total and conjugated bilirubin were calculated using Jendrassik-Grof method while uric acid was determined using Barham-Trinder method. It was observed that total and conjugated bilirubins were significantly (p < 0.001) higher in malaria patients (10.722 +/- 4.043 and 3.627 +/- 1.571 mg L(-1), respectively) when compared to control (6.830 +/- 2.436 and 1.777 +/- 0.729 mg L(-1)) and these bilirubin levels increased significantly with parasite count (p < 0.050). There was also significant increased (p = 0.021) of uric acid in malaria patients (56.262 +/- 13.963 mg L(-1)) compared to controls (49.838 +/- 15.419 mg L(-1)). No significant differences based on sex were observed on uric acid, parasite count, total and conjugated bilirubins in malaria patients. Positive correlations were obtained between parasite count and total bilirubin (r = 0.320, p < 0.050), conjugated bilirubin (r = 0.477, p < 0.001), uric acid (r = 0.060, p > 0.050) and between total and conjugated bilirubin (r = 0.729, p < 0.001). From this study, it has been hypothesized that the augmentation of plasma level ofbilirubin and uric acid could provide more protection against oxidative stress induced by malaria.

Urinary 3-(3,5-dihydroxyphenyl)-1-propanoic acid, an alkylresorcinol metabolite, is a potential biomarker of whole-grain intake in a U.S. population

5-n-Alkylresorcinols (AR) are a major group of phenolic compounds in whole-grain wheat, rye, and barley. As such, they may serve as potential biomarkers of whole-grain intake, because they are quantifiable intact in plasma and as metabolites in urine. We examined relationships between 12-h urinary excretion of AR metabolite 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA) and self-reported habitual intake of whole-grain foods measured by 3-d food record (3DFR) and FFQ. Urine samples from 100 men and women were analyzed for DHPPA using HPLC with coularray detection. DHPPA excretion ranged from 1.3 to 99.4 (mean +/- SE, 14.0 +/- 1.5) mumol/12 h. Whole-grain food intake, as determined by 3DFR and FFQ and adjusted for BMI and energy and fiber intake, was significantly associated with 12-h urinary DHPPA excretion. Based on 3DFR, whole-grain wheat + rye consumers had a 44% higher DHPPA excretion than nonconsumers [ratio of excretion (95% CI) = 1.44 (1.04, 1.97); P = 0.029]. Using whole-grain intake estimated by FFQ, a serving increase in whole-grain wheat + rye intake increased DHPPA excretion by 94% [ratio of excretion (95% CI) = 1.94 (1.35, 2.78); P = 0.001] and a serving increase in whole grains as defined more broadly in epidemiologic studies of whole-grain intake and disease risk (whole-grain wheat, rye, oats, and corn) increased DHPPA by 67% [ratio of excretion (95% CI) = 1.67 (1.28, 2.17); P < 0.0001]. This study supports the potential utility of urinary DHPPA as a biomarker of whole-grain intake in a U.S. population.