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The mechanisms by which brassica vegetables might decrease the risk of cancer are reviewed in this paper. Brassicas, including all types of cabbages, broccoli, cauliflower and Brussels sprouts, may be protective against cancer due to their relatively high glucosinolate content. Glucosinolates are usually broken down through hydrolysis catalyzed by myrosinase, an enzyme that is released from damaged plant cells. Some of the hydrolysis products, viz. indoles and isothiocyanates, are able to influence phase 1 and phase 2 biotransformation enzyme activities, thereby possibly influencing several processes related to chemical carcinogenesis, e.g, the metabolism, DNA-binding and mutagenic activity of promutagens. A reducing effect on tumor formation has been shown in rats and mice. The anticarcinogenic action of isothiocyanates and indoles depends upon many factors, such as the test system, the target tissue, the type of carcinogen challenge and the anticarcinogenic compound, their dosage, as well as the timing of the treatment. Most evidence concerning anticarcinogenic effects of glucosinolate hydrolysis products and brassica vegetables has come from studies in animals. Animal studies are invaluable in identifying and testing potential anticarcinogens. In addition, studies carried out in humans using high but still realistic human consumption levels of indoles and brassica vegetables have shown putative positive effects on health.

This paper first gives an overview of the epidemiological data concerning the cancer-preventive effect of brassica vegetables, including cabbages, kale, broccoli, Brussels sprouts, and cauliflower. A protective effect of brassicas against cancer may be plausible due to their relatively high content of glucosinolates. Certain hydrolysis products of glucosinolates have shown anticarcinogenic properties. The results of six cohort studies and 74 case-control studies on the association between brassica consumption and cancer risk are summarized. The cohort studies showed inverse associations between the consumption of brassica's and risk of lung cancer, stomach cancer, all cancers taken together. Of the case-control studies 64% showed an inverse association between consumption of one or more brassica vegetables and risk of cancer at various sites. Although the measured effects might have been distorted by various types of bias, it is concluded that a high consumption of brassica vegetables is associated with a decreased risk of cancer. This association appears to be most consistent for lung, stomach, colon and rectal cancer, and least consistent for prostatic, endometrial and ovarian cancer. It is not yet possible to resolve whether associations are to be attributed to brassica vegetables per se or to vegetables in general. Further epidemiological research should separate the anticarcinogenic effect of brassica vegetables from the effect of vegetables in general. The mechanisms by which brassica vegetables might decrease the risk of cancer are reviewed in the second part of this paper. Brassicas, including all types of cabbages, broccoli, cauliflower, and Brussels sprouts, may be protective against cancer due to their glucosinolate content. Glucosinolates are usually broken down through hydrolysis catalysed by myrosinase, an enzyme that is released from damaged plant cells. Some of the hydrolysis products, viz, indoles, and isothiocyanates, are able to influence phase 1 and phase 2 biotransformation enzyme activities, thereby possibly influencing several processes related to chemical carcinogenesis, e.g. the metabolism, DNA-binding, and mutagenic activity of promutagens. Most evidence concerning anticarcinogenic effects of glucosinolate hydrolysis products and brassica vegetables has come from studies in animals. In addition, studies carried out in humans using high but still realistic human consumption levels of indoles and brassica vegetables have shown putative positive effects on health. The combination of epidemiological and experimental data provide suggestive evidence for a cancer preventive effect of a high intake of brassica vegetables. Chemicals/CAS: Anticarcinogenic Agents

The effect of consumption of Brussels sprouts on levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in human urine was investigated in 10 healthy, male, non-smoking volunteers. Following a 3 week run-in period, five volunteers continued on a diet free of cruciferous vegetables for a subsequent 3 week intervention period (control group), while the other five (sprouts group) consumed 300 g of cooked Brussels sprouts per day, at the expense of 300 g of a glucosinolate-free vegetable. Levels of 8-oxodG in 24 h urine samples were measured by HPLC. In the control group there was no difference between the two periods in levels of 8-oxodG (P = 0.72). In contrast, in the sprouts group the levels of 8-oxodG were decreased by 28% during the intervention period (P = 0.039). The present findings support the results of epidemiologic studies that consumption of cruciferous vegetables may result in a decreased cancer risk.

The aim of this study was to determine the bioavailability and kinetics of the supposed anticarcinogen sulforaphane, the hydrolysis product of glucoraphanin, from raw and cooked broccoli. Eight men consumed 200 g of crushed broccoli, raw or cooked, with a warm meal in a randomized, free-living, open cross-over trial. Higher amounts of sulforaphane were found in the blood and urine when broccoli was eaten raw (bioavailability of 37%) versus cooked (3.4%, p = 0.002). Absorption of sulforaphane was delayed when cooked broccoli was consumed (peak plasma time = 6 h) versus raw broccoli (1.6 h, p = 0.001). Excretion half-lives were comparable, 2.6 and 2.4 h on average, for raw and cooked broccoli, respectively (p = 0.5). This study gives complete kinetic data and shows that consumption of raw broccoli results in faster absorption, higher bioavailability, and higher peak plasma amounts of sulforaphane, compared to cooked broccoli. © 2008 American Chemical Society.

Cruciferous vegetables, such as Brassica, which contain substantial quantities of glucosinolates, have been suggested to possess anticarcinogenic activity. Cutting and chewing of cruciferous vegetables releases the thioglucosidase enzyme myrosinase, which degrades glucosinolates to isothiocyanates and other minor metabolites. Cooking of cruciferous vegetables inactivates the myrosinase enzyme, allowing intact glucosinolates to reach the large intestine, where they can be degraded by the indigenous microflora into isothiocyanates. This local release of isothiocyanates may explain the protective effect of cruciferous vegetables on the colon epithelium. However, little is known about the amounts and identities of glucosinolate metabolites produced by the human microflora. The production of allyl isothiocyanate from sinigrin was investigated in a dynamic in vitro large-intestinal model, after inoculation with a complex microflora of human origin. Sinigrin and allyl isothiocyanate concentrations were analysed in the lumen and dialysis fluid of the model. Peak levels of allyl isothiocyanate were observed between 9 and 12 h after the addition of sinigrin. The model was first set up with a pooled and cultured human microflora, in which 1 and 4% of, respectively, 1 and 15 mM sinigrin, was converted into AITC. However, the conversion rate was remarkably higher if different individual human microflora were used. Between 10% and 30% (mean 19%) of the sinigrin was converted into allyl isothiocyanate. The results of this study suggest that allyl isothiocyanate is converted further into other, yet unknown, metabolites. Chemicals/CAS: Anticarcinogenic Agents; Glucosinolates; sinigrin, 534-69-0

A fuzzy model was developed to predict the glucosinolate content of rapeseed meal during solid-state fermentation. Process variables such as temperature, relative humidity, fermentation time and the resulting glucosinolate content of the meal were considered. The glucosinolate content calculated by the fuzzy model corresponded with the experimental results obtained by solid-state fermentation. A fuzzy model was developed to predict the glucosinolate content of rapeseed meal during solid-state fermentation. Process variables such as temperature, relative humidity, fermentation time and the resulting glucosinolate content of the meal were considered. The glucosinolate content calculated by the fuzzy model corresponded with the experimental results obtained by solid-state fermentation.

A high intake of glucosinolate-containing cruciferous vegetables, such as Brussels sprouts (Brassica oleraceae), has been linked to a decreased cancer risk, but the underlying mechanism is still unclear. The aim of this study was to reveal possible modulating effects of consumption of Brussels sprouts on duodenal, rectal and lymphocytic (i) glutathione S-transferase (GST) enzyme activity, (ii) GST isozyme levels and (iii) glutathione (GSH) content. Ten healthy non-smoking volunteers were randomly assigned to two groups in a cross-over design. Five persons started on a glucosinolate-free diet (control period), while the other five consumed 300 g/day cooked Brussels sprouts, at the expense of 300 g glucosinolate-free vegetables (sprouts period). After 7 days the regimen was changed for a further meek. At the end of both periods blood samples and duodenal and rectal biopsies were taken. Mean GST activity showed marked differences between duodenal, rectal and lymphocytic cytosols (737 ± 54, 321 ± 29 and 154 ± 14 nmol/min/mg protein respectively), but was uninfluenced by the dietary regimen. Isozyme distribution varied greatly between the tissues. In duodenum GST-α, -π and -μ isozymes were expressed in considerable amounts (8441 ± 1365, 3002 ± 223 and 536 ± 248 ng/mg protein respectively). Rectal biopsies also contained above three GST classes, but here GST-π was the most pronounced expressed isozyme (2849 ± 246) followed by GST-μ (495 ± 242), while GST-α was only present in minor quantities (149 ± 31). In lymphocytes only GST-π (755 ± 96) and GST-μ (83 ± 54) could be detected. As a result of the dietary regimen rectal GST-α and -π levels were slightly increased at the end of the sprouts period, by 30 and 15% respectively. GSH contents were uninfluenced by the dietary regimen. In conclusion, consumption of glucosinolate-containing Brussels sprouts for 1 week results in increased rectal GST-α and -π isozyme levels. We hypothesize that these enhanced detoxification enzyme levels may partly explain the epidemiological association between a high intake of glucosinolates (cruciferous vegetables) and a decreased risk of colorectal cancer.

An enzyme-linked immunosorbent assay for the detection of mustard protein was developed. The assay is based on a polyclonal antiserum directed against a mixture of mustard proteins raised in rabbits. The assay has a detection limit of 1.5 ppm (milligrams per kilogram) and is suitable for the detection of traces of mustard protein in mustard seed-derived flavoring ingredients. Limited cross-reactivity testing showed that no other plant proteins reacted significantly. From the animal proteins tested, only milk showed some cross-reactivity. With this sensitive assay, it was shown that refined mustard seed oil produced by steam distillation does not contain detectable amounts of mustard protein. Mustard seed oil is used as a flavoring in very low quantities, typically between 40 and 200 mg/kg. Thus, 100 g of a food product flavored with 200 mg of mustard seed oil per kg containing <1.5 mg of protein per kg would represent an amount of mustard seed protein of <30 ng. Taking into account the published literature on allergic reactions to the unintended ingestion of mustard, this conservatively low calculated level indicates that it is unlikely that food products containing mustard seed oil as a flavoring ingredient will elicit an allergic reaction in mustard-allergic individuals. Copyright ©, International Association for Food Protection.

The effects of consumption of glucosinolate-containing Brussels sprouts on plasma and urinary glutathione S-transferase (GST) class-α and -π were investigated. Five male and five female non-smoking volunteers were randomly assigned to two groups in a crossover design. Five persons started on a glucosinolate-free diet (control period), while the other five consumed 300 g of cooked Brussels sprouts per day, at the expense of 300 g of glucosinolate-free vegetables (sprouts period). Dietary regimes were reversed after 1 week, GST levels were measured by enzyme-linked immunoabsorbent assay. At the end of the sprouts period, a significant increase (1.5-fold) in plasma class-α GST levels was observed in males but not in females (control versus sprouts, paired t-test; P-values 0.031 and 0.317 respectively), while plasma GST class-π levels as well as secretion of urinary GST class-α and -π levels remained unchanged. We conclude that (i) increased plasma GST class-α levels in males originate probably solely from the liver and not from stomach, intestine or kidney; (ii) males are more susceptible for induction of hepatic GSTs than females; and (iii) urinary GST concentration seems less useful as a biomarker for hepatic GST induction.

This paper gives an overview of the epidemiological data concerning the cancer-preventive effect of brassica vegetables, including cabbage, kale, broccoli, Brussels sprouts, and cauliflower. The protective effect of brassicas against cancer may be due to their relatively high content of glucosinolates. Certain hydrolysis products of glucosinolates have shown anticarcinogenic properties. The results of 7 cohort studies and 87 case control studies on the association between brassica consumption and cancer risk are summarized. The cohort studies showed inverse associations between the consumption of cabbage, cauliflower, and broccoli and risk of lung cancer; between the consumption of brassicas and risk of stomach cancer; between broccoli consumption and risk of all cancers taken together; and between brassica consumption and the occurrence of second primary cancers. Of the case-control studies, 67% showed an inverse association between consumption of total brassira vegetables and risk of cancer at various sites. For cabbage, broccoli, cauliflower, and Brussels sprouts, these percentages were 70, 56, 67, and 29%, respectively. Although the measured effects might have been distorted by various types of bias, it is concluded that a high consumption of brassica vegetables is associated with a decreased risk of cancer. This association appears to be most consistent for lung, stomach, colon, and rectal cancer and least consistent for prostatic, endometrial, and ovarian cancer. It is not yet possible to resolve whether associations are to be attributed to brassica vegetables per se or to vegetables in general. Further epidemiological research should separate the anticarcinogenic effect of brassica vegetables from the effect of vegetables in general.

Nitrogen (N) balance was determined in 36 pigs (BW 24 to 30 kg) fed diets inducing different ileal endogenous N losses (ENL). We tested the hypothesis that enhanced ENL may be indicative of a higher recycling of endogenous proteins that will induce a greater urinary N loss and a lower efficiency of the dietary N utilization for retention. The corn-starch-based diets contained either soy concentrate (SC), soybean meal (SBM), a mixture of toasted and untoasted soybean meal (mSBM), dehulled-toasted rapeseed cake (RC1), non-dehulled-toasted rapeseed cake (RC2), or dehulled-untoasted rapeseed cake (RC3). The diets were balanced for their content of apparent ileal digestible (ID) CP (108 g/kg feed) and apparent ID of Lys, Thr, Met+Cys, Trp, and Ile. Feeding level was 2.7 times ME for maintenance per kilogram BW·75 and restricted to 88% of the requirements for ID Lys as the first-limiting amino acid. During a 5-d period, urine and feces were collected daily in metabolism cages. Compared with the SC diet (low END, the diets with SBM (medium ENL) and mSBM (high END resulted in a greater (P < .05) urinary N excretion. Nitrogen retention tended to be less (P = .08) in pigs fed diets that caused greater ENL. The utilization of ID N for retention in pigs fed the mSBM diet was lower (P < .05) than for those fed the SC diet. There were no differences in urinary N excretion, N retention, and the utilization of ID N for retention in pigs fed the rapeseed diets of different fiber contents (hulls as the NDF source). We concluded that, at similar intakes of the first-limiting ID amino acid, N retention in pigs fed soybeans tended to be reduced by greater ENL as induced by antinutritional factors (e.g., trypsin inhibitors). Rapeseed hulls, as the predominant fiber source, do not affect N retention and the utilization of ID N for retention.

Objective: The purpose was to study the association between vegetable and fruit consumption and lung cancer incidence using 1074 cases after 6.3 years of follow-up in the Netherlands Cohort Study. Methods: Dietary intake was assessed using a 150-item food-frequency questionnaire. Multivariate models were used including age, sex, family history of lung cancer, highest educational level attained, and smoking history. Results: Statistically significant inverse associations were found with total vegetables and most vegetable groups. Rate ratios (RRs) based on consumption frequency showed the strongest effect of vegetables from the Brassica group (RR 0.5, 95% confidence interval (95% CI) 0.3-0.9, for consumption ≥ 3 times per week versus ≤ once a month). RR of highest versus lowest quintile of total vegetable consumption was 0.7 (95% CI 0.5-1.0, p-trend 0.001). Statistically significant inverse associations were found for all fruits listed in the questionnaire. RRs for quintiles of total fruit intake were 1.0, 0.7, 0.6, 0.6 and 0.8 respectively (p-trend < 0.0001). Protective effects of fruits and vegetables were stronger in current than in former smokers, and weaker for adenocarcinomas than for other types of tumors. Conclusions: Inverse associations with lung cancer are found for both vegetable and fruit intake, but no specific type of vegetable or fruit seems to be particularly responsible.

The relation between vegetable and fruit consumption and colorectal cancer risk was comprehensively assessed in the Netherlands Cohort Study on Diet and Cancer using a validated 150-item food frequency questionnaire. After 6.3 years of follow-up (1986-1992), over 1,000 incident cases of colorectal cancer were registered. Using case-cohort analysis, the authors calculated rate ratios and 95% confidence intervals adjusted for age, alcohol intake, and family history of colorectal cancer. For colon cancer, no statistically significant associations with total vegetable intake or total fruit intake were found. However, among women, an inverse association was observed with vegetables and fruits combined (for the highest quintile vs. the lowest, the rate ratio was 0.66 (95% confidence interval: 0.44, 1.01)). Brassica vegetables and cooked leafy vegetables showed inverse associations for both men and women. Among women and, to a lesser extent, among men, inverse associations were stronger for distal colonic tumors than for proximal colonic tumors. For rectal cancer, no statistically significant associations were found for vegetable consumption or fruit consumption or for specific groups of vegetables and fruits; only Brassica vegetables showed a positive association in women. As in other cohort studies, the observed inverse relation between vegetable and fruit consumption and occurrence of colorectal cancer was less strong than relations reported in case-control studies.

Plant stanol esters are intended for use as an ingredient in food to reduce the absorption of cholesterol from the gastrointestinal tract. Consumption of plant stanol esters has a demonstrated diet-derived public health benefit, as shown by numerous clinical studies. Plant stanol esters are ring-saturated analogs of common dietary sterols that are transesterified with fatty acids from vegetable oils such as canola oil. The reproductive and developmental toxicity of plant stanol esters was investigated in male and female Wistar rats during F0 and F1 generations using dietary concentrations of 1.75, 4.38, and 8.76% stanol esters (equivalent to 1, 2.5, and 5% total stanols). No adverse treatment-related effects were noted on reproductive performance of male or female rats in any dose group. Increased food consumption was observed in high-dose F0 generation males throughout the entire premating period and in F1 males at specific time periods during the premating period. This increase in food consumption was also observed in F0 generation females (mid- and high-dose groups) and F1 generation females (low-, mid-, and high-dose groups) at specific time periods throughout the 10-week premating period. At different intervals throughout the gestation and lactation periods, increased food consumption was observed in F0 generation females of the mid- and high-dose groups, while increased food consumption was noted in F1 generation females of the mid- and high-dose groups during gestation, but not during lactation. Such increases in food consumption are expected as a result of the animals' attempt to compensate for the reduced caloric value of the test diet compared to controls. No adverse developmental effects were noted in F1 or F2 pups of the low- and mid-dose groups based on evaluation of the following parameters: litter size, pup mortality, pups weights, and sex ratio. However, a treatment-related effect on body weight and body weight change was observed in both F1 and F2 male and female pups of the high-dose group, particularly during the latter stages of lactation (postnatal days 14 and 21) in F1 pups, and during the majority of the lactation period (postnatal days 4-21). Lower body weight in the high-dose pups is attributed to a reduction in the caloric value of the test diet compared to control. The pups, unlike adult animals, are particularly sensitive to reductions in caloric value of feed since they are in a rapid growth phase of their development. It is likely that they could not increase their food consumption enough to adequately meet their caloric and nutritional needs. In conclusion, dietary concentrations of up to 4.38% plant stanol esters (equivalent to 2.5% total stanols in the diet) ere not associated with adverse effects on reproduction, pup mortality, pup body weight, or pup body weight change.

A selective, direct and relatively rapid method has been developed for the determination of thiodiglycol (TDG) in aqueous samples. TDG is the main hydrolysis product of the chemical warfare agent sulfur mustard. The method of analysis is based on the on-line coupling of reversed-phase microcolumn liquid chromatography and sulfur-selective flame photometric detection. To improve sensitivity and efficiency, peak compression by displacement was used in combination with large-volume injections. A concentration of 1% n-propanol was added to the sample to obtain the best sensitivity and efficiency after a 10 μl injection. Detection limits of 0.25 μg/ml were achieved with efficiencies of 4.105 plates per meter. The method was successfully applied during the Fourth Official Proficiency Test organized by the Technical Secretariat of the Organization for Prohibition of Chemical Weapons for the determination of TDG in a soil sample. Copyright (C) 1999 Elsevier Science B.V.

A method based on liquid chromatography (LC)-mass spectrometry (MS)/MS was developed for sensitive determination of a number of less gas chromatography (GC)-amenable organophosphorus pesticides (OPs; acephate, methamidophos, monocrotophos, omethoate, oxydemeton-methyl and vamidothion) in cabbage and grapes. For extraction, several solvents were evaluated with respect to the possibility of direct injection, matrix-induced suppression or enhancement of response, and extraction efficiency. Overall, ethyl acetate was the most favourable solvent for extraction, although a solvent switch was required. For some pesticide/matrix combinations, reconstitution of the residue after evaporation required special attention. Extracts were analysed on a C18 column with polar endcapping. The pesticides were ionised using atmospheric pressure chemical ionisation on a tandem mass spectrometer in multiple reaction monitoring mode. The final method is straightforward and involves extraction with ethyl acetate and a solvent switch to 0.1% acetic acid/water without further cleanup. The method was validated at the 0.01 and 0.5mg/kg level, for both cabbage and grapes. Recoveries were between 80 and 101% with R.S.D.<11% (n=5). The limit of quantification was 0.01mg/kg and limits of detection were between 0.001 and 0.004mg/kg. © 2003 Elsevier B.V. All rights reserved.

Prospective epidemiologic data on vegetables and fruits consumption and risk of subtypes of esophageal and gastric cancer are sparse. We studied the association between vegetables and fruits consumption and risk of esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAC), gastric cardia adenocarcinoma (GCA) and gastric noncardia adenocarcinoma (GNCA) in the Netherlands Cohort Study. In 1986, 120,852 Dutch men and women aged 55-69 filled out a questionnaire on diet and other cancer risk factors. After 16.3 years of follow-up, 101 ESCC, 144 EAC, 156 GCA, 460 GNCA cases and 4,035 subcohort members were available for case-cohort analysis using Cox proportional hazards models. Multivariable adjusted incidence rate ratios (RRs) were generally below unity. Total vegetable consumption was nonsignificantly inversely associated with EAC and ESCC risk, but not with GCA and GNCA risk. Significant inverse associations were observed for raw vegetables and EAC risk [RR per 25 g/day: 0.81, 95% confidence interval (CI) 0.68-0.98], and Brassica vegetables and GCA risk (RR per 25 g/day: 0.72, 95% CI 0.54-0.95). Total fruit consumption was associated with a nonsignificantly decreased EAC risk. Citrus fruits were inversely associated with EAC and GCA risk (RRs for highest vs. lowest intake: 0.55, 95% CI 0.31-0.98 and 0.38, 95% CI 0.21-0.69, respectively). Specifically for current smokers, vegetables and possibly also fruits intake was inversely associated with ESCC and EAC risk. Consumption of (specific groups of) vegetables and fruits may protect against subtypes of esophageal and gastric cancer. Copyright © 2011 UICC.

BACKGROUND. To the authors' knowledge, only a few prospective studies to date have investigated the correlation between vegetable and fruit consumption and the risk of ovarian carcinoma and their results have been inconclusive. METHODS. Vegetable and fruit intake was assessed in relation to ovarian carcinoma, among 62,573 postmenopausal women participating in The Netherlands Cohort Study on Diet and Cancer. Women reported on dietary habits and on other risk factors for cancer in a self-administered questionnaire in 1986. Follow-up of cancer was implemented by annual record linkage with The Netherlands Cancer Registry and a pathology register. After 11.3 years of follow-up, data regarding 252 incident invasive epithelial ovarian carcinoma cases and of 2216 subcohort members were available for case-cohort analyses. RESULTS. Multivariable-adjusted rate ratios (RR) of ovarian carcinoma for women in the highest compared with the lowest quintile of intake (RRQ5 vs. Q1) were 0.98 (95% confidence interval [95% CI], 0.61-1.58) for total vegetables and 1.11 (95% CI, 0.70-1.78) for total fruit. The RRQ5 vs. Q1 values of ovarian carcinoma with intake of cooked vegetables, raw vegetables, brassicas, legumes, cooked leafy vegetables, and raw leafy vegetables were 1.35 (95% CI, 0.83-2.21), 0.75 (95% CI, 0.48-1.18), 1.42 (95% CI, 0.88-2.29), 0.93 (95% CI, 0.60-1.44), 1.05 (95% CI, 0.66-1.67), and 1.23 (95% CI, 0.75-2.02), respectively. With the exception of raw endive (multivariable-adjusted RR, 0.24; 95% CI, 0.07-0.78), none of the individual vegetable or fruit items showed a statistically significant association with ovarian carcinoma. CONCLUSIONS. The results of the current study did not support a significant association between vegetable or fruit consumption and ovarian carcinoma risk in a cohort of postmenopausal women. © 2005 American Cancer Society.

In this review many examples are given of the complexities involved in using some biomarkers in relation to assessing the effects of dietary exposure, when there is frequently a need to determine changes following long-term low level exposure to dietary components. These range from understanding why the biomarker might be valuable and how best it can be measured, to the pitfalls which can occur in the interpretation of data. Analytical technique is considered in relation to folate and selenium, and flavonoid and carotenoid species are used to illustrate how the metabolism of a compound may alter the validity or adequacy of a marker. Vitamin A is discussed in relation to the difficulties which can arise when there are several biomarkers that may be available to assess exposure to one nutrient. Vitamin B12 is discussed in relation to the dietary choices made by individuals. Possible interactions and the role of measuring total antioxidant capacity is considered in some detail. In contrast to most nutrients, there is a marked lack of biomarkers of either exposure or effect for most non-nutrients. The role of biological effect monitoring is considered for dietary contaminants, fumonisins and polyhalogenated aromatic hydrocarbons. Aflatoxins are discussed to exemplify food contaminants for which the biomarker approach has been extensively studied. Finally some compounds which are deliberately added to foods and some which appear as processing contaminants are each considered briefly in relation to the requirement for a biomarker of exposure to be developed. Chemicals/CAS: Aflatoxins; Antioxidants; Biological Markers; Carotenoids, 36-88-4; Flavonoids; Folic Acid, 59-30-3; Food Additives; Free Radicals; Polycyclic Hydrocarbons, Aromatic; Selenium Compounds; Selenium, 7782-49-2; Vitamin A, 11103-57-4; Vitamin B 12, 68-19-9

The effect of consumption of glucosinolate-containing Brussels sprouts on flavin-containing monooxygenase functional activity in humans was investigated in 10 healthy, male, non-smoking volunteers. After a 3-week run-in period, 5 volunteers continued on a glucosinolate-free diet for 3 weeks (control group), and 5 others consumed 300 g of cooked Brussels sprouts per day (sprouts group). Human flavin-containing monooxygenase activity was measured by determining the levels of urinary trimethylamine and trimethylamine N-oxide. In the control group similar trimethylamine to trimethylamine N-oxide ratios were observed, while in the sprouts group the trimethylamine to trimethylamine N-oxide ratios were increased 2.6- to 3.2-fold, and thus flavin-containing monooxygenase functional activity was decreased significantly. To investigate the molecular basis for the in vivo inhibition of functional human flavin-containing monooxygenase activity, in vitro studies were carried out examining the effect of acid condensation products of indole-3-carbinol, anticipated to be formed after transit of Brussels sprouts through the gastrointestinal system, on the prominent cDNA-expressed human flavin-containing monooxygenase form 3 enzymes. Two indole-containing materials were observed to be potent inhibitors of human flavin-containing monooxygenases, having K(i) values in the low micromolar range. The results suggested that acid condensation products expected to be formed upon transit of Brussels sprouts materials through the gastrointestinal system were potent competitive inhibitors of human flavin-containing monooxygenase form 3 enzymes. The findings indicate that daily intake of Brussels sprouts may lead to a decrease in human flavin-containing monooxygenase activity, and this may have consequences for metabolism of other xenobiotics or dietary constituents. Copyright (C) 1999 Elsevier Science Inc.