EFSA's OpenFoodTox: An open source toxicological database on chemicals in food and feed and its future developments

Since its creation in 2002, the European Food Safety Authority (EFSA) has produced risk assessments for over 5000 substances in >2000 Scientific Opinions, Statements and Conclusions through the work of its Scientific Panels, Units and Scientific Committee. OpenFoodTox is an open source toxicological database, available both for download and data visualisation which provides data for all substances evaluated by EFSA including substance characterisation, links to EFSA's outputs, applicable legislations regulations, and a summary of hazard identification and hazard characterisation data for human health, animal health and ecological assessments. The database has been structured using OECD harmonised templates for reporting chemical test summaries (OHTs) to facilitate data sharing with stakeholders with an interest in chemical risk assessment, such as sister agencies, international scientific advisory bodies, and others. This manuscript provides a description of OpenFoodTox including data model, content and tools to download and search the database. Examples of applications of OpenFoodTox in chemical risk assessment are discussed including new quantitative structure-activity relationship (QSAR) models, integration into tools (OECD QSAR Toolbox and AMBIT-2.0), assessment of environmental footprints and testing of threshold of toxicological concern (TTC) values for food related compounds. Finally, future developments for OpenFoodTox 2.0 include the integration of new properties, such as physico-chemical properties, exposure data, toxicokinetic information; and the future integration within in silico modelling platforms such as QSAR models and physiologically-based kinetic models. Such structured in vivo, in vitro and in silico hazard data provide different lines of evidence which can be assembled, weighed and integrated using harmonised Weight of Evidence approaches to support the use of New Approach Methodologies (NAMs) in chemical risk assessment and the reduction of animal testing.

Validation of biomarkers of food intake-critical assessment of candidate biomarkers

Biomarkers of food intake (BFIs) are a promising tool for limiting misclassification in nutrition research where more subjective dietary assessment instruments are used. They may also be used to assess compliance to dietary guidelines or to a dietary intervention. Biomarkers therefore hold promise for direct and objective measurement of food intake. However, the number of comprehensively validated biomarkers of food intake is limited to just a few. Many new candidate biomarkers emerge from metabolic profiling studies and from advances in food chemistry. Furthermore, candidate food intake biomarkers may also be identified based on extensive literature reviews such as described in the guidelines for Biomarker of Food Intake Reviews (BFIRev). To systematically and critically assess the validity of candidate biomarkers of food intake, it is necessary to outline and streamline an optimal and reproducible validation process. A consensus-based procedure was used to provide and evaluate a set of the most important criteria for systematic validation of BFIs. As a result, a validation procedure was developed including eight criteria, plausibility, dose-response, time-response, robustness, reliability, stability, analytical performance, and inter-laboratory reproducibility. The validation has a dual purpose: (1) to estimate the current level of validation of candidate biomarkers of food intake based on an objective and systematic approach and (2) to pinpoint which additional studies are needed to provide full validation of each candidate biomarker of food intake. This position paper on biomarker of food intake validation outlines the second step of the BFIRev procedure but may also be used as such for validation of new candidate biomarkers identified, e.g., in food metabolomic studies.

Do we need long-term follow-up after EVAR and TEVAR or can we simplify surveillance protocols?

Endovascular repair is an increasingly preferred treatment modality for aortic pathology. Concerns regarding durability and postimplant complications have let to recommendations for rigorous surveillance regimens which are not entirely data-driven. Besides the costs of an excessive imaging follow-up protocol, deleterious effects may arise from repeated contrast administration and radiation exposure. Due to improvements in selection, planning and execution, coupled with technical improvements in devices, reported complications following endovascular repair have gradually decreased since the pivotal reports. Although late failure may be multifactorial and therefore not totally preventable with any surveillance regimen, patients may be stratified according to the expected risk (balanced by the potential benefit gained with surveillance) and be offered an individualized surveillance program. In this review, we aimed to describe current strategies for surveillance, modern outcomes after abdominal and thoracic endovascular repair, and proposed risk-adapted strategies for postoperative surveillance.

Intervention for type II endoleaks? "Primum non nocere": appraisal for the conservative management of low-pressure endoleaks after endovascular aneurysm repair

Endoleaks are the most common problem following endovascular aneurysm repair. The importance of a type II endoleak has often been subject of discussion in scientific literature. Conflicting data on the natural history of type II endoleak have been published. There is no consensus on the threshold for treatment of type II endoleak and controversy exists about the optimal treatment modality. This paper discusses the evidence behind treating type II endoleak and investigates the need for treatment.

Looking beyond borders: integrating best practices in benefit-risk analysis into the field of food and nutrition

An integrated benefit-risk analysis aims to give guidance in decision situations where benefits do not clearly prevail over risks, and explicit weighing of benefits and risks is thus indicated. The BEPRARIBEAN project aims to advance benefit-risk analysis in the area of food and nutrition by learning from other fields. This paper constitutes the final stage of the project, in which commonalities and differences in benefit-risk analysis are identified between the Food and Nutrition field and other fields, namely Medicines, Food Microbiology, Environmental Health, Economics and Marketing-Finance, and Consumer Perception. From this, ways forward are characterized for benefit-risk analysis in Food and Nutrition. Integrated benefit-risk analysis in Food and Nutrition may advance in the following ways: Increased engagement and communication between assessors, managers, and stakeholders; more pragmatic problem-oriented framing of assessment; accepting some risk; pre- and post-market analysis; explicit communication of the assessment purpose, input and output; more human (dose-response) data and more efficient use of human data; segmenting populations based on physiology; explicit consideration of value judgments in assessment; integration of multiple benefits and risks from multiple domains; explicit recognition of the impact of consumer beliefs, opinions, views, perceptions, and attitudes on behaviour; and segmenting populations based on behaviour; the opportunities proposed here do not provide ultimate solutions; rather, they define a collection of issues to be taken account of in developing methods, tools, practices and policies, as well as refining the regulatory context, for benefit-risk analysis in Food and Nutrition and other fields. Thus, these opportunities will now need to be explored further and incorporated into benefit-risk practice and policy. If accepted, incorporation of these opportunities will also involve a paradigm shift in Food and Nutrition benefit-risk analysis towards conceiving the analysis as a process of creating shared knowledge among all stakeholders.

State of the art in benefit-risk analysis: food and nutrition

Benefit-risk assessment in food and nutrition is relatively new. It weighs the beneficial and adverse effects that a food (component) may have, in order to facilitate more informed management decisions regarding public health issues. It is rooted in the recognition that good food and nutrition can improve health and that some risk may be acceptable if benefit is expected to outweigh it. This paper presents an overview of current concepts and practices in benefit-risk analysis for food and nutrition. It aims to facilitate scientists and policy makers in performing, interpreting and evaluating benefit-risk assessments. Historically, the assessments of risks and benefits have been separate processes. Risk assessment is mainly addressed by toxicology, as demanded by regulation. It traditionally assumes that a maximum safe dose can be determined from experimental studies (usually in animals) and that applying appropriate uncertainty factors then defines the 'safe' intake for human populations. There is a minor role for other research traditions in risk assessment, such as epidemiology, which quantifies associations between determinants and health effects in humans. These effects can be both adverse and beneficial. Benefit assessment is newly developing in regulatory terms, but has been the subject of research for a long time within nutrition and epidemiology. The exact scope is yet to be defined. Reductions in risk can be termed benefits, but also states rising above 'the average health' are explored as benefits. In nutrition, current interest is in 'optimal' intake; from a population perspective, but also from a more individualised perspective. In current approaches to combine benefit and risk assessment, benefit assessment mirrors the traditional risk assessment paradigm of hazard identification, hazard characterization, exposure assessment and risk characterization. Benefit-risk comparison can be qualitative and quantitative. In a quantitative comparison, benefits and risks are expressed in a common currency, for which the input may be deterministic or (increasingly more) probabilistic. A tiered approach is advocated, as this allows for transparency, an early stop in the analysis and interim interaction with the decision-maker. A general problem in the disciplines underlying benefit-risk assessment is that good dose-response data, i.e. at relevant intake levels and suitable for the target population, are scarce. It is concluded that, provided it is clearly explained, benefit-risk assessment is a valuable approach to systematically show current knowledge and its gaps and to transparently provide the best possible science-based answer to complicated questions with a large potential impact on public health.

State of the art in benefit-risk analysis: introduction

Risk-taking is normal in everyday life if there are associated (perceived) benefits. Benefit-Risk Analysis (BRA) compares the risk of a situation to its related benefits and addresses the acceptability of the risk. Over the past years BRA in relation to food and food ingredients has gained attention. Food, and even the same food ingredient, may confer both beneficial and adverse effects. Measures directed at food safety may lead to suboptimal or insufficient levels of ingredients from a benefit perspective. In BRA, benefits and risks of food (ingredients) are assessed in one go and may conditionally be expressed into one currency. This allows the comparison of adverse and beneficial effects to be qualitative and quantitative. A BRA should help policy-makers to make more informed and balanced benefit-risk management decisions. Not allowing food benefits to occur in order to guarantee food safety is a risk management decision much the same as accepting some risk in order to achieve more benefits. BRA in food and nutrition is making progress, but difficulties remain. The field may benefit from looking across its borders to learn from other research areas. The BEPRARIBEAN project (Best Practices for Risk-Benefit Analysis: experience from out of food into food; http://en.opasnet.org/w/Bepraribean) aims to do so, by working together with Medicines, Food Microbiology, Environmental Health, Economics & Marketing-Finance and Consumer Perception. All perspectives are reviewed and subsequently integrated to identify opportunities for further development of BRA for food and food ingredients. Interesting issues that emerge are the varying degrees of risk that are deemed acceptable within the areas and the trend towards more open and participatory BRA processes. A set of 6 'state of the art' papers covering the above areas and a paper integrating the separate (re)views are published in this volume.

State of the art in benefit-risk analysis: food microbiology

Over the past years benefit-risk analysis (BRA) in relation to foods and food ingredients has gained much attention; in Europe and worldwide. BRA relating to food microbiology is however a relatively new field of research. Microbiological risk assessment is well defined but assessment of microbial benefits and the weighing of benefits and risk has not been systematically addressed. In this paper the state of the art in benefit-risk analysis in food microbiology is presented, with a brief overview of microbiological food safety practices. The quality and safety of foods is commonly best preserved by delaying the growth of spoilage bacteria and contamination by bacterial pathogens. However, microorganisms in food can be both harmful and beneficial. Many microorganisms are integral to various food production processes e.g. the production of beer, wine and various dairy products. Moreover, the use of some microorganisms in the production of fermented foods are often claimed to have beneficial effects on food nutrition and consumer health. Furthermore, food safety interventions leading to reduced public exposure to foodborne pathogens can be regarded as benefits. The BRA approach integrates an independent assessment of both risks and benefits and weighs the two using a common currency. Recently, a number of initiatives have been launched in the field of food and nutrition to address the formulation of the benefit-risk assessment approach. BRA has recently been advocated by EFSA for the public health management of food and food ingredients; as beneficial and adverse chemicals can often be found within the same foods and even the same ingredients. These recent developments in the scoping of BRA could be very relevant for food microbiological issues. BRA could become a valuable methodology to support evaluations and decision making regarding microbiological food safety and public health, supplementing other presently available policy making and administrative tools for microbiological food safety management.

[The prevalence of the metabolic syndrome in the Netherlands: increased risk of cardiovascular diseases and diabetes mellitus type 2 in one quarter of persons under 60]

OBJECTIVE

To estimate the prevalence of the metabolic syndrome in the Netherlands in two populations in the age category 28-59 years and to compare this with the prevalence of hypercholesterolaemia in these populations.

DESIGN

Descriptive.

METHOD

Data from two Dutch population based studies were used: the 'Monitoring risicofactoren en gezondheid Nederland' (MORGEN) study ['Monitoring risk factors and health in the Netherlands' study] (1993-1995) and the 'Prevention of renal and vascular end-stage disease' (PREVEND) study (1998-1999). Subjects were identified as having the metabolic syndrome when they had at least three of the following five criteria according to the guideline of the 'National cholesterol education programme', 'Adult treatment panel III' (NCEP-2001): hyperglycaemia, low HDL-cholesterol level, hypertriglyceridaemia, hypertension or abdominal obesity. Final estimates were weighed according to the age- and sex distribution of the Dutch population during these survey years based on figures of the Dutch Central Bureau of Statistics.

RESULTS

On average, the prevalence of the metabolic syndrome was 14%, 19% in men and 12% in women in the MORGEN study, and 16% and 10% in men and women in the PREVEND study. The prevalence in subjects below 40 was 12% for men and 5% for women. The prevalence increased considerably with age. Among subjects with both abdominal obesity and hypertension the prevalence was 68%. Among subjects with 'hypertriglyceridaemic waist' the prevalence was 94%. The prevalence of the metabolic syndrome showed little overlap with the prevalence of hypercholesterolaemia (> or = 6.5 mmol/l). In total, 26% of the subjects had either the metabolic syndrome or high total cholesterol levels.

CONCLUSION

Approximately 1 million Dutch adults below 60 years of age had the metabolic syndrome in the 1990's. Based on the total prevalence of the metabolic syndrome and hypercholesterolaemia, one quarter of the Dutch population younger then 60 runs an increased risk of cardiovascular disease and type 2 diabetes mellitus.

Phytosterol consumption and the anabolic steroid boldenone in humans: A hypothesis piloted

The presence of the anabolic steroid boldenone in animals has become a research topic as its occurrence is proposed to be a marker for illegal hormone administration. However, boldenone can also be formed from beta-sitosterol, a phytosterol present in animal feed, as well as from endogenous sources. The observations in animals together with the increased consumption of phytosterol-enriched foods in the Western population led the authors to the hypothesis that consumption of phytosterol-enriched foods might possibly lead to increased boldenone levels in humans. The authors performed a pilot study among female volunteers (n = 10) to investigate whether boldenone concentrations in urine were detectable after consumption of 25 g day(-1) of phytosterol-enriched margarines for 1 week. Urine samples were collected at days 0, 3 or 4, and 7. Urine of a sitosterolemia (a rare autosomal recessively inherited lipid metabolic disorder) patient was collected as a positive control case. No traces of boldenone were detected in either the volunteers or in the patient. In conclusion, there is no evidence of formation of boldenone in women after consumption of the recommended amount of phytosterol-enriched margarines.

Extra-Anatomical Reconstruction in the Case of an Inaccessible Groin: The Axillopopliteal Bypass

Axillopopliteal bypass is a relatively unknown and uncommon therapeutic option for patients with critical limb ischemia in the presence of an inaccessible groin due to infection or excessive scar formation. In our center, this procedure is performed several times a year. The results of all axillopopliteal bypass reconstructions over an 11-year period were analyzed. Thirty axillopopliteal bypass grafts were performed on 24 patients (16 men, mean age 67 years). In 23 limbs, the indication was persistent groin infection after previous vascular surgery and a threatened limb. In seven limbs, the possibility to anastomose in the groin was absent. There were eight patients (27%) with diabetes mellitus, hypertension was present in 43% (n = 13), and 90% (n = 27) were current or previous smokers. During 5 years of follow-up, 11 patients died, eight during the first year after operation. The primary patency after 1 year was 64% (n = 9). The secondary patency after 1 year was 77%. Seven amputations (23%) were needed: six for ischemia and one for persistent infection. Limb salvage after 1 year was 84%. A limitation of the study is the small number of patients, which was not enough for uni- and multivariate risk analyses with sufficient statistical power. The results of axillopopliteal bypass surgery in patients with critical limb ischemia and an inaccessible groin demonstrate a high mortality rate of 29% after 1 year. However, surviving patients may benefit from the operation in terms of limb salvage because the primary patency was 64% and the secondary patency 77% at 1-year follow-up. We conclude that extra-anatomical axillopopliteal bypass is a valuable therapeutic option for limb salvage in this specific patient population.

Kinetics of biomarkers: biological and technical validity of isoprostanes in plasma

Isoprostanes, non-enzymatic peroxidation products of arachidonic acid, are attractive biomarkers of oxidative stress in research in biology, medicine and nutrition. For the appropriate use of biomarkers it is required that these are both biologically and technically valid. Whereas the biological validity of isoprostanes is well-established, it is technically quite complicated to measure isoprostanes and its metabolites in body fluids, and its rapid disappearance from plasma may hamper practical application. This paper shortly introduces isoprostanes as a biomarker for studies with humans, describes a novel fast and sensitive method for measuring isoprostanes in plasma by high-performance liquid chromatography and tandem mass spectrometry, and provides several examples of the use of the method in studies in humans. By taking care of the biological and technical validity of this biomarker it is possible to establish the antioxidant effects of some food ingredients in studies with human volunteers.

Risk-benefit analysis of micronutrients

Traditionally, different approaches have been used to determine the recommended dietary allowances for micronutrients, above which there is a low risk of deficiency, and safe upper levels, below which there is a negligible risk of toxicity. The advice given to risk managers has been in the form of point estimates, such as the recommended dietary allowance (RDA) and the tolerable upper level (UL). In future, the gap between the two intake-response curves may become narrower, as more sensitive indicators of deficiency and toxicity are used, and as health benefits above the recommended daily allowance are taken into account. This paper reviews the traditional approaches and proposes a novel approach to compare beneficial and adverse effects across intake levels. This model can provide advice for risk managers in a form that will allow the risk of deficiency or the risk of not experiencing the benefit to be weighed against the risk of toxicity. The model extends the approach used to estimate recommended dietary allowances to make it applicable to both beneficial and adverse effects and to extend the intake-incidence data to provide a range of estimates that can be considered by the risk manager. The data-requirements of the model are the incidence of a response at one or more levels of intake, and a suitable coefficient of variation to represent the person-to-person variations within the human population. A coefficient of variation of 10% or 15% has been used for established recommended dietary allowances and a value of 15% is proposed as default for considerations of benefit. A coefficient of variation of 45% is proposed as default for considerations of toxicity, based on analyses of human variability in the fate and effects of therapeutic drugs. Using this approach risk managers, working closely with risk assessors, will be able to define ranges of intake based on a balance between the risks of deficiency (or lack of benefit) and toxicity.

The 10 basic requirements for a scientific paper reporting antioxidant, antimutagenic or anticarcinogenic potential of test substances in in vitro experiments and animal studies in vivo

There is increasing evidence that chemicals/test substances cannot only have adverse effects, but that there are many substances that can (also) have a beneficial effect on health. As this journal regularly publishes papers in this area and has every intention in continuing to do so in the near future, it has become essential that studies reported in this journal reflect an adequate level of scientific scrutiny. Therefore a set of essential characteristics of studies has been defined. These basic requirements are default properties rather than non-negotiables: deviations are possible and useful, provided they can be justified on scientific grounds. The 10 basic requirements for a scientific paper reporting antioxidant, antimutagenic or anticarcinogenic potential of test substances in in vitro experiments and animal studies in vivo concern the following areas: (1) Hypothesis-driven study design; (2) The nature of the test substance; (3) Valid and invalid test systems; (4) The selection of dose levels and gender; (5) Reversal of the effects induced by oxidants, carcinogens and mutagens; (6) Route of administration; (7) Number and validity of test variables; (8) Repeatability and reproducibility; (9) Statistics; and (10) Quality Assurance.

Biomonitoring the intake of garlic via urinary excretion of allyl mercapturic acid

Allium vegetables (onions, leeks, chives) and in particular garlic have been claimed to have health-promoting potential. This study was conducted to get insight into the perspectives for monitoring the intake of garlic by a biomarker approach. Chemically, the biomarker results from exposure to gamma-glutamyl-S-allyl-l-cysteine, which is first hydrolysed by gamma-glutamine-transpeptidase resulting in the formation of S-allyl-l-cysteine. The latter compound is subsequently N-acetylated by N-acetyltransferase into S-allyl-mercapturic acid (ALMA) and excreted into urine. The mercapturic acid was measured in urine using gaschromatography with mass spectrometry. Thus the intake of garlic was determined to check the compliance of garlic intake in a placebo-controlled intervention study. Results indicate that S-allyl-mercapturic acid could be detected in 15 out of 16 urine samples of garlic supplement takers, indicating good compliance. In addition, the intake of garlic was also monitored in a cross-section study of vegans versus controls in Finland, in which no differences in garlic consumption nor in ALMA output were recorded between vegans and controls. These data indicate good possibilities for further studies in the field of biomarkers to investigate the putative chemopreventive effects of garlic and garlic-containing products.

Biomarkers in disease and health

Biomarkers have considerable potential in aiding the understanding of the relationship between diet and disease or health. However, to assess the role, relevance and importance of biomarkers on a case by case basis it is essential to understand and prioritise the principal diet and health issues. In the majority of cases, dietary compounds are only weakly biologically active in the short term, have multiple targets and can be both beneficial and deleterious. This poses particular problems in determining the net effect of types of foods on health. In principle, a biomarker should be able to contribute to this debate by allowing the measurement of exposure and by acting as an indicator either of a deleterious or of an enhanced health effect prior to the final outcome. In this review, the examples chosen - cancer (stomach, colon/rectal, breast); coronary heart disease and osteoporosis - reflect three major diet-related disease issues. In each case the onset of the disease has a genetic determinant which may be exacerbated or delayed by diet. Perhaps the most important factor is that in each case the disease, once manifest, is difficult to influence in a positive way by diet alone. This then suggests that the emphasis for biomarker studies should focus on predictive biomarkers which can be used to help in the development of dietary strategies which will minimise the risk and be of greater benefit.

A critical assessment of some biomarker approaches linked with dietary intake

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.

Antimutagenic activity of green tea and black tea extracts studied in a dynamic in vitro gastrointestinal model

An in vitro gastrointestinal model, which simulates the conditions in the human digestive tract, was used to determine potential antimutagenic activity of extracts of black tea and green tea. In this paper, results are presented on the availability for absorption of potential antimutagenic compounds present in tea and on the influence of the food matrix on this activity. Between 60 and 180min after the tea was introduced into the model, antimutagenic activity was recovered from the jejunal compartment by means of dialysis: the dialysate appeared to inhibit the mutagenicity of the food mutagen MeIQx in the direct plate assay with Salmonella typhimurium (Ames test). The maximum inhibition was measured at 2h after the start of the experiment and was comparable for black tea and green tea extract. To determine the influence of food matrices on the antimutagenic activity of tea, the model was loaded with black tea together with milk or a homogenized standard breakfast. The maximum inhibition observed with black tea was reduced by 22, 42 and 78% in the presence of whole milk, semi-skimmed milk, and skimmed milk, respectively. Whole milk and skimmed milk abolished the antimutagenic activity of green tea by more than 90%; for semi-skimmed milk the inhibition was more than 60%. When a homogenized breakfast was added into the model together with the black tea extract, the antimutagenic activity was completely eliminated. When tea and MeIQx were added together into the digestion model, MeIQx mutagenicity was efficiently inhibited, with green tea showing a slightly stronger antimutagenic activity than black tea. In this case, the addition of milk had only a small inhibiting effect on the antimutagenicity. Antioxidant capacity and the concentration of catechins were also measured in the jejunal dialysates. The reduction in antimutagenic activity corresponded with reduction in antioxidant capacity and with a decrease of concentration of three catechins, viz. catechin, epigallocatechin gallate and epigallocatechin. The in vitro gastrointestinal model appears to be a useful tool to study the antimutagenicity of food components.

Effects of acute (-)-hydroxycitrate supplementation on substrate metabolism at rest and during exercise in humans

BACKGROUND

(-)-Hydroxycitrate (HCA), a competitive inhibitor of ATP-citrate lyase, should reduce the extramitochondrial acetyl-CoA pool. It has been hypothesized that HCA ingestion can reduce malonyl-CoA concentrations and consequently increase fatty acid oxidation in vivo.

OBJECTIVE

This study investigated the acute effects of HCA supplementation on substrate utilization at rest and during exercise in endurance-trained humans.

DESIGN

Ten cyclists [x+/- SD) age: 24 +/- 2 y, weight: 73 +/- 2 kg, maximal oxygen uptake: 4.95 +/- 0.11 L/min, maximal work output (W:max): 408 +/- 8 W] were studied at rest and during 2 h of exercise at 50% W:max on 2 occasions. Both 45 and 15 min before exercise and 30 and 60 min after the start of exercise, 3.1 mL/kg body wt of an HCA solution (19 g/L) or placebo was ingested. Total fat and carbohydrate oxidation rates were assessed. Blood samples were collected at 15-min intervals at rest and every 30 min during exercise.

RESULTS

Plasma HCA concentrations increased after HCA ingestion up to 0.39 +/- 0.02 mmol/L (82.0 +/- 4.8 mg/L). However, no significant differences in total fat and carbohydrate oxidation rates were observed between trials. Accordingly, plasma glucose, glycerol, and fatty acid concentrations did not differ between trials. Plasma lactate concentrations were significantly lower in the HCA than in the placebo trial after 30 min of exercise but at the end of the exercise period they did not differ between trials.

CONCLUSION

HCA, even when provided in large quantities, does not increase total fat oxidation in vivo in endurance-trained humans.

Mediterranean diet of Crete: foods and nutrient content

OBJECTIVES

To describe the traditional diet of Crete and evaluate the nutrient composition of 3 types of diet common in Crete by means of chemical analyses of composite food samples. To compare results with dietary analyses from a nutrient database developed at the University of Crete, Greece.

DESIGN

Three composite diet samples were obtained based on 7-day weighed food records representing the traditional Cretan Mediterranean diet (diet A), typical diet of present-day Greek adolescents (diet B), and fasting diet of the Eastern Orthodox church (diet C). Analyses were performed chemically and using a nutrient database.

RESULTS

Chemical analyses provided a definitive measure, for the first time, of the nutrient composition of the complete Greek diet as it was in the early 1960s. In comparing chemical analyses with nutrient database analyses, differences greater than 15% of the analyzed value were found in all 3 diets for cholesterol and some vitamins. The differences between analyzed and calculated values in total fat and saturated fat content were less than 15% in all diets.

APPLICATIONS/CONCLUSIONS

The present study provides 2 practical examples of the Mediterranean diet, which although widely publicized has rarely been analyzed chemically. Diet A has been shown to be related to the lowest rates for coronary heart disease and cancer mortality compared with the diets of the other populations of the Seven Countries study. As such, it could be recommended for health promotion and prevention of disease. Diet C contains even lower amounts of saturated fatty acids and would be excellent for patients with hypercholesterolemia. The high antioxidants in diet C probably maintain very low levels of low-density lipoprotein cholesterol. Dietary analyses of the Greek diet could be based on an operational database such as ours if further chemical analyses are performed on specific foods. These would result in improved precision of the database and possible extension into national food composition tables and a national dietary database.

Ingestion of protein hydrolysate and amino acid-carbohydrate mixtures increases postexercise plasma insulin responses in men

To optimize the postexercise insulin response and to increase plasma amino acid availability, we studied postexercise insulin levels after the ingestion of carbohydrate and wheat protein hydrolysate with and without free leucine and phenylalanine. After an overnight fast, eight male cyclists visited our laboratory on five occasions, during which a control drink and two different beverage compositions in two different doses were tested. After they performed a glycogen-depletion protocol, subjects received a beverage (3.5 mL. kg(-1)) every 30 min to ensure an intake of 1.2 g. kg(-1). h(-1) carbohydrate and 0, 0.2 or 0.4 g. kg(-1). h(-1) protein hydrolysate (and amino acid) mixture. After the insulin response was expressed as the area under the curve, only the ingestion of the beverages containing wheat protein hydrolysate, leucine and phenylalanine resulted in a marked increase in insulin response (+52 and + 107% for the 0.2 and 0.4 g. kg(-1). h(-1) mixtures, respectively; P: < 0. 05) compared with the carbohydrate-only trial). A dose-related effect existed because doubling the dose (0.2-0.4 g. kg(-1). h(-1)) led to an additional rise in insulin response (P: < 0.05). Plasma leucine, phenylalanine and tyrosine concentrations showed strong correlations with the insulin response (P: < 0.0001). This study provides a practical tool to markedly elevate insulin levels and plasma amino acid availability through dietary manipulation, which may be of great value in clinical nutrition, (recovery) sports drinks and metabolic research.

Application of a dynamic in vitro gastrointestinal tract model to study the availability of food mutagens, using heterocyclic aromatic amines as model compounds

The TNO gastro-Intestinal tract Model (TIM) is a dynamic computer-controlled in vitro system that mimics the human physiological conditions in the stomach and small intestine. In the current TIM physiological parameters such as pH, temperature, peristaltic movements, secretion of digestion enzymes, bile and pancreatic juices, and absorption of digested products-by removal through dialysis-was simulated. Heterocyclic aromatic amines (HAA; viz. IQ, MeIQ, MeIQx and PhIP) were used as model compounds for food mutagens, and the passage through TIM was investigated for each of these compounds separately. Subsequently, the influence of a matrix and different rates of passage on the availability for absorption and distribution were studied in experiments with prepared meat, supplemented with MeIQx. Samples taken at various time points from the jejunal and ileal dialysates and from the lumen at the end of the small intestine (ileal delivery) were tested for the presence of mutagenic activity in the Ames test with Salmonella typhimurium strain TA98 as indicator, in the presence of mammalian metabolic activation (rat S9 mix). The results show that, comparable with the human in vivo situation, all four HAA are quickly removed (approx. 50% in 2 hr; approx. 95% in 6 hr) and mainly recovered from the lumen into the jejunal and ileal dialysates (94% of recovery). Only 5+/-1.5% is recovered in the chyme at the end of the small intestine. When MeIQx was added to meat, its availability for absorption was slower, although the influence of the gastrointestinal passage time on the availability of MeIQx was more pronounced than this matrix effect. More MeIQx was found in the jejunal dialysate (23%; P<0.01) and less in the ileal delivery (8%; P<0.01) when simulating the gastrointestinal passage of solid meals was compared to simulating that of liquid meals. The present experiments demonstrate that TIM can be applied to study in vitro the availability of heterocyclic aromatic amines in the gastrointestinal tract. More generally, these studies indicate that TIM shows promise as a useful tool for various research purposes dealing with the availability for absorption of mutagenic as well as antimutagenic components in food.

Intake of butylated hydroxyanisole and butylated hydroxytoluene and stomach cancer risk: results from analyses in the Netherlands Cohort Study

Both carcinogenic and anticarcinogenic properties have been reported for the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The association between dietary intake of BHA and BHT and stomach cancer risk was investigated in the Netherlands Cohort Study (NLCS) that started in 1986 among 120,852 men and women aged 55 to 69 years. A semi-quantitative food frequency questionnaire was used to assess food consumption. Information on BHA or BHT content of cooking fats, oils, mayonnaise and other creamy salad dressings and dried soups was obtained by chemical analysis, a Dutch database of food additives (ALBA) and the Dutch Compendium of Foods and Diet Products. After 6.3 years of follow-up, complete data on BHA and BHT intake of 192 incident stomach cancer cases and 2035 subcohort members were available for case-cohort analysis. Mean intake of BHA or BHT among subcohort members was 105 and 351 microg/day, respectively. For consumption of mayonnaise and other creamy salad dressings with BHA or BHT no association with stomach cancer risk was observed. A statistically non-significant decrease in stomach cancer risk was observed with increasing BHA and BHT intake [rate ratio (RR) highest/lowest intake of BHA = 0.57 (95% confidence interval (CI): 0.25-1.30] and BHT = 0.74 (95% CI: 0.38-1.43). In this study, no significant association with stomach cancer risk was found for usual intake of low levels of BHA and BHT.

Plasma insulin responses after ingestion of different amino acid or protein mixtures with carbohydrate

BACKGROUND

Protein induces an increase in insulin concentrations when ingested in combination with carbohydrate. Increases in plasma insulin concentrations have been observed after the infusion of free amino acids. However, the insulinotropic properties of different amino acids or protein (hydrolysates) when co-ingested with carbohydrate have not been investigated.

OBJECTIVE

The aim of this study was to define an amino acid and protein (hydrolysate) mixture with a maximal insulinotropic effect when co-ingested with carbohydrate.

DESIGN

Eight healthy, nonobese male subjects visited our laboratory, after an overnight fast, on 10 occasions on which different beverage compositions were tested for 2 h. During those trials the subjects ingested 0.8 g*kg(-)(1)*h(-)(1) carbohydrate and 0.4 g*kg(-)(1)*h(-)(1) of an amino acid and protein (hydrolysate) mixture.

RESULTS

A strong initial increase in plasma glucose and insulin concentrations was observed in all trials, after which large differences in insulin response between drinks became apparent. After we expressed the insulin response as area under the curve during the second hour, ingestion of the drinks containing free leucine, phenylalanine, and arginine and the drinks with free leucine, phenylalanine, and wheat protein hydrolysate were followed by the largest insulin response (101% and 103% greater, respectively, than with the carbohydrate-only drink; P < 0.05).

CONCLUSIONS

Insulin responses are positively correlated with plasma leucine, phenylalanine, and tyrosine concentrations. A mixture of wheat protein hydrolysate, free leucine, phenylalanine, and carbohydrate can be applied as a nutritional supplement to strongly elevate insulin concentrations.

Fruits and vegetables increase plasma carotenoids and vitamins and decrease homocysteine in humans

Observational epidemiologic studies have shown that a high consumption of fruits and vegetables is associated with a decreased risk of chronic diseases. Little is known about the bioavailability of constituents from vegetables and fruits and the effect of these constituents on markers for disease risk. Currently, the recommendation is to increase intake of a mix of fruits and vegetables ("five a day"). We investigated the effect of this recommendation on plasma carotenoids, vitamins and homocysteine concentrations in a 4-wk dietary controlled, parallel intervention study. Male and female volunteers (n = 47) were allocated randomly to either a daily 500-g fruit and vegetable ("high") diet or a 100-g fruit and vegetable ("low") diet. Analyzed total carotenoid, vitamin C and folate concentrations of the daily high diet were 13.3 mg, 173 mg and 228.1 microg, respectively. The daily low diet contained 2.9 mg carotenoids, 65 mg vitamin C and 131.1 microg folate. Differences in final plasma levels between the high and low group were as follows: lutein, 46% [95% confidence interval (CI) 28-64]; beta-cryptoxanthin, 128% (98-159); lycopene, 22% (8-37); alpha-carotene, 121% (94-149); beta-carotene, 45% (28-62); and vitamin C, 64% (51-77) (P < 0.05). The high group had an 11% (-18 to -4) lower final plasma homocysteine and a 15% (0.8-30) higher plasma folate concentration compared with the low group (P < 0.05). This is the first trial to show that a mix of fruits and vegetables, with a moderate folate content, decreases plasma homocysteine concentrations in humans.

Brassica vegetables and cancer prevention. Epidemiology and mechanisms

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.

In vitro and in vivo inhibition of human flavin-containing monooxygenase form 3 (FMO3) in the presence of dietary indoles

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 Ki 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.

The role of biotransformation in dietary (anti)carcinogenesis

The fact that dietary compounds influence the susceptibility of human beings to cancer, is widely accepted. One of the possible mechanisms that is responsible for these (anti)carcinogenic effects is that dietary constituents may modulate biotransformation enzymes, thereby affecting the (anti)carcinogenic potential of other compounds. This ambiguous theme is the basis for the present paper. The possible effects of enzymatic bioactivation and detoxification of dietary constituents are discussed using two representative examples of phase I and phase II biotransformation enzymes i.e., cytochrome P450 and glutathione S-transferase. Furthermore, the impact of genetic polymorphisms of these two enzyme systems is considered. Although it is very difficult on the basis of the enzyme inducing or inhibiting properties of dietary compounds, especially to characterize them as anticarcinogenic, for certain constituents it is acknowledged that they have anticarcinogenic properties. As such, this provides for an important mechanistic substantiation of the established cancer chemopreventive effect of a diet rich in fruits and vegetables.

Salinomycin-induced polyneuropathy in cats: morphologic and epidemiologic data

In April 1996, an outbreak of toxic polyneuropathy in cats occurred in the Netherlands. All cats had been fed one of two brands of dry cat food from one manufacturer. Chemical analyses of these foods, stomach contents, and liver and kidney of affected cats revealed contamination with the ionophor salinomycin. Epidemiologic and clinical data were collected from 823 cats, or about 1% of the cats at risk. In 21 affected cats, postmortem examination was performed. The affected cats had acute onset of lameness and paralysis of the hindlimbs followed by the forelimbs. Clinical and pathologic examination indicated a distal polyneuropathy involving both the sensory and motor nerves.

Effect of Brussels sprouts on oxidative DNA-damage in man

The effect of consumption of Brussels sprouts on the excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) into human urine was investigated. Ten non-smoking volunteers (five males and five females) were randomly assigned to two groups. Five volunteers started on a diet of 300 g of glucosinolate-free vegetables whereas the other five consumed 300 g of Brussels sprouts per day. After 1 week dietary regimes were reversed. Levels of 8-oxodG in 24-h urine samples were measured by high-performance liquid chromatography. In four of five males a reduction in 8-oxodG was found, whereas in the fifth male the 8-oxodG excretion was high in the control period and was even much higher in the sprouts period. In females no effect of consumption of Brussels sprouts on excretion of 8-oxodG was found. Our previous and present findings support the results of epidemiologic studies that consumption of brassica vegetables may diminish cancer risk.

Safety evaluation of lipase derived from Rhizopus oryzae: summary of toxicological data

A lipase enzyme, obtained from Rhizopus oryzae produced by a fermentation process was subjected to a series of toxicological tests to document the safety for use as a food additive. The enzyme product was examined for acute, subacute and subchronic oral toxicity, and mutagenic potential. An extensive literature search on the production organism has also been conducted. No evidence of (sub)acute oral toxicity or mutagenic potential was found. Administration of the lipase at dosages of 50, 200 and 1000 mg/kg body weight/day for 90 days did not induce noticeable signs of toxicity. A few minor changes in the chemical composition of the blood in the highest dose group were of no toxicological significance. The no-observed-adverse-effect level of the tox-batch in the subchronic toxicity study was 1000 mg/kg body weight/day. It can be concluded that no safety concerns were identified in the studies conducted with this lipase preparation derived from R. oryzae and produced under controlled fermentation conditions.

A review of mechanisms underlying anticarcinogenicity by brassica vegetables

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.

Do dietary phytochemicals with cytochrome P-450 enzyme-inducing activity increase high-density-lipoprotein concentrations in humans?

Low plasma concentrations of high-density lipoprotein (HDL) are associated with increased risk of coronary heart disease. Several drugs that induce the microsomal cytochrome P-450-dependent enzyme system in liver and intestine, the sites of HDL apolipoprotein (apo) A-I and A-II synthesis, raise plasma HDL concentrations in humans. To test the hypothesis that phytochemicals with cytochrome P-450-inducing activity may also increase plasma HDL concentrations, two controlled dietary trials were undertaken in healthy nonsmoking males aged 20-28 y. One study examined the effect of replacing 300 g glucosinolate-free vegetables with 300 g Brussels sprouts/d for 3 wk. The other study examined the effects of 150 mg eugenol/d in capsule form, using a double-blind, placebo-controlled crossover design. There were no significant increases in plasma apo A-I, apo A-II, HDL cholesterol, or HDL phospholipids. These results suggest that dietary phytochemicals that induce members of the cytochrome P-450 system do not necessarily raise plasma HDL concentrations in humans, but do not exclude the possibility that some phytochemicals may have such an effect.

Effect of a vegan diet on biomarkers of chemoprevention in females

1. In order to study the potential beneficial effects of a vegan diet, a cross-sectional study was performed and several biomarkers of chemoprevention were measured in a population of female 'living food' eaters ('vegans'; n = 20) vs matched omnivorous controls (n = 20). 2. White blood cells obtained from fresh blood samples were subjected to the single-cell gel-electrophoresis assay. There was no statistically significant difference between the vegans and controls in the parameters 'tail length' and 'tail moment'. However, the 'tail moment' was significantly lower in a subset of the vegans (i.e.in those who did not use any vitamin and/or mineral supplements). 3. Fresh blood samples were exposed in vitro to the mutagen mitomycin C just prior to culturing. After culturing the number of binucleated lymphocytes with micronuclei was scored. There was no difference between the controls and vegans in the incidence of baseline micronuclei, nor in the number of mitomycin C-induced micronuclei. However, a significant correlation (r = -0.64, P < 0.01) between the number of mitomycin C-induced micronuclei and the activity of erythrocyte superoxide dismutase was found in the vegans. The number of baseline micronuclei increased with age in both groups. These findings may be of biological relevance. 4. The content of glutathione-S-transferase-alpha in plasma was not different between the vegans (n = 12) and controls (n = 12). 5. The present data indicate a few differences in biomarkers of chemopreventive potential in strict vegans vs matched omnivorous controls. The significance of these changes as biologically relevant indicators of beneficial effects of vegan diets in humans needs to be determined in studies with a larger number of subjects.

Epidemiological studies on brassica vegetables and cancer risk

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 brassica 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.

Effect of eugenol on the mutagenicity of benzo[a]pyrene and the formation of benzo[a]pyrene-DNA adducts in the lambda-lacZ-transgenic mouse

To study the possible reduction by eugenol of the mutagenicity and genotoxicity of benzo[a]pyrene (B[a]P) in vivo, the lambda-lacZ-transgenic mouse strain 40.6 (Muta Mouse) was used. Male mice were fed a diet containing 0.4% (w/w) eugenol or a control diet for 58 days. On day 10, half of the mice received an i.p. dose of 100 mg/kg b.w. B[a]P. The lacZ mutants were recovered by packaging of DNA isolated from liver into lambda phage, and expressed in E. coli C lacZ-recA-galE- bacteria. In both control mice and mice fed the eugenol diet, B[a]P treatment resulted in a similar, significant increase in lacZ mutant frequency. Eugenol was not mutagenic by itself. By 32P-postlabelling analysis of the liver DNA using an analysis method with chromatographic conditions for B[a]P-DNA adducts, no effect of eugenol on the formation of B[a]P-DNA adducts in the lambda-lacZ-transgenic mouse was found. By 32P-postlabelling analysis using an alkenylbenzene solvent system the amount of B[a]P-DNA adducts was lower in mice fed the eugenol diet than in mice fed the control diet but the decrease was not statistically significant. However, one spot indicative of an eugenol-associated DNA adduct was detected. The present data provide no evidence for antimutagenic or antigenotoxic potential of eugenol in vivo. Furthermore, they suggest genotoxicity in vivo of eugenol per se.

Effect of short-term dietary administration of eugenol in humans

1. In order to study the antigenotoxic potential of eugenol in humans, ten healthy non-smoking males ingested a daily amount of 150 mg eugenol or the placebo for seven consecutive days. After a washout period of one week, groups ingesting eugenol or the placebo were crossed and received the other treatment for seven consecutive days. 2. On days 8 and 22 blood samples were taken for the assessment of standard clinical biochemical parameters. To study the possible antigenotoxic effect of eugenol, on day 8 and 22 blood samples were collected and exposed in vitro to the established genotoxic agents mitomycin C and vinblastine. After exposure the percentage of cells with chromosome aberrations and micronuclei was determined in cultured white blood cells. On days 8 and 22 paracetamol (500 mg p.o.) was administered as test substance to measure phase-II biotransformation capacity. Glutathione-S-transferase (GST) activities were determined in erythrocytes and blood plasma. 3. No significant differences in the clinical biochemical parameters were detected between the eugenol-period and the placebo-period, indicating that daily administration of 150 mg eugenol for 7 days has no toxic affects. 4. No significant differences on the cytogenetic parameters were found after ingestion of eugenol. Thus, there are no indications for an antigenotoxic potential of eugenol in humans, consuming daily 150 mg eugenol for 7 days. 5. A significant reduction in alpha-class GSTs in plasma (P < 0.05), but not in the other measured biotransformation parameters, was found in volunteers during the eugenol-periods as compared to the placebo-period. This may either reflect GST-inhibition by eugenol or protection against background damage of liver cells by eugenol.

Inhibition of rat, mouse, and human glutathione S-transferase by eugenol and its oxidation products

The irreversible and reversible inhibition of glutathione S-transferases (GSTs) by eugenol was studied in rat, mouse and man. Using liver cytosol of human, rat and mouse, species differences were found in the rate of irreversible inhibition of GSTs by eugenol in the presence of the enzyme tyrosinase. Tyrosinase was used to oxidize eugenol. No inhibition was observed in the absence of tyrosinase. The rate of irreversible inhibition of GSTs was highest in mouse cytosol, and lowest in rat cytosol. In addition, the irreversible inhibition of human and rat GSTs by eugenol was studied using purified isoenzymes of man and rat. The human GST isoenzymes A1-1, M1a-1a and P1-1 and the rat GST isoenzymes 1-1, 2-2, 3-3, 4-4 and 7-7 were irreversibly inhibited by eugenol in the presence of tyrosinase. In this respect human GST P1-1 and rat GST 7-7 were by far the most sensitive enzymes; human GST A2-2 was not inhibited. Indications were found that human GST P1-1 may be inhibited via three mechanisms: in addition to the well documentated nucleophilic addition of quinones and oxidation of cysteine residues, a covalent subunit cross-linking was also observed. The reversible inhibition of human and rat GST by eugenol, eugenol methyl ether, isoeugenol methyl ether, 2-allylphenol and 4-propylphenol was also studied using purified isoenzymes. The reversible inhibition of human and rat GSTs, using 1-chloro-2,4-dinitrobenzene as substrate, was expressed as I25. All compounds caused moderate reversible inhibition (I25 ranged from 0.2 to 5.4 mM for human GSTs and from 0.4 to 4.9 mM for rat GSTs). In rat, eugenol methyl ether was the strongest inhibitor. In human, the overall inhibiting capacities of eugenol, eugenol methyl ether, isoeugenol methyl ether and 4-propyl phenol were more or less similar; 2-allylphenol was the poorest inhibitor.

Effect of eugenol on the genotoxicity of established mutagens in the liver

The influence of in vivo treatment with eugenol on established mutagens was studied to determine whether eugenol has antigenotoxic potential. The effects of eugenol in rats was investigated in the unscheduled DNA synthesis (UDS) assay with established mutagens and the Salmonella typhimurium mutagenicity assay. In addition, the effect of in vivo treatment with eugenol on benzo[a]pyrene (B[a]P)-induced genotoxicity in human hepatoma cell line Hep G2 was investigated in the single-cell gel electrophoresis assay. The mutagenicity of B[a]P in the S. typhimurium mutagenicity assay was lower in liver S-9 fractions from control rats. Incubation of liver S-9 fractions from eugenol-treated rats with dimethylbenzanthracene (DMBA) had no antimutagenic effect. Eugenol did not modify UDS activity in hepatocytes isolated from rats pretreated with eugenol orally after exposure of these cells in vitro to DMBA and aflatoxin B1. Four different treatment schemes of combinations of B[a]P and eugenol were examined in Hep G2 cells: pre-treatment with eugenol; simultaneous treatment with eugenol and B[a]P; a combination of these (pretreatment/simultaneous treatment); and post-treatment with eugenol. An increase in the genotoxicity of B[a]P was found in Hep G2 cells. No effect of eugenol on the genotoxicity of B[a]P was found with the pre- and post-treatments. It is concluded that the effect of eugenol on genotoxicity induced by established mutagens is not univocal; in vivo treatment of rats with eugenol resulted in a reduction of the mutagenicity of B[a]P in the S. typhimurium mutagenicity assay, while in the UDS assay no effect of eugenol was found. In vitro treatment of cultured cells with eugenol resulted in an increase in genotoxicity of B[a]P. These findings indicate that there is only limited support for the antigenotoxic potential of eugenol in vivo.

Antioxidant status in long-term adherents to a strict uncooked vegan diet

Antioxidant status was investigated in 20 Finnish middle-aged female vegans and in one male vegan who were following a strict, uncooked vegan diet ("living food diet"), by means of a dietary survey and biochemical measurements (blood concentrations of vitamins C and E and beta-carotene, and the activities of the zinc/copper-dependent superoxide dismutase and selenium-dependent glutathione peroxidase). Values were compared with those of omnivores matched for sex, age, social status, and residence. Antioxidant supplementation was used by 4 of 20 female vegans and by 11 of 20 control subjects. Based on dietary records, the vegans had significantly higher intakes of beta-carotene, vitamin E, vitamin C, and copper, and a significantly lower intake of selenium than the omnivorous control subjects. The calculated dietary antioxidant intakes by the vegans, expressed as percentages of the US recommended dietary allowances, were as follows: 305% of vitamin C, 247% of vitamin A, 313% of vitamin E, 92% of zinc, 120% of copper, and 49% of selenium. Compared with the omnivores, the vegans had significantly higher blood concentrations of beta-carotene, vitamin C, and vitamin E, as well as higher erythrocyte superoxide dismutase activity. These differences were also seen in pairs who were using no antioxidant supplements. The present data indicate that the "living food diet" provides significantly more dietary antioxidants than does the cooked, omnivorous diet, and that the long-term adherents to this diet have a better antioxidant status than do omnivorous control subjects.

Short-term moderate energy restriction does not affect indicators of oxidative stress and genotoxicity in humans

Restriction of energy intake (ER), without malnutrition of essential nutrients, has repeatedly been demonstrated to increase longevity in rodents. In the antioxidant theory of aging the lack of balance between the generation of free radicals and free radical scavenging was thought to be a main causal agent, in the aging process. From this point of view the antiaging effect induced by ER might be due to the lower rate of free-radical production and related damage induced by a lower metabolic rate. The antiaging effects of ER might also occur in humans. This study explored the effects of a 10-week moderately energy-restricted diet (80% of habitual) in 24 non-obese middle-aged men (16 ER subjects, 8 controls) on resting metabolic rate (RMR) and indicators of the primary antioxidant defense system, oxidative stress and genotoxicity. RMR decreased significantly in both groups, even when adjustments were made for the change in body composition. The increase in blood vitamin C concentration correlated with the increase in urinary 8-hydroxydeoxyguanosine (80HdG) excretion. The change in urinary 80HdG excretion also correlated with the change in RMR per kg fat-free mass. No differences between groups were found for changes in indicators of genotoxicity, erythrocyte catalase, glutathione peroxidase and superoxide dismutase activity and in plasma vitamin E, A or beta-carotene concentrations. We conclude that 10 weeks of moderate ER did not affect indicators of antioxidative capacity, oxidative stress and genotoxicity of humans. Since subjects were not in energy balance at the end of the study, no conclusions can be made with respect to long-term effects.