Polyphenols: dietary assessment and role in the prevention of cancers.

PURPOSE OF REVIEW: Polyphenols are a large and diverse family of phytochemicals widely consumed by humans. Here we summarize the latest epidemiological evidence for associations between cancer risk and polyphenol intake, taking into account difficulties in the accurate estimation of exposure. RECENT FINDINGS: Flavonoids are the most studied subgroup of polyphenols with regard to cancer risk. In recent epidemiological studies, total flavonoid intake has rarely been associated with a reduction in cancer risk. However, isoflavones, whose main dietary source is soy foods, plausibly reduce the risk of colorectal, breast, and prostate cancers, especially in Asian countries. Findings depend heavily upon the assessment of polyphenol intake, which is usually measured by food frequency questionnaires coupled to databases of food polyphenol composition. To a lesser extent, nutritional biomarkers have been used whenever estimating associations of polyphenol intake with cancer. SUMMARY: Polyphenol intake may mitigate cancer risk but this depends on cancer site, the subgroup of compounds under study, and accurate assessment of dietary exposure. Further work must better characterize the effects of intake of different flavonoid subclasses and begin to investigate the role of phenolic acids and other minor polyphenol classes.

Dietary polyphenol intake in Europe: the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

BACKGROUND/OBJECTIVES: Polyphenols are plant secondary metabolites with a large variability in their chemical structure and dietary occurrence that have been associated with some protective effects against several chronic diseases. To date, limited data exist on intake of polyphenols in populations. The current cross-sectional analysis aimed at estimating dietary intakes of all currently known individual polyphenols and total intake per class and subclass, and to identify their main food sources in the European Prospective Investigation into Cancer and Nutrition cohort. METHODS: Dietary data at baseline were collected using a standardized 24-h dietary recall software administered to 36,037 adult subjects. Dietary data were linked with Phenol-Explorer, a database with data on 502 individual polyphenols in 452 foods and data on polyphenol losses due to cooking and food processing. RESULTS: Mean total polyphenol intake was the highest in Aarhus-Denmark (1786 mg/day in men and 1626 mg/day in women) and the lowest in Greece (744 mg/day in men and 584 mg/day in women). When dividing the subjects into three regions, the highest intake of total polyphenols was observed in the UK health-conscious group, followed by non-Mediterranean (non-MED) and MED countries. The main polyphenol contributors were phenolic acids (52.5-56.9 %), except in men from MED countries and in the UK health-conscious group where they were flavonoids (49.1-61.7 %). Coffee, tea, and fruits were the most important food sources of total polyphenols. A total of 437 different individual polyphenols were consumed, including 94 consumed at a level >1 mg/day. The most abundant ones were the caffeoylquinic acids and the proanthocyanidin oligomers and polymers. CONCLUSION: This study describes the large number of dietary individual polyphenols consumed and the high variability of their intakes between European populations, particularly between MED and non-MED countries.

Usage of plant food supplements across six European countries: findings from the PlantLIBRA consumer survey.

BACKGROUND: The popularity of botanical products is on the rise in Europe, with consumers using them to complement their diets or to maintain health, and products are taken in many different forms (e.g. teas, juices, herbal medicinal products, plant food supplements (PFS)). However there is a scarcity of data on the usage of such products at European level. OBJECTIVE: To provide an overview of the characteristics and usage patterns of PFS consumers in six European countries. DESIGN: Data on PFS usage were collected in a cross-sectional, retrospective survey of PFS consumers using a bespoke frequency of PFS usage questionnaire. SUBJECTS/SETTING: A total sample of 2359 adult PFS consumers from Finland, Germany, Italy, Romania, Spain and the United Kingdom. DATA ANALYSES: Descriptive analyses were conducted, with all data stratified by gender, age, and country. Absolute frequencies, percentages and 95% confidence intervals are reported. RESULTS: Overall, an estimated 18.8% of screened survey respondents used at least one PFS. Characteristics of PFS consumers included being older, well-educated, never having smoked and self-reporting health status as "good or very good". Across countries, 491 different botanicals were identified in the PFS products used, with Ginkgo biloba (Ginkgo), Oenothera biennis (Evening primrose) and Cynara scolymus (Artichoke) being most frequently reported; the most popular dose forms were capsules and pills/tablets. Most consumers used one product and half of all users took single-botanical products. Some results varied across countries. CONCLUSIONS: The PlantLIBRA consumer survey is unique in reporting on usage patterns of PFS consumers in six European countries. The survey highlights the complexity of measuring the intake of such products, particularly at pan-European level. Incorporating measures of the intake of botanicals in national dietary surveys would provide much-needed data for comprehensive risk and benefit assessments at the European level.

Dietary intakes and food sources of phenolic acids in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

Phenolic acids are secondary plant metabolites that may have protective effects against oxidative stress, inflammation and cancer in experimental studies. To date, limited data exist on the quantitative intake of phenolic acids. We estimated the intake of phenolic acids and their food sources and associated lifestyle factors in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Phenolic acid intakes were estimated for 36,037 subjects aged 35-74 years and recruited between 1992 and 2000 in ten European countries using a standardised 24 h recall software (EPIC-Soft), and their food sources were identified. Dietary data were linked to the Phenol-Explorer database, which contains data on forty-five aglycones of phenolic acids in 452 foods. The total phenolic acid intake was highest in Aarhus, Denmark (1265·5 and 980·7 mg/d in men and women, respectively), while the intake was lowest in Greece (213·2 and 158·6 mg/d in men and women, respectively). The hydroxycinnamic acid subclass was the main contributor to the total phenolic acid intake, accounting for 84·6-95·3% of intake depending on the region. Hydroxybenzoic acids accounted for 4·6-14·4%, hydroxyphenylacetic acids 0·1-0·8% and hydroxyphenylpropanoic acids ≤ 0·1% for all regions. An increasing south-north gradient of consumption was also found. Coffee was the main food source of phenolic acids and accounted for 55·3-80·7% of the total phenolic acid intake, followed by fruits, vegetables and nuts. A high heterogeneity in phenolic acid intake was observed across the European countries in the EPIC cohort, which will allow further exploration of the associations with the risk of diseases.

Differences in dietary intakes, food sources and determinants of total flavonoids between Mediterranean and non-Mediterranean countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

A greater adherence to the traditional Mediterranean (MED) diet is associated with a reduced risk of developing chronic diseases. This dietary pattern is based on higher consumption of plant products that are rich in flavonoids. We compared the total flavonoid dietary intakes, their food sources and various lifestyle factors between MED and non-MED countries participating in the EPIC study. Flavonoid intakes and their food sources for 35,628 subjects, aged 35-74 years and recruited between 1992 and 2000, in twenty-six study centres were estimated using standardised 24 h dietary recall software (EPIC-Soft®). An ad hoc food composition database on flavonoids was compiled using analytical data from the United States Department of Agriculture and Phenol-Explorer databases. Moreover, it was expanded to include using recipes, estimations of missing values and flavonoid retention factors. No significant differences in total flavonoid mean intake between non-MED countries (373·7 mg/d) and MED countries (370·2 mg/d) were observed. In the non-MED region, the main contributors were proanthocyanidins (48·2%) and flavan-3-ol monomers (24·9%) and the principal food sources were tea (25·7%) and fruits (32·8%). In the MED region, proanthocyanidins (59·0%) were by far the most abundant contributor and fruits (55·1%), wines (16·7%) and tea (6·8%) were the main food sources. The present study shows similar results for total dietary flavonoid intakes, but significant differences in flavonoid class intakes, food sources and some characteristics between MED and non-MED countries. These differences should be considered in studies about the relationships between flavonoid intake and chronic diseases.

Dietary acrylamide intake of adults in the European Prospective Investigation into Cancer and Nutrition differs greatly according to geographical region.

PURPOSE: Methodological differences in assessing dietary acrylamide (AA) often hamper comparisons of intake across populations. Our aim was to describe the mean dietary AA intake in 27 centers of 10 European countries according to selected lifestyle characteristics and its contributing food sources in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. METHODS: In this cross-sectional analysis, 36 994 men and women, aged 35-74 years completed a single, standardized 24-hour dietary recall using EPIC-Soft. Food consumption data were matched to a harmonized AA database. Intake was computed by gender and center, and across categories of habitual alcohol consumption, smoking status, physical activity, education, and body mass index (BMI). Adjustment was made for participants' age, height, weight, and energy intake using linear regression models. RESULTS: Adjusted mean AA intake across centers ranged from 13 to 47 µg/day in men and from 12 to 39 µg/day in women; intakes were higher in northern European centers. In most centers, intake in women was significantly higher among alcohol drinkers compared with abstainers. There were no associations between AA intake and physical activity, BMI, or education. At least 50 % of AA intake across centers came from two food groups "bread, crisp bread, rusks" and "coffee." The third main contributing food group was "potatoes". CONCLUSIONS: Dietary AA intake differs greatly among European adults residing in different geographical regions. This observed heterogeneity in AA intake deserves consideration in the design and interpretation of population-based studies of dietary AA intake and health outcomes.

Intake estimation of total and individual flavan-3-ols, proanthocyanidins and theaflavins, their food sources and determinants in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

Epidemiological studies suggest health-protective effects of flavan-3-ols and their derived compounds on chronic diseases. The present study aimed to estimate dietary flavan-3-ol, proanthocyanidin (PA) and theaflavin intakes, their food sources and potential determinants in the European Prospective Investigation into Cancer and Nutrition (EPIC) calibration cohort. Dietary data were collected using a standardised 24 h dietary recall software administered to 36 037 subjects aged 35-74 years. Dietary data were linked with a flavanoid food composition database compiled from the latest US Department of Agriculture and Phenol-Explorer databases and expanded to include recipes, estimations and retention factors. Total flavan-3-ol intake was the highest in UK Health-conscious men (453·6 mg/d) and women of UK General population (377·6 mg/d), while the intake was the lowest in Greece (men: 160·5 mg/d; women: 124·8 mg/d). Monomer intake was the highest in UK General population (men: 213·5 mg/d; women: 178·6 mg/d) and the lowest in Greece (men: 26·6 mg/d in men; women: 20·7 mg/d). Theaflavin intake was the highest in UK General population (men: 29·3 mg/d; women: 25·3 mg/d) and close to zero in Greece and Spain. PA intake was the highest in Asturias (men: 455·2 mg/d) and San Sebastian (women: 253 mg/d), while being the lowest in Greece (men: 134·6 mg/d; women: 101·0 mg/d). Except for the UK, non-citrus fruits (apples/pears) were the highest contributors to the total flavan-3-ol intake. Tea was the main contributor of total flavan-3-ols in the UK. Flavan-3-ol, PA and theaflavin intakes were significantly different among all assessed groups. This study showed heterogeneity in flavan-3-ol, PA and theaflavin intake throughout the EPIC countries.