Dietary polyphenol intake in Europe
Daily polyphenol intake across European countries
Diets high in fruits and vegetables are widely recommended for their health-promoting properties. Fruits and vegetables are rich in polyphenols, which have been extensively studied due to their antioxidant, anti-inflammatory and anti-carcinogenic properties. However, epidemiologic evidence for the impact of dietary polyphenols on the risk of chronic diseases is still limited1.
The dietary intake of individual polyphenols
has been estimated in a small number of studies, particularly in Europe2. Phenol-Explorer3, the only food composition database containing food composition data on all known individual polyphenols, and standardized dietary questionnaires allowed to compare intake of all polyphenols across countries in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study, where data on 10 European countries was pooled together. A wide range of total polyphenol intake values and a south-tonorth geographical gradient among EPIC centers is observed, with highest values found in non-Mediterranean countries (1284mg/d) and lowest in Mediterranean countries (1011mg/d). Highest intake is noted in Danish men (1786 mg/d) and the lowest intake in Greek women (584 mg/d)2.
What are the major polyphenol classes consumed?
The main polyphenol contributors are phenolic acids in non-Mediterranean countries (~55%) and flavonoids in Mediterranean countries (~49%). In the UK, flavonoids account for approximately 60% of total polyphenols. The contribution of other polyphenol classes such as stilbenes, lignans, alkylresorcinols or tyrosols is in total less important (<7%)2.
What are the main individual polyphenols consumed?
The Phenol-Explorer database contains food content values for 502 polyphenols, of which 437 are consumed in Europe, including 94 consumed at a level >1mg/d2. The most widely consumed polyphenols are for phenolic acids, the caffeoylquinic and feruloyl quinic acids; and for flavonoids, proanthocyanidins and hesperetin. It is very relevant to study individual polyphenols, since they may have different bioavailability and biological effects.
What about the main food sources of polyphenols?
Polyphenols are exclusively present in plant-based foods. Coffee, tea, and fruits are the most important food sources of polyphenols, although depending on the country their relative contribution can be quite different. Coffee is the main source of polyphenols in both non-Mediterranean and Mediterranean countries (41% and 36%, respectively) and the major source of phenolic acids everywhere (75%).Tea is the most consumed source of polyphenols in the UK (40%), being the main source of flavonoids in the UK (64%) and non-Mediterranean countries (34%), but not in Mediterranean countries (9%). Fruits and fruit juices are the most abundant source of flavonoids (48%) and the second of total polyphenols (26%) in Mediterranean countries. Vegetables are in comparison minor contributors of polyphenol intake (<5%), because concentration of polyphenols is usually lower in vegetables than in fruits and substantial amounts of polyphenols are also lost during cooking (25 to 75%)4. Wine, especially red wine, is also a primary source of polyphenols (10% of total polyphenols, mainly flavonoids) in Mediterranean countries. It is also the main source of resveratrol2.
Determinants of polyphenol intake
The intake of flavonoids is higher in women, older subjects with a BMI<25, non-tobacco consumers with a high educational level and physically active. Therefore, the intake of flavonoids tends to be associated with healthy lifestyle habits. In contrast, intake of phenolic acids is higher in younger men with a BMI≥30, and especially in smokers drinking more coffee2.
Summary and what is next?
There is a large variability in the nature and amount of polyphenols consumed in Europe, with a total intake ranging from 500 to 2000 mg/d and individual preference for coffee, tea and fruits largely explain these variations2. Flavonoids have been the most widely investigated polyphenol class. However more attention should also be paid to phenolic acids which also contribute to a major fraction of polyphenol intake. An accurate and comprehensive estimation of polyphenol intake will be very valuable for future research on the role of polyphenols in the prevention of chronic diseases such as diabetes, cardiovascular diseases and cancer. Further investigation in the validation of polyphenol intake using biomarkers is also needed1.
- Zamora-Ros R, Touillaud M, Rothwell JA, Romieu I, Scalbert A. Measuring exposure to the polyphenol metabolome in observational epidemiologic studies: current tools and applications and their limits. Am J Clin Nutr. 2014;100(1):11-26.
- Zamora-Ros R, Knaze V, Rothwell JA, Hémon B, Moskal A, et al. Dietary polyphenol intake in Europe: the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Eur J Nutr. 2015. Epub ahead of print.
- Neveu V, Perez-Jiménez J, Vos F, Crespy V, du Chaffaut L, et al. Phenol-Explorer: an online comprehensive database on polyphenol contents in foods. Database (Oxford). 2010;2010:bap024.
- Rothwell JA, Medina-Remón A, Pérez-Jiménez J, Neveu V, Knaze V, et al. Effects of food processing on polyphenol contents: a systematic analysis using Phenol-Explorer data. Mol. Nutr. Food Res. 2015, 59(1): 160-170.