Polyphenols excreted in urine as biomarkers of total polyphenol intake

Nutrition & Food Science Department, XaRTA, Instituto de Investigaciónen Nutrición y Seguridad Alimentaria, Pharmacy School, University of Barcelona, Barcelona, Spain.
Bioanalysis (Impact Factor: 3). 11/2012; 4(22):2705-13. DOI: 10.4155/bio.12.249
Source: PubMed


Nutritional biomarkers have several advantages in acquiring data for epidemiological and clinical studies over traditional dietary assessment tools, such as food frequency questionnaires. While food frequency questionnaires constitute a subjective methodology, biomarkers can provide a less biased and more accurate measure of specific nutritional intake. A precise estimation of polyphenol consumption requires blood or urine sample biomarkers, although their association is usually highly complex.

This article reviews recent research on urinary polyphenols as potential biomarkers of polyphenol intake, focusing on clinical and epidemiological studies. We also report a potentially useful methodology to assess total polyphenols in urine samples, which allows a rapid, simultaneous determination of total phenols in a large number of samples.

This methodology can be applied in studies evaluating the utility of urinary polyphenols as markers of polyphenol intake, bioavailability and accumulation in the body.

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Available from: Alexander Medina-Remón
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    • "Thus, it can be concluded from the urine excretion results that, among the three groups, the bioavailability of HT was more effective after the diet supplementation with OLE. In fact, it has been established that 24 h-urine offers advantages over plasma measurements, mostly because they allow an accurate evaluation of the total polyphenols absorbed due to the very short plasma half-lives of the polyphenols (Medina-Remón, Tresserra-Rimbau, Arranz, Estruch, & Lamuela-Raventos, 2012 ). Regarding the colonic phenolic metabolites detected in the intestinal contents and faeces, a very low concentration of these metabolites was detected in the urine samples, and no significant differences were observed among the three groups or compared to the control (data not shown). "
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    ABSTRACT: This study investigated and compared the absorption, metabolism, and subsequently, the tissue distribution and excretion of hydroxytyrosol (HT) administered either in its free form or through its naturally occurring esterified precursors, namely oleuropein (OLE) and its aglycone forms known as secoiridoids (SEC). Here, rats were fed a diet supplemented with the equivalent of 5 mg phenol/kg/day for 21 days and the HT metabolites in the gastrointestinal digesta (stomach, small intestine and caecum), plasma, urine and metabolic tissues (liver and kidney) were analysed. Compared to HT and SEC, OLE showed greater stability during digestion, and, consequently, the bioavailability based on the urine excretion of HT metabolites was higher. OLE, as a glycoside molecule, reached the colon unaltered generating more diverse microbial metabolites. In terms of bioavailability, findings suggest that OLE might be the most suitable precursor of HT for incorporation into foods or nutraceutical formulations.
    Full-text · Article · Feb 2016
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    • "The validity of the FFQ to assess total polyphenol intake was studied using total polyphenol excretion in spot urine samples in a clinical trial (r Z 0.48, P < 0.01) and in a cross-sectional study (r Z 0.26, P Z 0.04) [16]. This range is likely an underestimate of the true validity because spot urine polyphenol excretion likely best represents intake from the previous 3e12 h whereas the FFQ captures average intake over the previous year [17]. Daily food and nutrients intake was estimated from the FFQ by multiplying the frequency of consumption by the average portion size. "
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    ABSTRACT: An understanding of causal relations between phenol intake and its beneficial effects on health is hindered by the lack of robust biological markers of its exposure. This is particularly relevant in mid/long-term nutritional intervention studies. An analytical methodology based on UPLC-MS/MS has been developed to determine the metabolites of the phenolic compounds from olive oil and thyme in biological fluids after a sustained intake of two phenol-enriched olive oils for their further use as compliance biomarkers. In a randomized, double-blind, controlled, cross-over trial, 33 hypercholesterolemic volunteers received during 3 weeks 25 mL/day of (1) raw Virgin Olive Oil with a low phenolic content as a control (80 mg total phenols / kg oil; VOO), (2) Functional Virgin Olive Oil enriched with its own phenolics (500 mg total phenols / kg oil; FVOO), and (3) Functional Virgin Olive Oil enriched with its own phenolics plus complementary phenolics from Thyme (500 mg total phenols / kg oil, 50% from olive oil and 50% from thyme respectively; FVOOT). Plasma and 24 h-urine samples were collected. The results showed that some hydroxytyrosol (HT) metabolites presented low specificity as biomarkers of intake. However, hydroxytyrosol sulfate and hydroxytyrosol acetate sulfate appeared to be suitable biomarkers for monitoring compliance with olive oil intake as their values in plasma or/and 24-h urine were significantly higher after FVOO compared to baseline pre-intervention concentrations. They were also significantly correlated with the monitored level of compliance. On the other hand, metabolites derived from thyme were more specific, thymol sulfate and hydroxyphenylpropionic acid sulfate being the metabolites with the largest increase in both plasma and 24-h urine, whereas urinary p-cymene-diol glucuronide presented the greatest increase post-treatment. Their urinary excretion values also displayed significant correlations with the level of compliance and they were defined as FVOOT compliance biomarkers. This study enabled robust quantitative and qualitative compliance biomarkers after the ingestion of two phenol-enriched olive oils to be determined and provided a thorough analysis of the true phenolic exposure after a sustained consumption that could be further related to expected biological effects.
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