Urinary Total Flavonoid Excretion but Not 4-Pyridoxic Acid or Potassium Can Be Used as a Biomarker for the Intake of Fruits and Vegetables

Abstract

To gain better insight into the potential health effects of fruits and vegetables, reliable biomarkers of intake are needed. The main purpose of this study was to investigate the ability of flavonoid excretion in both 24-h and morning urine samples to reflect a low intake and moderate changes in fruit and vegetable consumption. Furthermore, the urinary excretions of 4-pyridoxic acid (4-PA) and potassium were investigated as other potential biomarkers of fruit and vegetable intake. The study was designed as a 5-d randomized, controlled crossover study. On d 1-3, the men (n = 12) consumed a self-restricted flavonoid-free diet. On d 4, they were provided a strictly controlled diet containing no fruits or vegetables (basic diet). On d 5, they consumed the basic diet supplemented with 300 or 600 g of fruits and vegetables. The total excretion of flavonoids in 24-h urine samples increased linearly with increasing fruit and vegetable intakes (r(s) = 0.86, P < 1 x 10(-6)). The total excretion of flavonoids in morning urine also increased, but the association was weaker (r(s) = 0.59, P < 0.0001). Urinary 4-PA in 24-h and morning urine samples increased significantly only with the 600-g increase in fruit and vegetable intake, whereas the excretion of potassium in urine did not reflect the changes in fruit and vegetable intake. We conclude that the total excretion of flavonoids in 24-h urine may be used as a new biomarker for fruit and vegetable intake.

Urinary excretion of 13 dietary flavonoids and phenolic acids in free-living healthy subjects – variability and possible use as biomarkers of polyphenol intake

“…As far as we know no other study has published correlations between polyphenols concentrations measured in a 24-h urine sample and a spot sample. Krogholm et al (2004) evaluated flavonoids in both a 24-h urine and a spot urine sample, but did not correlate the two. Weaker correlations were observed between polyphenols measured in a spot sample collected the day before the collection of the 24-h urine sample.…”

Diagnostic Performance of Urinary Resveratrol Metabolites as a Biomarker of Moderate Wine Consumption

“…However, the NPV was 60% because of a high percentage of false negatives among intermittent drinkers. Thus, urinary concentrations of resveratrol metabolites are particularly useful as biomarkers of wine intake for moderate and regular drinkers, just as other phenolic compounds have been shown to be useful biomarkers for the intake of fruits, vegetables, tea, or coffee (14,23 ). We selected resveratrol as a marker of wine intake because it is a characteristic polyphenol of grape and wine products.…”

Free fruit at workplace intervention increases total fruit intake: a validation study using 24 h dietary recall and urinary flavonoid excretion

“…Hence, the 24 h urine sample and the 24 h dietary recall questionnaire covered the same period of time. All urine samples were collected as previously described by Krogholm et al (2004). The employees were instructed on how to collect the urine and in the importance of providing complete samples.…”