Normal distribution of urinary polyphenol excretion among Egyptian males 7–14 years old and changes following nutritional intervention with tomato juice (Lycopersiconesculentum)

Abstract

Background The urinary flavonoids are considered a reliable biomarker for the intake of polyphenol-rich foods.

Objectives To assess the normal distribution of urinary polyphenol [PP] excretion among healthy male children and adolescents on a typical Egyptian diet. To follow up the impact of nutritional intervention with tomato juice on the urinary excretion of [PP].

Subjects Forty-nine male subjects 7–14 years old collected a 24-h urine sample and filled a dietary record during a 7-day period. A daily serving of 230 g fresh tomato juice was followed for 18 days in a subgroup. Total urinary [PP] excretions were measured before and after termination of the intervention program. The total urinary [PP] was analyzed after a clean-up solid-phase extraction step by the Folin–Ciocalteu reagent in the 96 micro plates. The results were expressed as gallic acid equivalents (GAE).

Results The urinary [PP] excretion averaged 48.6±5.5 mg GAE/24 h, equivalent to 89.5±8.4 mg GAE/g creatinine. The mean urinary [PP] excretion increased significantly (P<0.05) following the intervention with tomato juice (287.4±64.3 mg GAE/g creatinine) compared with the respective mean baseline level (94.5±8.92 mg GAE/g creatinine).

Conclusion Clinical laboratory reference limits for urinary polyphenols are presented for Egyptian male children and adolescents. Measuring the urinary polyphenol excretion proved a good biomarker for the dietary polyphenol intake and the results demonstrated that tomato [PP] was highly bioavailable in the human body.

• Male children and adolescents
• nutritional intervention
• tomato juice
• urinary polyphenol excretion
• biomarker