Free fruit at workplace intervention increases total fruit intake: a validation study using 24 h dietary recall and urinary flavonoid excretion.
OBJECTIVE
To validate 24 h dietary recall of fruit intake by measuring the total 24 h excretion of 10 different flavonoids in 24 h urine during an intervention with free fruit at workplaces.


METHODS
Employees at workplaces offering a free-fruit program, consisting of daily free and easy access to fresh fruit, and controls employees at workplaces with no free-fruit program were enrolled in this validation study (n=103). Dietary intake was assessed by using a 24 h dietary recall questionnaire at baseline and approximately 5 months later. Ten flavonoids, quercetin, isorhamnetin, tamarixetin, kaempferol, hesperetin, naringenin, eriodictyol, daidzein, genistein, and phloretin, were measured using HPLC-electrospray ionization-MS.


RESULTS
The 24 h urinary excretion of total flavonoids and the estimated intake of fruits were significantly correlated (r (s)=0.31, P<0.01). The dietary intake of citrus fruits and citrus juices was significantly correlated with total excretion of citrus specific flavonoids (r (s)=0.28, P<0.01), and orange was positively correlated with naringenin (r (s)=0.24, P<0.01) and hesperetin (r (s)=0.24, P<0.01). Phloretin in urine was correlated with apple intake (r (s)=0.22, P<0.01) and also with overall estimated intake of fruit (r (s)=0.22, P<0.01).


CONCLUSIONS
This study shows that a 24 h dietary recall can be used as a valid estimate of the intake of fruits in agreement with an objective biomarker of fruit intake in free fruit at workplace interventions.
Krogholm
K S
KS
Department of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Mørkhøj Bygade, Søborg, Denmark. kskr@food.dtu.dk
Bredsdorff
L
L
Alinia
S
S
Christensen
T
T
Rasmussen
S E
SE
Dragsted
L O
LO
D015415:Biomarkers / Q000737:chemistry / Q000652:urine; D004032:Diet; D005419:Flavonoids / Q000737:chemistry / Q000652:urine*; D005638:Fruit / Q000191:economics*; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D015990:Placebo Effect; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D017132:Workplace
D015415:Biomarkers; D005419:Flavonoids