Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2009
Publication Date: 8/12/2009
Citation: Burri, B.J. 2009. ABSORPTION ESTIMATES IMPROVE THE VALIDITY OF THE RELATIONSHIP BETWEEN DIETARY AND SERUM LYCOPENE. Journal of Nutrition. Vol 26, Issue 1: 82-89, 2010.
Interpretive Summary: Lycopene is a red pigment in tomatoes that may prevent prostate cancer. There are several large nutrition studies now that are trying to determine the effects of lycopene on human health. We need to develop methods to compare how differences in the amount of lycopene we eat translate into differences in lycopene in the blood. This has been surprisingly difficult to do. Current methods show little relationship between the amounts of lycopene people claim they eat and the amount of lycopene in their blood. We show that combining information from two different methods of collecting dietary information improves this relationship. We also show that correcting dietary information for differences in the type of food that lycopene was derived from further improves this relationship. We suggest that our results can be applied to other infrequently consumed nutrients.
Technical Abstract: Objective: Studies show low correlations between dietary intakes and serum concentrations of lycopene, which makes it difficult to assess the effectiveness of dietary interventions with lycopene. We hypothesized: 1) that the primary reason for these poor correlations was the difficulty of obtaining good dietary information, so that combining information from food frequency questionnaires (FFQ) and three day diet records (3D) by the triads method would improve the validity of this relationship; and 2) correcting dietary information for differences in the bioaccessibility of lycopene from its food matrices would further improve the validity of this relationship. Research Methods and Procedures: We measured dietary intakes of lycopene from 49 adults by 3D and FFQ. Serum lycopene was measured by reversed-phase chromatography with diode array detection. Cholesterol, triacylglycerol, and insulin concentrations were measured spectrophotometrically. Tomato containing foods were given a bioaccessibility factor based on literature values (Reboul et al 2006). Associations between dietary and serum lycopene were modeled using a multiple regression forward procedure. Furthermore, the triads method was used for validation amongst FFQ, 3D and serum lycopene. Statistical analyses were performed using SAS and R software. Results and Conclusions: Raw data gave low correlations between dietary and serum lycopene r = +0.15 for 3D, 0.35 for FFQ. Mathematical modeling showed that both 3D and FFQ contributed independently to the relationship between serum and dietary lycopene, demonstration that both methods must be used to collect accurate dietary information for lycopene. Correcting for bioaccessibility estimates increased the validity of the relationship between diet and serum lycopene. We suggest that the relationship between dietary intakes and serum concentrations of lycopene and other infrequently consumed nutrients can be improved by collecting both diet records and FFQ and when possible by correcting dietary information for bioaccessibility.