Serum beta-glucuronidase activity in response to fruit and vegetable supplementation: a controlled feeding study.

: Cancer Epidemiol Biomarkers Prev. 2008 Jul;17(7):1808-12. Links
Maruti SS, Chang JL, Prunty JA, Bigler J, Schwarz Y, Li SS, Li L, King IB, Potter JD, Lampe JW.
Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA.

BACKGROUND: Fruit and vegetable (F&V) intake may lower the risk of some cancers. One hypothesized, but understudied, chemopreventive mechanism is that plant food constituents inhibit beta-glucuronidase, an acid hydrolase that deconjugates glucuronides. METHODS: We conducted a crossover feeding trial in 63 healthy women and men ages 20 to 40 years to examine the effect of diet on serum beta-glucuronidase activity. Participants were randomized to two 2-week experimental diets with an intervening washout period: a diet high in selected citrus fruit, crucifers, and soy (F&V) and a diet devoid of fruits, vegetables, and soy (basal). Serum beta-glucuronidase activity was measured during the preintervention, F&V, and basal periods. Linear mixed models were used to obtain effect estimates and 95% confidence intervals (95% CI). RESULTS: We observed statistically significantly higher beta-glucuronidase activity during the F&V than the basal diet (ratio, F&V versus basal diet, 1.09; 95% CI, 1.05-1.13; P < 0.01). These results were probably due to decreased beta-glucuronidase activity during the basal diet (ratio, basal period versus preintervention, 0.93; 95% CI, 0.87-0.98; P = 0.01) rather than increased enzyme activity during the F&V diet (ratio, F&V period versus preintervention, 1.01; 95% CI, 0.96-1.06; P = 0.64). Response to the experimental diet did not differ by sex (P(interaction) = 0.30), but there was a suggestion of a short-term diet effect at 8 versus 15 days (P(interaction) = 0.06). CONCLUSION: This intervention of selected F&V did not lower beta-glucuronidase activity. Further investigation is needed regarding what other foods and phytochemicals may influence beta-glucuronidase activity and effect modifiers of this relation.