LIBRO-CONGRESO-CITRUS

W10
Citrus and health
Convener: Francisco A. Tomás-Barberán
CEBAS-CSIC. Murcia (Spain). Email: fatomas@cebas.csic.es
The effect of citrus fruits in human health has been an active field of research particularly during the last
twenty years. This activity has been associated with benefits for cardiovascular and bone health, and with
the decrease of cancer risk. Many of these studies have used in vitro models that do not reflect the complex
situation in vivo. Clinical studies, however, have shown large inter-individual variability, leading to nonsignificant
effects in many cases. The recent advances in the knowledge of citrus bioactives metabolism and
bioavailability, and in human nutrigenetics, and gut microbiome open great expectations to understand the
effects of citrus phytochemicals on health. In this workshop the research strategies, trends and perspectives,
to support the role of citrus fruits in human health will be discussed.
Are the in vitro studies valid to demonstrate citrus health effects?
Many mechanistic studies use human cell cultures to evaluate the biological effect of citrus extracts, or
isolated bioactives from citrus, and these studies are often extrapolated to the potential effects in vivo. Most
of these studies, however, have some mayor flaws, although they can be published in very good scientific
journals, although they usually do not correlate with the effects observed in vivo. The main problems found
are associated with the dose, the chemical nature of the citrus bioactive tested and the human tissue used
in the assay. The dose used is often much higher than the amounts found in vivo, and these high doses are
necessary to see a relevant effect. The long term approach, using low metabolite concentration or mixtures
of them, which is the situation found in vivo, is difficult to evaluate with the classical models. The type of
metabolite used in the assays is often that found in the food products, although these compounds are
metabolized but the gut microbiota and the human Phase II enzymes to produce metabolites that differ
from those found in citrus fruits. In addition, the tissue model used is often inappropriate for the metabolites
tested as many of these metabolites do not reach the tissues that are assayed for the effects. Therefore, a
new scientific approach is needed to evaluate the mechanisms of action using the appropriate cell lines, with
the appropriate metabolites and at the concentrations that reach the specific tissues, and providing systems
that mimic the long term effects that are found in vivo.
Can we explain the large inter-individual variability observed in clinical studies?
In clinical studies with citrus fruits and extracts, a large inter-individual variability is generally observed with
individuals that respond to the intervention with relevant biological effects, while other individuals do not
respond to the intervention in the same way. This behavior could be explained by differences in the genetic
background of the individuals (nutrigenetics, transporters, metabolic enzymes isoforms, etc.), by differences
in the metabolism of the bioactive compounds by the colon microbiota, or by a combination of both factors.
The relevance of these two factors in the evaluation of the health effects of citrus products will be discussed,
and the need of stratification of the population used in the studies to explain the results obtained will be
presented.
W11
Quarantine security for Tephritid fruit flies pests in citrus
Convener: N. J. Liquido
USDA-APHIS-PPQ, Center for Plant Health, Science and Technology, Plant Epidemiology and Risk Analysis Laboratory. Honolulu, Hawaii
(USA). Email: Nicanor.J.Liquido@aphis.usda.gov
Co-convener: R.L. Griffin
USDA-APHIS-PPQ, Center for Plant Health, Science and Technology, Plant Epidemiology and Risk Analysis Laboratory. Raleigh, North
Carolina (USA). Email: Robert.L.Griffin@aphis.usda.gov
Tephritid fruit flies are serious pests of citrus. They cause direct fruit damage through oviposition and larval
feeding, and warrant regulatory restriction on the movement of citrus fruits across national and international
boundaries. Current quarantine mitigations for fruit flies in citrus include fumigation, high-temperature
22 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012