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Observational epidemiological surveys (WG 3) page 80
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with the evaluation of cognitive functions. Contrarily, the biochemical compounds or gene
regulation effects from nutrients are not completely unravelled leading to speculative
mechanistic explanations in cancer field. This explain why most of the cardiovascular disease,
lung function and age-related eye pathology studies focused on antioxidants and not on other
nutrients of food, and why cancer studies covered both food and nutrients.
Both the number of the studies and the consistency of their results permit to say that eating
tomatoes daily reduces the risk of developing a cancer of upper aero-digestive tract, stomach,
and lung. For all other cancers results are insufficient. Most of the time studies do not
differentiate between raw and cooked tomatoes. But, if confirmed, the decreased risk for
prostate cancer is mainly related to cooked tomatoes.
In other disease, for the reasons presented above, there are insufficient data to fix a specific
role to tomatoes. Tomato is a very special plant fruit, rich in many nutrients and non-nutrients
of interest. Thus it might potentially contribute to reduce most of the chronic degenerative
diseases, except perhaps, age-related eye disease. These conditions appear to mainly benefit
from lutein, which is only present in tomatoes at low concentrations.
With lycopene, we could expect more data especially in diseases other than cancers which
focus on antioxidants, since this property is acknowledged for lycopene (see WG 1). Only one
case-control study based on adipose tissue lycopene concentration showed a CHD risk
reduction associated with high lycopene concentration, and for cancers, a possible effect is
suggested for prostatic cancers, and to a lesser extent for cervix and pancreas cancers.
However, there is only fragmentary food composition data about lycopene, and for a long
time analytical biochemistry did not differentiate the major carotenoids in human blood and
tissues. Thus most of the studies reported on β-carotene only, explaining the paucity of
results. Another point is the bioavailability of lycopene in humans, its transport in plasma and
its storage (see WG2). It is known that plasma levels are not good markers of the intake (the
correlation between intake and plasma concentrations ranges between 0,11-0,15). Beside,
lycopene is stored differently in the various tissues of the human body. Generally the
concentration is high in prostate, but there are contradictory results on the levels of malignant
prostatic tissues compared to normal prostatic tissues (Clinton et al., 1996; Rao et al., 1999).
All this might explain the little agreement between the effect of tomatoes and lycopene, and
the paradoxical observation of the EURAMIC study: the Malaga centre showed the lowest
lycopene concentration in the adipose tissues of its participants, whereas the MI incidence
was the lowest in this centre of the study, compared with the others (Gomez-Aracena, 1997).