world cancer report - iarc
world cancer report - iarc
world cancer report - iarc
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Fig. 2.54 The age-adjusted mortality rate for gastric <strong>cancer</strong> increases with increasing salt consumption,<br />
as measured by 24-hour urine sodium excretion, in selected regions of Japan.<br />
S. Tsugane et al. (1991) Cancer Causes Control, 2:165-8.<br />
a protective effect of animal protein (and<br />
meat) while some studies on colorectal<br />
<strong>cancer</strong> found an increased risk for animal<br />
protein (and meat).<br />
Results on carbohydrates are difficult to<br />
interpret because of inconsistencies in the<br />
way different food composition tables<br />
subdivide total carbohydrates into subfractions<br />
that have very different physiological<br />
and metabolic effects and which<br />
may affect carcinogenesis in opposite<br />
ways. The only pattern that seems to<br />
emerge so far is that consumption of simple<br />
sugars (mono- and disaccharides) may<br />
be associated with increased colorectal<br />
<strong>cancer</strong> risk, while consumption of complex<br />
polysaccharides, non-starch polysaccharides<br />
and/or fibre (partially overlapping<br />
categories based on different chemical<br />
and physiological definitions) is associated<br />
with lower <strong>cancer</strong> risk. Other less<br />
consistent findings suggest that a diet<br />
excessively rich in starchy foods (mainly<br />
beans, flour products or simple sugars)<br />
but also poor in fruit and vegetables, may<br />
be associated with increased gastric <strong>cancer</strong><br />
risk.<br />
The hypothesis that high fat intake is a<br />
major <strong>cancer</strong> risk factor of the Westernstyle<br />
diet has been at the centre of most<br />
64 The causes of <strong>cancer</strong><br />
epidemiological and laboratory experimental<br />
studies. The results are, however,<br />
far from clear and definitive. The positive<br />
association with breast <strong>cancer</strong> risk suggested<br />
by international correlation studies<br />
and supported by most case-control studies<br />
was not found in the majority of the<br />
prospective cohort studies conducted so<br />
far. Very few studies have investigated the<br />
effect of the balance between different<br />
types of fats, specifically as containing<br />
poly-unsaturated, mono-unsaturated and<br />
saturated fatty acids, on <strong>cancer</strong> risk in<br />
humans. The only moderately consistent<br />
result seems to be the positive association<br />
between consumption of fats of animal<br />
origin (except for fish) and risk of<br />
colorectal <strong>cancer</strong>. Additionally, olive oil in<br />
the context of the Mediterranean dietary<br />
tradition is associated with a reduced risk<br />
of <strong>cancer</strong> [10].<br />
Food additives<br />
Food additives are chemicals added to<br />
food for the purpose of preservation or to<br />
enhance flavour, texture or colour. Less<br />
than comprehensive toxicological data are<br />
available for most additives, although<br />
some have been tested for mutagenic or<br />
carcinogenic activity. In in vitro assay sys-<br />
Fig. 2.55 Consumption of salted fish (such as this<br />
salted cod) is associated with an increased risk of<br />
stomach <strong>cancer</strong>.<br />
tems, some additives, such as dietary phenolics,<br />
have both mutagenic and antimutagenic<br />
effects [11]. In the past, some<br />
chemicals were employed as food additives<br />
before their carcinogenicity in animals<br />
was discovered, e.g. the colouring<br />
agent “butter yellow” (dimethylaminoazobenzene)<br />
and, in Japan, the preservative<br />
AF2 (2-(2-furyl)-3-(5-nitro-2-furyl)<br />
acrylamide). Saccharin and its salts have<br />
been used as sweeteners for nearly a century.<br />
Although some animal bioassays<br />
have revealed an increased incidence of<br />
urinary bladder <strong>cancer</strong>, there is inadequate<br />
evidence for carcinogenicity of saccharin<br />
in humans [12]. The proportion of<br />
Fig. 2.56 Saccharin with a warning label recognizing<br />
a possible role in <strong>cancer</strong> causation.