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Available data on the presence of mycotoxins Meta-analyses of epidemiological studies found that
in grains and foods indicate that there may be an increased consumption of coffee may reduce the
a continuous low-level exposure to these toxic risk of liver cancer. [63-65] In a recent analysis of EPIC, a
metabolites. Foods mainly contributing to the large epidemiological study designed to investigate
[47]
intake of mycotoxins with diet are cereals, maize the association between diet, lifestyle and
being the most risky commodity due to the potential environmental factors and the incidence of various
co-occurrence of more than one mycotoxin. It has types of cancer and other chronic diseases, coffee
been postulated that individuals with increased consumers in the highest compared to the lowest
maize-based products consumption such as celiac quintile had 72% lower risk of developing HCC. [66]
patients could be particularly at risk of mycotoxin Consistently, high levels of coffee consumption were
exposure. However, studies have shown that the associated with reduced risk of incident HCC and
intake of mycotoxins in these potentially vulnerable chronic liver disease mortality in a population-based
populations is generally below the tolerable daily prospective cohort study of more than 215,000 men
[67]
intake. [51,52] and women from Hawaii and California. Coffee
has been shown to exert beneficial effects on body
Pyrrolizidine alkaloids weight, development of diabetes, the prevention of
Pyrrolizidine alkaloids such as riddelliine, which hepatic fibrosis in NAFLD, and other chronic liver
is found in Senecio riddellii (Riddell groundsel) and diseases, including chronic hepatitis C. There are
[68]
Senecio longilobus (also known as woolly groundsel approximately 1,000 substances in coffee, including
and thread-leaf groundsel), can be found as a caffeine, diterphenoic alcohols and chlorogenic acid
[37]
contaminant in foods such as meat, grains, seeds, [(CGA), a polyphenol]. It is uncertain which are the
[68]
milk, herbal tea and honey. In hepatocytes, exact substances and mechanisms responsible for
[53]
Cytochrome P450s convert dehydropyrrolizidine the beneficial effects of coffee on the liver. Several
alkaloides to 6,7-dehydropyrrolizine esters, i.e. substances as well as the method of preparation
the toxic metabolites. Dehydroretronecine and are thought to be of importance. As an example,
dehydroheliotridine that are produced from the filtered coffee may provide the most benefit due
initial toxic metabolites via ROS react rapidly with to a reduction in cafestol and kahweol, which can
the SH, OH, NH groups on nucleotides, as well as with raise serum cholesterol, while maintaining CGA and
proteins to form adducts, eventually leading to DNA caffeine content.
damage and carcinogenesis. There is a large body
[54]
of evidence from studies in animals supporting the Fish
carcinogenicity of pyrrolizidine alkaloids. Of note, By virtue of its high content in omega-3 fatty
[37]
there are published reports of primary liver tumors acids, which may have anti-carcinogenic and anti-
in natives of Central and South Africa associated inflammatory effects, fish might be protective
[69]
with the consumption of traditional medicinal plants against HCC. Evidence supporting a protective role
containing of pyrrolizidine alkaloids. [55-58] Honey and of fish comes from the EPIC study. In EPIC, total
tea have been reported to be a significant source fish intake was inversely associated with HCC risk
of pyrrolizidine alkaloids in Western countries. [59] (20% reduction in risk per 20 g/day of fish, after
Although health impairment due to chronic intake calibration). Lean/white fish (cod, haddock, and
[70]
of pyrrolizidine alkaloids is improbable for adult plaice), fatty fish (salmon, tuna, trout, herring,
consumers with average amounts of consumption of kippers, and mackerel, and crustaceans and mollusks
honey and tea, [60,61] longer-term regular consumption were independently associated with lower HCC risk,
of products with containing high amounts of even after adjusting for HBV/HCV status and liver
pyrrolizidine alkaloids could be associated with a function biomarkers. [70]
risk of health impairment.
Olive (Oleaeuropaea)
BENEFICIAL NATURAL PRODUCTS Epidemiological studies have shown that intake of
virgin olive oil is associated with low incidences of
Foods and beverages several types of cancer, likely due to its high content
[71]
Coffee in phenolic antioxidants. These include hydroxytyrosol
A protective effect of coffee against HCC was first and oleuropein. Hydroxytyrosol (HT) is a natural
[72]
suggested by Gallus et al. in 2002. Since then, polyphenolic compound with significant antioxidant
[62]
several other studies have confirmed this hypothesis. properties. It has been recently demonstrated
[73]
56 Hepatoma Research | Volume 2 | March 9, 2016