another month another food scare
- From: "Jim Webster" <Jim@xxxxxxxxxxxxxxxx>
- Date: Thu, 2 Feb 2006 17:37:32 -0000
And we are going to have a rehash of the beef scare.
Basically Researchers at the Medical Research Council (MRC) Dunn Human
Nutrition Unit in Cambridge and the Open University Department of Chemistry
in Milton Keynes have observed a mechanism which may explain why eating red
meat is linked to an increased risk of bowel cancer. The research is
published this week in the journal Cancer Research.
Basically they suspect that if you eat a pound of meat a day you have a
third higher chance of developing bowel cancer than someone who has what
amounts to a vegetarian diet.
I thought I'd enclose the following comments.
Jim
SUMMARY AND COMMENTS BY BRITISH NUTRITION FOUNDATION
Red Meat Enhances the Colonic Formation of the DNA Adduct O6-
Carboxymethyl Guanine: Implications for Colorectal Cancer Risk.
What the study found:
- Faecal ATNC increased in healthy volunteers in a metabolic suite following
a
high red meat diet (420g per day) compared to a vegetarian diet. This has
been shown many times before by the Bingham group. ATNC levels were
intermediate on when the high red meat diet was supplemented with fibre,
however.
- Colonocytes (epithelial cells that line the colon) isolated from fresh
stool
samples contained higher levels of the adduct O6-carboxymethyl guanine.
This adduct, which is effectively a small moiety attached to the DNA base
guanine, has been previously shown to cause a mutation pattern similar to
that seen in the k-ras oncogene in colorectal tumours (Bos 1989). Also,
mutations in k-ras have been associated with high 'animal protein' diets
(Kampman et al 2000). As yet, there is no direct evidence that the O6-
carboxymethyl guanine is mutagenic (this may change - a paper has been
submitted showing that the adduct induces mutations in p53, a tumour
suppressor gene). In this study no k-ras mutations were detected. This is
not
unsurprising though, as these were healthy individuals.
- The percentage of cells staining positive for the O6-carboxymethyl guanine
adduct was significantly correlated with the ATNC concentration.
Current levels of consumption:
- According to the EPIC study, current average consumption of red and
processed meat in the UK is around 80g per day for men and 50g per day for
women.
- Very few individuals consume 420g red meat per day, the level used in this
study.
ANNEX 2
Advice should be in the context of a healthy balanced diet
- The findings of the study also indicate the positive impact fibre can have
in
the diet (although, when corrected for faecal weight, the differences in
ATNC
concentration and percentage of positive cells were not significant).
- Epidemiological studies suggest that a diet rich in fruit, vegetables and
wholegrain cereals is also important for reducing the risk of bowel cancer.
- The risk of bowel cancer is also reduced by maintaining a healthy body
weight, taking regular physical activity, not smoking and consuming alcohol
only in moderation.
Positive attributes of meat
- Meat is a source of a number of essential nutrients, including protein,
vitamin
D, a range of B vitamins, the minerals iron and zinc and essential fatty
acids.
- In particular it contributes to the intake of some important nutrients
which
are consumed in inadequate amounts by many individuals. For example,
40% of females aged 11-34 years do not have enough iron in their diet. Meat
contributes, on average, 17% of total iron intake.
Overall message
- Colorectal cancer is the second most common cancer in western countries
and
although there is a genetic component in determining whether an individual
will develop colorectal cancer, dietary and lifestyle factors play a large
part.
- Red meat provides a range of essential nutrients, some of which are
already
in short supply in the diet, e.g. iron and zinc. Taken together with other
research, the findings from this study do not conflict with advice that meat
can be eaten in moderation, as part of a varied, balanced diet including
plenty
of fruit, vegetables and whole grain cereals.
- This study reinforces current UK recommendations on red and processed
meat intake, that individuals' consumption should not rise and that high
consumers (over 140g per day or 12-14 portions per week) should consider a
reduction in intake.
ANNEX 2
- This study is a small-scale study which is tentatively suggesting a
mechanism
by which red and processed meat might increase an individual's risk of
developing colorectal cancer. The authors themselves acknowledge that
larger-scale, prospective studies are needed to identify how important and
robust this mechanism is.
- It is important to research these mechanisms as they help us better
understand the development of cancers. Identifying the intermediate steps of
the cancer development process, such as the presence of adducts, may help
us to identify those at risk of developing the disease later on in life and
hence
take steps to prevent a malignant tumour growing.
Ends
.
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