genes also show signs of ageing – a process that can lead to cancer. A new
study indicates that healthy eating can prevent cancer development and explains
how this works.
increased dramatically in recent decades. However, there is a paradox in our
longevity: we now live long enough to develop cancer. Cancer is a genetic
disease and, as we age, our genes – like our body – become more vulnerable.
Some genes accumulate genetic mutations: if you think of genes as cookbooks for
proteins, then these mutations are like typing errors in the recipe. Others
acquire epigenetic modifications, which affect the way a gene works rather than
its content – which, to use our analogy again, is like not being able to open
and close the cookbook anymore. Both genetic and epigenetic changes can lead to
cancer; however, the latter are especially interesting because they are
affected by environmental factors that we can actually control, such as our
Belshaw, at the Institute of Food Research in Norwich UK, wanted to discover.
His team looked for environmental factors that affect epigenetic markers
associated with early colon cancer – a common and lethal cancer, responsible
for over 610,000 deaths worldwide each year. Preventing colon cancer with small
lifestyle changes would be a cheap, highly effective, and low-risk approach that
turns the tide against this disease.
called DNA methylation. Like other epigenetic markers, DNA methylation is a genetic
switch: it can turn genes on and off, it can make the cookbook readable or make
it impossible to open.
in every single cell of our body. In this state, genes cannot be read and used
by the cell to make proteins. Epigenetic switches can turn genes on by
unwinding them, or turn them off by folding them back up, as in the case of DNA
methylation. While this process is essential to our health, faulty folds
in the DNA, much like wrinkles, can disturb gene function and lead to cancer.
wrinkles in colon cancer? To answer this question, Belshaw’s group examined the
cells lining the gut wall in healthy, cancer-free volunteers who consumed their
usual diet without any supplements. The researchers looked at eleven risk genes,
that, when their methylation is turned on, increase the risk of developing
colon cancer. They then quantified the
relationship between methylated genes and cancer risk factors such as age, diet
and obesity. Age was associated with the highest gene methylation, which fits
with the observation that colon cancer risk increases exponentially after 50
years of age. However, other factors had small but significant effects. High
body fat increased cancer-related methylation whereas high levels of the
mineral selenium and vitamin D reduced it. This is consistent with what we know
about the link between obesity and a high risk of colon cancer, as well as with
the protective effects of vitamin D and selenium observed in previous studies.
like spinach, increased gene methylation associated with colon cancer. We have
been told that these foods are good for us, so how could they promote cancer? It
is actually still unclear whether folic acid is a friend or a foe as previous studies indicate it may
even have a protective function. This is an important issue as some countries add
nutrients such as folic acid to food and this may expose people to increased
risk of developing cancer. In a follow-up study, Dr Belshaw’s team will try to shed
light on the potential dark side of excess folic acid intake.
by what we eat. As we age, the epigenetic status of some genes can change
leading to disease like cancer. Our diet seems to affect this process and bring
important ingredients into our genes’ recipe. As Dr Belshaw says, “This raises
the exciting possibility that lifestyle interventions may
reverse age-related DNA methylation and consequently reduce the risk of disease”. An apple a day might be more effective in slowing
down the ageing process than an anti-wrinkle cream.