Cancer & Carotenoids
Dr Paul Clayton 2006
Lutein and zeaxanthin are carotenoids found in such yellow foods as corn and egg
yolks. They are also found in green vegetables and fruits. Examples include
avocados, broccoli, green beans and kale. They are strongly linked to
protection against Age-Related Macular Degeneration (Moeller at al '06).
They are also associated with a reduced risk of coronary artery disease
(Osganian et al '03, Dwyer et al '04). Moreover, data suggests that they may
reduce the risk of certain kinds of cancers. This includes non-Hodgkin Lymphoma
(Kelemen at al '06).
In this last study, a link was established between vegetables and non-Hodgkin
lymphoma. People who ate the most servings of vegetables had an incidence of
non-Hodgkin lymphoma less than half of that in the group which ate the least
vegetables.
There are several possible mechanisms which could explain this reduction in
risk. For example, the carotenoids are antioxidants, and reduce free radical
damage. They also have the ability to force cancer cells to redifferentiate
(i.e.normalise) or enter the apoptotic sequence (commit 'suicide').
It is also possible that the carotenoids are merely markers for a diet
containing high levels of fruit and vegetables. Especially those which contain
other chemo-protective compounds. Like the sulphur compounds that increase the
body's ability to excrete certain carcinogens.
In fact it is likely that all these mechanisms play a role. Thus, from the
average consumer's point of view, it is enough to know that a diet rich in
fruit and veg is strongly cancer-protective. It reduces the risk of most of the
degenerative diseases.
How many portions should you eat per day? The government says 5-a-day. It seems
to be enough to reduce the risk of heart disease. But the American cancer
Association recommends up to 9 portions a day to reduce the risk of cancer.
It all seems academic, however, when you realise that the average intake in the
UK is around 2.5 portions a day. This statistic is clearly linked to our poor
public health.
We need to find easier ways to increase our fruit and vegetable intake. The
government needs to find ways of making fruits and vegetables less expensive.
Will they do this? Or will pigs continue to fly in the airspace over
Westminster?
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