It has been empirically proven that diet is
a central environmental factor affecting the process of tumour
growth, whether by promoting it or preventing it. Moreover,
nutritional factors have a greater influence on some types
of cancer than others. This section will prominently look
at these elements and their food sources.
The human diet has a variety of different types of nutrients
- proteins, fat, carbohydrates, vitamins, minerals - and
epidemiological studies suggest that the intake of these
elements should be assorted. So why has there always been
such focus on the foremost value of fruits and vegetables?
The importance of antioxidants
One sort of naturally occurring chemicals found in
vegetables, fruits, and grains are phytochemicals, which
have cancer-preventive effects. These compounds can
prevent carcinogenesis by scavenging DNA reactive agents,
suppressing the abnormal proliferation of early damaged
cells, and inhibit certain properties of the cancer
cell. Phytochemicals are different from vitamins and
minerals because they have no nutritional value. Some
are antioxidants that help protect against cell lesions.
Other examples are:
Isochiocyanates: Cruciferous vegetables
(cabbage, broccoli, cauliflower, and kale).
Fruits and vegetables also contain substances called
antioxidants. These nutrients are in a group of vitamins
and minerals and are thought to protect against cancer,
heart disease, and maybe normal aging. Antioxidants
generally protect cells from oxidative damage, which
is a main cause of tumourigenesis. Various antioxidants
have different functions; such as deactivate free radicals
or transforming them to less toxic substances, as illustrated
in the next section.
Selenium: Brazil nuts, meat, seafood,
eggs, whole grains, legumes.
Also most plant-derived foods are good sources of
fibre, which may particularly reduce the risk of colon
cancer. Dietary fibre is found in cereal foods, beans,
lentils, fruit and vegetables. A diet rich in fibre
is associated with reduced risks of many gut diseases,
including bowel cancer, since it keeps the large intestines
healthy.
Nefarious foods
As shown above, nutritional ingredients have many anticarcinogens,
which can help avoid the potential growth of a tumour. However,
foods may also contain carcinogens, although, the respective
risk is low because if they are present, it is usually in
very small amounts. Nonetheless, carcinogens in foods may
be substances that occur naturally, they may be due to contamination,
or they may be formed during cooking or processing (e.g.
in smoked foods). Aflatoxins, which are toxic metabolites
produced by certain fungi in/on foods and feeds, are examples
of carcinogens in foods.
Despite the fact that there are scarce carcinogens in
foods, many types of nutrients have been linked to cancer
development. Meat, for instance, if consumed regularly,
has a higher effect on tumour growth in the colon. Red meat
presents a superior risk than poultry though. Total and
saturated fat also affect the same kind of cancer, and animal
fat is negatively prevalent over vegetable fat. Another
example is alcohol. People who drink large amounts of alcohol
have an increased risk of certain types of cancer, particularly
liver cancer and cancers in the mouth and oesophagus. Studies
have shown that an intake higher than 60g of ethanol per
day (roughly a consumption of a standard .75 litre bottle
of wine) will increase the risk of one of these cancers
9 times. Moreover, if tobacco consumption is also combined
to the drinking habit, the risk will augment to 50 times.
Finally, research continues to identify numerous anti-cancer
activities of the established essential nutrients as well
as phytochemicals. Here follow groups of elements with distinct
levels of cancer-fighting activity:
Highest level of protection: Cabbage,
garlic, ginger, liquorice, soybeans, unbelliferous vegetables
(carrots, celery, cilantro, parsley and parsnips).
Moderate: Onions flax, citrus, turmeric;
cruciferous and solanaceous (tomatoes, peppers) vegetables;
brown rice and whole wheat.
Lower but still significant: Mints,
rosemary, thyme, oregano, sage, basil; oats and barley;
cucumber, cantaloupe and berries.
