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| Photo by Dominik Martin on Unsplash |
As research studies continue, it is becoming clear that nutrition plays a major role in cancer.
According to
the statistics provided by the American Institute for Cancer Research and the
World Cancer Research Fund it has been estimated that 30–40 % of all cancers
can be prevented by appropriate diets along with other factors such as physical
activity and appropriate body weight [1].
In most of
the studies related to nutrition and cancer, a particular food or a nutrient is
studied in relation to its impact on tumour formation or regression. Sometimes,
an end point of cancer at a particular site in the body is also studied.
Although these
studies provide details of the mechanisms of a disease, they do not give a
complete picture of how to prevent cancer on a dietary level.
Also, they barely
explain how to eat when a person already has a cancer and would like to eat a
diet that helps them to recover.
In this
article, let’s focus on those dietary factors which increases the risk of
cancer and how they could be used to alter our existing diet patterns.
Obesity
Over consumption of
energy or eating too much food is one of the main risk factors for cancer.
This can be expressed in
2 ways:
(1) Obesity may cause
additional risks of malignancies (cancerous growth).
(2) Eating less food has
a protective effect.
64% percent of the adult
population in the United States is overweight or obese [2], which is an epidemic level.
A recent study estimated
that overweight and obesity accounted for 14 % of all cancer deaths in men and
20 % of those in women [3].
It was also found that
the higher death rates for the following cancers; oesophagus, colon and rectum,
liver, gallbladder, pancreas, kidney, stomach (in men), prostate, breast,
uterus, cervix, and ovary, were associated with obesity [3].
According to a recent research, if the adult population maintained a normal weight (BMI < 25.0), it is estimated that over 90,000 cancer deaths per year could be avoided [3].
Glucose Metabolism
Glycemic
index is an indication of the blood sugar response of the body to a
standardized amount of carbohydrate in a food. Glycemic load is also a related
term which refers to the amount of food eaten.
It is one
way of measuring the impact of foods on the body, particularly refined sugar,
concentrated sugars and refined flour products.
Refined
sugars e.g. white sugar, brown sugar, high fructose corn syrup are low nutrient
food or junk food. They are high in energy.
Honey and
evaporated cane juice are some "unrefined" sugars which are likely to
cause the same problems as refined sugar.
Refined
wheat flour products such as bread, biscuits, pizza etc. also contribute to the
above-mentioned.
Studies have found
consistent increased risk of a high glycemic load with the following cancers; gastric
[4], upper aero digestive tract [5], endometrial [6], ovarian [7], colon or colorectal [8, 9].
Accordingly, it is obvious
that severe dysregulation of glucose metabolism is a risk factor for cancer.
Foods containing refined sugar and refined flour products should be limited and best avoided for a cancer protective diet.
Low Fiber
Fiber is
abundantly found in unrefined plant foods; fruits, vegetables, leafy greens
etc.
Dairy
products, eggs and meat all have no fiber.
Refined
grain products (e.g. bread, white rice, white flour, crackers) also have less dietary fiber as most of them are removed during
processing.
Therefore, a
typical diet in the US is low in fiber; a diet high in animal products and
refined grains.
A research [10] has found that high intake of vegetable, fruit and whole grain intake were
associated with a lower risk of rectal cancer, whereas refined grains were
associated with increased risk of rectal cancer.
According to studies, it was said that at least 5 daily servings of vegetables were required to reduce cancer risk and the effect was stronger among elderly people [10].
Red Meat
Red meat has
been known for its association with colon and rectal cancer..
Many
scientific studies that investigated the link between diet and colon or
colorectal cancer has reported a strong relationship between red meat and colon
or colorectal cancer [11].
Another
recent study also found that red meat and processed meat to be significantly
associated with colorectal cancer [12].
A comprehensive study [13] on meat consumption and cancer incidence has shown that high intake of red meat was positively related with risk of
- breast cancer,
- endometrial cancer,
- colorectal cancer,
- colon cancer,
- rectal cancer,
- lung cancer, and hepatocellular carcinoma.
It has also been found in the same study, that high intake of processed meat (e.g. bacon, ham, sausage etc.) was positively associated with risk of
- breast,
- colorectal,
- colon,
- rectal, and lung cancers.
Therefore, red meat should be consumed in limited amounts for those who are concerned about a cancer protective diet.
Omega 3:6 Ratio Imbalance
A research [14] conducted using animal studies have reported that Omega 3 fats (e.g. alpha-linolenic
acid, EPA, DHA) have protective effects against cancer, while Omega 6 fats (e.g.
linoleic acid, arachidonic acid) have been found to be promoting cancer.
Omega 3 fat sources; Fatty fish such as sardine, mackerel, tuna and salmon, flax seeds, chia seeds, soybeans, walnut etc.
Omega 6 fat sources; eggs, sunflower seeds and oil, safflower oil, corn oil, sesame oil etc.
Several
studies [15] that have tested this hypothesis in relation to breast cancer have
confirmed an association between a higher ratio of Omega-3: Omega-6 fats and
reduced risk of breast cancer.
Research [16] has
found that flax seed oil and DHA from algae can be used to
increase the intake of Omega-3 fats. Among them, DHA is considered as a more
efficient source.
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| Key Takeaway |
Key Takeaway
If all of these factors mentioned above were taken into account and put into practice, an anticancer diet would have:
- Adequate calories (not excessive)
- High fiber
- No refined sugar
- No refined flour
- Low in total fat (containing necessary essential fatty acids)
- No red meat
- A balanced ratio of Omega 3 and Omega 6 fats (would include DHA)