Early in my cancer journey (November 2010) Maureen and I participated in the Gawler Foundation Cancer Retreat at Yarra, outside of Melbourne. The sessions focussing on the impact of nutrition on cancer inspired me to undertake my own reading and research on the relationship between nutrition and the prevention and management of cancer. I was particularly keen to get a better understanding of the ‘science’ of nutrition.
Although it will continue as “work in progress”, the overwhelming conclusion I draw from my reading and research is that nutrition has the potential to profoundly impact the cancer journey – for good and bad:
Some foods have the potential to ‘nurture’ cancer.
Others have the potential to strengthen the immune system and/or directly fight cancer.
So proactively addressing nutrition, as part of an integrative approach to managing cancer, is likely to significantly improve the wellness and survival time of a cancer patient.
Many, if not most, of the insights and conclusions I draw for my own cancer journey are relevant to the prevention and management of other modern diseases of civilisation such as diabetes, obesity, heart disease and alzheimers.
I had intended that my post would cover both the food categories above (the ‘fuelers’ and the ‘fighters’). It has turned out that my reading, particularly on the second category (the ‘fighters’), has diverted me into some serious research. This has taken me beyond an understanding the cancer-modulating ‘phytochemicals’ which superfoods contain, to recent research into the biological pathways through which these phytochemicals operate. That research has a little way to go.
So I have decided to focus this post solely on the first category. The second (foods that fight cancer) is work in progress. It should not be too far off.
Evolution, Food Selection and the Industrialisation of Food
The evolution of homo sapiens and their ancestors over the last 15 million years has gone hand in hand with a process of ‘natural selection’ of foods that provide humans with an advantage for survival. Natural selection has entailed both ‘trial and error’ (which undoubtedly involved quite a few deaths along the way) to determine which food sources are toxic, and the evaluation of non-toxic plants and food to chose those that have real nutritional value and/or significant additional health benefits. The development of civil society saw the great civilisations of Egypt, India, China and Greece record in detail their observations on the effects of plants and food on health and healing.
This empirical knowledge, gathered over hundreds of thousands of years, has only very recently begun to be augmented by scientific enquiry into the powerful ‘phytochemicals’ contained in these foods and the biological pathways by which they impact on health outcomes. (I discuss this in my next post).
But around 60% of the calories in modern Western diets come from food sources that have not been selected through this evolutionary process. Instead, it comes from four sources that were non-existent a little more than 100 years ago:
Refined sugars, including sucrose and high fructose corn syrups;
Highly processed simple carbohydrates, including bleached and refined flours;
Processed vegetable oils or “trans-fats” (hydro-generated oils such as soy bean, sunflower and corn) oil;
Foods containing phosphate additives (used by the food industry because they retain water and improve the texture of food).
These food sources contain nothing our bodies need and directly fuel the progression of cancer.
Refined Sugars and Processed Carbohydrates
In the case of the first two food sources, the “glycemic index” is a good indicator of their initial impact. It measures how quickly carbohydrates in different foods are digested and broken down in the intestine and converted into blood sugar in the two to three hours after eating. Foods with a high glycemic index rapidly increase levels of blood sugar or glucose. The body’s response to the rise in blood sugar levels is to immediately release a dose of insulin to enable the glucose to enter cells. The higher the glycemic index the greater the resulting sugar and insulin response. Refined sugars, high fructose corn syrups and refined and bleached flours are all highly processed simple carbohydrates that have a high glycemic index.
It is now known that insulin provides fuel and growth signals to cancer cells. Moreover, the secretion of insulin is accompanied by the release of a molecule called Insulinlike Growth Factor (IGF). The role of IGF is to stimulate cell growth. It does this through receptors which send signals into cells. While insulin responds immediately to the appearance of glucose in the blood stream, and so varies widely from hour to hour, IGF concentrations in the blood change only slowly over days or weeks. This means that well after blood sugar and insulin levels have subsided IGF will continue to send signals to cancer cells to grow and proliferate. In short, insulin and IGF work together to promote both the growth and metastasis of cancer. In addition, they promote inflammatory factors (cytokines and chemokines) which act as a ‘fertiliser’ for tumours.
In his book “Good Calories, Bad Calories” Gary Taubes puts it this way:
“IGF and insulin can be viewed as providing fuel to the incipient fire of cancerous cells and the freedom to grow without limit. The critical factor is not that diet changes the ‘nature’ of cells – the mutations that lead to cancer – but that it changes the ‘nurturing’ of those cells; it changes the environment into one in which cancerous and pre-cancerous cells survive and flourish.”
Refined sugars and highly processed carbohydrates are also implicated in a range of other diseases of ‘modern civilisation’ including heart disease, diabetes, obesity, dementia and alzheimers. These diseases are stimulated, not just by the impact of these food sources on blood sugar levels, but also through the effect of the fructose they contain on the liver, where it is metabolised and converted into triglycerides. We now know that excess levels of triglyceride are a significant risk for these diseases.
In a recent addition of its 60 Minutes programme the US television channel CBS highlighted the serious health of America’s high level of consumption of refined sugars and high fructose corn syrups. I have attached a segment of that programme which was forwarded to me by a friend.
There is very little doubt, therefore, that refined sugar, high fructose corn syrup, refined bleached flour and other ‘simple’ carbohydrates feed cancer. And as noted above, they are also leading culprits in a range of other modern diseases of civilisation.
Gary Taubes puts it more positively.
‘…. the current thinking is that a lifelong reduction in blood sugar, insulin and IGF bestows a longer and healthier life… “
There are three ways to negate the deleterious affect of these two food sources.
The first is to consume a lot less of them.
The second is to substitute foods with a low glycemic index for those with a high index. Examples include:
agave nectar, stevia and dark chocolate for sugar and syrups;
multigrain bread for white bread;
basmati and brown rice for ‘polished’ white rice;
lentils, beans and kumara (sweet potatoes) for potatoes (especially mashed potatoes);
oatmeal, buckwheat and all bran for high sugar, low fibre cereals;
tea (especially green or white tea) and water (flavoured with lemon or herbs) for sweetened drinks and sodas.
There are many other examples but the principle is to focus on reducing the glycemic index of the foods you consume. A reliable guide to the “GI” ranking of different foods can be found at www.mendosa.com.
This is an excellent site which also calculates the “glycemic load” of different foods (calculated as the GI of a food times its available carbohydrate content in grams per standard serving).
The third option is to eat garlic, onions, shallots (and any other member of the allium family) which, when mixed with other (higher glycemic index) foods, reduces blood sugar levels and insulin peaks.
For those of you who are interested in adjusting your diet but can’t resist the occasional sugar or carbo ‘rush’, then do it in combination with other foods (vegetables, fruit, ‘good’ fibres, olive oil etc) and try to avoid between-meal snacking. This will help slow the assimilation of sugar and reduce insulin peaks.
The third cancer-fuelling food source outlined above comprises ‘trans fats’. These are Omega-6 vegetable oils (soy, palm oil etc) which are hydrogenated or partially hydrogenated (think highly processed) so that they become solid at room temperature and do not go ‘stale’.
Omega-6 and Omega-3 oils are ‘essential’ fatty acids. This means that the human body cannot make them and they must be extracted from food sources. They work together to help control and balance our body functions. To quote David Servan-Schreiber in his book “Anti-Cancer, A New Way of Life”:
“… Omega-6’s help stock fats and promote rigidity in cells as well as coagulation and inflammation in response to outside aggression. They stimulate the production of fatty cells from birth onward. Omega-3’s are involved in developing the nervous system, making cell membranes more flexible and reducing inflammation.”
The diet issues that arise with trans fats are twofold.
First, the production and consumption of trans fats has exploded since 1940 and are now used in most processed foods that spend any length of time on supermarket shelves. This has radically changed the balance of Omega-6 and Omega-3 now consumed in Western diets. The human genetic ‘blueprint’ is programmed for a one-to-one ratio of Omega-6’s to Omega-3’s. Typical US diets produce a ratio of about 20 to 1. Such an imbalance puts an unreasonable load on the human immune system producing inflammation, blood coagulation and stimulation of cell growth – the terrain the cancer thrives on.
Second, the Omega-6’s contained in trans fats are different from Omega-6’s obtained from natural foods. The high temperature extraction process by which they are produced, changes their chemical make-up, making them less digestible and more inflammatory than Omega-6’s in the natural state. It leads to the formation of potentially toxic substances.
The fourth culprit in the pro-cancer food list above comprises foods containing phosphate additives. They are to be found in processed meat and pork products (with preservatives), certain processed cheeses and pastries, most sweet flavoured and fizzy soft drinks, fruit syrups and ready-made processed foods (such as frozen pizza and frozen fish sticks).
In 2008, researchers showed that tumour growth in mice selected to develop lung cancer was much greater in those that had been fed a diet rich in inorganic phosphates. Servan-Schreiber notes that their hypothesis was “..excessive amounts of phosphates activate genetic pathways that stimulate the development of lung cancer cells…” and “… that people who are being treated for non-small-cell lung cancer should avoid processed meats and all products whose listed ingredients include phosphate-based preservatives…”
There is strong evidence that such additives stimulate other forms of cancer also.
That does it for me. No more food with phosphate additives!
This summarises the key learnings from my reading on foods that nurture and promote cancer. My next post will focus on the foods that fight cancer.
In between times I will list my recommended readings on cancer and nutrition.