Bad quality food

7 most common foods that could cause cancer

Most of us have the intuition that wrong food choice would lead to cancer. But is that true, and if yes, which dietary habit could cause cancer?

One-minute summary :

Diet has a very important effect on your cancer risk. The 7 most common foods that could cause cancer are: sugar, vegetable oils, excessive empty starches, processed foods, industrially farmed foods, diet foods and alcohol.

There is a huge deal of confusion when it comes to cancer and nutrition. And sadly, a number of oncologists strongly believe that diet and cancer have no connection at all. Unfortunately, that is not the case. Or fortunately, perhaps, because knowing that food has an impact on health and that the right food can help you heal or recover from cancer faster and more completely will give you the power to act on it.

The first point I’d like to make is that indeed, having a bad diet is a cancer risk. This has been proven numerous times in research studies (see for instance this review in the Nutrition and Cancer Journal, and this one in the Nutrition Journal). At this point, denying the link between the two is just being misinformed.

The second point to bear in mind is that, after several decades of investigating a cure for cancer, we have made little progress to find a single mechanism that could be exploited to cure cancer. In fact, the current consensus in medical oncology is that cancer is not just one disease, but well over a hundred different diseases. This fits the theory that genetic mutations are the initiating process of the cancer. And yet, somehow, all of those diseases would manifest themselves in a similar way. A little odd, considering they are initiated from random genetic mutations, don’t you think?

However, there is an alternative scientific explication for cancer, and one that is quickly gaining considerable attention. This is the theory of metabolic origin of cancer. Based on the initial work of Nobel Laureate Otto Warburg (in the 1930’s, no less!) and recently redeveloped by Thomas Seyfried and others, the theory goes as such: virtually all cells in our body breathe oxygen through a small subsection of the cell called a mitochondria – think of it as a mini power plant. For whatever reasons (and causes can be very varied – bad diet, lack of exercise, toxic exposure, etc.) those mitochondria can get damaged. The cell then cannot respire anymore, and is forced to ferment sugar (as glucose) in order to survive.

Cancer could very well be a mitochondrial metabolic disease
Mitochondria in a cell – credits

Bearing this in mind, here is my list of the 7 most common foods that could cause cancer:

Sugar is toxic and can cause cancer

1/ Sugar

See my explanation above, on the metabolic origin of cancer. Today, the fact that tumour cells gobble up sugar is the basis of how PET scans works – basically you are injected with radioactive sugar, which goes straight to the tumour and is then picked up by the scan. High sugar consumption has also been directly linked to cancer in a number of studies (here, here, and here, and there). Besides a direct effect of feeding the tumour, sugar has other secondary mechanisms by which it exacerbates the problem:

  • High blood sugar not controlled by insulin promotes inflammation, which also raises cancer risk.
  • High blood sugar may decreases immune function, which means you are less able to fight it.
  • It promotes obesity, which is another cancer factor – although people may be obese because of eating too much sugar, in which case both obesity and cancer are a direct consequences of sugar consumption.
  • It messes up hormones function – guess what, this is another cancer risk factor.

And remember, sugar is not just that white powder you put in your coffee. It’s in that soda you drink, or in the ketchup sauce, or in that “healthy” innocent-looking smoothie, or in that low-fat diet yogurt. And if you think the “zero sugar but still sweet” option is healthier, I’m sorry but it is just not the case, in fact it may be even worse (read on for more on this).

2/ Vegetable oils

… or more exactly, vegetable oils extracted off a seed.

Here is something else that is on almost nobody’s radar. What I mean by oils extracted off a seed are such oils as Rapeseed, Sunflower, Soybean, Canola, Corn, Cottonseed oils and a few others. For one, most of they have the wrong omega 6 to omega 3 ratio, which has been shown to cause cancer (study, study). In addition, those oils are very fragile, and they start to get damaged during the extraction process, and then when they sit on the supermarket shelf. They are broken down even further during the cooking, and they degrade into very toxic compound. The effect this then has on the body is serious, with very real carcinogenic effect (see this study and this one). And you find them almost everywhere – French fries, salad dressing, fake butters, etc.

In contrast, coconut, avocado and olive oils are not extracted from a seed, but from the fruit itself. The extraction process is generally more gentle, and those oils are less fragile than the seed oils we just talked about. For those reasons, coconut, avocado and olive oil are much better choices. Or, if you feel adventurous, lard, beef tallow, suet or butter are also better options. Remember this is somewhat controversial, however the evidence backing the consensus on the fat-heart disease connection has been getting a lot weaker in recent years.

High carb diet possibly related to cancer

3/ Excessive refined starches

Our modern culture has us eat a very unbalanced diet. Quite often, way too rich in starches and carbohydrates. Cereal at breakfast, sandwich at lunch and pasta for dinner, with cake or chocolate dessert. All of those starches are converted in the gut in simple sugars. And because they are highly refined, they don’t have much nutritional value beside the energy they provide. So, we’re back to sugar. And this is not just theory, as some studies have linked the consumption of excessive empty starches to cancer (here and here). I think however the key here is in the “excessive” and “refined”. Our ancestors have eaten starchy roots for hundreds of thousands of years whenever they could get them, so we have evolved to tolerate some carbohydrates and starches.

In this section, wheat and gluten should have a special mention. As more and more research come through on non-coeliac gluten sensitivity, it is now obvious that wheat is one cause of inflammation for a relatively large section of the population (more studies here, here, and here). And chronic inflammation has been shown to be a strong cancer risk.

4/ Processed foods

What I mean by processed food is anything that came out of a factory. So we all know that popcorn and crisps aren’t good for you, but why stop there. Pizzas? Sausages? Fake vegetarian meat? Spreads? Ready-made cakes? Burgers? Snack bars? Morning cereals? Cheese imitation? Microwave dinners? They all suffer from the same issues: high carbs, high sugar, high in unhealthy seed oils, and lots of chemical additives, many of them would never be found in a kitchen. In 2019, many of them still have hydrogenated fats. You want to avoid and heal from cancer, you need to bin those. Now.

In fact a 2018 study found that a 10% increase in processed food leads to greater than 10% increase in cancer risk. This problem is not new, and has been debated for decades (see this 1975 paper). The problem is, the food industry will invent new chemicals, and put them on the market with minimal safety checks, until the authorities catch up and ban them (as in this 3 month old story).

5/ Industrially farmed foods

There are several aspects to the problem here. The first one is all the poison we spray on our food: pesticides, herbicides, fungicides and other “-icides”. Here there is no debate, the link with cancer has been proven times and times again. From the recent court ruling against Monsanto, to several lower-profile scientific studies (here, here, here, and an interesting summary on Integrative Oncology Essentials).

Next issue, largely ignored by official guidelines, is that our farming methods are depleting the soil of its nutrients. The plants we grow then become deficient in critical minerals, and this is then impacting our health (magnesium deficiency is a well known problem, zinc is another big one, and both nutrients deficiencies have been correlated to cancer – studies here and here among a few).

But the greed-inspired manufacture of cancer-causing food doesn’t stop there. You may have seen several reports that “red meat cause cancer”. It is almost certain that the meat included in the studies did include a very high percentage of industrially-farmed cattle. The fact is that industrially reared animals are kept in unnatural conditions, they are not free to feed on their natural diet, lack sun exposure, they get easily sick and have to be regularly injected with antibiotics (bad for your gut, therefore promotes inflammation), and various hormones (link to cancer). For instance, cows do not normally eat corn, they are herb-ivores (as in grass only). Feeding them grain will change the fatty acid profile of their body (typically too much omega-6 from the grains in the feedlot, another cancer factor), and make them sick quickly. They are also sprayed or somehow dispensed pesticides to in order to control flies and other pets.

6/ “Diet” foods

Don’t take me wrong here. Dieting and loosing weight if you are overweight is a good thing and will decrease your cancer risk. Salad (with the right virgin olive oil dressing) is an excellent thing. Vegetables and fruits, yes of course.

What you need to avoid is anything that is marketed as “diet” food. “Light” or zero-sugar soda, low fat butter, low fat cheese, low fat yogurt, weight watchers, slim fast, meal replacement shakes & bars, protein powders, etc. Why?

  • For a start, in most cases they don’t work very well. Obsessing over calories counting doesn’t do your body good. Unlike what those high-profile companies marketing would have you believe, calories counting doesn’t matter so much, and in fact it could have counter-productive psychological effect (food shouldn’t be a reward for exercise).
  • Their macro-nutrient ratio are often imbalanced. Protein powders have way too much protein and often imbalanced amino-acids. Fat in the diet is required for the body to work properly as there are some fats the body cannot make (essential fatty acids) and we must have them from food sources. Some vitamins are only found in fat (A, D, E and K). All cells from our bodies have walls made of mostly fat and cholesterol. Cholesterol is also a precursor for sex hormones and vitamin D.
  • They took all fat and/or all sugar out of the food. What did they replace it with? generally chemicals to give it some taste, chemicals to change the texture, chemicals to preserve shelf life, and more and more…

7/ Alcohol

OK, everyone should know about this one. The link between alcohol and cancer has been well-established, and is not questioned by anyone. Many studies have covered the topic extensively. (See here, here, here, and many other…)

I’d like to also say, if you don’t have a cancer diagnostic, and if your are staying clear of those foods most of the time, there is no need to be particularly paranoid about any of the above. A couple of drinks at your birthday party is not going to give you cancer. Nor is having jam on toast on Sunday morning or having the occasional piece of cake. Balance is everything.

Honorable mentions

  • Excessive muscle meat. Our ancestor used to eat the whole animal. In some cases, they would give the muscles to their dog and keep the rest. We never evolved on a chicken breast and egg white diet. In fact, a high-protein diet is almost the same as a high-carb diet, in that the body will use the proteins to make sugar. And while a vegan diet is not necessary for cancer prevention, a healthy and balanced diet must include offal, bone broth and other cuts – and that could also help your finances.
  • Canned food. Much has been said about Bisphenol-A in the tin. There are some studies showing that Bisphenol-A increase cancer risk. It is unclear how much of this component is present in canned food, and whether it is a problem.

So what can we eat?

I will in a future post explain my broad guidelines for healthy eating for cancer patients. In the meanwhile, I encourage you to follow my Pinterest board, where I collect varied recipes to give you inspiration. Note that, although I do go through all of the recipes myself to ensure quality, a few recipes below may use a few ingredients that may be a little counter-productive. This board should be used together with the information on my website. For personalised and best advice, I offer on-line consultations and nutritional therapy programmes.  

And here is a nice visual summary:

7 common foods that may cause cancer

2 thoughts on “7 most common foods that could cause cancer”

  1. stephen de la Bedoyere


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