Is Cancer Really Caused By Food?

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For decades, doctors and scientists have thought that it was chromosomal damage that caused cancer. It was widely also assumed that in addition to exposure to carcinogenic compounds, cancer was caused by genetic predisposition. But what if there was something far more innocuous that led to the development of cancerous tumors? What if it was simply a matter of eating the wrong things?

According to Dr. Gary Fettke, an orthopedic surgeon and nutrition expert based in Australia, that may be exactly the case. He and a growing number of other doctors are leading a movement in reviving the long forgotten metabolic theory of cancer.

This conflicts with the widely held belief that cancer was largely genetic in nature. The Cancer Genome Project failed to find a “smoking gun” link between cancer and genetics. So if cancer is happening in people with no genetic predisposition, what else could be causing it?


What Role Does Diet Play in Causing or Preventing Cancer?

It was traditionally thought that cancer was triggered by genetic defects in the cell nuclei, which then triggered cancerous growths. Mitochondrial damage was also observed, but this was thought to occur later in the process. The metabolic theory of cancer turns this on its head, claiming that it is actually mitochondrial dysfunction that happens first, which then leads to the nuclear genetic mutations associated with cancer.

But what do mitochondria do in the first place, and what could cause them to malfunction and lead our bodies down a cancerous path? Mitochondria are the components of our cells which are responsible for converting food into usable energy. The metabolic theory of cancer holds that providing the wrong fuel to the mitochondria in the form of specific, unhealthy types of foods can cause them to produce cancer.

What’s amazing is that this isn’t even a new idea; it was first proposed nearly 100 years ago by Dr. Otto Warburg. He believed that glucose metabolism affected the functioning of mitochondria and played a role in the development of cancer. This wasn’t some fringe idea. In 1931, Dr. Warburg actually won a Nobel Prize in Physiology or Medicine for his discovery. The experts agreed that cancer cells had different energy metabolism compared to normal, healthy cells.

Normal cells can produce energy using either glucose (from sugar and carbs) or ketones (from protein and fat). Cancer cells, however, are different; they can only make use of glucose to fuel their growth. Normal cells working with glucose convert most of it into adenosine triphosphate (ATP), which is the molecular compound of energy useful to the body. The rest is used for cell growth. Cancerous cells do the reverse. The majority of the glucose is diverted toward cell growth, and the remainder is used to produce energy. However, there are other materials required for cell growth, like proteins and fatty acids. Since the cancer cells cannot use ketones consumed through dietary sources, they instead “steal” them from surrounding cells. This, some proponents of the metabolic theory maintain, is how cancer metastasizes around the body.

Free radical compounds produced by oxidation may be the primary cause behind this process. “So if we can find the source of the oxygen free radicals,” argues Dr. Fettke in his lecture Nutrition and Cancer – Time to Rethink, “we may be on to something.”


Inflammation is one of the primary causes of free radical production in the body. The process of “burning” glucose for fuel releases some oxygen free radicals, but it doesn’t account for all of it. What causes the inflammation?

One of the biggest sources of inflammation is the modern Western diet, which is filled with processed foods rich in sugars as well as unhealthy and unnatural compounds. It is widely accepted that simply eating whatever and not making a conscious effort to choose healthy foods will lead to obesity and many other health issues. Many scientists and doctors acknowledge the highly inflammatory nature of the modern diet, but until recently, not many have connected the dots between food-induced inflammation and cancer.

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