Sugar Fuels Cancer Cell Growth: The Warburg Effect

I know I’ve written a lot about sugar recently, but something pretty interesting popped up on my radar the other day. I was reading Perfect Health Diet (a very well researched and logical book) and came to the section about macro-nutrition and the perils of hyperglycemia (high blood sugar). And while the whole section is really interesting reading (which I’ll probably come back to at some point), the heading “Hyperglycemia Promotes Cancer Progression” caught my eye. Cancer has been on our minds recently.

That section of the book says:

Cancer cells, like bacteria, cannot burn fats: if mitochondria in cancer cells are allowed to burn fats, the cell dies.

So cancer cells are dependent on glucose for energy. This is known as the Warburg Effect, after Otto Warburg, its discoverer (and subsequent Nobel Prize winner).

Higher blood glucose levels provide more fuel to tumor cells, stimulate their proliferation, and hasten the progression of cancer. If high blood glucose induces cells to start burning glucose, it may actually cause cancer by switching them from normal metabolism to tumor cell metabolism.

WHAT?!?! I was really surprised to read that. So I did some more digging to see what the Warburg Effect is about and why I’d never read about this before (see additional links at the bottom of this post). Among the more readable descriptions I found, the Wikipedia page for the Warburg Effect had an interesting introduction:

In oncology, the Warburg effect is the observation that most cancer cells predominantly produce energy by a high rate of glycolysis followed by lactic acid fermentation in the cytosol, rather than by a comparatively low rate of glycolysis followed by oxidation of pyruvate in mitochondria like most normal cells.[1] The latter process is aerobic (uses oxygen). Malignant rapidly-growing tumor cells typically have glycolytic rates that are up to 200 times higher than those of their normal tissues of origin; this occurs even if oxygen is plentiful. [Emphasis mine.]

Wow. Cancer cells are sugarholics!

Going a bit farther, there’s an interesting study that looked at some data to quantify this a bit. Prospective study of hyperglycemia and cancer risk (which was cited in the book) looked at a bunch of data to see if there was a correlation:

In the Västerbotten Intervention Project of northern Sweden, fasting and postload plasma glucose concentrations were available for 33,293 women and 31,304 men and 2,478 incident cases of cancer were identified. Relative risk (RR) of cancer for levels of fasting and postload glucose was calculated with the use of Poisson models, with adjustment for age, year of recruitment, fasting time, and smoking status. Repeated measurements 10 years after baseline in almost 10,000 subjects were used to correct RRs for random error in glucose measurements.

When they say “postload plasma glucose concentrations” they’re referring to an after meal blood sugar test, much like diabetics routinely perform on themselves.

Their conclusion? Simple and to the point.

The association of hyperglycemia with total cancer risk in women and in women and men combined for several cancer sites, independently of obesity, provides further evidence for an association between abnormal glucose metabolism and cancer.

In science speak, they’re saying the data is pretty clear. I haven’t read the paper myself (yet) but the book says the following about the study’s findings:

…people who had fasting blod sugars over 110 mg/dl or who scored over 160 mg/dl two hours after a glucose tolerance test had much higher rates of cancer.

Presumably when I get a copy of the paper, I’ll see exactly what “much higher” means, but the fact that conclusion says the study “provides further evidence” means we can assume it was significant.

Another study is referenced by Dr. Bass on his Cancer & The Warbug Effect page where he discusses ketogenic (very low carb) diets as a possible tool to fight cancer:

Thomas Seyfried (the same Thomas Seyfried mentioned in the article) has shown that ketogenic diets in animals and humans can stop malignant brain tumors. There is no reason to believe they wouldn’t work in humans as well.

A group in Germany is looking at such diets in a small pilot study. Patients are only admitted to the study when all standard therapies – chemotherapy, radiation, surgery, etc. – have failed and they have basically been sent home to die. In fact, a few were so far gone that they died within the first week of starting the study. You couldn’t ask for a study group more destined for failure, but, according to the Times article

The good news is that for five patients who were able to endure three months of carb-free eating, the results were positive: the patients stayed alive, their physical condition stabilized or improved and their tumors slowed or stopped growing, or shrunk.
If you understand the Warburg effect and the metabolism of cancer cells, it’s easy to see why this therapy works, even in patients who at at death’s door. Since the cancers can use only glucose, and since glucose is made in the cancer cells slowly and inefficiently, the cancer cells have to rely on outside glucose to provide nourishment for their rapid growth and replication. People on very-low-carb diets produce ketones, which take the place of glucose in other cells that can use these ketones for fuel. But cancer cells can’t use the ketones since ketones have to be burned in the mitochondria, which are dysfunctional in cancer cells. If you can keep blood sugar low, then growth of the cancer cells may be held in check long enough for the body’s own previously overwhelmed immune system to rally and beat the vulnerable cancer back.

Diabetes and cancer have both taken off in the last few decades. It’s interesting to see how sugar is a major (if not dominant) factor in both. It’s too bad this hasn’t been more widely reported in by the news media.

See Also:

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About Jeremy Zawodny

Jeremy is a software engineer for craigslist and enjoys flying and cooking in his spare time. He lives in the Sierra Nevada foothills (Groveland, California) with his wonderful wife Kathleen and five cats. He also reads far too much about nutrition, food, health, and biology.

2 thoughts on “Sugar Fuels Cancer Cell Growth: The Warburg Effect

  1. Did you see any references as to how often this happens? eg do people with blood glucose over 160 get cancer 100% of the time or .1%? These reports of various correlations/causations tend to leave out details like that in the summaries which makes it harder to see just how pronounced the effect is. (I’m not sceptical or denier, just curious.)

    My favourite statistical measurement is NNT – number needed to treat. The wikipedia page is quite nice with a good example of a cholesterol drug. There is a BusinessWeek article titled “Do Cholesterol Drugs Do Any Good?” which has lots more detail and analysis around NNT and drug effectiveness.

    Looping back to your blog, generally the NNT is quite high for many medical treatments today (ie they don’t really help many people) while lifestyle and diet changes tend towards lower NNT (ie they do benefit most people, but not all). In short the societal belief that you can just take a pill to fix things is very wrong – you really do need to work on diet and lifestyle.

    I have diabetes and take metformin, which lowers blood sugar and digestion resulting in sugar by about a third. If you search for [metformin cancer] you can see lots of results of correlation of lowered cancer rates in those taking metformin. The few numbers I could find indicated about a third reduction, but with very small population sizes.

  2. It certainly looks like the Atkins diet can be of benefit for patients with canc er. The big risk is avoidance of heart problems which may be the other side of this coin. Determining the numbers for those using a ketogenic program and the actual contrasting numbers for those who continue with the typical American diet is an important next step in informing the public. Numbers do count for many. Those with a strong genetic inheritance of cancer may experience benefits prior to active, advanced disease. Those who have a heavy inhertance of vascular and heart disease may want to be cautious. Of course, this issue is one , not all of the dietary issue.

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