By Jerome Burne, medical journalist
How about this for a crazy, irresponsible idea? If you’ve got cancer, cut the amount of carbohydrates you’re eating down to no more than 25 grams a day (that’s just under an ounce) as a way of shrinking the tumour and boosting your health into the bargain. Out go pasta, rice, all sugars – cakes and biscuits of course – along with most root vegetables, and replace them with fatty foods such as cheese, meat, eggs, coconut and avocado oils.
Of course the very idea of such a switch is enough to give conventional nutritionists, not to mention oncologists, heart attacks, before they’ve even had time to condemn it as irresponsible, evidence-free and dangerous.
However there is some sensible science behind the idea, which has already been successfully tested on American patients in a small trial published last year. This found this sort of diet either slowed right down or stopped tumour growth in five out of 10 seriously ill cancer patients who didn’t want to or couldn’t have any more chemotherapy.
(Targeting insulin inhibition as a metabolic therapy in advanced cancer)
The science behind this approach involves some still controversial ideas about the links between carbohydrates, glucose, insulin and cancer. It works like this. Eating a very low carbohydrate diet brings down the amount of blood sugar in your blood (carbs get turned into blood glucose) and that in turn lowers your insulin level – when you raise blood sugar you start producing more insulin to clear it away; less carbs less insulin. So far, so conventional.
The next step is less well generally accepted, but has some good research to back it. Insulin’s best known job is to turn excess glucose into fat and put it into storage. But it’s also linked with cell growth. A closely related hormone called Insulin Growth Factor 1 (IGF1) is what children need to grow; one cause of dwarfism is a lack of IGF1. But cell growth is happening all the time as part of repair processes and of course cancer is uncontrolled cell growth.
This is why nutritional therapists regularly suggest to cancer patients that they cut out sugar and avoid refined carbohydrates. Dr Eugene Fine of Albert Einstein College of Medicine, New York, researcher who ran the study cutting carbs on cancer patients, would consider this very sound advice.
“We now have a pretty clear picture of the basic biology of insulin signally and what it’s doing in the cell,” he says. “This explains why lowering carbohydrates can have a beneficial effect on cancer as well as obesity, diabetes and general health.”
And there is another very good reason why cutting back on carbohydrates makes a lot of sense for cancer patients. That’s because tumours are well known to use up glucose at a much faster rate than healthy cells. In fact it’s why oncologists use PET scans, which track glucose consumption, to detect tumours. Less glucose means less energy is available to cancer cells to repair the damage caused by treatments such as chemotherapy.
But the cancer/carbs connection gets even more interesting. When you bring your carbohydrate intake right down to the 25 grams level for about five days or a week, something else happens. You should starting running out of energy because, as we all know, it’s glucose that provides the energy to power your muscles, brain and other organs in the body. But people who do this, like those seriously ill cancer patients or indeed people on the Atkins diet, don’t come to a grinding halt. Why?
The reason is that evolution has equipped us with a back-up system, developed over millions of years, which kicks in when there aren’t enough carbohydrates in the diet and the insulin starts dropping. After all, it’s only in the last 60 years or so that carbohydrates have become available on tap around the clock in western countries.
This alternative system, known as ketosis, makes use of the fact that we have huge amounts of another source of energy stored in our bodies in the form of fat. Low insulin levels trip a switch that allows fat to be released from fat cells (ironically a high level of insulin, which is what you get with the classic high carb/low fat diet weight loss diet, makes it much harder to get fat out of storage).
Now fat can’t be used directly by the brain or the muscles so in ketosis it gets ferried to the liver where some of it is turned into something called ketone bodies. These are an alternative energy source that can be used by all cells in the body, with one hugely important exception — cancer cells.
This is the secret of the very low carbohydrate diet that hasn’t yet been understood by regular dieticians, let alone oncologists. This is the point where the theory gets even further away from the mainstream but it’s still very plausible. The details can get complicated but the short version runs like this.
In normal healthy cells the ketone bodies are fed into the tiny power plants (mitochondria) found in every cell, which use oxygen together with either glucose or ketones to produce the body’s energy molecule ATP.
But most cancer cells have damaged mitochondria, possibly due to gene mutations, and they are also low in oxygen. So they use a different pathway that doesn’t need oxygen (so called anaerobic) to turn the glucose they are so hungry for into ATP. That pathway is less efficient, which is why they need so much more glucose.
Just how far conventional cancer treatment is from the low carb approach can be seen from the advice given to cancer patients at the UK’s Royal Marsden hospital, where the focus is totally on getting easily digestible calories into patients.
The hospital’s diet sheet does begin by suggesting that patients avoid sugary drinks but then goes on to recommend bread, potatoes, sweet potatoes, pasta, rice, chapatis, rotis, noodle; to use evaporated milk, condensed milk or cream to top desserts, cakes or hot drinks; to use extra sugar, honey or syrup with cereal, drinks, fruit and desserts and ends by saying: “Lots of puddings can be bought ready-made from your local supermarket.”
So questions about whether it might be worth cutting back on sugar and other refined carbs, let alone going for ketosis, is likely to get a pretty negative response. But there is research on the ketone/cancer connection going on in America. For more details and journal references see an article I wrote for the website HealthInsightUK.org. It’s at: