Does Sugar Cause and Promote Cancer?

keto food

A low carb diet for diabetes makes sense because it rapidly reduces the amount of glucose and insulin in the blood, and diabetics have a problem with controlling both.

The link with cancer is not so obvious because cancer is supposedly the result of rogue gene mutations but this ignores how a healthy cell converts to a cancer cell in the first place.

PET body scans that tell you where your cancer is, also reveal the glucose connection. That’s because the way these scans identify cancer cells is to give you fluoridiated glucose (the tracer) which accumulate in cancer cells precisely because of their hunger for sugar to survive.

Cancer cells are voracious for sugar to fuel their rapid growth, so starving cancer seems a good strategy.

Does sugar cause and promote cancer?

There is compelling evidence that a high sugar, high GL, high carb diet increases the risk of developing cancer and provides the fuel for cancer cells to grow faster. But could too much sugar – and an increased glycemic load – actually cause a normal cell to become cancerous? In other words, is sugar a carcinogen? Professor Mina Bissell from the University of California, believes that it is: ‘A dramatic increase in sugar intake could be a cause of oncogenesis,’ she says. Bissell bases her theory on the fact that a protein called GLUT3 is required to move glucose into cells, and it is found in very high concentrations in cancerous breast tissue. This is yet another example of how cancer cells are magnets for sugar.

Bissell’s research revealed that pushing up GLUT3 production in healthy cells turned them cancerous, while dampening it down in cancerous cells switched off the cancer-causing genes. The result was that the latter cells became healthy again, even though the cancerous mutations remained. Nevertheless, all of the major cancer charities still refuse to acknowledge the link between high sugar/high GL diets and cancer. An example of this is Cancer Research UK, who, despite recently promoting obesity as a significant risk factor for cancer, still claim, ‘There’s no evidence that following a “sugar-free” diet lowers the risk of getting cancer, or boosts the chances of surviving if you are diagnosed.’66 There is, however, clear evidence that a low GL diet, which effectively means consuming less sugar, does substantially reduce risk.

We can only hope that this current position will change as the medical profession starts to wake up to the fact that what you put in your mouth, especially sugar and fast carbs, has a big influence on cancer risk.

Change Your Diet to Reduce Your Risk

Recent research consistently links the increased risk of developing cancer to environmental factors, including diet and lifestyle. According to the World Cancer Research Fund, 30 to 50 per cent of all cancers are preventable – by not smoking, changing your diet and keeping physically active.

Does the ketogenic diet have a part to play in cancer treatment?

Cancer cells rely on sugar for their survival because they find it difficult to extract energy from ketones. Ketogenic diets are recording some staggering results against hard-to-treat cancers, such as brain glioblastomas and lng carcimonas. However, do not assume that all cancers will therefore respond to a ketogenic diet, which swaps glucose for ketones as fuel. Many cancers prefer sugar as their fuel but some thrive on protein or even ketones. Prostate cancer is more ketone friendly

Nevertheless, public health authorities around the world continue to advocate conventional chemotherapy as their main – and often only – treatment for cancer.
So, are they ignoring a simple low carb solution that might stem the exponential rise in cancer that has occurred over the last forty years?

Case Study: Raffi’s Story

In 2007, Miriam Kalamian, an American business woman, scoured the internet for something that might help her seven year-old son Raffi, who was suffering from seemingly terminal brain cancer. She came across an article by Dr Thomas Seyfried, a researcher at Boston University who reported that he had slowed down or even reversed the growth of tumours in lab animals by feeding them a high fat, ketogenic diet. This involved drastically reducing the animals’ intake of carbohydrates, which reduced their level of blood glucose and soon pushed them into ketosis. Crucially, it seemed that those little packets of energy that are so valuable for the brain and the muscles – ketones – were useless to the tumours. They needed glucose to grow . . . and there wasn’t any!

It was a very long shot, but Raffi had already undergone two unsuccessful operations and he was responding very badly to a new cocktail of chemotherapy. The tumour was still growing, putting increasing pressure on his brain. He was constantly nauseous, fatigued and unable to focus. One morning, he collapsed and started talking gibberish. ‘Raffi desperately needed something different,’ said Miriam. ‘After all, what did we have to lose?’

Miriam was a pioneer when she put Raffi on a high fat diet. In effect, she set off alone with little in the way of guidance, back-up or advice from the oncology establishment. However, there was a ray of hope. Another group of clinicians had already prescribed high fat diets for children with severe epilepsy, and the results were remarkable, with 80 per cent of the patients experiencing a reduction in seizures. So, high fat diets had proved effective in the treatment of seriously ill children, but there was no hard evidence that it would have a similar impact on Raffi’s brain cancer.

Indeed, many self-proclaimed experts soon issued dire warnings: Raffi would get insufficient nutrients from the new diet and his ketone levels would increase, which could kill him. Amazingly, though, within three months, Raffi’s tumour had shrunk by 10 to 15 per cent. Meanwhile, his quality of life improved dramatically and he returned to the talkative, energetic little boy he had been before the illness. His remarkably open-minded oncologist had predicted that he had just a one-in-three chance of responding and swimming at our favourite hot springs.’

Nevertheless, more than a decade later, treating cancer with high fat diets is still considered beyond the medical pale. Indeed, the UK’s largest cancer charity terms the approach a ‘myth’. Yet, thousands have followed Miriam’s lead, and there are now even some guides to help you on the journey. Miriam herself was so impressed by the results that she enrolled in a nutrition degree and has spent the last ten years dispensing information to others. Her detailed and compelling book – Keto for Cancer – was published in 2017.

The official line of the cancer charities and the medical establishment is that there have been no rigorous scientific studies into the treatment of cancer with high fat diets. But this merely begs the question: why have there been no trials, especially as the approach’s efficacy in the treatment of epilepsy has been well known for more than a century? Belatedly, though, there are some signs that the high fat diet might be inching into the mainstream. For instance, several cautiously favourable pieces of research were published in the summer of 2017, including one which found that a common cancer drug was more effective when mice were put on the diet.25 One of the drug’s usual side-effects is raised blood glucose, but the high fat diet counteracted this and the tumours shrank as a result. Even the NHS has admitted that the approach is ‘tolerable and feasible’, and research among patients suggests that most would be willing to participate in trials.

When Raffi started on the diet, a major obstacle was the official dietary advice, which stated that cancer patients should avoid fat and fill up on carbs instead. However, as we have seen, recent reports of the high fat diet’s success in reversing diabetes should SY prompt a rethink about its use among cancer patients. This is because both disorders are linked to high levels of glucose and insulin in the bloodstream, and diabetes itself is a significant risk factor for cancer. Then there are the individual success stories.

Case Study: Charles’s Story

One UK patient – let’s call him Charles – developed a ‘vascular highly malignant brain tumour’, known as an anaplastic astrocytoma, in 2013. The chemotherapy left him feeling terrible, so he decided to abandon it and turned to the high fat diet instead. Young, fit and a personal trainer with a degree in sports nutrition, he felt it was worth the risk, although his oncologist warned him that the diet would have no effect on the tumour, and cutting out carbs would be dangerous because his brain needed glucose to function. Charles ignored the advice and began the standard ketogenic combination of reducing his intake of carbs and replacing the lost calories with low sugar fruits and vegetables, coconut milk and oil, nuts, cheese, avocados and so on. Unfortunately, this diet left him feeling ‘absolutely awful’: his migraines and seizures – common side effects of brain cancer – grew so bad that he remained in bed for months.

However, Charles didn’t give up. Indeed, rather than going back to chemotherapy, he had the courage to try an even more high-risk strategy. Having searched through the internet, he learned that his symptoms might be due to a reaction to salicy lates in the plant foodstuffs he was eating, so he cut all of them out immediately. ‘The result was amazing,’ he says. ‘The headaches and seizures reduced almost at once.’ But this left Charles with a major challenge: how could he replace what had become the staples of his diet? After further research, he concluded that he could meet all of his nutritional needs with animal-based foodstuffs.

Thereafter, Charles continued to tinker with his diet until he achieved the best possible balance for his personal needs. At first, he relied on bone broth and organ meats (liver, kidney, brain and sweetbreads), which kept his headaches and seizures at bay while his brain scans continued to show improvement. Then he took another leap: ‘I added insects to my diet, along with some MCT [medium-chain triglyceride] oil, which the liver can turn directly into ketones.

I’ve tried other versions over the last few years, but this particular zero carb ketogenic diet is the only one that has given me near-complete symptom relief. The ingredients include two to four eggs, liver, lamb’s brain from a local sheep farmer, sardines or mackerel, bone broth, crickets or other insects, such as wax worms, bacon or red meat with Cheddar cheese.’

Many people would find it impossible to follow such a diet: it comprises over 200g of fat and 70–75g of protein each day.

Moreover, most nutritionists would probably consider it dangerous. But it works for Charles, and it illustrates just how flexible the ketogenic diet can be. And he is still experimenting. For instance, he recently introduced raw cacao, a form of MCT called C8 from coconut oil and even home-grown sprouted broccoli (which is rich in an anti-seizure compound). He also fasts every few months.

The Oncologists’ Response The lack of scientific trials and the persistent assumption that cancer cannot be beaten or even alleviated through diet mean that most oncologists refuse to regard the high fat diet as a serious treatment option. However, Matthew Williams, a consultant clinical oncologist at Charing Cross Hospital in London, is something of an exception to this rule. ‘There is evidence that, when combined with existing treatments, such as radiotherapy, it can improve them,’ he says. ‘And it may reduce side-effects.

But the only real data for that comes from rats. This is why I’m interested in running a human trial – to see if it translates. We have to be cautious about making claims because the rat brain is a poor model for human brains, and what works for rats often doesn’t benefit humans. I certainly wouldn’t recommend it was used on its own.’ But what about the individual success stories, such as Charles? ‘The trouble is that they are the only ones we can talk to,’ says Williams. ‘There are others who followed the diet and died. Usually, we don’t know if they did better or worse. The diet clearly doesn’t work for everyone, but we don’t yet know if it helps ten per cent or ninety per cent.

That means we have to be very careful about who we put on it, because it is not a minor intervention. It involves a whole shift in your lifestyle, especially if you are in a family, and there are side-effects.’ At the time of writing, Williams was planning to address these issues by launching a small-scale trial on tolerability and quality of life. While this is certainly a welcome development, it is unlikely to convince his more sceptical colleagues, and we are probably still a long way from an irrefutable, large-scale study.

‘In patients with aggressive brain tumours, a full trial to see if it improved survival would need about six hundred patients for the results to be considered reliable. That will be hard to do,’ explains Williams. Scepticism about the benefits of the diet among the oncology establishment isn’t just related to the lack of trials. It also directly challenges conventional wisdom that cancer begins with random genetic mutations.

More research is certainly needed in this area. On the other hand, Valter Longo, Professor of Gerontology and Biological Science at the University of Southern California, found strong evidence that the high fat diet can significantly reduce the side effects of chemotherapy. And there is mounting evidence that it has an impact on neurogliomas (also called glioblastomas) – particularly aggressive brain cancers. This could be due to the fact that brain cells function particularly well on ketones, whereas cancer cells find it difficult, if not impossible, to derive energy from these compounds.

Extracts from The Hybrid Diet (Piatkus, 2019). For more details of research in this area please see the book. References for the book available on the 5 Day Diet page under The Science and Testing.

Upcoming Podcast

Listen to my upcoming podcast with Jane McLelland, stage 4 cancer survivor and author of How to Starve Cancer, on Friday 6 August.

Faced with grade 4 lung cancer secondaries (there’s no grade 5), my podcast guest Jane McLelland sharpened her scientific mind and delved deep into how to starve cancer and kill it, which she did twice when it returned as leukemia. Her just out new second edition of her book ‘How to Starve Cancer and Kill it with Fferoptosis’ is, in my opinion, a masterpiece representing a paradigm shift in understanding how to kill cancer.

Professor Thomas Seyfried, a hero of mine who has the best success with aggressive brain cancers, describes it as ‘A monumental accomplishment. A strategy for surviving advanced cancer regardless of the tissue or organ involved. Jane has done a great service to mankind!” I agree with him. In vibrant health, this former chartered physiotherapist has charted the murky water that too many people find themselves in and found a way through.

My Hybrid Diet

Inspired by the research and case studies, in 2019 I wrote the book The Hybrid Diet, with award-winning medical journalist Jerome Burne explaining the theory and some practical information so you could create your own keto diet combined with a low GL maintenance diet.

Unlike the Atkins diet, we focus on all kinds of fatty foods not just meat so suitable whether you’re carnivorous or vegetarian – but without carbs. Think avocado, halloumi and salmon. We show you how to enjoy slow carbs so you don’t have to shun all pasta and bread. The Hybrid Diet explains why, when and how to switch, and provides you with the simple and delicious recipes you need to do it.
For example, on a high fat day you can start your day with a Hybrid Latté made with no-carb almond milk, almond butter, coconut butter, coffee, cacao and cinnamon and lunch on a delicious pesto butter sautéed spinach with salmon.

On a slow carb day you could have a slice of carrot and walnut cake as a snack and, for dinner a big bowl of chestnut and butterbean soup with oat cakes, both made in 5 minutes.

Switching regularly between slow carbs and high fat you become ‘carb adapted’ – craving less sweet foods, and ‘fat adapted’ – able to burn and derive energy efficiently from fat. It’s like nutritional yoga as your metabolism becomes more flexible.

The 5 Day Diet

I followed up The Hybrid Diet with the more prescriptive 5 Day Diet in 2020.

If you think you’d like to try a diet based on this new science, and if you are a cancer patient and want to discuss them with your health practitioner or nutritionist – these books are available from HOLFORDirect.

The 5 Day Diet is FREE with the supplement combo needed to get cracking with the diet – or the book is available on its own.


If you want to read what others who have done the diet have to say about it you can read their testimonials here.