One of the most exciting things to happen for cancer patients in recent years is the growing understanding of tumour metabolism – and with it come new opportunities to bring an end to this dread disease. But it is also bringing a new threat: people are confused between what their tumour ‘eats’ and what their body needs to eat. Do you know the difference?
These are exciting times for cancer patients, as evidenced by a new wave of cancer cognoscenti who are fearlessly getting to grips with the swings and roundabouts of Krebs cycle in order to understand their own bodies and to try and fix the mess they’re in. The metabolic approach to cancer allows us mere mortals to take an active role in our own cancer care – which is a hugely empowering thing to do. There are many routes into this new territory but Jane McLelland’s ground-breaking ‘metro map’ is leading the way, providing new inspiration for patients with advanced cancer.
I’m so excited to see people moving beyond what the NHS currently offers to increase their chances of survival, it’s something I’ve advocated for decades, but I’m also worried about some of the ‘facts’ that are doing the rounds. Metabolic pathways are tricky to understand, and they don’t always work according to the text book. Moreover, there is a minefield of difference between nutrition for whole body health and nutrition for tumour starvation. So, while it’s great to see Facebook forums buzzing with cancer patients offering each other nutrition advice focussed on tumour starvation, it’s also cause for concern. Controlling nutrient delivery to your tumour cells is a lot more complicated than it sounds, and there is a real risk that in trying to starve your cancer out of existence you might accidentally do the same to yourself, or at least disable some of the ways your body is trying to heal you.
This post is an attempt to add some clarity to the subject. It’s a long read, cramming several years of study and clinical experience into an acceptable length article, so please “bear with”. And if I’m teaching you to suck eggs, forgive me.
1. The fate of macronutrients
The most important thing to be clear about is that the nutrients you put into your mouth don’t determine the nutrient supply to your tumour: they rarely reach your cells in the same format. So, for example, if you want to starve your tumour of fats, a low fat diet might not be the way to do it. Likewise, if you want to limit key amino acids (the building blocks of protein) a vegan diet might not be the best way.
The macronutrients we eat are, by and large, broken down into smaller particles for absorption and frequently rebuilt in an entirely different way when they hit the bloodstream.
- Proteins, for example, are eaten whole as ‘beef’ or ‘tofu’ and then broken down by digestion to their component amino acids (eg glutamine, asparagine) and rebuilt on the other side into the ‘you’ shaped molecules that your body needs. Rarely are they used for energy though both healthy and cancerous cells can do so.
- As far as carbohydrates are concerned, the digestible ones are broken down into sugars before crossing into the blood to be burned for immediate energy or stored as glycogen or fats if we eat too much. Again both healthy and damaged cells can easily use a range of sugars to make energy.
- Fats are eaten mainly as triglycerides and broken down during digestion into free fatty acids and monoglycerides for absorption. They are either used immediately for energy or reassembled into triglycerides and stored if we have consumed more energy than we need. There is some evidence that cancer cells find it more difficult to use fats and ketones for energy but we know that some can: more on this later in the article.
More importantly, these raw materials can all be transformed into other energy forms. We can manufacture fats from sugar, and make sugar from both proteins and fats if metabolic conditions dictate. So the food you put in your mouth can and will be made into something else to meet your metabolic needs – depending on your metabolic state. And if our diets are inadequate the nutrients we need, or our tumour needs, may be released them tissue stores.
2. The metabolic impact of macronutrients
Thus, your metabolic state is the most important driver of nutrient utilisation – more important than the composition of your diet in many ways.
Nutritionists recognise two contrasting metabolic states, normally referred to as ‘fed state’ and ‘fasting state’, or absorptive and post-absorptive. Your prevailing metabolic state is controlled by hormones triggered by food, but also by exercise, stress and environment. Insulin, triggered by eating glucose and to a lesser extent by protein, controls fed state metabolism and is associated with growth and reproduction (not something we want to encourage in tumour cells). Glucagon, secreted when glucose levels are low, when we’re hungry and during vigorous exercise, predominates during fasting state and is associated with a lack of available nutrients, or ‘nutrient sparing’ – a very important concept where cancer is concerned.
Fasting state metabolism is currently considered to be the optimal metabolic background to help your body deal with cancer, not only because it can minimise fuel supply but also because it reverses many of the other risk factors associated with cancer – like insulin resistance and other hormonal imbalances, inflammation, oxidative stress and growth signals – and triggers nutrient sensing mechanisms to switch on the body’s innate survival programmes. It has also been shown to augment the effects of various cancer treatments because it appears to weaken and sensitise the cells to drugs and toxins, and promote autophagy – the breakdown and recycling of damaged cells.
3. What does your tumour eat?
Thus, the debate concerning the ‘right diet’ for cancer needs to be wider than the question of what is fuelling your tumour. Not only because we cannot ignore the influences of the wider metabolic environment but also because we don’t fully understand what fuels tumour cells at any given moment, so using this as a catch-all cancer strategy is too risky. So I worry when I see posts that say, for example, that triple negative breast cancer is fuelled by glutamine, or prostate cancer is fuelled by fatty acids. At this stage in our knowledge of cancer metabolism it takes a brave or foolish person to be categoric about that. We know that the individual cells within a tumour are not identical: they don’t necessarily share the same gene mutations and they may not share the same fuel supply. Studies have shown that when tumour cells migrate they can change their fuel supply according to what’s available, and we know the same is true for cancers at different stages. To be on the safe side, it’s best to assume that any given tumour may be able to use a wide range of fuels, so when we focus in on fuel for tumours, it makes sense to stick to a diet that limits overall fuel supply across a range of energy substrates, rather than one particular macro.
4. About the ketogenic diet
Which brings us neatly to a discussion of the ketogenic diet, or the ‘fasting mimicking diet’ as it is also known. Ketosis is a metabolic pathway favoured by the body when glucose is in short supply, and it activates many of the same pathways as fasting state metabolism. The only thing we know that may be better for cancer than keto is fasting, which obviously has its limitations as a nutritional strategy. Thus, the ketogenic diet creates the optimal tissue microenvironment for cancer patients who also want to eat.
Like many popular diets, the ketogenic diet is much misunderstood. The biochemistry of ketosis (what Atkins called the metabolic advantage) allows people to overeat fats and still lose weight, which has led to a glut of ‘unhealthy’ keto recipes (fat bombs, bulletproof coffee, and steak with cream and cheese), and created a widespread belief that the ketogenic diet is an unbridled fat fest. Of course, you can do keto that way but you don’t have to.
Done well, the ketogenic diet is a way of training your body to use fuel efficiently and to switch seamlessly between the two metabolic states, promoting healing and repair while ensuring optimal nutritional status. This way of doing Keto is more properly called Keto-adaptation. It’s a brilliant way of matching your energy intake to your energy requirement to ensure that you’re not overeating anything and, more importantly, not overfeeding your tumour. Which makes it the ideal anti-cancer diet and the best way to accompany integrated cancer protocols, including Jane’s McLelland’s metro map.
Keto experts tend to recommend blood testing for ketone levels but for this aspect of the diet I particularly like using urinary ketone testing because it gives you a visual guide to when you are overeating. It works like this:
- carbohydrates – if you’re “in ketosis” we know your blood glucose and insulin are way down low so your tumour is not being overfed with glucose.
- fats – measuring urinary ketone output shows you if you are overeating fatty acids (and potentially oversupplying your tumour) and allows you to adjust accordingly.
This means that whether your tumour is fuelled by sugars or fats (and to be honest, most tumours are not that fussy when they are pushed) the keto-adapted diet is the best way to restrict both sources of energy and monitor what’s happening.
5. The ketogenic diet and glutamine
But what if your tumour is glutamine driven? Does the keto-adapted diet still work for that?
This is the main problem that Dr Thomas Seyfried struggled with in his anti-cancer mouse studies. When starved of glucose, glutamine can be used as an alternative source of energy by tumour cells. Since glutamine is the most abundant amino acid in the human body, and forms a major component of nearly all proteins, it is difficult to restrict. Quite simply, if you try to restrict glucose and glutamine by reducing your dietary intake, your body will start to eat you instead – to get at your stored glutamine supply. This inconvenient truth has led many people to abandon the ketogenic diet as a false dawn. But are they right?
It’s correct that studies have shown that glutamine is readily broken down to make glucose in fasting state human metabolism when glucose is scarce. On the other hand, a meta-analysis of studies suggests that the ketogenic diet tends to protect muscle mass because ketone bodies can be used by brain and muscle tissue in place of glucose. Therefore, since ketogenic diets preserve muscle mass better than fasting it follows that they are more likely to limit glutamine supply to tumours, and may be a better choice than other diets (and better than fasting) for restricting glutamine.
6. Nutrition and repurposed drugs
If the aim of your anti-cancer diet is to reduce tumour uptake of any of the major macronutrients (or their component molecules) then the keto-adapted diet, or nutrient sparing diet, is the best way to achieve that nutritionally, based on current research. Intermittent fasting or time-restricted feeding can combine well with this approach to provide synergistic support for medical protocols including chemotherapy, radiotherapy AND repurposed drugs.
Jane McLelland’s protocol is pure genius, zeroing in on the individual metabolic pathways that cancer cells use and healthy cells don’t. But the metro map doesn’t scale up to provide a nutrition blueprint for the whole body. Any anti-cancer diet needs to focus primarily on rebooting and rebalancing the body’s systems to awaken the healing response of the whole body, and the ketogenic diet is the best way we know of creating a cancer-hostile tissue environment.
As far as I’m aware, I was the first nutritional therapist to write about the ketogenic diet for cancer – harnessing ‘fasting state metabolism’ to promote anti-cancer pathways. The Dissident Diet is a plant-based ketogenic programme that forms a healthy cornerstone of many integrated cancer protocols, and you can download it here for your Kindle.
It must be said that no one has all the answers for cancer at this point in time, and the information shared here may be confounded by future research – but I think any future understanding is likely to build on what we are learning rather than turn it on its head. Thank you for staying with me through such a long and convoluted post. I hope it has helped you make up your mind about the diet you want to follow and I wish you well in your quest for health.
My specialist area is breast cancer and if you are struggling to improve your health after diagnosis I’d be happy to help. Please book a free exploratory chat.