This is one of the most common questions I get! I’ve written on it 6 times so far (I guess this makes 7!). And it’s not just me. It’s oncology dietitians and treatment center employees everywhere!
Here’s the bottom line:
Every cell in the body requires glucose for fuel, including cancer cells. So sugar does feed cancer. BUT, sugar also feeds the rest of your body and you cannot pick and choose which cells get what nutrients/fuel. For those who are going through treatment, remember that your healthy cells need energy especially during this time. Avoiding sugar completely will not help treatment, but it could leave your healthy cells low on energy.
At this point, it has not been shown that eliminating dietary sources of sugar and carbohydrate actually results in slower growth of tumors. It does result in your body having to work extra hard to make the glucose that it needs to function.
Here are my previous articles on the topic:
- The Mystery of Sugar: How Your Body Digests It and the Difference Between Simple Sugars and Complex Carbs.
- Does Sugar Feed Cancer? It’s not a simple question!!
- Insulin, Sugar and Cancer: The Facts
- The Connection Between Diabetes and Cancer
- Does Sugar Feed Cancer? Part II
- Does Sugar Feed Cancer? Part I
Recently, our national group of Board Certified Specialists in Oncology Nutrition had a discussion about how to address this question when patients ask. Angelea Bruce, RD, CSO, CNSC, oncology dietitian for Sharp Healthcare in San Diego, uses this analogy for helping her patients understand. I REALLY like it!!
Cells use glucose the way cars use gas!
“Every cell in the body requires glucose for fuel, including cancer cells.
We get glucose from all carbohydrate foods. If we don’t eat enough carbohydrates, the cells (normal and cancer) still demand a source of glucose and the body makes it by breaking down protein from our muscles and immune system. In order to minimize muscle loss and immune compromise, we need to provide a consistent source of carbohydrates through the diet whenever possible.
Cells use glucose the way cars use gas. With normal driving, our car uses varying amounts of gas depending on whether we are idling or accelerating. Normal cells divide at varying rates, some every 3 days and some every 3 months, or more. During cell division, more glucose is used, much like an accelerating car uses more gas. But after cell division, it returns to more of an idling state, using less glucose.
Cancer cells are like cars with the accelerator stuck to the floor, using glucose at high rates, because they are dividing at much faster rates than normal cells. If you still want to be able to drive your car, you cannot fix it if it has the accelerator stuck down simply by letting it run out of gas. For the same reason, you cannot starve cancer cells of glucose because you will also be depriving your healthy cells of fuel. The cancer cells are much more tenacious than the normal ones and will persist at the expense of the rest of the body.”
Obviously, we don’t want people to over consume simple sugars. It is a reasonable goal to balance carb portions with protein and fat in order to minimize high circulating levels of insulin and IGF-1. And of course, getting most of your carbs from whole grains, vegetables and fruits is a very nutritious way to eat, as opposed to getting most of your carbs from added sugars.
Check out my PRINTABLE Handout With This info!
Check out my podcast on this topic! EPISODE 1 – DOES SUGAR FEED CANCER?
Read More!
You can also read more in this Cure Magazine article: The Sweet Truth: Does Sugar Feed Cancer? and this other Cure Magazine article that covers even more in depth: Sweet and Vicious Sugar.
If you’re not convinced at this point, I’m afraid that there’s no other evidence I can present that would change your mind.
Usually, I find that the “Sugar Feeds Cancer” myth originates or is purported through the alternative therapy circles, which can be a dangerous place to put your trust. This article gives an oncologists view of some of the treatments that patients choose based on claims of “Natural Healing.” I found it to be very true to my experience working as a practitioner somewhere in between clinical cancer care and integrative therapies.
It’s a sad day when a patient chooses a therapy that’s not been proven (or has been proven to NOT work), over a traditional treatment that has a good chance of extending the person’s life.
Your best bet is to combine the evidence-based cancer treatment with things that promote the health and well-being of your whole body. And by the way, those things that promote health and well-being should not cost you a fortune.
– Julie
Then why does a pet scan work? You starve yourself of all carbohydrates, including sugar for 48 hours before the scan. Then you ingest a tracer bound to sugar which the cancer hungrily devours because it has been starved of sugar and voila, you can see where the cancer is because that is where the sugar went. I also note that you made no mention of the extensive research done on the suppression of the immune system that occurs when you consume sugar. Nor did you mention the known fact that sugar feeds candida and that there is a high correlation between cancer and candida and the fascinating research being done there. You are not doing cancer patients or anyone else a service by steering them to sugar.
Hi Kaiulani,
Thanks for taking the time to comment. Typically, you don’t have to avoid carbs for an entire 48 hours prior to a scan. Also – it sounds like it might benefit you to read the CURE articles that were linked in my post, and they explain in more depth regarding how a PET scan works and the metabolic rate of cancer cells vs. normal cells. Also – if you want to hear more about how food impacts immunity, you can watch my video on Nutrition for Immunity, where I cover what types of eating patterns enhance the immune system and what eating patterns tend to result in more inflammation. I definitely address the difference between simple carbs and complex carbs. When it comes to candida, there is not strong evidence to even measure growth in the body, much less how it grows in response to any particular eating pattern. Finally, I don’t think that I am steering anyone towards excessive sugar intake. My message is consistently one of moderation and plant based eating. – Julie
Excellent response.
Thanks! 😀
Well said!
Thanks!!! 🙂
I hear this all the time from my patients!! I have really enjoyed reading your artciles. I am an outpatient RD working in the Oncology setting. I am still fairly new (about a year and a half) here, so I am still focusing on the basics. Really enjoy all of your information with references though!
Glad you’re enjoying them. I remember being new to oncology and wondering why on earth this kept coming up! Here I am 10 years later and can’t believe it’s hanging around. It was around long before I started and I’m sure it will stay around long past my career. Oh well. Educate one patient at a time and we’ll at least be helping them feel less anxious! 🙂
I had vulva cancer twice. Is there anything diet wise I can be doing to help firght this cell from coming back? Thank-you Diane Nalitz
Hi Diane – thanks for your comment. I recommend a plant based diet with 4-5 cups of fruits and vegetables a day, quality protein (plants or meat/dairy) and complex carbs. You might want to check out my webinars for more!
What about to ketogenic diet? My family did a lot of research into that and started this diet to aid our young son who is battling stage 3 melanoma.
There is some preliminary data showing that ketogenic may help certain types of cancers, but it’s very restrictive so it’s difficult to follow it and still meet key nutrient needs. It’s essential to work with a skilled dietitian if you try it. I do not recommend it since there’s not much data on it and because it’s so hard to follow. Unless it’s absolutely necessary, I prefer a more moderate approach to nourishment that allows for more freedom in food choices and therefore more enjoyment in life, in general. 🙂 julie
It’s not hard to follow. I’ve been doing it for years and have had no outbreaks of psoriasis/RA since.
It is a very easy sustainable diet. I am healthier now than when I was eating the diet you recommend, plant based, healthy protein, and complex carbs. That diet only fueled uncontrollable cravings and kept my diabetes progressing. Instead of saying how bad the ketogenic diet is why don’t you try it yourself for a couple of months and see for yourself.
I need help as a care taker for my daughter and cousin, both are extremely thin, want to increase diet to gain, very sad about their appearance, hard to get them to socialize at times, sleep most all day, little exercise, in constant pain, what steps to move towards, doctors just up dosage of pain meds, etc so just need high calories diet for starters, thanks God bless
Hi Myrna, I would try to find a dietitian in your area to work with. Ask their doctor for a referral, or you can try the “find an expert” page at http://www.eatright.org. They are lucky to have you helping them. – Julie
Yes, of course our bodies run mostly on glucose, and glucose is a sugar. But what do you really believe people are taking away from your sound bite? And why did you choose a picture of a sweet shop to go with the headline? When most people hear sugar, they think about things full of sucrose and fructose.
When this headline scrolls past on their facebook feed, it’s the only message most people will get, because they won’t read further about glucose and complex carbohydrates, they’ll just say, “yay, sugary treats are good!” and pass it on. Maybe promoting your blog is more important to you than helping people make choices that will keep them healthy. Sad.
I appreciate the time you to look to comment. Actually I wrote this in response to many patients who were given well intentioned, but extremely inaccurate information from someone who told them this. They came to me confused and concerned and through education, they felt confident in making good health decisions for themselves. I believe that nutrition advice is not a simple sound bite. Promoting my blog is not one of my strategies, however helping people make choices that nourish their bodies and enrich their lives is what I have done for the last 10 years, and will continue to do. My blog is part of a non profit agency and I have no advertisements on it.
Ah, it seems that this is written for someone who has decided to eliminate all carbohydrates in order to try and stop cancer growth? In that case, a picture of fruit and grains (instead of a sweet shop) would be more appropriate for your message.
I apologize if I misread your motives. I do still feel that this headline/photo combination is irresponsible, because of the dangerous message that casual facebook skimmers take away. Metabolic syndrome is such a widespread problem, and it really upset me to see what looks at first glance like a promotion of sweets coming from a nutrition blog.
Yes, I can’t tell you how many times over the last 10 years someone has asked or commented that “sugar feeds cancer” and they are being told this from a variety of different sources. It’s probably at least once a week! I definitely wrote this to help explain how carbohydrates work and that simple sugars are one type. I have had clients come to me attempting to eliminate all sources of sugar (healthy or not), as a result of this statement and I have to help them understand how the body works. You can tell how common it is by how many times the article has been shared and by the responses from survivors who share it. They’ve been told this so many times they want to scream! 🙂
My goodness… Really feeling like the information here isn’t correct; or at least the subject line isn’t really helpful.
When glucose levels are low, most normal cells will switch to using ketone bodies for fuel. Ketones allow normal cells to be metabolically flexible. Even the brain and nerve cells, which are heavily dependent on glucose, can utilize ketone bodies for fuel. Cancer cells have dysfunctional mitochondria and limited metabolic flexibility. They can’t access mitochondrial energy pathways so they can’t utilize ketones, which leaves ONLY the pathway of glycolysis for them. And when glucose is very low in blood (in a ketogenic state), then this CAN have the effect of starving cancer cells, and preventing metastasis. Cancer cells run out of fuel without the presence of glucose – healthy cells switch over to using ketone (fat) bodies. (This from an e-book by Ellen Davis, MS – concepts from Seyfried, Warburg, Christofferson, etc.).
This stands in direct contrast to what you wrote above… Healthy cells can switch to ketone bodies for fuel, where cancer cells cannot. If that’s the case, couldn’t a low carb, even ketogenic diet be incredibly promising?
And if a low carb, ketogenic diet could be promising, even therapeutic, then wouldn’t the next step up the ladder be to assume that sugar/glucose is problematic in cancering processes (at least those 95% that are PET positive).
Even though you shared the caveat at the end about people obviously avoiding simple sugars, I’ve now seen, very unfortunately, this article posted in different online cancer communities, and people using it as a “See! Sugar doesn’t feed cancer! I was right! My [clueless] oncologist was right! Look at the headline! Now I can run and eat my cake!”
I know that’s not the intent of your writing here, but the subject line lends itself to that… and it’s unfortunately happened.
I saw you mention elsewhere that idea that yes, sugar feeds cancer, but also healthy cells (and we need sugar for healthy cells and energy) – a basic summary. I’d love your thoughts and input on the concept above, that healthy cells can run on ketone bodies, not glucose? Where cancer cells cannot? Also, the concern for a patient in treatment is not weight loss, it’s cachexia, and there’s a huge difference. So often doctors are worried about weight loss, and encourage massive caloric intake, but conversely, things like intermittent fasting can be immensely therapeutic, even during chemo. Not only causing healthy cells to sort of hibernate, therefore less side effects, but also can almost uncloak cancer cells.
I’d love to hear your thoughts here… And hope you’ll consider at least changing the subject line which I think could have the opposite effect you’d want?
In response to this: couldn’t a low carb, even ketogenic diet be incredibly promising? Actually, even if you consume a low carb, ketogenic diet – what would be the blood sugar level you are going for? And what are the risks you are taking to get that level? In theory this sounds good, but research has NOT proven it to work this way in the human body. You can cut out all the carbs and your body will still produce glucose. Yes – there are some very specific times when ketogenic diets are helpful (1/3 of certain types of seizures in kids respond to ketogenic diet). It would make the most sense with brain tumors but still the data is not very strong when they have looked at it. Besides…. we’re talking about real people, with real lives and goals for their lives other than simply preventing cancer metastasis. Consuming a ketogenic diet is not an easy thing to do, nor something that would be recommended to every single person facing cancer. However, it seems that those who state “sugar feeds cancer” seem to think it is the answer for everyone. My experience with that statement is that it has not ever been a productive, nor helpful thing to say to someone facing cancer.
We absolutely are dealing with real people, some of whom have massive goals they’re striving to accomplish in their lives. There’s a lot of information out there concerning the ketogenic diet, it’s just not mostly found in peer-reviewed medical journals. For myself, when I see hundreds or thousands of individuals willing to run the risk and stay in a ketogenic state for an extended period of time (with small breaks interspersed) and see real, big improvements in labs, health, and fitness – it raises my eyebrow.
As an advocate of the ketogenic diet (it worked for me, but I’m not guaranteeing its right for others), my opinion is definitely biased. You’re likely aware that there are various ‘levels’ of ketosis that make the diet a bit easier to stick to – 5-10-15% carbs. Still not easy, but neither is fighting cancer the traditional way. I hear you that the ketogenic diet is difficult, but if an individual *has* cancer, so is combating that cancer – any way you slice it; given the choice, I’d rather try modifying my diet than hoping for the best the traditional way. Hope this didn’t come off as attacking or insulting.
I think you are presenting yourself in a very respectful way and not “shoulding” on others. Thank you for being a positive example that we can all have our own opinions and choices regarding healthy behaviors and still respect and listen to each other. We need more of this!!! 🙂
Let me give you one tangible example of what this article (by its heading alone) is inspiring in one online forum… The commenter says this following several other posts by folks excited that “diet doesn’t matter” because a cancer dietician “said so”:
“My onc told me that I have no restrictions on food and encourages me to eat all the ice cream I want, milk shakes, etc to get my weight back up. I trust him.”
This commenter got several likes, and several, “See! Let’s all enjoy life! Cancer is 100% genetic, and we have no control…”.
Sure – people are responsible for reading your articles fully, doing “due diligence” and, frankly, not being dumb (jokes!), but I really think that as an advocator of health in the severe disease process of cancer, sugar isn’t something to be moderate about. Maybe a change to the article’s title?
I hope these comments are helpful to you; as I do not intend to stir the pot for stirring’s sake. Please let me know if you think my previous comment about ketones for fuel v. glucose is founded, or if you have counter-info. I love learning, and am open…
I appreciate your very thoughtful and respectful comments! It’s not everyday that I get a commenter who makes sense and says it nicely! 🙂 Agreed – people need to fully read things before they cite them. I would guess that none of those people actually read the article through, which is annoying for sure! I still believe that we should stop saying “sugar feeds cancer”, unless for everytime I had someone come and ask me if it was true, the person was also being told that “oranges feed cancer” and that “chicken feeds cancer” and that “avocados feed cancer.” I think it’s completely ridiculous for this ONE nutrient to get so much focus. There are so many different foods that are important. Just focusing on the absence or presence of sugar is not a benefit to the person. It gives them more fear than empowerment. And many of these people are not just avoiding added sugars, they are actually being told to avoid ALL sources of glucose, which is completely wrong and also potentially harmful. 🙂 Julie
Thank you for your responses to my comments. I know many OVCA patients (or should I say champs) who are doing Keto, and seeing great results. In fact, there was a conference recently in Florida centered around the Metabollic Theory of Disease – it’s over, but you might find the topics interesting, and links to more information interesting. http://metabolictherapeutics.com/conference/
I completely agree with you on one thing: Low Carb, Keto and Glucose-Cutting is NOT easy. It initially takes a lot of work, and a lot of personal advocacy and understanding. My concern, however, is that cancer patients do not have the luxury of being moderate in their approach to wellness. To be in a cancering state automatically assumes systemic imbalances, and what greater way to alter a person’s whole terrain. than through altering a person’s fuel (their food), dramatically.
I think moderate approaches are excellent – when one is healthy, when one doesn’t have high IGF-1, IGF-2, elevated blood glucose, elevated inflammation markers (common in most cancers). When those are all normal, when we’re not dealing with metastatic spread, when nothing is showing up on PET scans – then moderation, the very occasional dessert, all good.
If a person has the wherewithal to want to tackle cancer from every angle, it can’t be from moderacy when it comes to nutrition. There are no neutral foods. It either fuels your body, and helps you, or it does the opposite.
Again, it’s all such a personal decision. Some may choose to not approach their health from the food/lifestyle angle, and that’s okay. 🙂 Personal choice, and in many cases, in early stage cancers, chemo/radiation does the trick.
But, I think people are here on your website because they do want to learn about tackling their disease from a 360 degree approach. I just hope that moderacy (I see, for example, your mention of an occasional diet soda being okay, etc.) isn’t what they walk away with. I think that dramatically changing one’s lifestyle is key…
I wish you the best, and I will say that it’s awesome that you’ve created a space where you’re drawing a strong link between what we eat, and the health of our bodies. Thank you for creating a space where the gap is bridged between traditioanl oncologists who say diet doesn’t matter (I want to flip out when I hear that – they should lose their license!) and the opposite camp who says that diet is everything… 🙂
I think it is an interesting theory but the evidence isn’t strong in human trials. Certainly if someone really wants to try it, I think that’s their choice and they need to be under close supervision. Weight loss during treatment (lean body mass loss) definitely has poor clinical outcomes, so it’s important to avoid that. The evidence isn’t strong enough at this point for me to “recommend” a ketogenic diet. There’s a pretty great and very thorough review here: https://www.sciencebasedmedicine.org/ketogenic-diets-for-cancer-hype-versus-science/#more-32073.
Great article Julie. I have just discovered your blog and must say I’m impressed. My wife and I run a cancer charityIn Australia although our patients are worldwide. My wife, Grace Gawler, has joined your newsletter. Grace has 42 years experience helping patients safely navigate the complex cancer maze. Each day, each week, new patients contact us who have failed their alternative treatments and suffer from massive tumour loads as a result.
We witness many unnecessary deaths as a result of patients embracing alternative medicine while delaying or abandoning conventional medicine. Even complementary medicines, taken while receiving medical treatments, are causing serious problems. The tragedy is that many enthusiastic patients are hindering their medical treatments in this way. It’s a very complex field. Our Cancer navigation Services help patients deal with such issues. http://Www.GraceGawlerInstitute.com
Thanks again for some sanity in a world that appears to have abandoned science. Pip
It seems that Australia has a significant amount of problem with that. Glad you guys are there helping people make informed choices about their care! Thanks for your kind words. Let me know if there are any topics you think I should cover! 🙂 Julie
I think it might have been a mistake to join. Your articles are way to complicated for me to understand…….make it simple!
Near the top of the feed, on 3/11/18, ‘Teresa’ closed the door on this conversation and I now I will throw the lock on it with these words: Pure Therapeutic Ketones. Used by Navy/DoD personnel, NASA, and human trials at Moffitt. *turning off lights on my way out*
I can’t believe how obnoxious people can be. Loved your article. Eight months NED breast cancer. After chemo and multiple surgeries. Keep the information coming thank you for your work.
Thanks!!! Yes, sometimes people can be rude. Especially here on the internet/social media space since they don’t have to look the other person in the face when they say it. It’s too bad that not everyone thinks kindly before they comment. But, I do my best to not take it personally. And it’s always a big boost when people like you leave a comment! Congrats on NED, hooray!!! 😀 <3 <3
I will never stop saying
“Sugar Feeds Cancer” and why?
I lost my 25yr son to a brain tumour in 2015..6 months from diagnosis.
I researched so much while by his side..as we all do ..when I discovered this report by Scientists University College London which I wish to share.
It states ‘is based on the FACT that tumours consume much more glucose (a type of sugar) than normal, healthy tissues in order to sustain their growth’
Based on the FACT.
I read your full report above and now understand your point of view but this headline is misleading as most will just scroll through this only taking on board your bold lettered headline.
‘Sugar Does Feed Cancer’ and you agree.
I quote from the above report
“Every cell in the body requires glucose for fuel, including cancer cells. So sugar does feed cancer”
Attached is the report I discovered written in 2013.
While I appreciate your view everyone needs to make their own informed choice.
I just feel your headline, while written with good intent is misleading.
https://www.ucl.ac.uk/news/2013/jul/sugar-makes-cancer-light-mri-scanners
First of all, I am so sorry for your loss. It’s not fair for anyone to lose a child and I hope that you have found some sense of peace and are often reminded of the happy memories from his life. He was lucky to have you as a caregiver and advocate for his health.
I had someone else comment regarding concern with the headline being misleading. I might suggest that my headline is a good example as to why stating that “sugar feeds cancer” is also misleading. The article you cited states that “tumours consume much more glucose (a type of sugar) than normal, healthy tissues in order to sustain their growth” which is exactly my point. However, eliminating dietary sources of glucose has not shown to affect the update by tumors. If you choose not to consume glucose, your body will produce it endogenously and the tumors will take it from there. They do not care whether the source is from inside the body or from dietary sources. But if you force your body to produce the glucose, you are def at higher risk of malnutrition.
Also – I do not suggest overconsumption of simple sugars. Yes – Everyone needs to find the right balance. 🙂
This was such an informative article! I’m so disappointed by the comments of warriors of one diet or another, and those making excuses for people who can’t read past a headline. You’ve done a great job breaking down what can be a complex topic. Ultimately there are a lot of people who, for whatever reason, are taking this piece as a personal attack which is truly remarkable and sad for them, but I have enjoyed this and other content from your site. Keep up the great work and know that it is appreciated!
Tnank you!! 😀 😀 I always appreciate level headed people willing to take the time to comment. 😀
I have to agree with the comments that the picture attached to this report is inappropriate. It has been clearly shown that the modern diet contains too much added sugar and that it is detrimental to health, (as is excessive body fat). I try to eat as cleanly as possible. This includes Pure water, preference for organic, non gmo, No added sugar, no alcohol, No dairy milk red meat or chicken, No additives or preservatives. No caffine, No gluten. I use small amounts of stable pure fats such as Coconut, Olive, and butter. Eat whole foods fruits and vegetables and occasionally fish and seafood. I make and use only natural skin care and household products to reduce toxic overload. I make my own gluten free bread that contains ground linseed and chia seeds. I use turmeric to assist with inflammation, and probiotics for gut health. I find collodial silver works as well (if not better than) antibiotics when required. At 57 I take no prescription medications and use herbs and natural treatments instead. I consider this to be my anti- cancer diet/ lifestyle approach. As two of my sisters, and other family members have been victims of cancer I am trying my best to avoid it. I came to your site researching the benefits of ground flaxseed in breast cancer. I am also interested in the positive effects of intermittent fasting and the potential of the keto diet for cancer treatment. I do believe in a nutrient dense approach to healing. At this stage of my research I think I would adopt a raw vegan and build on immune support as an approach for cancer treatment. Definitely not chemotherapy.
Researchers did publish results from following certain cancer patients who opted for alternative treatments rather than evidence based standards of care. Results showed alternative medicine use was associated with a 2.5-fold increased risk of death for combined breast, prostate, lung, or colorectal cancer patients, and a 5.7-fold increased risk of death for breast cancer patients. Read the study here: https://academic.oup.com/jnci/article/110/1/121/4064136. Not a risk I would take myself, nor would I advise it for my clients. Another study here: https://jamanetwork.com/journals/jamaoncology/article-abstract/2687972. Their results showed “patients who received complementary medicine were more likely to refuse other conventional cancer treatment, and had a higher risk of death than no complementary medicine; however, this survival difference could be mediated by adherence to all recommended conventional cancer therapies.” It is certainly the patient’s choice to refuse treatments for a variety of reasons. However, I think you should be fully informed on the risks and benefits that each treatment offers before making that decision. Let’s hope you never have to face the decision.
Julie,
As an oncology dietitian myself, I am amazed at the prevalence of the statement that sugar feeds cancer. Also amazed at how ineffective I am when I try to explain it to patients to get them to believe it. There is just too much on the internet that keeps erroneously stating this, without a good reason. I have seen patients become weak and malnourished avoiding all foods with ‘sugar’ i.e. carbohydrates. I have to say to everyone out there, we, as a profession are not saying simple sugar is ok, just that every glucose molecule from you diet, comes from carbohydrates and this includes, good for you, complex carbs like fruits and whole grains, sweet potatoes, etc. I just wish that I had a dollar for every time I have had to explain that ‘it is not that simple’. I would be rich!! Thanks for your efforts here.