sugarYesterday I went to talk by a local oncologist. It was an opportunity to hear first-hand an update on the latest technological developments in fighting cancer, and I was impressed that several lifestyle issues were covered too. This included the risk of alcohol and obesity, and the benefits of exercise. A very good start.

After the presentation, questions flowed from the audience and, unsurprisingly, it wasn’t long before more specific questions about diet and lifestyle arose. This is because we want to know whether there are things that we can d to improve our odds, and whether it’s worth the effort of making changes which may mean denying ourselves things we really do quite like. In particular, is it true that sugar causes cancer?

Immediately my blood pressure rose and my heart started beating so hard it felt like it would explode from my chest. This was MY question, one amongst many that I’ve been researching over 12 years in my quest to learn as much as possible about how to prevent a recurrence. Prevention is indeed the name of my game.

Yet here I was, in the audience, without a voice. Instead, this God like individual, with his awesome credentials and absolute authority was holding centre stage. And what would he say?

“Absolutely not, there is no evidence at all that sugar cause’s cancer”.

WHAT??? You cannot be serious! This room full of cancer patients past and present has just been given license to sit on the sofa and eat chocolate. Any hope of personal responsibility has been dashed. Quite obviously it doesn’t matter a jot what we eat. Hallelujah.

I was stunned, but not surprised. Yes, it is true there are no randomised control trials to prove beyond a shadow of a doubt that sugar causes cancer. But conversely, there are no RCTs to prove that it doesn’t either.

Research around diet and lifestyle is complicated. You cannot isolate humans and change just one variable. Instead I believe we need to look at other streams of evidence and build up a picture of knowledge rather like a detective builds up a profile of a criminal. A further complexity is that one man’s meat is another man’s poison – we do not all have the same nutritional needs. Welcome to the world of functional, or individualised, medicine. Shades of grey not black & white.

So how did I respond?

With respect, I do consider myself an expert on diet and lifestyle and my book Eat to OUTSMART Cancer contains over 200 scientific references which inform my position. Regarding sugar, here are just a few facts:

–          Cancer cells primarily use glycolysis to fulfil their energy requirements. This is an inefficient process and results in them having a huge need for sugar – a fact that is the basis of PET scans, which use radioactive sugar to identify tumours.[1]

–          Current evidence supports that it is sugar (not fat) that is driving obesity.[2] And obesity is a significant risk factor for cancer.[3]

–          In vitro studies show that sugar drives cancer proliferation.[4]

–          Animal studies show increased rates of cancer with higher carbohydrate (aka sugar) diets.[5]

–          Human studies are less definitive, precisely because the variables cannot be tightly controlled. However there are studies to support that higher glycaemic diets drive cancer rates.[6]

– Intervention studies, where the outcomes of two groups are compared, can be used to study more holistic approaches. One landmark study compared prostate cancer patients on a holistic (diet and lifestyle) programme versus regular advice. All markers of cancer progression were significantly lower in the holistic group.[7]

The bottom line is that our doctors are the experts in medicine and killing cancer. But building health and coaching people to improve their outcomes through diet and lifestyle interventions requires a different set of skills.

A more rounded answer to that sugar question could have been:

“Whilst there are no RCTs that prove beyond a shadow of a doubt that sugar causes cancer, there are many causes for concern. There is a growing body of evidence that sugar is driving many of society’s chronic illnesses by driving obesity and contributing to metabolic problems. To help your recovery from cancer it may prudent to focus a diet which is rich in fresh, natural and unprocessed foods.”


[1] Walker Samuel et al. (2013) In vivo imaging of glucose uptake and metabolism in tumors. Nature Medicine. 19:1067–1072

[2] Malhotra A. Saturated fat is not the major issue. BMJ. 2013 Oct 22;347

[3] Preetha Anand, Ajaikumar B. Kunnumakara, Chitra Sundaram, Kuzhuvelil B. Harikumar, Sheeja T. Tharakan, Oiki S. Lai, Bokyung Sung, and Bharat B. Aggarwa. (2008) Cancer is a Preventable Disease that Requires Major Lifestyle Changes Pharm Res. Sep; 25(9): 2097–2116

[4] Masur K, Vetter C, Hinz A, Tomas N, Henrich H, Niggemann B, Zänker KS. (2011) Diabetogenic glucose and insulin concentrations modulate transcriptome and protein levels involved in tumour cell migration, adhesion and proliferation. Br J Cancer. Jan 18;104(2):345-52

[5] Ho VW , Leung K, Hsu A, Luk B, Lai J, Shen SY, Minchinton AI, Waterhouse D, Bally MB, Lin W, Nelson BH, Sly LM, Krystal G. (2011) A low carbohydrate, high protein diet slows tumor growth and prevents cancer initiation. Cancer Res. Jul 1;71(13):4484-93

[6] Sieri S1, Pala V, Brighenti F, Agnoli C, Grioni S, Berrino F, Scazzina F, Palli D, Masala G, Vineis P, Sacerdote C, Tumino R, Giurdanella MC, Mattiello A, Panico S, Krogh V. (2013) High glycemic diet and breast cancer occurrence in the Italian EPIC cohort. Nutr Metab Cardiovasc Dis. Jul;23(7):628-34

[7] Ornish D et al,(2005) Journal of Urology Sep; 174(3):1065-9

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