Is There a Link Between Sugar & Cancer?

We all know a high diet of sugar isn't good for you – but is it worse than we realise?

Cancer is a group of diseases characterised by unregulated cell growth. To date, there are more than 200 types of cancer that have been classified, each having a different name and treatment. One of the difficult conundrums that oncologists came across a lot is “Does sugar feed cancer cells?”. The short answer to the conundrum is: Yes, it does. However, it is important for us to understand and bear in mind that glucose (a type of sugar) is the primary energy source of every cell in our body.

Having said that, normal healthy cells break down glucose to obtain energy, in the form of adenosine triphosphate (ATP), for normal cellular functions differently from cancer cells. In normal healthy cells, glucose molecules are broken down through the process called oxidation, through which one molecule of glucose will yield 36 molecules of ATP. Most cancer cells however, metabolise sugar through a different process known as glycolysis.

Otto Warburg, a German biochemist, has observed and claimed that cancer cells are able to produce energy through a high rate of glycolysis which is known as the “Warburg effect”. 

Unlike oxidation, glycolysis is an anaerobic process, i.e. it takes place in the absence of oxygen. This allows cancer cells to produce energy even when they are oxygen-deprived (especially those far away from the blood vessels where efficient oxygen exchange takes place). Glycolysis is also 18 times less efficient than oxidation whereby with every single molecule of glucose metabolised, there are only two ATP molecules produced.

However back in the 1920s, Otto Warburg, a German biochemist, has observed and claimed that cancer cells are able to produce energy through a high rate of glycolysis which is known as the “Warburg effect”. This phenomenon poses two big questions for the cancer research community: Why would cancer cells evolve to adapt such an inefficient process when they require lots of energy; And, how does this rewired glycolysis relate to cancer development and progression?

How the Warburg Effect leads to cancerous cell proliferation. Image: Bcndoye [CC BY-SA 3.0], via Wikimedia Commons

How the Warburg Effect leads to cancerous cell proliferation. Image: Bcndoye [CC BY-SA 3.0], via Wikimedia Commons

While the why question remains unknown to the cancer research world, a recently published study by three Belgium research groups has shone some light into the relationship between sugar and cancers. Using yeast model, the Belgium scientists have found that high glucose level overstimulate ras proto-oncogene that is found to be mutated in as many as half of all cancer types.

One of the lead authors of the study, Professor Johan Thevelein, said on the press statement that, “…the hyperactive sugar consumption of cancerous cells leads to a vicious cycle of continued stimulation of cancer development and growth… explain the correlation between the strength of the Warburg effect and tumour aggressiveness”.

An independent cancer researcher not involved in the study, Dr Victoria Stevens from the American Cancer Society, agreed that the study is great and provides a potential cause of cancer development and progression. However, she also commented that the study focused on “one product made during the breakdown of glucose to produce energy” and is still “a long way away from saying this could actually happen”.

Breast Cancer Cells. Image: Dr. Cecil Fox (Photographer) - National Cancer Institute, via Wikimedia Commons

Breast Cancer Cells. Image: Dr. Cecil Fox (Photographer) – National Cancer Institute, via Wikimedia Commons

While a recent study showed possible positive correlation between sugar and cancer progression, it is important to bear in mind that total elimination of sugar consumption is harmful to the human body as healthy cells require energy to carry out normal biological functions.

Besides, eliminating fruits, breads, whole grains, starchy vegetables, dairies et cetera to create sugar-free diets lacks important antioxidants, fibre, vitamins and minerals. Nonetheless, limiting the total amount of sugar intake is beneficial to human health for excessive sugar intake can lead to overweight and obesity, which increase cancer risk over time.

The take home message here is, consume moderate amount of sugar and lead a healthy lifestyle for over- or under-consumption of sugar (or any other food) are detrimental to human health. MODERATION IS THE KEY.

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