Cancer, in essence, is a condition caused by cells dividing more rapidly than they should to form a clump of abnormal cells. Lots of things appear to have the capacity to trigger cancerous change in cells (some chemicals, free radical damage, radiation, for example), but once cancerous cells form, they still need feeding to survive. Cancerous tumour can develop their own blood supply, through which they can be fed vital nutrients to stay alive and proliferate.
It has been long recognised that cancerous cells tend to do well when fed glucose – a key fuel in the bloodstream. One might argue then that, as much as possible, it makes sense for those with cancer to avoid consuming foods that cause gluts of sugar in the blood stream such as sugary foods and starchy carbohydrates such as bread, potatoes, rice, pasta and many breakfast cereals.
I was interested this week to read about a study which assessed the effect of not glucose, but fructose, on cancer cell growth [1]. Fructose is found naturally in fruits and vegetables, and it also makes up half of sucrose (table sugar) – the other half being glucose. And last, but by no means least, fructose can be found in ‘high fructose corn syrup’ (HFCS), which over the last couple of decades has increasingly pervaded the Western diet.
Fructose has, until relatively recently, enjoyed a ‘healthy’ reputation on the basis that it does not lead to spikes in blood sugar. It’s been particularly recommended for diabetics for this reason. However, it turns out that fructose has the potential for quite toxic effects in the body. See here, here, here and here for some recent posts about this.
Back to cancer…
The study in question found, in summary, that feeding cancer cells fructose caused them to proliferate. Obviously, this is not a good state of affairs. The authors of the study suggest that reducing intake of refined fructose may disrupt cancer growth.
When fructose is consumed it travels to the liver. The vast majority, if not all, of it is metabolised in the liver, meaning that little or any reaches the general circulation. However, there is always the potential that uric acid might exert a considerable direct effect on the liver. We can perhaps see the potential for fructose to be directly toxic to the liver in some evidence linking its consumption with ‘fatty liver’ (a build-up of fat within the tissue of the liver).
But what about other tissues in the body?
One of the effects of fructose is to cause a ramping up of uric acid in the liver. Uric acid is, as its name suggests, acidic. And the relevance of this is that some cancer cells grow better in an acidic environment. Now, the body has processes by which it regulates the pH (acidity/alkalinity) of the bloodstream within quite a narrow range. However, there is the potential for the pH to drop (become more acidic) and this might perhaps encourage cancer growth.
I’m not aware of any evidence linking fructose consumption and cancer in the scientific literature. However, this recent study, I think, gives us another potential reason for giving fructose and high fructose corn syrup a miss.
References:
1. Liu H, et al. Fructose induces tranketolase flux to promote pancreatic cancer growth. Cancer Research 2010;70(15):6368-76
