Sugar has had a pretty bad image for a long time now, we think of it as something that rots our teeth, makes us fat, and can lead to developing type 2 diabetes. New research is adding yet another ugly string to the bow of sugar: cancer. Cancer now affects 1 in 3 people in the UK, and according to Cancer Research UK at least 50% of cancers are preventable through dietary or lifestyle change¹.

A connection between obesity, diabetes and cancer was first reported in 2004 in large population studies by researchers from the World Health Organisation’s International Agency for Research on Cancer². This study reported that you are more likely to develop cancer if you are overweight, or if you have diabetes or metabolic syndrome. Metabolic syndrome is the term used to describe a collection of medical markers that are a pre-cursor to type 2 diabetes: overweight, high cholesterol, high blood fats, high blood pressure, high blood sugar and high insulin.

Since this study there has been further research looking at the link between sugar, insulin and cancer growth. It seems that the cells of many human cancers depend on insulin to provide the fuel and materials they need to grow and multiply. Insulin and the hormone insulin-like growth factor also provide the signal to do it. In other words, the more insulin that is available to cancer cells, the more they will grow and spread.

Insulin is produced by the pancreas in response to sugar in the blood stream. When we eat carbohydrate foods they are broken down into simple sugars by the digestive process. We then need to produce sufficient insulin to allow the sugars to be stored in the muscles and the liver as glycogen for future energy stores. Insulin is like a key that opens the door to the cells and allows the sugar in.

If we eat a diet high in sugars then we are asking our pancreas to produce a lot of insulin all the time. Over time this can become problematic as our cells may become resistant to the insulin and a condition called Insulin Resistance (IR) develops. A bit like an old key getting worn out from over-use - it sometimes won’t work in the lock any more. The main physical sign of insulin resistance is fat around the middle – as a result of the sugars that can’t get stored as glycogen inside muscle cells being stored as fat around the middle instead. The medical signs of IR are high blood sugars and high levels of circulating insulin. In a nut-shell someone with IR is producing lots of insulin but it is not having the same effect on the cells and therefore blood sugar levels remain high too. This is a dangerous combination for many reasons.

We know IR is a pre-cursor to Metabolic Syndrome and type 2 diabetes, but now it seems it is also a major risk factor for cancer. To avoid large amounts of circulating insulin and high blood sugars there are a few simple dietary rules we can follow:

• Eat a low glycaemic load diet i.e. avoid refined carbohydrates (white bread, pasta and rice, fizzy drinks, sweets, crisps, biscuits, cakes, pastries, muffins, donuts etc)
• Eat plenty of fresh vegetables and some fruit
• Eat plenty of fibre-rich foods i.e. wholegrains such as wholemeal bread, brown pasta and rice, oats, lentils, pulses, and vegetables
• Take regular exercise

If we follow these rules we will maintain a healthy weight, have more energy and reduce our risk of developing cancer. 

References:

1. http://info.cancerresearchuk.org/healthyliving/introducingcancerprevention
2. http://www.iarc.fr/en/research-groups/sec7/index.php