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Cancer is the biggest fear of many people. One in three of us in the UK will develop some type of cancer in our lifetime and there is growing evidence to suggest over 5% of cancers are directly linked to being overweight or obese . In 2011, 331,000 people were diagnosed with cancer, but could more than 16,500 of these cases have been prevented if the patients had maintained a healthy weight?
‘Obesity is a major preventable cause of cancer’
Cancer Research UK has stated that ‘obesity is a major preventable cause of cancer’ and estimate that over 17,000 people each year may avoid cancer if they maintain a healthy weight. Healthy eating and regular exercise sound like two simple steps to keep a healthy weight and reduce cancer risk, but how easy is this in reality?
In the UK, levels of obesity have tripled over the last 25 years and this is putting huge pressure on health services. The majority of the UK population is overweight and 25% of adults are obese . While we continue to eat more calories than we burn, there is no sign of a decline in obesity, indicating that government policy has been insufficient to tackle obesity.
What is the scientific evidence?
Carrying excess fat around our belly, known as visceral fat, is directly associated with the two most common cancers – bowel and post-menopausal breast cancers – and three of the most difficult cancers to treat – pancreas, gallbladder and oesophageal cancers . Being obese can also make it more difficult to treat some cancers and promote disease progression, thus increasing mortality from most types of cancer .
Obesity occurs when a person carries excessive levels of fat. Fat tissue secretes hormones and proteins that send messages to the cells around them telling then when they should grow and divide or take up different nutrients. These messages have both direct and indirect effects on cell growth regulators and must be tightly regulated to prevent cancer.
Too much fat results in the release of excess amounts of hormones, such as oestrogen and leptin. Excessive levels of oestrogens (the primary female sex hormones) are associated with breast and womb cancer risk. Leptin is important to regulate our appetite but, if in excess, it has been shown to cause cancer progression by sending proliferation messages to cells .
Many obese people suffer from hyperinsulinemia (insulin resistance), due to increased levels of the important regulators of our blood sugar, insulin and insulin-like growth factor-1, and this may promote cancer. Additionally, chronic low level inflammation is associated with obesity, because fat tissue releases protein messengers called cytokines that induce inflammation, and inflammation is linked to cancer development .
What’s already being done to tackle obesity?
Based on scientific research, UK governments have begun to implement policies to reduce obesity, not only to aid the prevention of diseases such as cancer, but to promote a healthier economy. The Organisation for Economic Co-Operation and Development (OECD) is working with governments of member countries, including the UK, to reduce obesity.
In 2010, the Scottish government published their obesity strategy , defining four key areas: the need to reduce the excessive demand and consumption of high calorie foods and drinks; increase opportunities for physical activity; improve the health and lifestyle of children; and make employers more responsible for the health and wellbeing of employees. The government in England also admitted that new approaches were needed to tackle obesity and published their White Paper ‘Healthy Lives, Healthy People’ in 2011 . They have introduced a ‘Change4Life’ social marketing programme, regulated the requirements for labelling nutrient and calorie contents of food and drink and provided guidance on physical activity.
The overall aim is for a ‘sustained downward trend’ in obesity in the UK by 2020.
How about taxing ‘unhealthy’ foods?
Some countries have attempted to encourage people to eat and drink more healthily by implementing taxes on certain foods, such as the controversial saturated fat tax in Denmark . This proved costly for the food industry to implement and consumers simply obtained their chocolate fix from neighbouring countries, so the fat tax was abandoned a year later.
Hungary, on the other hand, has been more successful, achieving a 27% reduction in sales of taxed foods and generating revenue which could be contributed back into their public health .
January 2015 will see the implementation of the next initiative from Public Health England (PHE) to reduce our sugar consumption and rebalance calorie intake . In general, the population consumes more sugar than it should. We should consume the equivalent of no more than 11 to 14 level teaspoons of sugar per day, but the World Health Organisation (WHO) and PHE’s advisory committee are considering reducing this recommendation.
The challenge of sugar reduction is to be met by a digital ‘Sugar Swaps’ promotion, which will suggest alternative products to promote a healthier diet (e.g. switch to sugar free products). Colour coded nutritional labels are now being used on some foods, making it easier for people to swap ‘reds’ for more ‘greens’ and ‘ambers’. The food industry has also been encouraged to use healthier recipes, decrease portion sizes, develop low calorie options and importantly encourage consumers to choose these healthier options.
It is critical that the public are made aware of the diseases associated with our lifestyle choices. This should be backed by government initiatives. Scientific evidence must provide the basis to structure policies to control diet. This method will reduce obesity, thereby preventing some cancers and other obesity-related conditions.
Article by Elspeth Macdonald
 Cancer Research UK (15 Sept 2014) Obesity, body weight and cancer.http://www.cancerresearchuk.org/cancer-info/healthyliving/obesity-bodyweight-and-cancer
 Organisation for Economic Co-operation and Development (2014) Obesity Update. OECD 1-8
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 The Scottish Government (2010) Preventing overweight and obesity in Scotland: A route map towards healthy weight. The Scottish Government 1-50
 Department of Health (2011) Healthy lives, healthy people: A call to action on obesity in England. HM Government 1-54
 Tedstone A et al (2014) Sugar reduction: Responding to the challenge. Public Health England 1-32