Information sheet: Sugar and cancer risk

From National Cancer Control Policy
Obesity > Information sheet: Sugar and cancer risk


Information sheet: Sugar and cancer risk



Key messages and recommendations

  • Sugar is not a carcinogenic (cancer-causing) substance. However, over-consumption of sugar, particularly added sugars in processed beverages and foods, can contribute to obesity which is an important risk factor for cancer. There is no evidence that consuming sugar makes cancer cells grow faster or cause cancer.
  • Cancer Council encourages healthy eating and maintaining a healthy weight to help protect against cancer. Cancer Council supports the Australian Dietary Guidelines that recommend people enjoy a wide variety of nutritious foods from the five food groups every day. It is also recommended that adults and children limit intake of foods containing added sugars such as confectionery, biscuits, cakes, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks.
  • Public health policies decreasing access to and marketing of high-energy, nutrient-poor processed foods, particularly to children, are recommended.

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Background

Sugar is a carbohydrate which provides energy to the body. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose and galactose. Monosaccharides can join together to make the disaccharides maltose, sucrose and lactose.

Sugar can occur naturally, for example in fruit, dairy products and grains, or can be added to food and drinks for flavour, as a sweetener or preservative. Added sugars mainly take the form of sucrose, glucose, dextrose or high-fructose corn syrup. High-fructose corn syrup is a fructose-glucose liquid sweetener which is not commonly used in Australia but is widely used in the United States. Sucrose, in the form of cane sugar, is commonly used in Australia and is made up of glucose and fructose. Newer alternative forms of sugar that are often promoted as natural alternatives such as coconut sugar, agave syrup, rice malt syrup, honey and maple syrup are also sources of added sugars. White (refined) cane sugar is no different from brown (unrefined) sugar or honey with regard to the effects on the body. Other than providing energy, sugar has no nutritional benefits.

In this information sheet added sugars in processed beverages and foods refers to foods such as confectionery, sugar-sweetened soft drinks, cordials, fruit drinks, vitamin waters, energy and sports drinks.

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Glucose metabolism

Glucose is the main source of energy for all cells in the body, including the brain, and plays an important role in maintaining the body’s internal conditions known as homeostasis. All carbohydrates are broken down in the body into glucose. Proteins and fats are also broken down to glucose if the body does not have sufficient carbohydrates to meet its energy needs.

Simple sugars, unlike complex carbohydrates, are digested quickly and can cause blood glucose levels to increase quickly. As blood glucose levels increase, the pancreas produces insulin, a hormone that prompts cells to absorb glucose. Glucose can be stored or used for energy. As cells absorb glucose, levels in the blood begin to fall and the pancreas produces glucagon, a hormone that signals the liver to start releasing stored glucose. This biological process ensures that cells throughout the body have a steady supply of glucose.

There is a view that sugar “feeds” cancer cells. Most cancer cells grow faster than normal cells and therefore require more energy. It has been shown that glucose metabolism is often altered in cancer cells to meet the increased demand for glucose[1]. However, this does not mean that consuming sugar will make cancer cells grow faster or cause cancer. All foods are broken down into glucose as all cells, not just cancer cells, require glucose for energy.

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Epidemiological evidence

The National Health and Medical Research Council (NHMRC) has reviewed all available evidence to update the Australian Dietary Guidelines and concluded that consumption of sucrose is not associated with an increased risk of cancer[2]. The NHMRC review looked at the association between sucrose and cancer, it did not look at the association between sucrose, excess weight and cancer[2]. There was sufficient evidence to conclude that there was no association between sugars and cancer of the pancreas, bowel, breast and bladder[2]. There was no evidence of a direct association between sugar consumption and an increased risk of cancer of any type[2].

Four cohort studies and one case-control study were used to form the body of evidence for determining the association between sucrose and cancer. Of the four cohort studies, two studies looked at the association between sucrose and pancreatic cancer[3][4], one looked at the association with bowel cancer[5], and one looked at the association with breast cancer[6]. The case-control study looked at the association with bladder cancer[7]. Adult female and male populations aged 30-89 years from the US, Canada and Uruguay were included in the studies. Overall, there was no evidence for an effect of sucrose on cancer of the pancreas, bowel, breast, or bladder. Sugar-sweetened beverages were strongly related to bladder cancers in the case-control study [7]. Three studies showed positive associations between fructose and pancreatic cancer[3][4] and bowel cancer[5] but, overall, there was insufficient evidence to include a separate statement for fructose and cancer risk.

This finding is consistent with other review articles. The World Cancer Research Fund found that there was no convincing or probable evidence of increased risk of cancer with sugar intake but there was some limited suggestive data for an association between bowel cancer and high sugar intake[8]. Convincing and probable are the highest levels of evidence of an association and denote causal or probable causal association. Limited suggestive means that the evidence is too limited to permit a convincing or probable causal judgement.

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Current consumption levels in Australia

The 2011–2012 National Nutrition and Physical Activity Survey found that carbohydrates contributed on average 45% of total energy per day for Australians aged 2 years and over[9]. Within carbohydrates, sugars contributed 20% of energy. The major source of total sugars (natural and added) in Australian diets were:

  • fruit (16%) and fruit and vegetable juices and drinks (7.5%),
  • soft drinks and flavoured mineral waters (9.7%),
  • dairy milk (8.1%),
  • sugar, honey and syrups (6.5%),
  • cakes, muffins, scones, cake-type desserts (5.8%).

Only 16% of total sugar intake in the Australian diet came from fruit. Just over half (54%) of Australians consumed the recommended serves of fruit with females (58%) more likely than males (50%) to meet the recommendation. While discretionary foods such as soft drinks, cakes, confectionery, biscuits and chips contributed 35% of total energy intake for adults and 45% in children.

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Sugar and weight gain

A systematic review conducted in 2015 found that intake of sugars is a determinant of body weight with increasing sugar consumption associated with weight gain[10]. Data suggested that weight gain is due to excess energy intake rather than physiological or metabolic consequences of sugar consumption[10]. Most studies have examined sugar-sweetened beverages and found consumption to be associated with weight gain in adults and children[11]. Sugar-sweetened beverages contain high amounts added-sugars and have low satiety.

Overweight and obesity are set to overtake tobacco as the number one cause of preventable disease burden in Australia[12]. There is convincing evidence that excess body fat causes bowel cancer, post-menopausal breast cancer and cancers of the kidney, pancreas, oesophagus and endometrium [8]. Maintaining a healthy weight is an important way of reducing the risk of cancers associated with overweight and obesity.

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Guidelines for a healthy diet

Fruit and vegetables contain natural sugars and are a source of nutrients, such as fibre, vitamins and minerals, which are potentially protective against cancer. Consumption of fruit and vegetables as an alternative to high-energy, nutrient-poor processed foods also plays an important role in weight management. For further information see Cancer Council’s [[Position_statement_-_Fruit,_vegetables_and_cancer_prevention|position statement on Fruit, vegetables and cancer prevention].

  • Cancer Council supports the Australian Dietary Guidelines that recommend eating plenty of fruit and vegetables, and the population recommendation of at least two serves of fruit and five serves of vegetables daily.

The consumption of sugar-sweetened beverages is associated with increased energy intake and in turn, weight gain and obesity. It is well established that obesity is a leading risk factor for diabetes, cardiovascular disease and some cancers. For further information see Cancer Council’s [[Position_statement_-_Sugar-sweetened_beverages|position statement on Sugar-sweetened beverages].

  • Cancer Council Australia recommends that adults and children limit sugar-sweetened beverages and instead drink water or reduced fat milk.

Limiting excess energy intake in the form of added sugars can help to maintain a healthy weight. Many discretionary foods which are energy-dense and nutrient-poor are also high in added sugars. The Australian Dietary Guidelines recommend limiting the intake of foods and drinks containing added sugars such as confectionery, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks. In March 2015, the World Health Organization issued a guideline on sugar and recommended that adults and children restrict their sugar intake to less than 10% of total daily energy intake, which is the equivalent of around 12.5 teaspoons of sugar for adults[13]. A further reduction to below 5% or 6 teaspoons per day would provide additional health benefits[13].

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Policy context

Current trends towards increasing portion sizes and consumption of energy-dense, nutrient-poor beverages and foods, compounded by insufficient physical activity, have contributed to the obesity epidemic in Australia.

Public health policies that create an environment where the easiest choice is the healthy choice are required to address obesity in Australia. Measures to decrease access to and marketing of energy-dense, nutrient-poor foods, particularly to children, are recommended. A tax on food products that offer no nutritional benefit (e.g. sugar-sweetened beverages) should be investigated with the aim of changing consumer habits and achieving healthier diets. Revenue generated could either be used for general revenue, hypothecated for use in health promotion, to off-set the cost of subsidising healthy foods either for the wider population or for those on low incomes, or all of these uses. Enhancing regulatory mechanisms to increase nutritional information, restrict marketing of unhealthy food and reduce the exposure to the marketing of unhealthy food across a range of platforms and settings, particularly to children, is an important area for obesity prevention.

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Key messages

  • Sugar is not associated with an increased risk of cancer. Consumption of added sugars is positively correlated with high energy intake, and through it, excess weight and obesity.
  • Cancer Council encourages healthy eating and maintaining a healthy weight to help protect against cancer. Cancer Council supports the Australian Dietary Guidelines that recommend people enjoy a wide variety of nutritious foods from the five food groups every day. It is also recommended that adults and children should limit intake of foods containing added sugars such as confectionery, biscuits , cakes, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks.

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Information sheet details

This information sheet was reviewed and approved by the Public Health Committee August 2015.


References

  1. Annibaldi A, Widmann C. Glucose metabolism in cancer cells. Curr Opin Clin Nutr Metab Care 2010 Jul;13(4):466-70 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/20473153.
  2. 2.0 2.1 2.2 2.3 National Health and Medical Research Council. A review of the evidence to address targeted questions to inform the revision of the Australian Dietary Guidelines. Canberra: NHMRC; 2011 Available from: https://www.nhmrc.gov.au/_files_nhmrc/file/publications/n55d_australian_dietary_guidelines_evidence_report.pdf.
  3. 3.0 3.1 Michaud DS, Liu S, Giovannucci E, Willett WC, Colditz GA, Fuchs CS. Dietary sugar, glycemic load, and pancreatic cancer risk in a prospective study. J Natl Cancer Inst 2002 Sep 4;94(17):1293-300 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/12208894.
  4. 4.0 4.1 Nöthlings U, Murphy SP, Wilkens LR, Henderson BE, Kolonel LN. Dietary glycemic load, added sugars, and carbohydrates as risk factors for pancreatic cancer: the Multiethnic Cohort Study. Am J Clin Nutr 2007 Nov;86(5):1495-501 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17991664.
  5. 5.0 5.1 Michaud DS, Fuchs CS, Liu S, Willett WC, Colditz GA, Giovannucci E. Dietary glycemic load, carbohydrate, sugar, and colorectal cancer risk in men and women. Cancer Epidemiol Biomarkers Prev 2005 Jan;14(1):138-47 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15668487.
  6. Silvera SA, Jain M, Howe GR, Miller AB, Rohan TE. Dietary carbohydrates and breast cancer risk: a prospective study of the roles of overall glycemic index and glycemic load. Int J Cancer 2005 Apr 20;114(4):653-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/15609324.
  7. 7.0 7.1 De Stefani E, Boffetta P, Ronco AL, Deneo-Pellegrini H, Acosta G, Mendilaharsu M. Dietary patterns and risk of bladder cancer: a factor analysis in Uruguay. Cancer Causes Control 2008 Dec;19(10):1243-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/18592382.
  8. 8.0 8.1 World Cancer Research Fund, American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington DC: AICR; 2007.
  9. Australian Bureau of Statistics. Australia heath survey first results 2011-12. Canberra: ABS; 2012. Report No.: Cat no. 4364.0.55.001. Available from: http://www.abs.gov.au/ausstats/abs@.nsf/mf/4364.0.55.001?OpenDocument.
  10. 10.0 10.1 Te Morenga L, Mallard S, Mann J. Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ 2012 Jan 15;346:e7492 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23321486.
  11. Malik VS, Pan A, Willett WC, Hu FB. Sugar-sweetened beverages and weight gain in children and adults: a systematic review and meta-analysis. Am J Clin Nutr 2013 Oct;98(4):1084-102 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23966427.
  12. Hoad V, Somerford P, Katzenellenbogen J. High body mass index overtakes tobacco as the leading independent risk factor contributing to disease burden in Western Australia. Aust N Z J Public Health 2010 Apr;34(2):214-5 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23331368.
  13. 13.0 13.1 World Health Organization. Guideline-Sugars intake for adults and children. Geneva: WHO; 2015 Available from: http://who.int/nutrition/publications/guidelines/sugars_intake/en/.

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