Cancer
*This content has been reviewed by Dr. Vera Mazurak (Agriculture, Food, and Nutritional Sciences, University of Alberta)
Cancer is a large group of diseases that starts when abnormal cells grow and divide uncontrollably (1, 2).
- Risk Factors for Developing Cancer. There are many risk factors for developing cancer; some cannot be controlled while others can be modified to reduce risk.
- Reducing Cancer Risk. Lifestyle factors that can help reduce risk of cancer include maintaining a healthy body weight, consuming a balanced diet, being physically active, and limiting alcohol intake.
- Sugars and Cancer. The collective evidence from systematic reviews and meta-analyses (3- 5) suggests an indirect link between added sugars and cancer risk from sugar’s contribution to calorie intake. Consuming excessive calories, including calories from sugars, can increase the risk of overweight and obesity, which then increases risk of some types of cancer.
- Sugars in the Diets of Individuals with Cancer. Dietary recommendations about sugars for individuals with cancer are not different from recommendations for individuals without cancer The recommendations emphasize reducing intake of foods and beverages high in added sugars.
Risk Factors for Developing Cancer
There are several factors that increase a person's risk of developing cancer. Some cannot be controlled while others can be modified to reduce risk. The Canadian Cancer Society and US National Cancer Institute (6, 7) identify the following risk factors for cancer:
| Non-modifiable risk factors | Modifiable risk factors |
|---|---|
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Reducing Cancer Risk
Obesity or excess body weight has been associated with an increased risk of many types of cancer. One lifestyle factor that can contribute to overweight and obesity is consuming Calories in excess of what is required everyday for normal body functions, movement, and physical activity.
To reduce the risk of cancer, the Canadian Cancer Society (8) recommends:
- Living smoke-free
- Protecting your skin and eyes from the sun
- Achieving and maintaining a healthy body weight
- Eating a healthy and balanced diet
- Being physically active
- Limiting alcohol consumption
The overall recommendation to maintain a healthy body weight includes the following dietary and lifestyle recommendations:
- Following recommendations in Canada’s Food Guide to eat a well-balanced diet that includes a plenty of vegetables and fruit, whole grains, and fibre, with healthy fats and very few highly processed foods;
- Limiting consumption of red and processed meats, and foods and beverages high in sodium, saturated fat, and sugars;
- Replacing sugars-sweetened beverages with water most of the time; and
- Being physically active
Sugars and Cancer
Does consuming sugars cause cancer cells to grow? The idea that “sugar feeds cancer” is a common misconception. Some of the tests used to detect cancer measure the amount of glucose taken up by tumor cells. In fact, all cells (including cancer cells) need glucose (a type of sugar) for energy. However, this does not mean that the sugars you eat “feed” the tumor.
The level of glucose in the blood is tightly regulated and is not directly linked to the amount of sugar in the diet. Eating more sugars does not make cancer cells grow faster, nor does depriving them of sugar slow their growth (9). There is also a lack of evidence that limiting sugar intake “starves” cancer cells or lowers the risk of getting cancer (10). Excess sugar consumption can contribute to weight gain and obesity, which are risk factors for several types of cancer.
Evidence from systematic reviews and meta-analyses does suggest that:
- There may be an indirect link between sugars and cancer through sugar’s contribution to calorie intake. Foods higher in calories may be higher in sugars -> consuming high calorie foods on a regular basis may lead to weight gain -> weight gain is associated with an increased risk for some types of cancers (9-11).
- There is a correlation between drinking sugar-sweetened beverages, weight gain and increased risk of some cancers (4, 5).
National and international agencies recommend:
- Limiting consumption of sugars-sweetened drinks;
- Avoiding high-calorie / nutrient-poor foods and drinks; and
- Limiting consumption of fast foods and other highly processed foods high in fat, starches, or sugar (10- 13).
Many healthy foods, including whole grains, cereals, fruits, and dairy products, naturally contain sugars, along with vitamins, minerals, fibre, and other nutrients that reduce the risk of some cancers. Dietary fibres and certain micronutrients such as folate, vitamin C, selenium and carotenoids have been shown to be protective against cancer development (14). On the other hand, foods high in added sugars tend to have less of these types of nutrients.
Sugars in the Diets of Individuals with Cancer
Dietary recommendations about sugars for individuals with cancer are not different from recommendations for individuals without cancer (11).
Recommendations include:
- While avoiding sugars is not necessary nor feasible, it is best to consume most sugars from naturally occurring sources and nutrient-dense sources, such as vegetables, fruits, plain dairy, and whole grains.
- Limit the amount of added sugars in the diet by reducing portion sizes of desserts and sweets, reducing intakes of processed foods high in added sugars and limiting sugar-sweetened beverages.
For more information, additional resources include:
Recent news items include:
References
- Canadian Cancer Society. What is Cancer? [Internet]. Canadian Cancer Society; 2024 [cited 2024 Mar 20].
- World Health Organization. Cancer [Internet]. World Health Organization; 2024 [cited 2024 Mar 11].
- Makarem N, Bandera EV, Nicholson JM, Parekh N. Consumption of Sugars, Sugary Foods, and Sugary Beverages in Relation to Cancer Risk: A Systematic Review of Longitudinal Studies. Annual review of nutrition. 2018 May 25(0).
- Jatho A, Myung SK, Kim J, Han SS, Kim SY, Ju W. Consumption of sugar-sweetened soft drinks and risk of gastrointestinal cancer: A systematic review and meta-analysis of observation studies. Oncology. 2024;102(2):141-56.
- Feng L, Gao J, Xia W, Li Y, Lowe S, Yau V, Ma S, Zhou Z, Ding P, Cheng C, Bentley R, Wang Y, Zhou Q, Wang K, Birong W, Xie P, Liu H, Sun C. Association of sugar-sweetened beverages with the risk of colorectal cancer: a systematic review and meta-analysis. Eur J Clin Nutr. 2023 Oct;77(10):941-52.
- Canadian Cancer Society. What Causes Cancer? [Internet]. Canadian Cancer Society; 2024 [cited 2024 Mar 1].
- National Cancer Institute. Risk Factors for cancer [Internet]. National Cancer Institute; 2015 Dec 23 [cited 2024 Mar 1].
- Canadian Cancer Society. Reduce Your Risk [Internet]. Canadian Cancer Society; 2024 [cited 2024 Mar 20].
- Canadian Cancer Society. What’s the Link Between Sugar and Cancer? [Internet]. Canadian Cancer Society; 2024 [cited 2024 Mar 20].
- Cancer Research UK. Sugar and Cancer – What You Need to Know [Internet]. Cancer Research UK; 2023 Aug 16 [cited 2024 Mar 20].
- Canadian Cancer Society. The Health Costs of a Sweet Tooth [Internet]. Canadian Cancer Society; 2024 [cited 2024 Mar 20].
- BC Cancer. Sugar and Cancer [Internet]. BC Cancer; 2023 Oct 2 [cited 2024 Mar 20].
- World Cancer Research Fund. Cancer Prevention Recommendations [Internet]. World Cancer Research Fund; 2018 [cited 2024 Mar 20].
- Willett WC. Micronutrients and Cancer risk. Am J Clin Nutr. 1994;59:1162S-1165S.
