Does Sugar Increase Cancer Risk? Scientific Evidence Explained
Understand the link between high sugar intake and cancer risk, including metabolic changes, inflammation, and tumor growth pathways.
Effect of High Sugar Diet on Cancer development
Relationship between sugar intake and cancer growth
Nowadays, sugar has become an essential part of many diets. Despite being aware of the health risks of sugar side effects, many people continue to consume it, especially after meals. Excess sugar intake is a leading cause of diabetes worldwide.
Many researchers worked on the effects of sugar on various diseases, including cancer. Some studies suggest that there is association between high sugar consumption and cancer development. In contrast many researchers claim that there is no link between high sugar diet and cancer development.
This raises the question: is there a true relationship between sugar intake and cancer growth, or is it just a myth?
In this section, I will explore the scientific evidence on the link between sugar and cancer.
Worldwide Consumption of Sugar
Sugar consumption is common in Western countries, where people tend to consume highly processed foods with added sugars. Recently, many Asian countries have started following the same trend.
In India, the average sugar consumption per person is approximately 20.2 kg, which is lower than the global average of 24.8 kg. However, sugar consumption in India is increasing, with a 13% rise in demand, accounting for 5% of global sugar production.
Occurrence of cancer is highest in high-income countries, but it is now becoming more common in low- and middle-income countries (LMICs). The World Health Organization (WHO) estimates that in next 20 years, there will be 22 million new cancer cases and 13 million cancer deaths annually, a 57% increase in new cases and a 65% increase in cancer-related deaths.
Countries such as Brazil, India, and China, which previously had low cancer rates, are now experiencing significant increases in cancer incidence. Studies have shown that Chinese, Japanese, and Filipino women born in the U.S. have a 60% higher risk of breast cancer than those born in Asia. Moreover, Asian American women with all four grandparents born in Asia have breast cancer incidence rates similar to those of White women living in the same regions.
In India, cancer incidence increased by 1.1–2.0% per year between 2010 and 2019, with breast cancer being the most common in women and lung cancer in men. India and China also have the highest incidence of diabetes, a known risk factor for many cancers. By 2040, global cancer cases are expected to increase by over 40%, with two-thirds of cases occurring in LMICs.
Changes in diet including higher consumption of fast foods, highly processed foods, and added sugars are hypothesized to contribute to the rising cancer incidence in LMICs. Numerous research studies indicate that sugar consumption may influence the development and progression of various cancer types.
Consumption of excess carbohydrate and sugar increase the blood sugar level, promote insulin resistance, and increase inflammatory cytokines and insulin-like growth factors, all of which may support tumor growth and spread. However, high sugar consumption does not always correlate with higher cancer rates, sometimes other factors such as diet, lifestyle, and genetics also play important role. Thus, while sugar may contribute to cancer development in certain contexts, it is not a definitive cause.
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How high sugar diet promote cancer cell?
Cancer cells are dependent on glucose for energy through increased glycolysis (the Warburg effect), making high blood glucose levels favourable for tumor growth; this phenomenon is clinically proved through PET imaging.
Research studies found that there is a linear association between high sugar intake, particularly from sugar-sweetened beverages and increased prostate cancer risk.
Other study showed that higher sugary drink intake was associated with increased overall cancer and breast cancer risk.
Insulin resistance and IGF-1
High-sugar diets lead to repeated spikes in blood glucose, triggering increased insulin release. Beyond regulating glucose, insulin can increase cancer cell growth directly through insulin receptors and indirectly by increasing insulin-like growth factors and other growth signals that enhance proliferation and reduce apoptosis.
Inflammation
Various studies suggests that sugar induced hyperglycemia that can further promote the cancer cell growth by increasing pro-inflammatory cytokines such as IL-1β, TNF, and CRP. These inflammatory signals create a tumor-promoting environment by stimulating angiogenesis, enhancing cell proliferation, inhibiting apoptosis, and facilitating metastasis.
High glucose levels upregulate cancer-related pathways, including miR-467–mediated suppression of thrombospondin-1 in breast cancer, leading to increased angiogenesis and macrophage infiltration, and activation of the RAGE–NOX pathway in lung cancer, which enhances oxidative stress and inflammation.
Effect of Different Types of Sugar on Cancer Cells
Recent research suggests that sugar may play a significant role in the development and progression of cancer. Breast, colorectal, pancreatic, and other cancers have been linked to high sugar intake, often independent of obesity or weight gain. Notably, many individuals with normal body mass index (BMIs) still develop metabolic conditions such as diabetes, hypertension, heart disease, and non-alcoholic fatty liver disease.
Glucose
Glucose, a primary energy source, rapidly raises blood sugar levels and triggers insulin release. Elevated insulin can promote cell proliferation and cancer growth.
Fructose
Fructose is primarily metabolized in the liver, and excessive intake can promote fat accumulation, inflammation, and insulin resistance, increasing cancer risk.
Unlike glucose, fructose does not cause immediate insulin spikes but can lead to long-term metabolic disorders, including non-alcoholic fatty liver disease, which is linked to liver cancer.
Fructose metabolism also generates uric acid and reactive oxygen species, contributing to oxidative stress and cellular damage that may promote carcinogenesis.
Sucrose
The link between sucrose and cancer may be indirect, occurring through obesity and metabolic syndrome, which are established cancer risk factors. While some studies suggest high sucrose intake could increase cancer risk via inflammatory effects of glucose and fructose, other studies find no significant association.
High-fructose corn syrup (HFCS)
High-fructose corn syrup (HFCS), widely used in processed foods and soft drinks, contains more fructose than glucose and has been linked to obesity and metabolic syndrome, both established cancer risk factors.
Animal studies, show that HFCS can promote larger tumor growth in mice with preexisting colon polyps, suggesting a potential role in colorectal cancer.
Overall, glucose, fructose, and HFCS appear more strongly associated with cancer development due to their metabolic effects, whereas sucrose shows a weaker direct link. Further research is needed to clarify these differences.
Link Between Sugar and Different Types of Cancer
Breast Cancer
High sugar consumption is associated with an increased risk of breast cancer in both high-income and low- and middle-income countries. Among women diagnosed with breast cancer, frequent intake of sugar-sweetened beverages is linked to higher breast-cancer-specific and all-cause mortality. In contrast, replacing sugary drinks with coffee, tea, or water is associated with reduced mortality risk.
Additional evidence from Europe supports this association, study in Italy reported a higher breast cancer risk among women with the greatest intake of desserts and sugars, while a French study found that consumption of sugary drinks was significantly associated with increased breast cancer risk.
A U.S. case–control study found that women under 45 years who frequently consumed sweets had a significantly higher risk of breast cancer compared with those consuming sweets less.
Colorectal Cancer
Evidence suggests that high sugar intake may contribute to colon cancer development and progression.
Research study of colon cancer patients found that consuming two or more daily servings of sugar-sweetened beverages significantly increased the risks of cancer recurrence (by 75%) and mortality.
Other study also reported a more than two-fold increased risk of colorectal cancer with higher sucrose intake and a clear dose–response relationship.
In contrast, some research studies have reported no significant association between sugar-sweetened carbonated beverages and colon cancer risk, highlighting the need for further research.
Pancreatic Cancer
Studies indicate that high intake of sugar, sugar-sweetened beverages, and fructose is associated with an increased risk of pancreatic cancer, with reported risk increases ranging from ~50% to over 90%.
In contrast, some studies report no association or even an inverse association with juice or soft drink consumption, though these results should be interpreted cautiously due to added sugar content.
Overall, despite BMI adjustment across studies, evidence remains mixed, and further research is needed to clarify the role of added sugars in pancreatic cancer risk.
Impact of Sugar on Other Types of Cancers
Evidence from studies on multiple cancer types suggests that high sugar intake is associated with increased cancer risk and mortality, largely independent of body weight or BMI.
Even modest daily intake of sugary drinks (≈100 mL/day) has been linked to higher overall cancer risk.
Reviews and research studies report positive associations between added sugars and several cancers, including pancreatic, prostate, liver, colorectal, breast, small intestine, esophageal, pleural, lung, hepatocellular, biliary tract, gallbladder, kidney cancers, as well as hematologic malignancies.
High consumption of sugar-sweetened beverages is also associated with poorer survival and increased cancer-specific mortality in several cancers.
However, findings are not uniform. Some studies report no association between sugar intake and certain cancers, inverse associations with ovarian cancer.
Overall, while substantial evidence links added sugars and sugar-sweetened beverages to increased cancer risk and mortality, results are heterogeneous, and further research is needed to clarify cancer-specific effects.
Impact of Sugar During Cancer Treatment and Management
Impact on cancer treatment
Hyperglycemia and insulin resistance can impair cancer treatment effectiveness and increase recurrence risk. Chronic high blood glucose creates a pro-inflammatory state, with elevated cytokines such as TNF-α and IL-6, which weakens the immune system’s ability to effectively attack cancer cells, potentially reducing the efficacy of such treatments.
In diabetic individuals, this metabolic reprogramming enhances tumor growth and weakens anti-tumor immune responses.
High glucose in the tumor microenvironment also contributes to tumor progression and multidrug resistance, with increased glucose transporter (GLUT-1) expression linked to reduced effectiveness of chemotherapy drugs like cisplatin and methotrexate.
Dietary recommendations
For cancer patients and survivors, dietary guidance emphasizes reducing sugar intake to help control blood glucose and support treatment outcomes.
Recommended strategies include consuming low glycemic index foods to avoid rapid blood sugar spikes, increasing fiber intake to slow sugar absorption, and limiting added sugars. Overall, a balanced diet promotes an environment that can aid in cancer prevention and recovery.
Conclusion
This review found consistent evidence linking added sugar consumption with increased cancer incidence and mortality, with the strongest epidemiologic support for breast cancer and notable evidence for colon cancer.
Findings for pancreatic cancer were mixed, but overall suggest a positive association. While many studies, particularly large prospective ones reported increased cancer risk with high sugar intake, study designs and sample sizes varied.
Preclinical studies indicate that high sucrose or fructose diets activate inflammatory and metabolic pathways that may promote cancer development and progression. While direct human prospective evidence is limited, strong human and primate data link added sugar intake to metabolic syndrome, a known cancer risk factor, supporting a biological connection between excess sugar consumption and cancer that may operate independently of obesity. Inflammation and metabolic dysregulation appear to be key mechanisms, highlighting the need to investigate immune system involvement.
A major knowledge gap is the lack of human clinical trials, which are ethically and logistically challenging, and animal findings may not fully translate to humans. Further studies in both humans and animals are needed.
Until clearer evidence is available, greater caution may be warranted when advising the general population and cancer patients about added sugar consumption.
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