Many studies show that regular intake of highly concentrated sugary foods may cause or feed cancer. Some studies also show that high dietary sugar (from sugar beet) consumption may interfere with certain treatment outcomes in specific cancer types. A research team also has uncovered the cellular pathways and mechanisms that link high blood sugar levels found in diabetics to increased DNA damage, through forming DNA adducts (chemical modifications of DNA), which causes mutations, the underlying cause of cancer. Hence, cancer patients should avoid regular intake of high concentrated sugar. However, cutting off sugar completely from our diet is not a solution as it leaves the healthy cells low on energy! Maintaining a lifestyle with a healthy diet with reduced intake of sugar (eg: from sugar beet) and increased physical activity can help with lowering the risk of cancer or stop feeding cancer.
“Does Sugar Feed Cancer?” “Can Sugar Cause Cancer?” “Should I cut off sugar completely from my diet to stop feeding my cancer?” “Should cancer patients avoid sugar?”
These are some of the most frequent queries being searched over the internet for many years. So, what are the answers to these questions? There are many conflicting data and myths around sugar and cancer in the public domain. This becomes a concern for cancer patients and their families while deciding on the patients’ diet. In this blog, we will summarize what the studies say about the connection between sugar and cancer and the ways to include the right amount of sugar as part of a healthy diet.
Sugar and Cancer
Sugar is present in most of the foods that we take daily in one form or the other. Sucrose is the most common type of sugar that we usually add to our foods as table sugar. Table sugar is processed or refined form of sucrose extracted from the stalks of sugarcane plants or sugar beets. Sucrose is also found in other natural foods including honey, sugar maple sap and dates but it is found to be available in the most concentrated form in sugarcane and sugar beets.It is made up of glucose and fructose. Sucrose tastes sweeter than glucose, but less sweeter than fructose. Fructose is also known as “fruit sugar” and is mostly found in fruits. Adding too much refined sugar extracted from either sugar beets and sugarcanes is unhealthy.
The cells in our body need energy for its growth and survival. Glucose is the primary source of energy for our cells. Most of the carbohydrate and sugar rich foods that we take as part of our daily diet such as cereals and grains, starchy vegetables, fruits, milk and table sugar (extracted from sugar beet) get broken down into glucose/blood sugar in our body. Just as a healthy cell requires energy to grow and survive, the fast growing cancer cells also require lots of energy.
Cancer cells extract this energy from blood sugar/glucose which is formed from carbohydrate or sugar based foods/diets. Over-consumption of sugar has rapidly increased all over the world. This significantly contributes to overweight and obesity that can drive cancer. In fact, obesity is one of the main risk factors for cancer.The question on whether sugar feeds or causes cancer stems from this.
Different studies/analyses have been carried out by researchers across the world to evaluate the association between consumption of highly concentrated sugary foods such as sweetened beverages and cancer. The findings of many such studies are collated below. Let us see what the experts say!
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Association of Consumption of Sugary drinks with Breast Cancer
A recent meta-analysis used data from the French NutriNet-Santé cohort Study which included 1,01,257 participants aged 18 and over. The study evaluated the association between consumption of sugary drinks such as sugar sweetened beverages and 100% fruit juices, and artificially sweetened beverages and cancer based on a questionnaire based data. (Chazelas E et al, BMJ., 2019)
The study suggested that those who had an increased consumption of sugary drinks were 18% more likely to develop overall cancer and 22% more likely to develop breast cancer compared those who did not or seldom consume sugary drinks. However, the researchers suggested more well designed prospective studies to establish this association.
A similar study was conducted which evaluated data from 10,713 middle-aged, Spanish females from the Seguimiento Universidad de Navarra (SUN) cohort study with an average age of 33 years, who didn’t have a history of breast cancer. The study evaluated the association between consumption of sugar-sweetened beverages and incidence of breast cancer. After a mean follow up of 10 years, 100 breast cancer incidences were reported. (Romanos-Nanclares A et al, Eur J Nutr., 2019)
This study found that compared to zero or seldom consumption of sugar sweetened beverages, a regular consumption of sugar sweetened beverages may be associated with a higher incidence of breast cancer, especially in postmenopausal women. They also found that there was no association between intake of sugar sweetened beverages and breast cancer incidence in premenopausal women. However, the researchers have suggested larger well designed studies to support these findings. In any case, it is better that cancer patients avoid regular, very high intake of sugar sweetened beverages.
Association of Consumption of Concentrated Sugars with Incidence of Prostate Cancer
A recent study analyzed data of 22,720 men from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial who were enrolled between 1993-2001.The study evaluated the association between consumption of added or concentrated sugars in beverages and desserts and prostate cancer risk. After a median follow-up of 9 years, 1996 men were diagnosed with prostate cancer. (Miles FL et al, Br J Nutr., 2018)
The study found that increased consumption of sugars from sugar-sweetened beverages was associated with an increased risk of prostate cancer for men who consumed very high levels of sugar. The study suggested that limiting the intake of sugar from beverages may be important in reducing the risk of prostate cancer. Prostate cancer patients may have to avoid very high intake of concentrated sugar.
Association of Sugary Drink Intake with Pancreatic Cancer
A recent study did a similar analysis using questionnaire-based data from 477,199 participants included in the European Prospective Investigation into Cancer and Nutrition cohort study, most of which were women with a mean age of 51 years. During a follow up of 11.6 years, 865 pancreatic cancers were reported. (Navarrete-Muñoz EM et al, Am J Clin Nutr., 2016)
Unlike the previous study, this study found that total sweet beverage consumption may not be associated with pancreatic cancer risk. The study also found that juice and nectar consumption might be associated with a slight decrease in pancreatic cancer risk. Pancreatic cancer patients may have to avoid very high intake of drinks with concentrated sugar.
Association of High Blood Sugar levels with Treatment Outcomes in Colorectal Cancer Patients
In a retrospective study done by the researchers in Taiwan, they analyzed data from 157 stage III colorectal cancer patients who were classified into 2 groups according to their fasting blood sugar levels – one group with blood sugar levels ⩾126 mg/dl and another with blood sugar levels <126 mg/dl. The study compared the survival outcomes and chemoresistance of the oxaliplatin treatment in the two groups. They also carried out in vitro studies to evaluate the impact of an anti-diabetic drug on cell proliferation after administering glucose. (Yang IP et al, Ther Adv Med Oncol., 2019)
Glucose addition increased the colorectal cancer cell proliferation in vitro. It also showed that administration of an anti-diabetic drug called metformin could reverse the enhanced cell proliferation and increase the sensitivity of the oxaliplatin treatment. The study on the two groups of patients suggested that a high blood sugar may be associated with a higher incidence of the disease relapse. They also concluded that patients with stage III colorectal cancer and high blood sugar levels may exhibit markedly poor prognosis and may develop resistance to the oxaliplatin treatment in a short period.
Findings from this study suggest that high blood sugar can impact the oxaliplatin treatment outcomes in Colorectal cancer patients. Hence, colorectal cancer patients undergoing this treatment may have to avoid very high intake of concentrated sugar.
What is the association between Diabetes and Cancer?
Diabetes is a global epidemic with over 30 million Americans and over 400 million people globally affected by this disease. As per the world health organization, the prevalence of diabetes is increasing more rapidly in low to middle-income countries, this trend being linked to unhealthy diet, lack of physical activity and obesity. There have been multiple studies and meta-analysis that showed a strong correlation between diabetes and increased risk of cancer, but it has always been unclear as to why exactly this is the case. Dr. John Termini and his team from City of Hope, a cancer research institute in California, explored this association and was able to link hyperglycemia (high sugar level) to DNA damage, a key cause of developing mutations that can lead to cancer. Dr Termini presented his findings last year in the 2019 American Chemical Society National meeting.
Before we dive into this incredible breakthrough, we should get a basic understanding of some fundamental terms and functions to fully understand the significance of Dr Termini’s research. As humans, we get the energy that our bodies need to function through eating food, which when broken down, releases glucose or blood sugar into the body. However, for the body to turn this glucose into energy, it uses insulin, a hormone produced in the pancreas, to get the glucose absorbed by the cells and tissues of the body. People diagnosed with diabetes have lower insulin levels and insulin sensitivity in their body, which leads to an excess of glucose to remain in the blood, which is known as hyperglycemia and can lead to a multitude of health problems. Another concept to understand is that cancer is caused by cell mutations due to DNA damage, that lead to uncontrolled and unchecked mass cell divisions spreading through the body.
In a summary of Dr Termini’s findings and presentations in an article by ASCO (American Society of Clinical Oncology) Post journalist, Caroline Helwick, Helwick writes that Dr Termini and his colleagues found “that elevated glucose increases the presence of DNA adducts – chemical modifications of DNA that can be induced endogenously” (Helwick C, ASCO Post, 2019). The team found that high blood glucose levels can not only form these DNA chemical modifications (DNA Adducts) but also prevent their repair. DNA adducts can lead to miscoding DNA during its replication or translation into proteins (leading to DNA mutations), or even induces strand breaks which interrupts the whole DNA architecture. The inherent DNA repair process that is supposed to fix any errors in the DNA during DNA replication, is also interrupted by formation of the DNA adducts. Dr Termini and his team have identified the exact adduct and proteins that are directly involved in the process due to having increased glucose in the blood. The common understanding of increased cancer risk in diabetics was linked to hormonal dysregulation, but Dr Termini’s research explains the mechanism of how hormonal dysregulation leading to glucose imbalance and high glucose/sugar levels in the blood cause DNA damage which increased cancer risk in diabetics.
The next step, which different researchers have already started working on, is how to use this breakthrough information to drastically reduce cancer rates around the globe. “ In theory, a drug that lowers glucose levels could also potentially help fight cancer by “starving” malignant cells to death” (Helwick C, ASCO Post, 2019). Termini and many other researchers are exploring the anti-cancer effects of a commonly used diabetes drug called metformin, used for regulating and lowering blood sugar levels. Multiple experimental studies in many cancer models have shown that metformin has the ability to regulate specific cellular pathways that facilitate DNA Repair.
What do these studies suggest- does sugar cause or feed cancer?
There is conflicting data on the association between sugary food intake and cancer risk. However, most of the studies indicate that sugar consumption in restricted quantities may not cause/feed cancer. These studies also highlight that a constant intake of high sugary foods which can increase the blood glucose to a very high level leading to overweight and obesity is not healthy and can increase the risk of cancer. Regular intake of highly concentrated sugary food (including table sugar from sugar beet) may cause/feed cancer. Some studies also show that high sugary food consumption may interfere with certain treatment outcomes in specific cancer types.
Should we cut off sugar completely from our diet to prevent cancer?
Cutting off all forms of sugar from the diet may not be the right approach to avoid cancer, as the healthy normal cells also require energy to grow and survive. However, keeping a check on the following may help us stay healthier!
- Avoid regular intake of high sugar sweetened beverages, sweetened carbonated beverages, high concentrated sugary drinks including certain fruit juices and drink lots of water.
- Take just the right amounts of sugar as part of our diet by having whole fruits instead of separately adding table sugar (extracted from beet sugar) or other forms of sugar to our foods. Restrict the amount of table sugar (from sugar beet) in your beverages such as tea, coffee,milk, lime juice and so on.
- Reduce the consumption of processed foods and include more fruits and vegetables.
- Avoid sugary and fatty foods and keep a check on your weight, as obesity is one of the major risk factors for cancer.
- Take a personalized cancer diet which supports your treatment and cancer.
- Along with healthy food, do regular exercises to stay healthy and avoid gaining weight.
“What should I eat?” is the most frequently asked question to cancer dieticians and physicians. The right answer depends upon cancer type, underlying genomics, current treatments, any allergies, lifestyle information, and factors like BMI.
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Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer.Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.