By sugar, we mean ordinary table sugar (sucrose). This category also includes extremely sweet foods such as candy and desserts incorporating very high levels of sugar. A high sugar intake can contribute to high body mass index (BMI) and type 2 diabetes, which in themselves can increase breast cancer risk. Consumption of simple sugars has been shown to have a strong positive association with markers of oxidative DNA damage in healthy adults. A sucrose-rich diet has been found to increase the mutation frequency in rat colon cells in a dose-dependent manner. Added sugar has been found to be associated with increased risks of pancreatic, gastric, colorectal and prostate cancer.
Breast cancer-related effects of consuming sugar
Consumption of added sugar, sugary sweets and sodas, and high-sugar desserts are associated with increased breast cancer risk, including for women who are not overweight and not insulin resistant:
Sugar promotes breast cancer growth and metastasis in animal models
One study evaluated carcinogen-induced mammary tumors in rats fed diets containing high levels of either sugar (dextrose or sucrose) or starch (wheat, rice or potato starch). Rats fed sugar diets were found to develop significantly more mammary tumors than those fed starch diets, at both low and high levels of dietary fat. Mice bearing HER2/neu overexpressing (HER2+) or triple negative (ER-/PR-/HER2-) tumors and fed sugar equivalent to the average U.S. sugar intake experienced faster tumor growth and metastasis than control mice in another study. The same study reported that the sugar-enriched diet doubled the number of lung metastases in mice prone to metastatic spread.
Sugar consumption contributes to known breast cancer risk factors
Sugar consumption is associated with other known risk factors for breast cancer in addition to obesity and type 2 diabetes. Sugar consumption increases systemic inflammation. Girls who are frequent consumers of sugar-sweetened beverages are more likely to experience early menarche (first period) at a relatively young age. Sweetened soda consumption has been shown to increase the level of circulating estradiol, the most important estrogen, in premenopausal women. In addition, high sugar consumption is associated with increased breast density.
Sugar contributes to breast cancer growth and metastasis at the molecular level
Consumption of simple sugars has been shown to cause oxidative DNA damage in healthy adults. Glucose, in combination with associated elevated concentrations of insulin, has been shown to induce anti-apoptotic activities (inhibiting programmed cell death), thereby permitting proliferation of cancer cells. A high glucose level also stimulates breast cancer motility (the ability to move, which is required for invasion and metastasis). Cancer cell glucose uptake has been associated with resistance to chemotherapy.
High levels of glucose in the diet caused increased expression of mutant p53 genes in a mouse model of breast cancer. Activation of p53 results either in the death of the cell by apoptosis (programmed cell death) or survival of the cell by cell cycle arrest and DNA repair. However, harmful mutations don't just disrupt the normal functioning of p53, they can also endow p53 with new functions that promote, instead of inhibit, cancer formation.
Population studies confirm link between sugar and breast cancer
A U.S. case-control study found that consumption of sweets, particularly desserts, was associated with an increased risk of breast cancer. An Italian case-control study found that women with the highest intake of desserts (including cookies, brioches, cakes, pastry puffs and ice-cream) and sugars (including sugar, honey, jam, marmalade and chocolate) had increased risk of breast cancer. The results held when adjusted for body mass index and total calorie intake. A Mexican case-control study found that carbohydrate intake was positively associated with risk of breast cancer for both premenopausal and postmenopausal women after adjusting for total calorie intake. The strongest associations were observed for sucrose and fructose intake. Another Italian case-control study found that breast cancer risk increased with increasing consumption of bread, pasta and refined sugar. A Japanese case-control study found that breast cancer risk was positively associated with higher intakes of bread, cake, and soft drinks made with sugar.
Using honey as a sweetener instead of table sugar could be beneficial to overall health and reduce breast cancer risk.
Confectioners' sugar (also know as powdered sugar and icing sugar) consists primarily of sucrose. It is granulated sugar which has been ground into a very fine powder with a small amount of cornstarch added to prevent lumping.
The idea that breast cancer is "fed by sugar" is at best a partial explanation for the association between sugar consumption and breast cancer risk. Sucrose is converted to glucose by enzymes in the digestive tract. All of our cells require energy in the form of glucose to survive. It is true that cancer cells typically consume glucose at a much higher rate than normal cells and compounds that cause inhibition of glucose uptake by tumor cells may inhibit their growth and viability. However, cancer cells will obtain glucose from a variety of foods in the diet, not just sugar. Sugar acts in direct ways to promote breast cancer, not just as a fuel for cell metabolism and growth.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on sugar.