We've all been warned about sugar, with experts saying it can wreak havoc on everything from our teeth to our waistline. Those with a sweet tooth may now also face increased risk of breast cancer, according to a new study from the University of Texas MD Anderson Cancer Center.
Researchers have highlighted dietary sugar's effect on a particular enzymatic signaling pathway, called 12-LOX (12-lipoxygenase). Prior research has linked higher intake with breast cancer development, suggesting inflammation is at play. The current study, however, focuses more on how sugar effects mammary gland tumor development in mouse models.
"Prior research has examined the role of sugar, especially glucose, and energy-based metabolic pathways in cancer development," said Dr. Peiying Yang, assistant professor of palliative, rehabilitation, and integrative medicine, in a press release. "However, the inflammatory cascade may be an alternative route of studying sugar-driven carcinogenesis that warrants further study."
Yang and her team found mice with sucrose levels comparable to levels found in Western diets (so, a lot) were at greater risk for breast cancer tumor growth and metastasis compared to mice on a non-sugar starch diet. One idea is that eating more sugar can increase expression of 12-LOX and 12-HETE, a related fatty acid.
But instead of glucose, Yang and her team were able to determine "that it was specifically fructose," found in table sugar and high-fructose corn syrup, behind the increased risk.
Yang also noted that no other studies have explored the direct effect of sugar consumption on the development of breast cancer through animal models, or at least looked at the specific mechanisms involved. Not only does this study do that, but it also shows that the number of lung metastases is higher in mice eating a sucrose- or fructose-enriched diet.
The authors of the study claim identifying risk factors for tumor growth and metastases is a top public health priority, and that these findings further support the idea that moderate sugar consumption is critical. Per capita consumption of sugar in America has ballooned to over 100 pounds per year, especially the consumption of sugar-sweetened beverages. On its own, sweetened drinks are considered to be a massive force behind the obesity, cancer, and heart disease epidemic, respectively.
"This study suggests that dietary sucrose or fructose induced 12-LOX and 12-HETE production in breast tumor cells in vivo," study co-author Dr. Lorenzo Cohen said. "This indicates a possible signaling pathway responsible for sugar–promoted tumor growth in mice. How dietary sucrose and fructose induces 12-HETE and whether it has a direct or indirect effect remains in question."
The team believes the association warrants further research.
Source: Jiang Y, Pan Y, Thea P, Tan L, Gagea-lurascu M, Cohen L, et al. Dietary sugar induces tumorigenesis in mammary gland partially through 12 lipoxygenase pathway. Cancer Research. 2015.