“The bottom line is the modern diet contains a lot of refined sugar, including fructose, and it’s a hidden danger implicated in a lot of modern diseases, such as obesity, diabetes, and fatty liver,” said Anthony Heaney, an associate professor of medicine and neurosurgery, a Jonsson Center researcher, and senior author of the paper. “In this study, we show that cancers can use fructose just as readily as glucose to fuel their growth.”
The research is especially meaningful because of the enormous increase in fructose consumption by people in the West over the past 40 years. Fructose comes in particular from cane sugar (sucrose) and high fructose corn syrup. The latter, derived from corn and introduced in about 1970, now amounts to more than 40 percent of food and beverage caloric sweeteners, and is present in virtually all American sodas.
From 1970 to 1990, U.S. use of high-fructose corn syrup rose over 1,000 percent, according to an article in the American Journal of Clinical Nutrition. Food producers utilize the syrup because it’s cheap and easily transported.
In the UCLA study, the researchers removed pancreatic cancer tissue from patients and grew the tumor cells in glass dishes. To one group of dishes, they added glucose, and to another fructose. They then used an analytical technique known as mass spectrometry to follow radioactively labeled sugars to see just how they were being utilized at the cellular level.
Despite the great structural similarity between glucose and fructose, the scientists found that pancreatic cancer cells could easily tell the two apart, and metabolized them very differently. The malignant cells used fructose in a particular biochemical pathway that constructs nucleic acids, the precursors of RNA and DNA – both essential for cell division and multiplication.
“Traditionally, glucose and fructose have been considered as interchangeable monosaccharide substrates that are similarly metabolized, and little attention has been given to sugars other than glucose,” the paper said. “However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters ... These findings show that cancer cells can readily metabolize fructose to increase proliferation. They have major significance for cancer patients, given dietary refined fructose consumption.”
Heaney suggested it may become advisable for the federal government to undertake an anti-fructose campaign similar to those against smoking – especially if the same fructose-centered dynamic is at play in other types of cancer, as may be the case.