Scientists have often wondered if there's a link between the amount of sugar we consume and cancer. Can eating too much sugar increase your cancer risk or make cancer cells grow faster if you already have it?
Sugar feeds all the cells in the body — including cancer cells — but research has been divided on what kind of impact it has on cancer growth or cancer risk.
The Mayo Clinic says giving more sugar to cancer cells doesn't speed their growth, and depriving cancer cells of sugar doesn't slow their growth, but the group also issued a caveat.
"However, there is some evidence that consuming large amounts of sugar is associated with an increased risk of certain cancers, including esophageal cancer. It can also lead to weight gain and increase the risk of obesity and diabetes, which may increase the risk of cancer."
Dr. Stacy Kennedy of the Dana-Farber Cancer Institute addresses the subject with similar uncertainty.
"One of the most common questions we hear from our patients is, 'does sugar feed cancer?' As with most nutrition research, the answer to this seemingly simple question is actually quite complex," she writes.
"Overall, most of the research in sugar and cancer uses data from preliminary studies with animal and test tube data to draw conclusions. Recent research has looked at the details of an individual’s diet and sugar intake and how it may affect cancer risk or survivorship outcomes, but there have not been any randomized, controlled trials showing that sugar causes cancer."
But new research may have cracked the link.
The Warburg effect
In 1924, German doctor and physiologist Otto Warburg suggested that cancer cells require sugar to grow and their glucose (sugar) intake is much higher than normal, healthy cells. Called the Warburg effect, this idea that cancer cells quickly break down sugars, which rapidly stimulate their growth, was the basis for continued research through the following near-century, including the use of PET scans to search the body for cancer.
In hopes of taking a closer look at the Warburg effect, Belgian researchers conducted a nine-year study, searching for a correlation between sugar and cancer. In what they are calling a "crucial breakthrough," the researchers say the discovery "provides evidence for a positive correlation between sugar and cancer, which may have far-reaching impacts on tailor-made diets for cancer patients." Their research has been published in the journal Nature Communications.
“Our research reveals how the hyperactive sugar consumption of cancerous cells leads to a vicious cycle of continued stimulation of cancer development and growth," said study author Johan Thevelein of VIB (Flanders Institute for Biotechnology) and KU Leuven university, in a statement.
"Thus, it is able to explain the correlation between the strength of the Warburg effect and tumor aggressiveness. This link between sugar and cancer has sweeping consequences. Our results provide a foundation for future research in this domain, which can now be performed with a much more precise and relevant focus."
The team used yeast cells for the research because they have the same "Ras" proteins that commonly found in cancer cells. As Science Alert explains, they found that in the yeast cells with an overactive influx of glucose, the Ras proteins activated too much, and that then allowed the cells to grow at an accelerated rate.
But the researchers clarified that this is far from the final word on sugar and cancer and that a breakthrough in research is not the same thing as a medical breakthrough.
"The findings are not sufficient to identify the primary cause of the Warburg effect," Thevelein said. "Further research is needed to find out whether this primary cause is also conserved in yeast cells."