High intakes of sucrose and fructose may contribute to an increased risk of pancreatic cancer, suggest data from a cohort study, but the researchers say insulin resistance could also play a part.
Researchers at the University of Hawaii and University of Southern California were aware of previous studies indicating an association between high blood glucose concentrations and risk of pancreatic cancer.
From this, it has been hypothesised that a high glycaemic load - that is, blood glucose response after the consumption of food, could also be a risk factor. Data to support this, however, were said to be "scarce and inconsistent".
While in the event they did not actually find evidence to support their hyptopthesis on glycaemic load and cancer risk, Laurence Kolonel and team did find that some connections with sucrose and fructose intake.
The research could give more weight to the trend towards foods and beverages with lower sugar (sucrose) content. Fructose, meanwhile, is a natural sweetener that is also known as fruit sugar and laevulose.
Food ingredient associations have sought to encourage differentiation of fructose and high fructose corn syrup (HFCS), the latter of which is oft used as a sweetener in beverage products and consists of 55 per cent fructose and 42 per cent glucose.
HFCS has been criticised by some campaigners as playing a role in increasing obesity; however industry associations like the Corn Refiners Association have repeatedly claimed there is no scientific evidence to suggest that HFCS is uniquely responsible for people becoming obese.
The researchers analysed food consumption data for 162,150 participants in the Hawaii-Los Angeles Multiethnic Cohort Study.
At baseline, each participant filled in a quantitative food frequency questionnaire. They were then followed up over an eight year period, during which time 434 of them developed pancreatic cancer.
The team looked at consumption data on dietary carbohydrates, sucrose, fructose, total sugars and added sugars.
In fact, they found that glycemic load and added sugars were not significantly associated with cancer risk - thus casting doubt on their original hypothesis.
But a significant association was seen with fructose when the highest and lowest quintiles were compared (1.35; 95% CI: 1.02, 1.80; P for trend = 0.046).
Interestingly, a significant association was found with fruit and fruit juice intake, but not with soda intake (1.37; 1.02, 1.84; P for trend = 0.04).
In the past, high-calorie soda and soft drinks have come under fire for their purported contribution to overweight and obesity. Major soft drink manufacturers have been shifting more towards health and functional offerings in their product mix.
When it came to statistical evidence for a connection between body mass index (the common measure for under-, normal-, over-weight and obesity, measured in kg per m2), a link was only seen for sucrose intake (P=0.04).
Moreover, a greater risk was seen in overweight and obese patients who ate a lot of sucrose, but the association was not significant in participants whose weight fell within the normal bracket.
"High fructose and sucrose intakes may play a role in pancreatic cancer etiology," concluded the researchers. "Conditions such as overweight or obesity in which a degree of insulin resistance may be present may also be important."
While such cohort studies are interesting as they can indicate interesting areas for future investigation, the food frequency questionnaire does have its limitations, since it relies on the individual reporting their own consumption of foods.
The American Journal of Clinical Nutrition Vol. 86, No. 5, 1495-1501, November 2007
Title: "Dietary glycemic load, added sugars, and carbohydrates as risk factors for pancreatic cancer: the Multiethnic Cohort Study."
Authors: Ute Nothlings, Suzanne Murphy, Lynn Wilkens, Brian Henderson, and Laurence Kolonel.