A specific genetic variation may help explain why some people consume more sugary foods than others.
Confectioners can take heart from these findings which suggest that in a health conscious world some people may always be tempted by the sweeter option.
The study, undertaken by researchers at the University of Toronto and published in Physiological Genomics, suggested that individuals with a genetic variation of glucose transporter type 2 (GLUT2) consumed more sugars (sucrose, fructose and glucose) regardless of age or sex.
The study offers the first evidence of the role that a variation in the GLUT2 gene has on sugar intake - GLUT2 controls sugar entry into the cells.
Dr El-Sohemy, the study's senior researcher, said in a statement: "We have found that a variation in the GLUT2 gene is associated with a higher intake of sugars among different populations. These findings may help explain some of the individual variations in people's preference for sugary foods."
According to background information by the researchers, glucose sensing in the brain was thought to be involved in regulating food intake, but the mechanism was not known.
GLUT2-null mice fail to control their food intake in response to glucose, suggesting a potential role for this transporter as a glucose sensor in the brain.
The researchers tested the effects of the genetic variation in two populations. One population was of older adults who were either overweight or obese. The other population was of healthy, young and generally slim adults.
The diets of those in the first population were assessed by recording all they consumed over a three day period. This exercise was repeated two weeks later. The participants were also interviewed face-to-face.
The diets of those in the second populations were assessed via questionnaire that asked about their food and beverage intake over a one month period. Additionally, each participant had their blood taken and their DNA extracted.
The genotype distribution was compared with the food intake data between individuals with the variation and those without the variation in GLUT2.
The DNA samples that carried the variation in GLUT2 were associated with consuming more sugars in both populations.
The two sets of food records from the older group showed that those with the variation consumed more sugar than their non-variant counterparts. At the first visit people with the variation consumed 112 compared to 86 grams of sugar per day (g/d) for their non-variant counterparts, and 111 g/d at the second visit, compared to 82 g/d.
Moreover, individuals in the younger population who carried the variant consumed more sweetened beverages than their non-variant peers (0.49 versus 0.34 servings per day, respectively) and more sweets (1.45 vs 1.08 servings per day, respectively).
There were no differences in the amount of protein, fat, starch or alcohol that was consumed by those with or without the variant.
"Taken together, our findings show that a genetic variation in GLUT2 is associated with habitual consumption of sugars, suggesting an underlying glucose-sensing mechanism that regulates food intake," said the researchers.
Dr El-Sohemy noted that the results of this research are particularly important given the rising rates of obesity and diabetes in some parts of the world.
The study was funded by the Advanced Food and Materials Network and the Canadian Institutes of Health Research.
Source: Physiological Genomics
May 2008, Volume 33, pp 355-360
"Genetic variant in the glucose transporter type 2 is associated with higher intakes of sugars in two distinct populations"
Authors: A. El-Sohemy, K.M. Eny, T.M.S. Wolever, B. Fontaine-Bisson