Added sugar has infiltrated the food industry because of its ability to mask other, less desirable flavors. The average American consumes about 130 lbs. of sugar a year (1). When we compare how much we were eating back in 1822 to how much we eat now, we find that on average we eat 725 grams MORE sugar every 5 days (1). So, what effect is this abundance of sugar having on our bodies? A recent study published in the Journal of Pediatric Gastroenterology and Nutrition suggests that high fructose (a key component of sugar) consumption may be linked to non-alcoholic fatty liver (NAFL) in obese populations (2).
This study, a cohort study, examined 592 adolescents from ages 14 to 17, at which point findings were analyzed. At age 14 the subjects each completed a 3-day food record and BMI measurement. Three years later the then 17 year old subjects underwent an ultrasound to determine NAFL status. The results indicated that while there was no significant difference in fructose intake between teens with NAFL than those without. There was however, one exception. Among teens that were obese, fructose consumption was much lower among those without NAFL than any other obese teens.
Things to consider when analyzing this data is that the key measurement used to assess health status was BMI, which is a notoriously inaccurate measurement because it fails to take into account those with a higher muscle mass. The study failed to measure levels of physical activity and did not clearly state their method of dietary data collection at the time of the 17 year olds assessment. This raises the question of how accurate their measurement of fructose intake was. We could assume that they did a 3-day recall similar to what was done at the 14-year assessment. If that were the case, a 3-day recall would be a poor measure in determining fructose intake over the 3-year period. The researchers did not obtain information for intake of fiber, saturated fat, or gender, all of which could be potential confounding factors in this research. It is also important to remember that adolescents who are obese may be more prone to developing chronic disease such as NAFL.
Fructose can be found in fruits, sucrose (commonly referred to as table sugar), and in the form of high-fructose corn syrup. Fructose differs from other sugars such as glucose and galactose in that our liver digests it almost completely, after which it is then converted into fat (3). This is the reason why fructose is believed to contribute to NAFL, in addition to the more common problem of belly fat. The digestion of fructose has been compared to ethanol (or, alcohol) but “without the buzz” (3). The fact that there is not a single function in the body that requires fructose is another argument as to why we should be consuming less of it. Fructose has also been shown to have a greater effect of increasing our lipids than glucose, indicating that it may be more likely to promote fat production (4). Biochemistry provides strong arguments for the detrimental effects of fructose, but human research has yet to prove equally convincing evidence.
The Fructose Hypothesis estimates that because chronic diseases such as diabetes and cardiovascular disease are increasing, in correlation with an increase in fructose consumption, fructose is the root of many current health problems. Other researchers suggest that this hypothesis is based off of inaccurate data and that glucose consumption has increased in step with fructose, thus making it difficult to pinpoint fructose as the culprit (5). Research on this topic is preliminary and conflicting. More needs to be done before we can identify a causal effect on chronic disease. But, at least among the obese, we may want to be thinking twice about fructose.
1. Blodget, H. American Per-Capita Sugar Consumption Hits 100 Pounds Per Year. Business Insider. February 19, 2012. Accessed March 4, 2014.
2. Oʼsullivan, T. A., Oddy, W. H., Bremner, A. P., Sherriff, J. L., Ayonrinde, O. T., Olynyk, J. K., … & Adams, L. A. (2013). Lower Fructose Intake May Help Protect Against Development of Non-Alcoholic Fatty Liver In Obese Adolescents. Journal of pediatric gastroenterology and nutrition.
3. Lustig R. Fructose: it’s “alcohol without the buzz”. Advances In Nutrition [serial online]. January 1, 2013;4(2):226-235. Accessed February 19, 2014.
4. Bray, G.A. Fructose: Pure, White, and Deadly? Fructose, by Any other Name, is a Health Hazard. Journal of Diabetes Science and Technology [serial online]. July 1, 2010;4(4):1003-1007. Accessed March 4, 2014.
Reviewed by Viktoriya Wolff