Potential Health Risks From Beverages Containing Fructose Found in Sugar or High-Fructose Corn Syrup

http://care.diabetesjournals.org/content/36/1/11.full

Fructose is a sweet tasting sugar that is found naturally in fruits and some vegetables and has been part of the human diet—in modest amounts—for eons. The increasing consumption of sugar has dramatically increased our exposure to fructose (1). Sugar consumption has risen more than 40-fold since the Declaration of Independence was signed 250 years ago, and more than 40% of the added sugars in our diet are in sugar-sweetened beverages and fruit drinks (2,3). Thus, the principal sources of fructose in our diet are now sugar and high-fructose corn syrup, each of which has about 50% fructose. The intake of soft drinks has risen fivefold since 1950 (4,5) (Fig.1) and with it the intake of fructose. The rise in the consumption of high-fructose corn syrup in beverages has paralleled the rise in the prevalence of obesity and the metabolic syndrome and is associated with the appearance of nonalcoholic fatty liver disease (6–8). Although association does not prove causation, it has stimulated research to understand whether current levels of fructose intake in beverages pose a health risk.

COMMENT: This is the opening paragraph of a commentary by George Bray on the metabolic effects of high-fructose corn syrup.  I would urge you to read the entire article and the study in the same issue of Diabetes Care cited in this commentary.  The controversy regarding high-fructose corn syrup is unlikely to go away soon.  We clinicians need to be informed and expect that our patients, especially parents are going to ask us about the advisability of drinking such beverages or serving them to their children.   I also would like to hear your views on the topic.

Effects of Fructose vs Glucose on Regional Cerebral Blood Flow in Brain Regions Involved With Appetite and Reward Pathways

JAMA. 2013;309(1):63-70. doi:10.1001/jama.2012.116975.

ABSTRACT 

Importance  Increases in fructose consumption have paralleled the increasing prevalence of obesity, and high-fructose diets are thought to promote weight gain and insulin resistance. Fructose ingestion produces smaller increases in circulating satiety hormones compared with glucose ingestion, and central administration of fructose provokes feeding in rodents, whereas centrally administered glucose promotes satiety.

Objective  To study neurophysiological factors that might underlie associations between fructose consumption and weight gain.

Design, Setting, and Participants  Twenty healthy adult volunteers underwent 2 magnetic resonance imaging sessions at Yale University in conjunction with fructose or glucose drink ingestion in a blinded, random-order, crossover design.

Main Outcome Measures  Relative changes in hypothalamic regional cerebral blood flow (CBF) after glucose or fructose ingestion. Secondary outcomes included whole-brain analyses to explore regional CBF changes, functional connectivity analysis to investigate correlations between the hypothalamus and other brain region responses, and hormone responses to fructose and glucose ingestion.

Results  There was a significantly greater reduction in hypothalamic CBF after glucose vs fructose ingestion (−5.45 vs 2.84 mL/g per minute, respectively; mean difference, 8.3 mL/g per minute [95% CI of mean difference, 1.87-14.70]; P = .01). Glucose ingestion (compared with baseline) increased functional connectivity between the hypothalamus and the thalamus and striatum. Fructose increased connectivity between the hypothalamus and thalamus but not the striatum. Regional CBF within the hypothalamus, thalamus, insula, anterior cingulate, and striatum (appetite and reward regions) was reduced after glucose ingestion compared with baseline (P < .05 significance threshold, family-wise error [FWE] whole-brain corrected). In contrast, fructose reduced regional CBF in the thalamus, hippocampus, posterior cingulate cortex, fusiform, and visual cortex (P < .05 significance threshold, FWE whole-brain corrected). In whole-brain voxel-level analyses, there were no significant differences between direct comparisons of fructose vs glucose sessions following correction for multiple comparisons. Fructose vs glucose ingestion resulted in lower peak levels of serum glucose (mean difference, 41.0 mg/dL [95% CI, 27.7-54.5]; P < .001), insulin (mean difference, 49.6 μU/mL [95% CI, 38.2-61.1]; P < .001), and glucagon-like polypeptide 1 (mean difference, 2.1 pmol/L [95% CI, 0.9-3.2]; P = .01).

Conclusion and Relevance  In a series of exploratory analyses, consumption of fructose compared with glucose resulted in a distinct pattern of regional CBF and a smaller increase in systemic glucose, insulin, and glucagon-like polypeptide 1 levels.

Editorial

Fructose Ingestion and Cerebral, Metabolic, and Satiety Responses

JAMA. 2013;309(1):85-86. doi:10.1001/jama.2012.190505.

COMMENT:  These are intriguing studies suggesting that fructose and sucrose have differing effects on hypothalamic centers controlling satiety and hormonal responses.  If substantiated, these differences would explain why fructose ingestion could result in excess calorie intake.  As the editorialists point out this is not a trivial issue.  We generally think of high fructose corn syrup as a key ingredient of soft drinks, however;

“Products containing fructose are preferred by consumers and cooks over those containing only glucose, owing to the intrinsically greater sweetness of fructose and its ability to improve the appearance and texture of baked goods. As a result, sucrose and high-fructose corn syrup are added not just to sodas, energy drinks, and sports drinks favored by adolescents and adults but also to juice drinks consumed by infants and toddlers and to snacks, processed meats, sauces, and many other foods consumed by people of all ages.”  Stay tuned.