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Pennington Biomedical Research Center
6400 Perkins Road
Baton Rouge, LA 70808
E-mail: brayga{at}pbrc.edu
Dear Sir:
The current obesity epidemic should be of concern to all Americans, because it will affect their future health and health care costs. We thus welcome the letter from Jacobson in response to our article in the Journal (1).
Jacobson makes several points with which we entirely agree, and these deserve to be emphasized again. We agree that massive soft-drink advertising campaigns, the increase in serving sizes from 6.5 oz (192 mL) to bottles containing up to 64 oz (1893 mL), and the increased intake of soft drinks by children and adults at fast-food restaurants, cinemas, and convenience stores are major contributors to the higher calorie intake that is fueling the obesity epidemic. Our paper cites extensive evidence of these trends (2, 3). We also agree that the ubiquitous vending machines (including in schools) make access to these sources of calories all too easy for children, who are becoming obese at an alarming rate.
We agree that excessive consumption of either sucrose-sweetened or high-fructose corn syrup (HFCS)-sweetened beverages could contribute to the epidemic. In his discussion of this issue, Jacobson supports the idea of an upper limit for intake of added caloric sweeteners (sugars) and uses the US Department of Agriculture value of 40 g/d for individuals eating 2000 kcal. Forty grams per day of sucrose or HFCS would contribute 160 kcal/d or 12.5% of the caloric value of a 2000-kcal diet. We would prefer a slightly lower figure of not >10% of energy from added sweeteners.
We interpret the data on the rapid rise of HFCS differently than does Jacobson and want to highlight that point. Consuming a sweetener with the fructose and glucose components separated as found in HFCS, compared with the conjoined molecule in sucrose, does 2 things. First, it changes the "sweetness" of the solution, because in the case of HFCS, separate molecules are competing for the same sweet-taste receptor, whereas with sucrose there is but a single molecule acting on this receptor. As we argued in our paper, the HFCS beverages are thus probably slightly sweeter and could never have exactly the same sweetness as do sucrose beverages. Second, the 2 molecules of glucose and fructose in HFCS give the solution a higher osmotic pressure than that in a beverage sweetened with the same weight of sucrose. This osmotic difference will influence the amount of fluid secreted in the stomach, and this occurs until the sucrose has been cleaved in the intestine to produce glucose and fructose. As we noted in the title to our paper, we believe that the use of HFCS in beverages is an added contributor to the obesity epidemic beyond what would occur if a person consumed soft drinks sweetened with sucrose.
How much the switch to HFCS from sucrose contributed to the increasing consumption of soft drinks in the United States we will never know. However, reduction of caloric intake from any source would be beneficial in combating the epidemic of obesity, and we believe that significant reduction in the use of caloric sweeteners, both HFCS and sucrose, would be beneficial. In our paper, we cited the clinical trial conducted by Raben et al (4), who showed that subjects with access to calorically sweetened soft drinks gained weight, whereas those drinking diet drinks lost weight, during a 10-wk trial. In a recent trial in children, consumption of soft drinks was associated with an increase in body mass index, whereas the rate of weight gain decreased in the intervention schools that reduced their intake of soft drinks (5).
Finally, after our paper was published, we noted that in Figure 1, the prevalence figures for obesity and overweight were incorrect. An erratum published in this issue of the Journal corrects those errors (1).
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