Minutes of the Columbia University Seminar on Appetitive Behavior(#529)Date: September 3rd, 2008 Speaker's Name and Affiliation: Seminar Title: "Glycemic Response in Relation to Gastric Emptying and Satiety" Presiding Chair: Harry R. Kissileff, Ph.D. Rapporteur: Kathleen L. Keller, Ph.D. Attendees and their Affiliation:
Summary: (Prepared by the Rapporteur) The glycemic index (GI) is defined as the incremental area under the blood glucose response curve for a food divided by the corresponding area of a equicarbohydrate portion of a reference food. Clinically, the GI is of interest because there is some evidence that foods with lower GIs may be beneficial for regulating blood sugar, and possibly, body weight. In a recent report in AJCN, Hlebowicz et al. (2007) found that adding 6 g of cinnamon to a rice pudding significantly lowered the GI of that food, compared to the same rice pudding without the cinnamon. Other resent data (Anderson RA, 2008) suggests that cinnamon polyphenols may also improve insulin sensitivity, suggesting a therapeutic role for this spice. In addition, the speaker also noted that gastric emptying rate (computed as the % change in the antral cross sectional area between 15 and 90 minutes) was lower after consumption of the cinnamon adulterated pudding, although these did not translate to significant differences in perceived satiety. The speaker also discussed experiments to determine if lesser doses of cinnamon (1 and 3 gram doses) would produce the same effect as 6 grams of cinnamon. Although satiety responses again did not differ, plasma GLP-1 (a satiety peptide) was increased at 60 and 90 minutes in both the 1 and 3 gram doses of cinnamon, compared to the no cinnamon control. Plasma insulin was lower in the group that got the highest cinnamon dose. Gastric emptying rate, blood glucose, and ghrelin were not affected by either cinnamon dose. The effect of different breakfast cereals was also tested to determine influences on GI and satiety responses. Results suggested that intake of commercially available breakfast cereals did not affect postprandial blood glucose or satiety. However, gastric emptying rate was slowed down slightly after the ingestion of all bran flakes (compared to whole meal oat flakes and corn flakes). Finally, the speaker presented data on the effects of vinegar added to white bread on postprandial satiety responses. Results showed that intake of white-wheat bread or whole meal bread with vinegar did not affect post-prandial blood glucose, gastric emptying rate, or satiety. Furthermore, intake of whole-kernel bread with vinegar did not affect postprandial blood glucose or gastric emptying rate. However, intake of whole-kernel bread with vinegar increased satiety and this may be explained by increased antral distension. In closing, the speaker suggested that further research is needed the determine the post-prandial satiety effects of typically consumed meals with mixed macronutrients. In addition, discussion time was given to discuss the limitations of the scaling procedures used, and how they may have limited the ability to see differences in perceived satiety. References:
Discussion: Q. How do you measure the area of the stomach?
Q. Why do you only use the antral area?
Q. Can you relate these antral areas to the percent of food left in the stomach?
Q. How much rice pudding did your subjects ingest?
Q. Is that the amount of cinnamon needed for the effect, or have you tried with less?
Q. Did you measure insulin levels?
Q. Did you look at CCK levels?
Q. Did you look at the correlations between GLP-1 and insulin in individual subjects?
Q. Has anyone thought of using cinnamon to treat diabetes?
Q. Did the cinnamon affect the palatability of the rice pudding?
Q. There are some studies that say that oatmeal increases CCK release. Do you think that is a factor in lowering gastric empyting?
Q. In your concluding slide, you said that glycyemic index was related to satiety. Can you explain which findings led you to conclude this?
Q. Have you analyzed that?
Q. Why did you choose the scale that you did?
Q. One of the issues with the scale is that the numbers do not relate 1:1 with the descriptors/adjectives on the scale. A labeled magnitude scale or an end-anchored analog scale might produce different results.
Q. Is there any possibility these results could be caused by cephalic phase response differences from different foods?
Q. Individual differences in the size of people may effect the glucose or insulin response. Should they be adjusted for individual differences in size?
Q. What are some of the unanswered questions you would like to address in the future?
Q. Are there any practical conclusions that you might suggest?
Q. Do you have any idea what the long-term effects of cinnamon might be?
Q. How much cinnamon do you get in a piece of cinnamon gum?
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