January 18, 2012

 For those who did not see, I received this question last week in regards to artificial sweeteners:

For the first part, there is a fairly recent study looking at the effects of stevia, aspartame (the most popular artificial sweetener found in diet soda), and sucrose on food intake, satiety, and post-prandial glucose and insulin levels.  As you can see in the first figure, aspartame did well indeed cause an increase in insulin after ingestion but I would not consider this a “spike” (clearly it is not as much as sucrose).  The researchers didn’t speculate on this subtle increase but it does show that the artificial sweetener, aspartame, can indeed increase insulin levels but it is worth noting that this is not that high.  As far as energy intake, you can see in the second figure that the three different loads of either stevia, sucrose, or aspartame did not effect hunger levels throughout the day at other meals.  The only difference was total energy intake but this makes sense since aspartame has no calories compared to sucrose.

On to the next part of the question and whether or not artificial sweeteners can increase appetite.  This time we’ll use another artificial sweetener, sucralose, or as you might know it, Splenda.  An article published last year states that sucralose cannot effect hormones responsible for the satiety response (GLP-1, PYY), insulin levels, or appetite.

Furthermore, does the human gut respond the same way to sugar and artificial sweeteners?  Well, in this study, glucose seems to be the driving factor in activating mechanisms for appetite whereas other sugars or artificial sweeteners did not.  The authors state that sweetness per se does not effect secretion of gastric peptides but the sugar must have a structural integrity similar to that of glucose for these effects to exist.

Let’s move on now to the brain, specifically the amygdala (sorry Waterboy), which is a part that can respond to food aromas and the insula, which relates oral sensations with internal states.  This study shows that in fact, artificial sweeteners can affect these two regions of the brain and interrupt brain chemistry for sensing normal sugars such as sucrose.

As far as safety, it is documented scientifically in this review that artificial sweeteners are in fact safe to use. 

Et voilà. In summary, artificial sweeteners will not affect your appetite and therefore you can go back to ordering a large fast food meal (no really, don’t) with that barge of diet softdrink.  As far as the insulin response, I feel a lot of people downplay the ability of the brain in regards to hunger or satiety.  It is similar phenomena as Pavlov’s dogs salivating in anticipation of a meal after they hear the tuning fork.  Even at the smell of food, your gut will release gastric hormones in anticipation of the food that will soon be eaten and digested.  It could be the same response as to why there was a slight increase in insulin to aspartame.  The mind thought something sweet was being consumed when in fact it was not.  I hope this clarified some of the issues and answered the proposed question.

Nick

April 30, 2011
Reasonable Quantities of Red Pepper May Help Curb Appetite, Study Suggests

"We found that consuming red pepper can help manage appetite and burn more calories after a meal, especially for individuals who do not consume the spice regularly," said Richard Mattes, distinguished professor of foods and nutrition who collaborated with doctoral student Mary-Jon Ludy. 

Click to read more.