A couple of weeks ago, a joint statement came out from the American Heart Association and the American Diabetes Association that while non-caloric sweeteners may be useful for limiting carbohydrates and added sugars in the diet, the evidence is inconclusive as to whether it works in the long run to cut calories, reduce sugar, and lose weight. The statement in itself was a bit curious since it states that the non-caloric sweeteners may be useful for limiting added sugars in the diet, but the evidence is inclusive that it reduces sugar in the diet. On the contrary, data from a number of epidemiologic studies found that the evidence seems more in favor of the sweeteners increasing sugar and calorie intake and weight gain. Why is this? Here are two proposed reasons:
1. They cause us to overcompensate. Because the taste of sweet is normally followed by calories, as is the case with real/natural sugars, consuming artificial sweeteners may lead to overeating to compensate for the lack of calories. Studies in adults showed that while consuming sucrose before a meal helped to lower the number of calories consumed at a subsequent meal, artificial sweeteners like aspartame did not. This was also demonstrated in rats that were fed either water with sucrose/glucose or an artificial sweetener before a meal. The rats fed artificially sweetened water ate more and gained more weight than the rats that drank sugar water, suggesting that a mechanism for energy balance is in play.
2. They leave us wanting more. There are two branches of the food reward pathway that target different regions of the brain. The first involves the hypothalamus. Functional MRI studies have shown that glucose and sucralose act differently on the hypothalamus. In addition, aspartame binds to sweet taste receptors differently than sugar and activates the second branch of the pathway (that involves the insula, orbitofrontal cortex, and amygdala regions of the brain) to a lesser extent than sugar. This all suggests we don't derive the same pleasure from artificial sweeteners as we do from natural sugars.
On the topic of whether artificial sweeteners are safe to consume, I mentioned last week that the data is inconclusive but there is plenty of human experiences to suggest that they cause problems for many people. If you read this Citizen’s Petition against aspartame on the FDA site, you will get a glimpse into some of the findings about aspartame during it’s development and testing. A search on their site also turns up a number of complaints submitted to the FDA.
In addition, while there has been some concern about aspartame and a risk of cancer, in one study, rats that developed higher numbers of lymphomas and leukemias that were fed aspartame, were given doses equivalent to 8 - 2,083 cans of diet soda per day. Anything in excessive doses can be toxic, even water.
Would I recommend using artificial sweeteners on a regular basis? Not unless you can tolerate them and you can truly reduce your sugar/simple carb intake with them. For many people, I don’t think an occasional diet soda is harmful unless you know for sure that you experience specific reactions to artificial sweeteners. For example, people with PKU who cannot metabolize the amino acid phenylalanine should avoid aspartame entirely. In addition, while many people do not react to sucralose with a rash, knowing what it can do, I choose not to take the risk.
In my mind, the real issue here is not whether or not we should be consuming artificial sweeteners, but rather, why do we need so much “sweet” in the first place? Yes, we have sweet receptors and there are lots of natural foods that can activate them, like fruits and sweet vegetables. Why isn’t this enough for us and why is our food supply swimming in both calorie-containing and non-caloric sweeteners? If we were sweetening our lives in other ways, perhaps our need for sweet taste would dissipate.
Image courtesy of Audfriday13