Chewing Gum
Does it really take 7 years to digest?
We are taught from a young age that when we swallow chewing gum, it will remain in our digestive tracts for up to 7 years. Have parents created this myth in order to prevent children from swallowing their gum or is gum that difficult to digest? If you haven't noticed, children end up swallowing gum often however they are rarely visiting doctors because of it. Although it is mainly indigestible, gum is no different than anything else that is passing through the digestive system.
Although gum is able to pass through the digestive tract, it is not needed like some ingestible carbs and fiber. To understand the indigestibility of gum, you must understand its composition. Gum is primarily made up of synthetic materials, called gum resin, that give gum its ability to be constantly chewed yet maintain its composition. Gum resin is the component of gum that is indigestible. Normally, food begins breaking down in the mouth by mechanical digestion. The gum resin and synthetic materials prevent this initial digestive process from occurring therefore deeming gum indigestible.
Because gum is not actually digested, it relies on peristalsis to push it through the digestive tract. Peristalsis (pictured below) is a wave of muscle contractions that pushed food through the digestive tract. Because gum is not digested as a regular food molecule would be, it relies on peristalsis to shove it through the digestive system at an efficient rate.
Even though gum is indigestible, the digestive tract is efficient in moving food through the system whether it is digestible or indigestible. Gum will make it through the digestive system at a regular rate. This does not mean it will be changed at all- like most foods ingested- throughout the trip.
In extreme cases, gum accumulates and blocks the digestive tract. Gum also has other components that are easily digested (favoring, sweeteners, softeners). It is only the gum resin that gives our digestive tract trouble.
Check out this entertaining video about gum digestion!
Personally, I was surprised to find that gum did not really take 7 years to digest! The myths we are taught as children really do become personal truths.
This relates to class discussions because we recently discussed the digestive system. In the digestive process, which the digestible parts of gum (flavoring, softeners, sweeteners) would experience, many things occur. First, food enters the mouth where mechanical digestion (chewing) occurs. The indigestible gum resin, however, is resistant to this. Saliva then moistens food to make a bolus for swallowing. Salivary amylase begins chemical digestion of starch. Food then enters the esophagus, where a wave a muscle contractions called peristalsis (earlier discussed) push the bolus into the stomach. When food is in the stomach, muscular contractions continue mechanical digestion. Acid kills the bacteria and pepsin begins digestion of proteins. Food then enters the first part of the small intestine, which is called the duodenum. There, the bile from the liver and gall bladder neutralizes acid and emulsifies fats. Pancreatic amylase and lipase digest carbohydrates and fats. Trypsin then digests polypeptides into amino acids. When the stomach enters the lower half of the small intestine, otherwise known as the ileum, the villi absorbs nutrients into the blood. The bolus then enters the large intestine where water is reclaimed and returned to the blood, leaving semi solid feces. This is the stored in the rectum. Feces if then forced out of the rectum via the anus. I explain the digestive process to show the connection between gum digestion and topics discussed in class and to show how the digestible components of gum are digested. Below is a picture of the digestive system for further understanding.
Sources:
http://kidshealth.org/kid/talk/yucky/swallowed_gum.html
http://gizmodo.com/5904618/what-really-happens-when-you-swallow-your-gum
http://science.howstuffworks.com/science-vs-myth/everyday-myths/gum-seven-years.htm
http://www.snopes.com/oldwives/chewgum.asp
