This article was first published in The Montreal Gazette.
I don’t think I have chewed gum more than a handful of times in my life. It just never appealed to me. But judging by the flattened relics ground into the pavement on sidewalks and the yucky, sticky blobs on the undersides of lecture room desks, I seem to be an outlier when it comes to this practice. However, I’m all in when it comes to exploring the chemistry of chewing gum.
Most accounts of the history of chewing gum take us back a couple of millennia to the Mayans of Mesoamerica, who tasted the sap of the sapodilla tree and discovered that it did not disintegrate in the mouth. The sap came to be known as “chicle” from the native word “tzictli” that translates as “sticky stuff.” By the 19th century, workers known as “chicleros” were tapping the trees, collecting and drying the sap for sale to the Wrigley Company in Chicago to be turned into sticks of gum given out as a premium with the company’s prime product, which was baking powder. The gum became so popular that Wrigley gave up the baking powder business and went into chewing gum production. It turned out to be a good decision. By 1920, the average American was chewing 105 sticks of gum a year. At the time of his death in 1932, William Wrigley was worth about half a billion in today’s dollars.
During the First World War, Wrigley had even managed to convince the U.S. Department of War to include his gum in soldiers’ rations, arguing that it would quench thirst, alleviate hunger and dissipate nervous tension. He wasn’t completely wrong. Studies eventually did link chewing gum with reducing hunger and improved alertness when performing tasks. The increasing popularity of gum demanded more chicle, a demand that could not be met due to the loss of many sapodilla trees because of excessive draining of the sap. Enter synthetic chemistry.
The main ingredient of chicle is cis-1,4-polyisoprene, the same polymer found in the latex of the rubber tree. Chicle also contains smaller molecules like lupenyl acetate, along with fatty acids and waxes that contribute to elasticity and texture. Chemists went to work to reproduce and even improve on chicle’s properties and came up with various combinations of synthetic polymers, sweeteners, flavourings and preservatives to produce the gums on the market today. Companies are not required to reveal the exact compositions of the main ingredients that allow for chewing without disintegration, having successfully argued that the information is proprietary. On the label, they can be collectively referred to as “gum base.” This can consist of some combination of polyvinyl acetate, polyisobutylene, polyethylene and butadiene-styrene rubber. If these sound like plastics, it is because they are. And therein lies a problem that has recently surfaced.
The media has been ablaze with news of micro- and nanoplastics being found in every body part that has been tested, from brain to penis. The usual suspects for the source of these microscopic particles are the plastic bottles, shopping bags, disposable cutlery, synthetic fabrics, car tires, water pipes and personal care products on which we have come to rely. Whether our health is at risk from the tiny plastic particles that we ingest through food and water or inhale from the air isn’t clear, but it is concerning that they show up in greater amounts in coronary artery deposits and in the brains of people who have died with a diagnosis of dementia. Of course, this does not necessarily mean that the microplastics cause the problem. Perhaps a diseased artery or brain accumulates them more readily. But now we have the added concern that chewing gum also releases micro- and nanoplastics. And their numbers aren’t small. Some 250,000 particles have been detected in the saliva after one hour of chewing.
Anyone concerned about this might be tempted to reach for one of the “natural” gums on the market that are advertised as being free of plastics, sugar, artificial flavours and colours. But as it turns out, that doesn’t mean they are free of micro- or nanoplastics. Researchers at the University of California found equal numbers of particles in the saliva after chewing synthetic or natural gum. It isn’t surprising that they found particles in natural gum because the polyisoprene in chicle is really a naturally occurring plastic, but it is curious that the “natural” gums also contained some of the same polymers as in the synthetic gum. So maybe these are not quite as natural as the manufacturers claim.
As I mentioned, my gum chewing experience is extremely limited, but there is one episode that is quite memorable because of its failure to be memorable. Back in 1999, a company called KR Research Inc. introduced “Brain Gum” that claimed to “switch on the brain.” It was supposed to improve concentration, improve name recognition and improve recall of the location of misplaced objects. The magical ingredient that was supposed to accomplish all this was phosphatidylserine, described on the label as a substance naturally present in the brain that has a role in signal transmission.
Indeed, phosphatidylserine is a fatty substance that protects nerve cells in the brain and enables them to communicate with each other. But that doesn’t mean that a supplement can produce the claimed effects. In any case, it was interesting enough for me to try, and I tried a simple word-matching test after chewing regular gum and after chewing “Brain Gum.” There was no difference. But one test in science doesn’t mean much, so a couple of days later I thought I would give it another go. But there was a problem. I couldn’t remember where I had put the gum.
My next gum encounter was in 2005 when I came across an ad for Bust-Up gum that had gained popularity in Japan with a claim of improving bust size and firmness with its key ingredient being an extract from the Pueraria mirifica plant. This plant grows in Thailand and Burma and contains miroestrol, deoxymiroestrol and isoflavones, all of which have estrogenic activity. Marketers claimed that chewing the gum three or four times a day will increase breast size in more than 90 per cent of women, but I could find no scientific studies that backed up the claim or attested to the safety of the product. I had no need for an increased breast size, but I did want a sample to display in the showcase in my office alongside the Brain Gum that I eventually did find. But when I went to order the Bust-Up gum, I learned that the company had gone bust.
