The chewing of gum is said to be the world's most common habit, with about 100,000 tons of it being consumed every year. Most of us are familiar with the negative aspects of chewing gum, when we find it on chairs, stuck under desks or contaminating pavements and therefore our shoes. However, there are also many benefits to chewing gum.

History of Chewing Gum

The chewing of gum dates from very early times. Indeed, in 1993 archaeologists found three wads of 9000 year old honey-sweetened, chewed birch resin in the bark flooring of a hut used by hunter-gatherers on the Swedish island of Orust. Dental experts say the imprints on one, well-preserved piece come from a fully-grown person whose teeth had not yet been worn down by the stresses of Stone Age life; and so, amusingly, could only have been a teenager.

The habit of chewing gum was popular with the Greeks, who chewed mastic gum, a resin obtained from the mastic (or mastiche, pronounced 'mas-tee-ka') tree. This is a small shrub-like tree found mainly in Greece and Turkey, and the resin was particularly favoured by Grecian women who found that it both cleaned their teeth and sweetened their breath. Indeed, the Greek pharmacologist Dioscorides, pioneered the use of powdered mastiche as a medicine about 50AD; and it has been used for this purpose on the island of Chios ever since.

It is interesting to note that the name 'mastic' is probably derived from the Greek 'mastichon', which means 'to chew', and it is also the root of the English verb, 'masticate'.

Furthermore, settlers in New England discovered that the natives were chewing a gum-like resin that formed on spruce trees when the bark was cut, and lumps of spruce gum were sold in the eastern USA during the early 1800s, making it the first commercial chewing gum in the country.

In about 1850, sweetened paraffin wax became popular and eventually succeeded spruce gum in popularity.

Chicle

Chewing gum assumed its modern formulation when, during the 1860s, chicle was brought to the United States and tried as a chewing gum ingredient by a dental technician, Dr Thomas Adams - who was actually trying to invent a new form of rubber! Chicle comes from the milky juice (latex) of the sapodilla tree, which grows in the tropical rain forests of Central America. Dr Adams owned a sweet shop, and also had the habit of chewing on his pencil, which helped him to concentrate. This gave him the idea of trying the gum to perfect the existing forms of chewing gum. Although this gum apparently tasted vile, he sold it in his shop, thus being the first person to sell chewing gum in its modern form.

At this stage, William Wrigley, a flour factory owner, bought the rights to the gum and also found a way to flavour it with mint. In 1892 he decided to give away two packs of his chewing gum with each can of baking powder he sold, and the offer was a huge success! People were buying the baking powder just to get the gum, and it was not long before chicle gum succeeded spruce gum and paraffin wax as the base for chewing gum. This was due to its smooth, springy, chewy texture and its capacity to retain flavours.

Nowadays 90% of chewing gum is manufactured by Wrigley, and the basic process has changed little since manufacture began in 1892.

Sugar-Free Chewing Gums

Sugar-free formulations tend to include the synthetic sweetener, aspartame or the naturally-occurring xylitol, which are low-calorie sweeteners.

In recent years, the sugar-free sector of the total chewing gum market has been steadily increasing and, across Europe, depending on the country, now accounts for between 40% and 85% of the total chewing gum market. The reasons for this are that they enhance flavour and sweetness, enabling manufacturers to produce a good-tasting, longer-lasting chewing gum. Furthermore, the non-cariogenic (Does not cause dental caries) nature of sugar-free chewing gums brings significant dental benefits, partly because they do not contain the sugars which would cause an increase in acid levels in the mouth.

Health Benefits of Chewing Gum

The popular perception is that chewing gum is bad for the teeth. However, many dentists (one source says 90%!) believe that chewing sugarless gum after meals actually has health benefits! Indeed, Wrigley's Orbit sugar-free gum was the first sugar-free chewing gum to be awarded accreditation by the British Dental Association (BDA) in recognition of its contribution to good oral health. The benefits arise from the fact that tooth decay occurs when essential minerals are dissolved from the tooth enamel by acids produced by the bacteria in plaque. Teeth are at their most vulnerable directly after meals and snacks, when plaque acid levels can rise dramatically.

Normally, it can take up to two hours for these acids to be either flushed away or neutralised, during which time the teeth are under attack. This is why people are extolled to eat something crispy like an apple immediately after meals.

However, chewing gum removes these acids within minutes, thus slowing down the process of tooth decay. One reason for this is that chewing can stimulate saliva production by up to ten-fold, thus flushing out oral bacteria. Furthermore, saliva contains hydrogen carbonate ions, a mild alkali, which serves to neutralise plaque acids. For this reason, hydrogen carbonate is used in some toothpastes. Saliva also contains minerals such as calcium, phosphate and fluoride - all components of tooth enamel - which can be assimilated and thus help to repair early decay and also strengthen tooth enamel.

Another theory is that amylase, an enzyme present in saliva, speeds up the digestion of carbohydrates in food.

Nicotine Replacement Therapy (NRT)

It is said that the chewing of gum can act as a displacement activity to reduce the craving for nicotine.

However, this can be insufficient for some individuals when they are trying to give up smoking, and so it is possible to buy gum that contains nicotine. The action of chewing releases nicotine. This is then absorbed through the mouth, in exactly the same manner as nicotine from a 'smoke' and travels directly to the brain to produce its effects. Chewing a nicotine gum produces a steady level of nicotine in the body, which reduces the craving to smoke; and alleviates the withdrawal symptoms of irritability, restlessness and hunger.

Nicotine gums are available in varying strengths according to an individual's smoking habits. For example, a 2mg-strength gum is available for those who smoke less than 20 cigarettes per day.

Miscellaneous Benefits of Chewing Gum

Mention has already been made of the fact that chewing gum can be an aid to concentration. One theory behind this is that the action of chewing stimulates a part of the brain called the hypothalamus, which releases hormones which serve to keep us alert.

The act of chewing gum also requires some input of energy and, in fact, an extra twelve kilocalories (50kJ) per hour is burned in the process. Thus someone who chewed gum all day, everyday would burn off about 5kg of weight in a year!

Chewing gum when travelling on an aircraft can counteract the irritation caused by changes in air pressure.

Dangers of Chewing Gum

If gum is chewed too often or too vigorously, it can cause a chronically painful jaw condition called temporomandibular joint disorder.

Miscellaneous Uses for Chewing Gum

Chewing gum is extremely handy for effecting all kinds of temporary repairs. Tales abound of using gum -in its ABC (Already Been Chewed) state - to seal car radiators and tyres, to fix radio connections or musical instruments and even, on one occasion, to fix the hydraulic piping of a bomber's landing gear! Dentists have been known to recommend the use of chewing gum to effect temporary fillings pending a more permanent solution; or to act as a cushion against teeth with sharp edges. On one occasion, as a child, this Researcher used chewing gum to repair a hole in a gas pipe caused by an errant dart. The gas board engineer was very complimentary and said he would probably have done the same thing.

Removing Chewing Gum Contamination

Chewing Gum has become one of most offensive non-recoverable items of litter in public places and now presents one of the UK's biggest public cleansing problems.
- (Quotation from the website of a specialist cleansing firm).

• Indeed, it has been reported (2005) that local authorities in the UK pay some £150m a year to clean streets of chewing gum discarded in a 'non-environmentally friendly' way.

• As chewing gum can be so extremely difficult to remove, there are specialist firms who will deal with this.

• Chewing gum contamination commonly affects fabrics, for example clothing; and surfaces such as pavements.

• Removal from fabrics is best achieved by placing the affected item into the freezer for a few hours, whereupon the chewing gum can be cracked off. Any remaining gum may then be removed by using liquid lighter fuel on a clean cloth, although this should always be tested first on a hidden section of the fabric.

• It is very difficult to remove gum from surfaces such as pavements and flooring. It would appear that manual scraping of the gum is all that can be recommended.

Towards a Biodegradable Chewing Gum

Due of the persistence of chewing gum, Wrigleys has invested heavily into research into biodegradable¹ chewing gums since about 1988, but no new products are yet ready for consumer testing.

The reason for this is that chewing gum is essentially a flavoured, synthetic rubber; that is, it is made up of polymers, which are very long molecules. It is the polymeric nature of gum which provides its texture, making it stretchy and pleasant to chew; but these same polymers also make gum sticky. A further problem is that the polymers in gum have a particular affinity with the polymers in asphalt and thus stick to it extremely fastly.

In 2005, university scientists in the USA did succeed in producing a biodegradable gum based on a protein called corn zein, a byproduct of ethanol production for use as a biofuel. The gum hardens, instead of becoming sticky, once it is spit out. When this gum is spit out onto the ground it hardens instead of becoming sticky, and is completely decomposed in about two weeks.

Other potential applications for this product include providing a matrix for the growth of cells in tissue engineering.