Chew, Chew, Chew: Part Three

Chew, Chew, Chew: Part Three

Chewing Gum

Bear with me while I meander towards explaining the value of chewing gum. On the way I will cover some more material on the scientific benefits of chewing. I never realized there was so much material on the subject, but since these studies on chewing are full of interesting facts, I thought we would look at some of them not covered in the first two newsletters on this subject.


Stress is defined as the biological and psychological response to environmental changes and toxic stimuli.  The effect of chronic stress on physical and mental health in turn leads to disease.  The point to note here is that, “stress activates the neuroendocrine system via the autonomic system and hypothalamic-pituitary-adrenal (HPA) axis, which leads to the release of corticosteroids and hormones”.

Chewing properly obviously influences nutritional status, and thus overall health, but chewing is also an effective means of coping with stress.  This was established in early animal studies where it was demonstrated that, “when exposed to an inescapable stressor, animals assume coping behaviours, such as chewing, that attenuate some elements of the stress response.”

In other words, when lab animals are immobilized, or unnaturally restrained, if given the opportunity to chew or bite wooden sticks, they will show decreases in “stress-induced plasma corticosterone levels and attenuated HPA axis and autonomic nervous system responses to stress”.

In humans we recognize certain oral behaviors, such as nail-biting, teeth-clenching, and biting on objects, as outlets for emotional tension or stress. Thus the baseball players who chew gum or tobacco.

One might be forgiven for thinking this type of stress relief, provided by chewing, to only be of value in dealing with low level stressors. However, the fact is that studies have found using chewing to relieve chronic stress can prevent the formation of stress-induced ulcers, reduce deficits in spatial learning ability, and prevent bone loss.


Bone loss? That was a surprise. Nonetheless, “a large body of evidence from animal and human studies indicates a link between chronic mild stress and bone loss. Chewing under chronic stress prevents the increase in plasma corticosterone and noradrenaline levels, which attenuates both the reduced bone formation and increased bone resorption, and improves the trabecular bone loss and microstructural bone deterioration induced by chronic mild stress”.


Let’s have a further look at the idea that chewing is involved in reducing deficits in spatial learning ability.  Tooth loss is considered a risk factor for Alzheimer’s disease, and studies have found that older people with fewer teeth are more likely to develop cognitive dysfunction.

Poor or incomplete chewing, due to tooth loss or incorrect positioning of the teeth (such that they do not meet correctly to facilitate good chewing), induces chronic stress. This has been shown to cause detrimental changes in the hippocampus region of the brain, which leads to learning deficits and memory problems.

We see this occurring because chewing sends a variety of information to the brain, activating several areas of the brain essential for cognitive processing (including the hippocampus and prefrontal cortex).

Anxiety and Depression

One study induced long-term depression in rats, via induced stress. It was then  discovered that chewing reduced the development of long-term depression by positively affecting regions of the hippocampus.  Furthermore “this study demonstrates that chewing could be an active coping strategy for relieving stress-induced anxiety-like behaviors, which may be involved in the dopaminergic neuronal pathway”.

As most of you are aware, dopamine circuits are involved in most addictive behaviors, and low dopamine is also linked to depression. So, by activating the dopaminergic pathways, chewing may serve to help humans reduce depression, and cope with quitting addictive behaviors.

Prenatal Stress

It is well proven that “pregnant mothers exposed to social, emotional, or hostile experiences have offspring with an increased susceptibility as adults to mental disorders, such as depression, schizophrenia, and cognitive deficits”.  Given that a number of studies have demonstrated the ability of chewing to reduce “stress-induced functional and morphologic changes in the hippocampus”, it is no surprise that mothers chewing during prenatal stress prevents prenatal stress-induced learning deficits in their offspring.

Heart Health

The aforementioned effects of chewing on the hypothalamic-pituitary-adrenal (HPA) axis, “also ameliorate stress-induced cardiac imbalances and reduce susceptibility to stress-induced arrhythmias by inhibiting neuronal responses in the hypothalamus”.


Now, the studies referred to above deal with allowing stressed animals to chew on sticks, and observing the benefits. For us humans, gum is preferred to sticks, though chewing on tobacco was extremely popular at one time, and chewing on licorice sticks is a viable, though somewhat messy, option. (Chewing on licorice root sticks, or slices, will also serve to heal gut lining and ulcers, due to its medicinal properties.)

People know why they choose to chew gum, finding that the act of chewing can improve concentration, alleviate stress, and/or reduce sleepiness. And, indeed clinical studies done with humans have confirmed that gum chewing can relieve stress, increase alertness and attention, and improve task performance.

In one study, researchers set out to investigate the effects of chewing gum on “mode and cognitive performance both in the laboratory and naturalistic work situations. Their findings revealed that chewing gum during the workday enhanced productivity and reduced cognitive problems. Thus, chewing gum can attenuate reductions in alertness and enhance worker performance”.

And that is only one study. In a systematic review of 151 published reports on the relationship between chewing and attention, “more than half of the reports indicate that chewing has positive effects on attention, especially sustained attention, and the effects seem to coincide with an improvement in mood”.

In fact, chewing gum may do even more than that. “A recent functional magnetic resonance imaging study revealed that gum chewing during exposure to a loud noise inhibits the propagation of stress-related information in the brain.”

Thus, chewing gum may have the potential to mildly reduce the formation of stress-induced trauma in some people. So, for example, those who are hypersensitive to noise would benefit from using chewing gum on a regular basis when entering into potentially noisy environments.

Gum and Food

Before we examine what type of gum is even worth chewing, I will touch briefly on the principles of gum chewing with regards to digestion.  It has been shown in studies that chewing gum before a meal “can decrease food intake and help prevent obesity via neural pathways”. (Covered in more detail in the last newsletter.)

And, chewing gum after a meal can help with poor digestion, as the body is tricked into thinking you are ingesting food. Therefore, it continues to produce saliva, and release digestive fluids, both of which can help speed up a sluggish digestive system.  On the other hand, for those with ulcers, releasing extra stomach acid can aggravate the condition, and so for those people, chewing gum should be especially avoided on an empty stomach.


Xylitol is a natural sugar substitute which does not affect blood sugar levels nor feed candida yeast in the body. It is defined as a sugar alcohol (like sorbitol and mannitol), though it does not actually contain alcohol. Xylitol occurs naturally in small amounts in fibrous fruits and vegetables, trees, corncobs, and even the human body. While it was originally made from birch bark, it is now commonly derived from corn.

The sweetness of xylitol is comparable to sugar: a teaspoon of xylitol has the same sweetness level as a tsp of sugar, so can be substituted for sugar in baking recipes, unlike stevia which has a far more concentrated level of sweetness. (It is also a far better sweetener for coffee than stevia, in my opinion.)

But, xylitol has much more going on than other sugar alcohols, having actual health benefits that go beyond just replacing sugar with a neutral agent. Clinical studies have shown that xylitol can prevent cavities (dental caries).  In one study, subjects prone to cavities were given xylitol gum (2.5 gr) daily for one year. The subjects chewed two pieces of gum in the morning, two after the midday meal, and one in the afternoon. They were instructed to chew for 5 minutes, and to make no changes in their dietary and oral hygiene habits. Tooth brushing was not allowed for at least one hour after the use of chewing gum. The results? “Subjects using the low-dose xylitol chewing gum showed a significantly lower increment of initial and extensive caries lesions and overall a lower increment of caries experience.”

How Does Xylitol Work?

Dental caries are a result of “interaction between host and environmental factors, with the dental biofilm as the key element”.

“Dietary fermentable carbohydrates are the main triggering factor for development of cariogenic biofilm. When biofilm is matured, the presence of sugars promotes a higher plaque cariogenicity, frequently keeping pH value under the critical levels for preventing  demineralization of enamel and dentine. The acidic environment within biofilm favours the growth of more acid-tolerant bacteria such as mutans streptococci (MS) and lactobacilli.” (Remember that lactobacillus acidophilus in the mouth is a cause of cavities; something noted in earlier newsletters on probiotics.)

So, how does xylitol help prevent cavities? Well, for one thing those using the xylitol chewing gum showed a decrease in the concentration of mutans streptococci, a cavity-causing bacteria, and a reduction in plaque formation.

Furthermore, xylitol stimulated increased saliva flow, which “promotes oral clearance and enhances the buffering capacity to neutralize plaque pH”.  (Xylitol, in the form of gum, mints or oral spray, is used as a treatment for insufficient saliva production.)

Other studies have used from 3 to 8 grams of xylitol daily, however, in one trial where adults used 5 grams of xylitol (or placebo) lozenges for almost 3 years, there was no “significant effect observed in the xylitol group regarding reduction in caries increment even if at dose almost double those administered in the present (above) study”.

Why no benefit, even with more xylitol? Note that that study used lozenges: “In the present one, xylitol was administered via a chewing gum; this led to the release of xylitol many times higher than that of other studies. Xylitol was administered via a chewing gum far from main meals, allowing the polyol to act for a quite long period, and due to a prolonged residence time of xylitol in the oral cavity”.


If you are looking to chew gum for any of the benefits we have discussed, but especially for preventing cavities, use xylitol gum. Other gums, whether sweetened with sugar or artificial sweeteners, do more harm than good.  And, one note of warning. Sugar alcohols, like xylitol (including erythritol) will cause some people to experience flatulence. This stops after one adapts to the substance, so it is a good idea to start slowly, and gradually increase the dose, in order to minimize the potential for this side effect.


Mastication as a Stress-Coping Behavior

Chewing, Stress-Related Diseases, and Brain Function

The caries preventive effect of 1-year use of low-dose xylitol chewing gum.

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