Dental caries is a medical term for tooth decay or cavities. These occur when bacteria living in our mouth produce acid, which then begins to eat away at our teeth or erodes the tooth enamel. One cannot see, feel or taste such bacteria. There are over 700 different strains of tiny oral bacteria (though most people are host to less than 100), which do us no harm. Most of them are, in fact, beneficial, called probiotics, which aid in the digestion of foods. Nevertheless, there are some species in the mix that cause tooth decay and gum diseases. The two most known ‘bad’ bacteria are streptococcus mutans and porphyromonas gingivalis.
The process of acid formation begins when, after meals or snacks, the bacteria in the mouth metabolises the food, resulting in acidic byproduct. Along with the saliva and food particles, the bacteria accumulate on the surface of the teeth in a sticky film called plaque. The plaque forms easily in cracks, pits or fissures in the back teeth, between teeth and near the gum line. So, the villain is plaque, and plaque’s evil minion is acid. The question also is what happens if the food itself is acidic (food with low pH rating)? If so, there is probably no need for the bacteria to metabolise these acidic foods to form a plaque, which themselves could be dangerous for our teeth.
However, it is clear that whether contained in foods or converted by our mouth’s bacteria, acids can potentially erode our teeth’s enamel, causing cavities and tooth decay. Therefore, it is important to realise that the kind of foods we eat play an important role in affecting or protecting our teeth. Clearly, if the food is acidic or assists the ‘bad’ bacteria in metabolising it into acid, it is not good for our teeth. However, and quite importantly, the threat could be averted if such acid formed or caused to be formed is not allowed to form a plaque on our teeth. In other words, we can protect our teeth by: (a) reducing our intake of acidic foods and/or, (b) ensuring that the foods or acids are not allowed too much time to form plaque on our teeth.
Let us address the first concern about intake of acidic foods. For that we should know which are these acidic foods, having very low pH value (a pH of 0 indicates a high level of acidity, and a pH of 7 is neutral, whereas a pH of 14 is most basic or alkaline). Highest on the list would be citrus fruits, lemons, pickles, grains, tomatoes, coffee, processed foods, high protein foods, sodas, fresh & processed meats, etc. It’s surprising to see a lot of ‘good’ foods in the acidic list, but that’s how it is. For example, lemon juice has a very low pH of 2-2.35 and tomatoes have a pH of 4.3-4.9, and so on. Unfortunately, some fruits like blue plums (pH 2.8-3.4), grapes (pH 2.9-3.82), pomegranates (pH 2.93-3.2) and even apples and mangoes, having pH of below 4.8, are acidic.
On the other hand, pure water is neutral with pH of 7, whereas most vegetables have a pH of 6.5-7, and are almost neutral. Foods like yoghurt, milk, herbs & spices, beans & lentils, herbal teas, olive oil, nuts, mustard, millet, soybeans, etc, are alkalising or neutral. Unlike what people may perceive, sugar has a pH of around 7, and thus is not acidic, but is absolutely neutral.
Therefore, unlike popular belief and myth, sugar, in itself, cannot form a plaque on our teeth and eat the enamel. Can we then say that sugar is not harmful to our teeth? For that, we need to look at the second aspect on whether the ‘bad’ bacteria needs only sugar to form acids/plaque. Is the evil minion for the bacteria only sugar, or are there other factors that help the ‘bad’ bacteria in forming the plaque?
To metabolise any food, the bacteria requires adequate time. Therefore, the faster a food is removed, the less chance it will have to feed the bacteria. It also, however, means that sticky foods, which don’t get easily washed away, either naturally with saliva or with the water we drink, give more time to the bacteria to metabolise them into acid. Numerous studies conducted by the New York University College of Dentistry, on the staying power of food and teeth, found that cooked starches, particularly potato starch in products such as potato chips, cling longer to the teeth than many sugar foods, like chocolate bars.
Other studies have found that tooth decay is related to the frequency of eating than to the amount of starch or sugar. Frequent snacking reintroduces food particles, enabling plaque buildup. One can eat any food, including sweets or starch, at reasonable gaps for them to be washed away, either naturally by saliva or through continuous intake of water, or even by brushing or flossing regularly. Despite what one believes or people write, no health study has conclusively demonstrated a link between tooth decay and soda drinks.
Concluding, one can safely say that:
(a) Since sugar is not acidic, it does not directly harm our teeth and cannot cause tooth decays on its own;
(b) The ‘bad’ bacteria form acid/plaque by feeding on and metabolising several foods, and not only sugar;
(c) Sticky foods are dangerous and too much snacking, not giving time between meals for the saliva or water to wash away the acid or plaque, are more dangerous and stronger threats to tooth decay;
(d) Regular cleansing, including brushing and flossing, will check all teeth decay, and allow us to eat anything we want.
The author is Director General, Indian Sugar Mills Association. (Views are personal)