Carbohydrates and Tooth Decay

Which carbohydrates can cause dental problems? Most of us would be aware that sugars and obviously sweet foods are a problem.

What is not so well known is that many foods that don’t have sugar listed as an ingredient can also cause decay, especially when a child is a snacker or a grazer.

Have you ever heard that simple sugars are bad for you, and complex carbohydrates are ok?

Well, that’s not entirely true.

The body’s mission is to try as hard as it can to break down all carbohydrates into single sugar molecules (carbohydrates are like strings of sugar molecules). Single sugar molecules can cross into the bloodstream to be used as energy. 

Carbohydrates such as starches and refined complex carbohydrates are examples of strings of sugars all connected together. The body can easily break these down into simple sugar molecules.

In the mouth, this can happen on the tooth surface.

Have you ever eaten a packet of potato crisps and noticed the crumbs are packed into your molars? Or a Sao biscuit and needed to rinse your mouth with water afterwards?

Well the enzymes in your saliva would have been busy breaking up those chains of sugar into simple sugars. The bacteria on your tooth would have been eating up the simple sugars and spitting out acid.

When this happens too many times a day, decay starts. 

We like to think of starches and refined complex carbohydrates as ‘orange light food’.

Ok sometimes as part of a balanced diet, but not every day. Definitely not multiple times a day as we see with some children who often eat only these foods, and do so at every main meal and snack. We affectionately call these kids ‘beige eaters’ as they don’t like to see colour on their plates!

Starches and refined complex carbohydrates include:

White bread, crackers, pasta and any other foods made from white flour (pastry, pizza dough, batters), white rice, potato and any grain that has been turned into ‘flakes’, ‘puffs’, ‘shreds’, ‘cakes’ or chips.

Fibre is a complex carbohydrate that is an exception.

Fibre is put together in such a way that it can’t be broken down into sugar molecules, and so it passes through the mouth (and the body) undigested. It is found in the outer layers of grains and is removed during processing (milling and grinding) to make white flour, white rice and cereals. Fibre is indigestible to bacteria in the mouth and promotes health in many ways.

Soluble fibre binds to fatty substances in the intestines and carries them out as a waste, thus lowering cholesterol. It also helps regulate the body’s use of sugars, helping to keep hunger and blood sugar in check. Insoluble fibre helps push food through the intestinal tract, promoting regularity and helping prevent constipation.

Fibre is found in:

Beans (eg. haricot, kidney, cannellini, lima, chickpeas)

Whole grains (whole wheat, whole oats, barley, millet, brown rice, quinoa)




Nuts (especially almonds, Brazil nuts, peanuts and walnuts)

Seeds (linseed, chia seeds)

Fruit eg raspberries, strawberries, cherries, blackberries & banana

Vegetables e.g. broccoli, peas, cabbage, spinach, carrots & brussel sprouts.


So in summary:

  1. Serve as many fibre-rich foods as you like to your kids. 
  2. Be cautious with refined, processed or packaged ‘white’ foods (even if there’s no sugar listed on the label). These foods are just a digestive enzyme away from being the same as a lolly. 
  3. Keep obviously sweet foods for sometimes (we as paediatric dentist suggest aiming for a sweet treat once a week).