This week I had two patients complaining about bloating and diarrhoea after eating a couple of mints. They were surprised at the level of gastrointestinal drama and discomfort that came from two little lollies. Lollies that didn’t even contain sugar. And therein lies the problem. As we all know, sugar is Satan’s Crystals, and for the past decade, sugar has been weathering a very dark and unrelenting media storm. Nowadays, everyone avoids sugar like the plague. However, it seems we still have a sweet tooth. Enter the sugar alcohol.
Fortunately (or unfortunately), sugar alcohols including xylitol, mannitol, sorbitol, maltitol and erythritol do not make you tipsy. In chemical speak, sugar alcohols are simple carbohydrates with an OH (hydroxyl group) stuck somewhere on their anatomy, causing them to behave differently in the body than other carbohydrates. Sugar alcohols taste sweet, yet are low in calories, don’t impact insulin levels, and some can even prevent tooth decay. What’s not to love?
It is how sugar alcohols behave in the body that explains why some people have an ‘issue’ with these sweeteners. While carbohydrates are generally broken down and absorbed in the upper reaches of the small intestine, sugar alcohols choose a different route. They are largely ignored in the first part of the small intestine, moseying their way further down the tube where they will be partially absorbed and used as fuel, and partially devoured by various in situ bacteria (See below).
For most of us, this process occurs behind the scenes without incident. However, there are two reasons why things can go horribly wrong. Firstly, in an example of osmosis, the concentration of sugar alcohols within the intestine may draw water from outside the bowel in a bid to reduce the concentration, resulting in diarrhoea. Osmotic diarrhoea usually occurs with an intake of over 30g of sugar alcohol, but for sensitive people (like my patients) may occur with less. The second reason for an unwanted reaction is that, while the sugar alcohols are not broken down and absorbed upstream, bacteria further down will take a liking to these carbohydrate-y molecules, chow down, and in the process create unwanted gas resulting in bloating and fluffing.
Sugar alcohols are here to stay. It’s up to you and your belly, to enjoy or stay away.