Xylitol has been in the news, on and off over the last thirty to forty years, whether it is about it being a miracle substance or fatal for your dog. It is still viewed by some sceptically, while others are true advocates. This article takes you through various news and views as well as the facts that have followed this naturally occurring substance.
Xylitol has been harvested for over a hundred years. It is odourless and colourless and found naturally in some foods such as strawberries and cauliflower, although it is commercially manufactured from the fibres of birch leaves and other hardwood trees. Chemically it is a polyol - a carbohydrate or sugar alcohol and unlike the more common sorbitol that has a six-carbon ring, xylitol has a five-carbon ring.
It is one of a number of non-sugar sweeteners, with around a third less calories than sucrose, and it dissolves easily leaving a cool sensation in your mouth. There have been hundreds of studies and papers written on it dating back as far as the early 1970’s. It was first approved for use in foods in the UK in the early 1980’s and you can now buy bags of it on the high street.
The global market for xylitol, over the last year has been estimated at nearly 200,000 metric tonnes, at a value of over $700million. It is expected to reach just over a billion dollars by 2022, with the main reason for the increase being cited as the need for us to reduce higher calorific sugar, because of the global increase in obesity and type 2 diabetes.
Where is xylitol used?
You will have heard of it in sugar-free gum and sweets and it can be found in many other products from chewable vitamins and nut butters to cake mix, face creams and even clothes. It is used mainly in sports clothes for its ‘cooling effects’ – apparently whenever the label mentions ‘icefil fabric’ it means the clothes have xylitol in them.
In 2009 the innovators behind innocent smoothies started ‘Peppersmith Mints’, that The Daily Mail picked up on a few years later dubbing Peppersmith's Mints as ‘The sweets that can actually PREVENT tooth decay’ which are labelled as 'sugar-free and good for teeth’.
Peppersmith provide compelling evidence, stating on their website that xylitol ’has been the subject of over 600 clinical studies and it is well established that habitual xylitol consumption decreases caries occurrence’. They add that ‘Products containing xylitol are now endorsed by over 15 dental associations worldwide and xylitol gum has a European Food Standards Authority approved health claim for plaque reduction.’ They include a quote from Dr. Nigel Carter, OBE, Chief Executive of the Oral Health Foundation, stating that “Xylitol may be the biggest advance in dentistry since fluoride.”
Wrigley also use the recognisable ‘ice cool’ taste of xylitol in their gum and have done since 2011. And Brush-Baby have been including it in their baby and toddler toothpaste since they launched it in 2007
In a 2011 review of xylitol’s health claims, the European Food Safety Authority (EFSA) accepted the claim that xylitol has a lesser effect on blood sugar levels than sugar, due to its slow absorption rate. This means it could help people with impaired glucose tolerance, which is a risk factor for diabetes and cardiovascular disease.
So how does it work in the oral cavity?
The caries preventing effect of xylitol is more complex than just the simple act of excluding sugars from your diet. It actually promotes mineralization by increasing saliva as all sweeteners do; what makes xylitol different is that it is not affected by oral bacteria. It has actually been seen to inhibit the growth and metabolism of Mutans Streptococci (MS). By consuming xylitol gum regularly over a short period of time, plaque has been shown to decrease. It also didn’t have an effect on the microbial composite of plaque and saliva in general and the counts of MS have been shown to decrease in your mouth. It has also been cited to prevent mother-child transmission of the bacteria.
Xylitol seems like the miracle substance, so what’s the catch?
In a 1985, the EU’s Scientific Committee on Food reported that if you ingested 50g of xylitol a day it can cause diarrhoea. Since then, any xylitol you buy must carry the warning ‘excessive consumption may induce laxative effects.’ All polyols are banned from soft drinks in Europe because of this laxative affect.
What happens is that xylitol is slowly and only partially absorbed in the intestine, and is converted into glucose in the liver. Too much xylitol in the intestine can cause water retention, which can result in diarrhoea. If consumed in large amounts, side effects can also include bloating and gas, as unabsorbed xylitol is broken down into carbon dioxide and eliminated.
More of concern with xylitol is the industrialization process that is used to manufacture it. When a xylitol is manufactured it is hydrogenated to form a sugar alcohol. To hydrogenate anything you need a catalyst, in this case nickel is used. First, the fact that xylitol is hydrogenated could raise some concerns because hydrogenated foods are known to cause Alzheimer’s, cancer, diabetes and liver dysfunction. Secondly, nickel is a known toxin that has been linked to asthma attacks, dermatitis, kidney problems and lung disorders, amongst other things. At this point, there is no research proving that chewing xylitol gum or eating xylitol sweets will cause these things, but it might not be the answer to our daily natural health regime just yet.
It is also expensive compared to sugar, so it isn’t an easy substitute in poorer countries that could perhaps benefit from its positive properties.
Another big issue that hit the headlines recently, especially as so many products now contain Xylitol, is that fact that it is deadly for dogs. The FDA, the US Food and Drug Administration had to issue a warning a couple of years ago stating that it can kill your dog as it triggers a sudden release of insulin, causing a dramatic drop in blood sugar that can lead to liver damage.
Since the pivotal study from the University of Turku in Finland in the early 1970’s, there have been countless papers looking into more detail at the claims. As well as researching the current effect of xylitol in your diet, they have also looked at its effectiveness with combinations of other substances such as fluoride, including as a varnish and chlorhexidine.
A paper published last year found that chlorhexidine, another chemical with mixed reviews, when combined with xylitol had a more powerful effect on MS and the biofilm that either xylitol gum or chlorhexidine mouthwash alone.
Also last year a study was undertaken to again review if the xylitol gum on the market actually contained enough xylitol to have a marked effect on preventing caries. This small study found that most producers didn’t actually state how much xylitol was in the product and that the majority of products on the market didn’t actually provide consumers with clear labelling that confirms the recommended daily dose for the prevention of caries.
This year, a study was submitted that demonstrated that xylitol can be extracted by a genetically modified industrial strain of Saccharomyces Cerevisiae (also known as baker’s yeast) by using glycerol as a co-substrate. Also a new production method using another new strain of yeast has been found to produce greater amounts of xylitol from poplar wood, more revolutionary strategies are being discovered all the time to maximise the amount of xylitol we can harvest to fulfil our needs. The compound, 6-Anhydro-l-galactose - a rare sugar from agar - is also being mentioned in scientific papers to replace xylitol in the future. Whatever your view, it’s time to watch this space; xylitol and other manufactured sugar substitutes are not going to go away anytime soon.
References available on request.
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