The changing face of sugar: sugar alcohols

First published 28 Jan 2016. When you’re trying to reduce the amount of sugar in your diet, it’s not just those ‘obvious’ culprits – soda drinks and sweet snacks – to be aware of. Perhaps even more insidious are the hidden sugars in savoury foods and the high sugar content in so-called ‘healthy foods’. The advice is always to clear out your fridge and pantry first. Go through everything you have stocked up at home and read the labels (see our article ‘Decoding Food Labels’).

And if you are ’sugar sensitive’ like me, you’ll also want to avoid artificial sweeteners as they can still spike blood sugar, raise insulin levels and stimulate cravings.

There are those ‘obvious’ sugars – like white sugar (sucrose), brown sugar, caster sugar, icing sugar (the word ‘sugar’ in their names is a bit of a giveaway) – but there are also many other names for sugar and processed food often contain any number of them, such as this list of sugar and its many disguises (Dolson, 2014):

Agave Dextrose Maple syrup
Barley malt syrup Evaporated cane juice Molasses
Beet sugar Fructose Palm Sugar
Brown rice syrup Fruit juice concentrate Raw sugar
Brown sugar Glucose Rice Syrup
Cane crystals/cane juice crystals High-fructose corn syrup Saccharose
Cane Sugar Honey Sorghum/sorghum syrup
Coconut sugar/coconut palm sugar Invert sugar Sucrose
Corn sweetener Lactose Syrup
Corn syrup or corn syrup solids Maltodextrin Treacle
Dehydrated cane juice Malt syrup Turbinado Sugar
Dextrin Maltose Xylose

Damon Gameau’s decision to focus on the hidden sugars in a so-called ‘healthy’ Western diet was a clever way of heightening the impact of That Sugar Film. He proved that you don’t have to be consuming soft drinks (soda), chocolates (candy) or pastries to overdose on sugar. He easily consumed the equivalent of 40 tsps of sugar (considered to be the average daily sugar consumption of Australians, which includes fruit juices, concentrates and other sweeteners) by eating foods such as breakfast cereal, yoghurt, fruit juice, bread and other grains recommended by dieticians and promoted in public health messages.

Those of us who are Banting know that carbohydrates are broken down into glucose in the body. This is the reason for keeping carbs low, generally below 25g per day. By necessity, this places fruit (other than berries), bread, pasta and most sweeteners on the Real Meal Revolution’s Red List. But what does the food industry do when there’s a shift in public awareness or government guidelines?

As Robert Lustig (2009) explains in Sugar: The Bitter Truth, when the fat got taken out of food, sugar was put in. Foods marketed as ‘low fat’ generally contain very high levels of sugar, and those that already contained sugar became even sweeter and more desirable as our palates changed and manufacturers established the ‘bliss point’ – the exact mix of fat and sugar that makes their products so irresistable. And when the focus was put on sugar, we saw the introduction of many different names for sugar (see list above); by using a number of different sugars in a product and listing them individually (from the largest to the least amount) it could look as if sugar was not the main ingredient and these high sugar foods went under the radar for most consumers.

Sugar alcohols 

Just as we became aware of the multiple ways of referring to what is essentially ‘sugar’ and consumers started to avoid the more obvious sweeteners, manufacturers found alternatives to what we have traditionally called sugar.

One group of sweeteners marketed heavily to the ‘sugar-free’ community is sugar alcohol. Known as polyols, sugar alcohols are hydrogenated starch molecules primarily from fruit or berries or the byproduct of grain processing. They are still a form of carbohydrate and about half the sugar in sugar alcohols should be counted (Diabetes Education Online, n.d.)

Sugar alcohols include:

  • Maltitol syrup
  • Hydrogenated starch hydrolysate
  • Maltitol (powder)
  • Xylitol
  • Isomalt
  • Sorbitol
  • Lactitol
  • Mannitol
  • Erythritol (Livesey, 2003).

When I first quit sugar in 2012 by following David Gillespie’s advice in Sweet Poison, I had no intention to give up chocolate for good. I not only loved chocolate, I had made it my profession, taking a break from academic work to run my own small artisan chocolate company. After reading his book, I was convinced that fructose was the main culprit (regular chocolate contains sucrose which is 50% glucose and 50% fructose), so I spent the rest of that year searching for a healthy alternative to the sugar-sweetened chocolate I had been used to.

After several months, I finally located an overseas supplier of organic fructose-free chocolate (sweetened only with glucose) and I then spent the next year or two experimenting with this chocolate and finally developing our own range of fructose-free chocolate products. It seemed to provide a bridge from a high sugar diet to later excluding all sugars and sweeteners from my life.

It was only when I discovered Low Carb High Fat (LCHF) in late 2014 that I realised the glucose-sweetened chocolate I had been making was still very high in carbohydrates. I experimented with making chocolate sweetened with polyols such as maltitol, xylitol and a new sugar alcohol that I discovered relatively recently called Thaumatin. I was searching for the holy grail, a chocolate that was (truly) healthy. Low carb. Low sugar. That wouldn’t spike blood sugar. And wouldn’t keep me coming back for more.

It’s probably worth mentioning at this point that raw cacao that is unheated and minimally processed IS a good source of antioxidants and magnesium. However, most chocolate that is commercially-made and sold around the world is a highly processed product. And in terms of sugar content, 100g of chocolate with 70% cacao content contains about 29g sugar, 85% dark chocolate (often recommended as an allowable treat even for those on a low carb diet) contains about 14g sugar, 90% dark chocolate still has almost 9g sugar and even 100% unsweetened cacao, although it contains almost no sugar (0.3g), it still contains 7g ‘Available Carbohydrates’. The standard cacao content of most dark chocolate used in food products is generally 54% cacao which contains 44g sugar (46.8g ‘Available Carbohydrates’); almost the same amount of sugar and carbs as in milk chocolate (50.8g sugar, 51.4g ‘Available Carbohydrates’).

When I first went LCHF, I managed to produce a xylitol-sweetened chocolate for my own consumption. It had the characteristics of ‘good’ chocolate: smooth mouth feel, snap, sheen and so on. I was happily consuming it (and using xylitol to make other Banting-friendly sweets) until I noticed that this too – like glucose and other sugars – was feeding my sugar addiction. It not only kept me hooked on sweet tastes, it was pushing out the ‘real’ foods from my diet. If I made a chocolate fat shake sweetened with xylitol, I would feel like one again the following day or later that week and if I used it as a meal replacement I would be missing out on more nutrient-dense food.

Xylitol has the same degree of sweetness as sugar and therefore needs to be used in similar amounts, making it an expensive sweetener for manufacturers. It must also be stored carefully away from pets (particularly dogs) and it affects some people’s digestion causing abdominal bloating and gas. And – to my surprise – it may still spike insulin levels. I had already discovered that as soon as my brain recognised sweetness on my tongue (or even by thinking about sweet foods) my body prepared for the onslaught of sugar by releasing insulin. And when I found out that indeed sugar alcohols may be at least partially metabolised as sugar and therefore can raise blood sugar levels, I decided not to pursue chocolate-making with sugar, polyols or any other alternative sweeteners.

Sugar alcohols can spike blood glucose levels

The use of the Glycemic Index (GI) and the related concept of Glycemic Load (taking into account GI in relation to common serving sizes of these foods) has long been debated. This is because there are many other factors that affect blood glucose levels, not just the food itself. These include your levels of blood glucose and insulin at time of eating, your degree of insulin resistance, whether you take blood glucose-lowering medication, the amount of complex carbohydrates also consumed in the same meal and so on (Warshaw, 2010).

In his article ‘Net carbs: Can you really exclude sugar alcohols, glycerin, polydextrose and fiber’, David Mendosa (2004) warns: ‘If the sugar alcohols had no impact on our blood glucose, they would have a glycemic index of zero’.This being so, it is worthwhile comparing the GI of the various sugar alcohols to give some indication of their impact on blood glucose levels. And for interest, I have also included their caloric value.

Glucose is the standard used to calculate GI, being set at 100 (regular table sugar has a GI of 60 – see Note 1 below). The GI of other common sugar alcohols and their caloric value per gram (see Livesey, 2013) are:

  • Maltitol syrup: GI 48-53 (3 cals) – (see Note 2 below)
  • Maltitol: GI 36 (2.7 cals)
  • Xylitol: GI 13 (3 cals)
  • Sorbitol: GI 9 (2.5 cals)
  • Erythritol: GI zero (0.2 cals)
  • Mannitol: GI zero (1.5 cals)

As long as it doesn’t lead you back into a sugar-addiction, Erythritol is generally considered to be one of the best sugar alcohols as it has no glycemic impact, fewer calories and little to no gastrointestinal symptoms when eaten in small amounts (Zimmer, 2014).

Sugar alcohols will affect some people and not others. It appears that some people metabolise sugar alcohols as sugar whilst others (who lack the enzymes to digest them) cannot turn polyols into glucose and therefore do not experience a rise in blood sugar. Usually, these people experience gastointestinal reactions to sugar alcohols for the very reason that they lack the enzymes to metabolise them and so the starches pass into the colon undigested where they are fermented by bacteria causing gas and cramping or attract water from the lining of the lower bowel causing diarrhea (Diabetes Education Online, n.d.).

Maltitol and other sugar alcohols

Maltitol is one of the most commonly used sugar alcohols in food manufacturing, including chocolate manufacturing, despite the fact that it may have a considerable effect on blood glucose: 75% of the blood sugar impact of sugar as well as 75% of the sweetness (Dolson, 2014).

Maltiol may spike blood sugar ‘almost as much as a starchy new potato’ (Mercola, 2011). It is metabolised to glucose and sorbitol, about 65% of the sorbitol reaching the bloodstream and transported to the liver where it is converted to fructose. The remaining 35% feeds the bacteria in the large intestine resulting in gas and diarrhoea.

This can be described as a ‘lose lose’ situation. If polyols do not spike your blood sugar, in all likelihood they will produce intestinal distress; but if they don’t cause intestinal distress, in all likelihood they will spike blood sugar levels. This is why foods sweetened with Maltitol carry a mandatory warning cautioning consumers “Excessive consumption may have a laxative effect”. Furthermore, ‘Some [sugars], such as sorbitol .. will raise blood sugar more slowly than glucose but still too much and too rapidly to prevent a postprandial blood sugar rise in people with diabetes’ (Dr Bernstein 2003, cited in Mendosa, 2004).

The level at which a reaction to sugar alcohols may occur is variously reported to be anywhere from greater than 10-20g (Mercola, 2011), greater than 50g (Ruskoné-Fourmestraux et al, 2003) up to greater than 100g per day. Consumption of less than 10g is generally considered to be safe with no laxative effect.

Last word 

David Gillespie warns his readers: ‘People wanting to avoid fructose (and who doesn’t) should avoid products containing sorbitol, isomalt, maltitol and mannitol’ (Gillespie, n.d.). Sarah Wilson simply calls chocolate sweetened with Maltitol ‘bad’ (Wilson, 2011).

My advice is if you see any chocolate or other supposedly ‘low carb’ or ‘Banting-friendly’ sweets marketed as ‘sugar-free’ or ‘the perfect alternative for a low-carb lifestyle’, you’d better check the ingredients very, very carefully.

Notes 

  1. If you’re wondering why regular sugar only has a GI of 60, this is because it is half glucose (which raises blood sugar) and half fructose (which goes straight to the liver to be metabolized and has little immediate effect on blood sugar although still very harmful) (see Taubes, 2008).
  2. Maltitol syrup is not used in chocolate making because of its high moisture content. Maltitol powder (GI 36) is used instead.

References

Diabetes Education Online (n.d.) ‘Counting Sugar Alcohols’, article on Diabetes Education Online, Diabetes Teaching Center at the University of California, San Francisco, http://dtc.ucsf.edu/living-with-diabetes/diet-and-nutrition/understanding-carbohydrates/counting-carbohydrates/learning-to-read-labels/counting-sugar-alcohols/, last accessed 28 Jan 2016.

Dolson, L. (2014). ‘Sugar’s many disguises: Recognising sugar on food labels’, article posted on About Health, 19 Dec 2014, http://lowcarbdiets.about.com/od/whattoeat/a/sugars.htm, last accessed 23 Jan 2016.

Gameau, D. (2015). That Sugar Filmhttp://thatsugarfilm.com/, last accessed 23 Jan 2016.

Gillespie, D. (2008). Sweet Poison, Penguin Australia.

Gillespie, D. (n.d.) ‘Sorbitol, Maltitol, Mannitol and Isomalt’, article on David Gillespie’s website, http://davidgillespie.org/sorbitol-maltitol-mannitol-and-isomalt/, last accessed 28 Jan 2016.

Livesey, G. (2003). Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties, Nutrition Research Reviews, 16(2), 163-191.

Lustig, R. (2009). Sugar: The Bitter Truth, University of California Television, https://www.youtube.com/watch?v=dBnniua6-oM, last accessed 28 Jan 2016.

Mendosa, D. (2004). ‘Can You Really Exclude Sugar Alcohols, Glycerin, Polydextrose, and Fiber?’, article posted 13 Feb 2004 (updated 13 May 2005) on Mendose.comhttp://www.mendosa.com/netcarbs.htm, last accessed 28 Jan 2016.

Mercola, J. (2011). ‘The 4 Best, and 3 Worst, Sweeteners to Have in Your Kitchen’, article posted 8 Oct 2011 on mercola.doc, http://articles.mercola.com/sites/articles/archive/2011/10/08/the-4-best-and-3-worst-sweeteners-to-have-in-your-kitchen.aspx, last accessed 28 Jan 2016.

Ruskoné-Fourmestraux, A.; Attar, A.; Chassard, D.; Coffin, B.; Bornet, F. & Bouhnik, Y. (2003).
‘A digestive tolerance study of maltitol after occasional and regular consumption in healthy humans’, European Journal of Clinical Nutrition, 57, 26–30, http://www.nature.com/ejcn/journal/v57/n1/full/1601516a.html, last accessed 28 Jan 2016.

Taubes, G. (2008). Good Calories, Bad Calories: Fats, Carbs and the Controversial Science of Diet and Health, Random House, New York.

Warshaw, H. (2010). Can Glycemic Index help control blood glucose? Article posted on Diabetic Living website, http://www.diabeticlivingonline.com/expert-qa/can-glycemic-index-help-control-blood-glucose, last accessed 24 Jan 2016.

Wilson, S. (2011). ‘Artificial sweeteners…are any ok?’, article posted on Sarah Wilson’s website on 22 Mar 2011, http://www.sarahwilson.com/2011/03/artificial-sweeteners-are-any-ok/, lass accessed 28 Jan 2016.

Zimmer, M. (2014). ‘Sugar-Free Labels Can Be Deceptive’ article posted on Diabetes Self-Management on 2 Dec 2014, http://www.diabetesselfmanagement.com/blog/sugar-free-labels-can-be-deceptive/, last accessed 28 Jan 2016.

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