The Doctor is in the Kitchen Q&A: Sugar Alcohols

Q:  I swim most mornings before work and keep protein bars in my filing cabinets to eat along with a piece of fruit for breakfast afterwards.  I love the thinkThin High Protein Bars in the chocolate fudge flavor but was confused about the presence of Sugar Alcohol.  They advertise 0g sugar (something I love about this protein bar) but what are the 12g of sugar alcohol?  Is it better or worse than other sugars?  Am I being mislead by package advertising and am better off eating a different bar with some grams of sugars vs this one with sugar alcohol?

Cindy M. from Laurel, MD

A:  Great question, Cindy!  What are sugar alcohols? 

They are a type of reduced-calorie sweetener.  You can usually find them in sweet foods like ice cream, candy and gum and increasingly in many diet and health-related foods like energy bars.  They are commonly found in products marketed as “sugar free” or “reduced sugar” and in foods targeted for diabetics and those on low carbohydrate diets.

Sugar alcohols get their name from their chemical structure, which resembles both sugar and alcohol.   But technically they're neither one.  In fact, sugar alcohols belong to a group of carbohydrates called “polyols” that sweeten foods with fewer calories than table sugar. 

Some sugar alcohols are extracted from plants but most of them are commercially manufactured from other sugars and starches.  There are several specific types of sugar alcohols and they usually end with the letters “-ol”.  Some of the most common ones are: Erythrotol, Glycerol (also known as Glycerin), Isomalt, Lactilol, Maltilol, Mannitol, Sorbitol and Xylitol.  If you look at the ingredients in the protein bar that Cindy asked about, it contains both Glycerin and Maltilol.

Sugar alcohols are similar to sugar in some ways, but they differ in that they are not completely absorbed by the body. Because of this, the blood sugar impact of sugar alcohols is less and they provide fewer calories.  However, each sugar alcohol has a slightly different effect on the body.  They range in caloric content from zero to three calories per gram compared to table sugar (sucrose), which has four calories per gram.  So how do you calculate the total amount of digestible carbohydrates in a product with sugar alcohols?  The general rule is that if a food contains more than 5 grams of sugar alcohols, first divide the number of grams of sugar alcohols in half.  Then subtract this amount from the total carbohydrates.  For example, this specific protein bar has 12 grams of sugar alcohols and 25 grams of total carbohydrates. First divide 12 grams by half, which gives you 6 grams.  Then take 25 grams and subtract the 6 grams, which leaves you with 19 grams of carbohydrates that should be counted.

Why are you noticing sugar alcohols popping up on nutrition labels now?  They’ve actually been used for many years in a wide variety of food products and are always listed in the ingredient list.  But now it is a requirement that manufacturers list the sugar alcohol count separately on the nutrition label if the product is labeled as “sugar-free” or “no added sugar.” And with these products gaining popularity, you’ll be seeing sugar alcohols popping up more and more often on nutrition labels. 

Advantages of sugar alcohols:

• Fewer calories- because sugar alcohols are not completely absorbed by the body,  they provide fewer calories than regular sugar. 
• Heat stable- they do not lose their sweetness when heated like many artificial sweeteners do
• Retain moisture in products- they keep foods like energy bars from getting hard and brittle
• No dental caries- sugar alcohols don't promote tooth decay as sugars do because they’re not metabolized by the bacteria that cause dental caries.  In fact, they are often used to sweeten chewing gum and xylitol specifically inhibits bacterial growth in the mouth.  

Disadvantages of sugar alcohols:

• GI upset- because sugar alcohols are not completely absorbed, they pass through the small intestine and are fermented by bacteria in the large intestine.  This can cause gas, bloating and diarrhea.
• May not end up saving calories- Be sure to check the total carbohydrates in your products.  Some manufacturers of sugar free products may use a large amount of sugar alcohols, which drives the calorie count up, defeating the purpose.
• May end up consuming more fat- you’ll also want to check the fat content on the nutrition labels.  To add flavor, there is often more saturated and or trans fat in sugar free baked products.

So what’s the conclusion?  

Foods with sugar alcohols are popping up all the time on supermarket shelves because of the increasing popularity of “sugar free” products.  When used appropriately, these products can play a role in weight management for people controlling their sugar intake such as diabetics.  However, like most sugar substitutes, long-term benefits have not been established for sugar alcohols and further research is needed to fully clarify their health effects.  Until then, it’s up to you to weigh the pros and cons.  Some people prefer to use the regular version of a food and cut back on the amount they eat rather than buying the sugar free version.  Whatever your decision, always check the nutrition labels on your food products because sugar free products can often contain significant amounts of carbohydrates, calories and fat.