What are sorbitol and mannitol?

Sorbitol and mannitol are types of sugar alcohols, also known as polyols. They are naturally found in a range of fruit and vegetables, and can also be added to diet versions of food and drinks.

How are they digested?

Polyols (sorbitol and mannitol) are poorly digested by many people. These sugars are partly absorbed into the blood by passive diffusion in the small intestine. A person’s transit time (how long food stays in the digestive tract) and the molecular size of the sugar will influence how much is absorbed.

Due to their very small size, these sugars have the ability to draw water into the small intestine (this also can happen with undigested fructose and lactose), resulting in watery diarrhea. After that, undigested sorbitol or mannitol will finally reach the large intestine, where the gut microbes will start to break them down into gases (like hydrogen) and other beneficial fermentation products (like Short Chain Fatty Acids – SCFAs).

What are the common symptoms associated with poor digestion of polyols?

Even small doses of sugar alcohols can result in osmotic diarrhea, bloating, and increased flatulence, in particular in people with IBS. It is important to identify your unique tolerance, as this can vary considerably from person to person.

Can I test this myself?

The answer is yes! If you suspect that you have a malabsorption/ intolerance issue with sorbitol/mannitol why not try our 6-Week Discovery Plan? In 6 weeks you will test your tolerance to 4 hard-to-digest food components; lactose, fructose, sorbitol, and inulin as well as get access to exclusive new app features to help you on your gut journey

The sorbitol sachet contains 10g of sugar, which you mix with water and drink. Then you measure your breath hydrogen levels every 15 minutes for the next three hours.

It is also important to assess your level of symptoms during and especially after the testing period. In many cases, an increase in breath hydrogen may occur before you experience symptoms. This is because it can take some time for the gases to build up. In some cases, you might not see an increase in breath hydrogen but do experience watery diarrhea, due to the osmotic ability of sugar alcohols.

If you have completed a sorbitol breath test and experienced symptoms, we recommend you repeat the test (when you have no symptoms) using a much lower dose, around 3.5g or 5g. You could also try a custom food challenge using a portion of food containing either sorbitol or mannitol. Finding your tolerance level is key to maintaining a balanced and healthy diet.

Sorbitol and Mannitol in Food

Examples of vegetables containing sorbitol

• Aubergine – 75g is low FODMAP
• Green beans – 75g is low FODMAP
• Bok choy – 75g is low FODMAP
• Sweet corn – 75g is high FODMAP

Examples of vegetables containing mannitol

• Butternut squash – 75g contains moderate FODMAPs
• Cauliflower – 75g is high FODMAP
• Celeriac – 75g is low FODMAP
• Celery – 75g is high FODMAP
• Fennel, bulb – 75g contains moderate FODMAPs
• Leek, leaves – 75g contains moderate FODMAPs
• Button mushrooms – 75g is high FODMAP
• Snow peas – 75g is high FODMAP

Examples of fruits containing sorbitol

• Apple (fresh) – 160g (one apple) is high FODMAP
• Apricot – 70g (two apricots) is high FODMAP
• Avocado – 80g (half an avocado) is high FODMAP
• Blackberries – 160g is high FODMAP
• Coconut – 95g contains moderate FODMAPs
• Nectarine – 150g is high FODMAP
• Peach (contains both sorbitol and mannitol) – 145g is high FODMAP
• Plum – 65g is high FODMAP

Examples of fruits containing mannitol

• Peach (contains both sorbitol and mannitol) – 145g is high FODMAP
• Watermelon (mannitol) – 150g is high FODMAP