Carbohydrate Intolerance and How It Affects Your Health

Heather Rivera, MS, RDN
Oct 27, 2020
3 min read

“Carbohydrate intolerance” refers to an inability to digest certain types of carbohydrates. In particular, people with carbohydrate intolerance may struggle to digest lactose, fructose, sugar alcohols, and/or certain fermentable fibers.

Here, we'll give you an overview of carbohydrate intolerance and the major signs and symptoms.

What carbs are people typically intolerant to?

Lactose is one of the sugars found in dairy products.
Fructose exists in high concentrations within many sweeteners as well as, to a lesser degree, within fruits and vegetables.
Common sugar alcohols include sorbitol, xylitol, mannitol, erythritol, and lactitol, and are often found in processed foods.
Fermentable fibers refer to fructans, and galacto-oligosaccharides. These exist within a wide variety of fruits, vegetables, and whole grains, although most people are only sensitive to certain foods containing specific concentrations of these fermentable carbohydrates.

Intolerance vs. sensitivity

Carbohydrate intolerance may be confused with what is commonly referred to as “carbohydrate sensitivity,” otherwise known as insulin resistance. These are two separate issues. While insulin resistance results in an abnormally high spike in blood sugar after the consumption of carbohydrates, carbohydrate intolerance refers to the inability to digest carbohydrates and results in unpleasant symptoms such as gas, bloating, and diarrhea.

What the science says

Carbohydrate intolerance results from the lack of one or more digestive enzymes. The result of carbohydrate intolerance is that certain carbohydrates are not broken down and absorbed within the small intestine. This allows them to pass into the colon where they create what is called a high osmotic load and are fermented by the bacteria in your gut.

A high osmotic load is something you definitely don’t want in the colon. This means that water from the blood will rush into the large intestine, causing diarrhea.

The bacterial fermentation is what causes gas and bloating. The fermentation process results in the creation of hydrogen, carbon dioxide, and methane. This excess gas causes bloating, flatus, and abdominal pain. The production of hydrogen also makes it possible to diagnose carbohydrate intolerance via a hydrogen breath test.

Treatment of carbohydrate intolerance is avoidance of trigger foods and possibly use of digestive enzymes. Lactase is often used as medical management for lactose intolerance. Similarly, xylose isomerase is a new digestive enzyme that has shown to be promising for management of fructose intolerance. Unfortunately there are not yet digestive enzymes available to assist with the digestion of sugar alcohols or fermentable carbohydrates.

Our take

If you consistently suffer from bloating, gas, abdominal pain, and diarrhea it’s worth investigating whether or not you might have a carbohydrate intolerance. Treatment of these digestive disorders is fairly simple and has the potential to greatly improve digestive health and overall quality of life.

Think you might be carbohydrate intolerant?

We recommend speaking to your Client Advocate to determine the best course of action is based on your unique situation. They can help analyze your symptoms in relation to your current diet to assess whether carbohydrate intolerance may be causing you to experience unpleasant symptoms.

If carbohydrate intolerance is suspected, likely the first step will be to try removing dairy from your diet since this is the most commonly problematic carbohydrate. If symptoms improve that’s a pretty clear sign you are lactose intolerant.

If the removal of dairy doesn’t work try avoiding sugar alcohols. This one is a little trickier since it involves closely reading ingredient labels. If symptoms improve upon removal of sugar alcohols from the diet then, similarly, this is also a pretty clear sign that you have an intolerance to these carbohydrates.

If you’ve tried eliminating dairy and sugar alcohols and are still experiencing symptoms of gas, bloating, and diarrhea it’s best to speak with a nutritionally-informed doctor. It can be a bit trickier to navigate fructose intolerance and fermentable carbohydrates intolerance. A healthcare professional can help you determine exactly which foods you might need to avoid and how to support healthy digestion overall.