The Benefits of Adding Oligosaccharides and Prebiotics to Your Diet

Jerusalem artichokes on a cutting board

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You may not be familiar with them, but sandwiched between simple sugars (monosaccharides) and starches (polysaccharides) are oligosaccarides. This group of carbohydrates plays an important role in nutrition. You've likely seen ingredients like inulin and oligofructose listed on food labels and may have heard phrases like “prebiotic fiber." Here's how these work in your body.

Sources of Oligosaccharides

Oligosaccharides are a type of carbohydrate formed when three to 10 simple sugars are linked together. Small amounts occur naturally in many plants, but chicory root and Jerusalem artichokes (the root of a member of the sunflower family) have the most oligosaccharides. They are also found in onions (including leeks and garlic), legumes, wheat, asparagus, jicama, and other plant foods.

North Americans get about 1 to 3 grams of oligosaccharides naturally in their diets each day. Europeans get slightly more: around 3 to 10 grams.

Most oligosaccharides have a mildly sweet taste. Other characteristics, such as the mouthfeel they lend to food, have drawn the interest of the food industry. Many manufacturers are exploring oligosaccharides as a partial substitute for fats and sugars, as well as a way to improve a product's texture. Due to these attributes, the amount of synthetically produced oligosaccharides present in the food we eat is on the rise.

Non-Plant-Based Sources of Oligosaccharides

The most common oligosaccharide food additives are inulin and oligofructose. Quest Bars, for example, feature inulin in their line of protein bars. Other brands also include inulin, though it's listed on the label as "chicory root fiber" because it can be derived from chicory.

Inulin is also available as an over-the-counter vitamin supplement you can purchase in health food stores or online. You can also get the prebiotic benefits of oligosaccharides by adding more fermentable fiber, including resistant starch, to your diet.

Prebiotic Fiber

The nutrition community has become more interested in oligosaccharides for a different reason: The human digestive system has a difficult time breaking down many of these carbohydrates. About 90% bypass digestion in the small intestine, eventually reaching the colon. Here, oligosaccharides take on a new role—that of a prebiotic.

Prebiotics are not to be confused with probiotics. While both terms relate to gut health, pre- and probiotics have different roles, health benefits, and sources.

Prebiotics are components in the large intestine that support the growth of certain kinds of bacteria in the colon.

At first, oligosaccharides were believed to be the main form of prebiotics, but it turns out bacteria in the colon also feed on resistant starch and fermentable fiber. We now understand there's an entirely different (and crucial) digestive process happening in the colon that influences the rest of the body.

Health Benefits of Oligosaccharides

Bacteria that feed on fermentable carbohydrates produce many beneficial substances, including short-chain fatty acids (SCFAs) and certain B vitamins. Some early evidence suggests the bacteria could promote absorption of certain minerals, including calcium and magnesium, that escape the small intestine during digestion.

While research is ongoing, SCFAs likely provide many benefits, both in the colon as well as in the rest of the body. Specifically, butyrate may protect colon tissue from damage caused by conditions like colon cancer and ulcerative colitis. Other possible benefits of SCFAs include:

  • Lower cholesterol
  • Lower triglycerides
  • Improved insulin sensitivity and glucose metabolism
  • Improved immune system function

Different oligosaccharides tend to produce different SCFAs—a good reason to eat a variety of oligosaccharide-containing foods.

Why Oligosaccharides Aren't Always Labeled as Fiber

While oligosaccharides do fall under the categories of both soluble fiber and fermentable fiber, they are not currently included under dietary fiber on food labels in the United States. One exception is inulin from chicory root, which may be listed as fiber on nutrition labels.

In March 2019, in response to a citizen's petition for inclusion of synthetic carbohydrates on food labels under the product's dietary fiber content, the FDA proposed changes to current guidelines. The changes include listing added oligosaccharides and other isolated or synthetic non-digestible carbohydrates (NDCs) as part of a food's dietary fiber content.

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