The term oligosaccharide refers to a short chain of sugar molecules. Fructo-oligosaccharides (FOS) and inulin, which are found in many vegetables, consist of short chains of fructose molecules. Galacto-oligosaccharides (GOS), which also occur naturally, consist of short chains of galactose molecules. These compounds can be only partially digested by humans. When oligosaccharides are consumed, the undigested portion serves as food for friendly bacteria, such as Bifidobacteria and Lactobacillus species.FOS is provided in a pleasant tasting powder, two teaspoons is equal to the recommended daily intake of 10 grams (the average diet provides only 2-3 grams of FOS per day).