Fructo-oligosaccharides (FOS) also sometimes called oligofructose or oligofructan are primarily used as a alternative sweetener to sugar. FOS can be extracted from natural food produce or chemically produced.

In recent times, FOS has become more popular due to its beneficial dietary effects. It has prebiotic properties that allow it to be used as a food additive instead of just a sweetener. Today FOS is being increasingly classified and used as a dietary fiber.