Innovative Quality Since 1932 Dietary Supplement 1 Daily 100% Pure Powder ProBiotic Enhancer Discussion: KAL NutraFlora FOS is 100% pure, all natural Fructooligosaccharides (FOS). FOS is considered a pre-biotic and selectively promotes the growth of Bifidobacterium & Lactobacillus in the digestive tract. This flavor-free powder dissolves easily in water, and can be added to other beverages and foods.