 The increased activity of these health-promoting bacteria results in a number of effects, both directly by the bacteria themselves or indirectly by the organic acids they produce via fermentation.Examples of effects are stimulation of immune functions, absorption of essential nutrients, production of the powerful anti-oxidant H2 gas and syntheses of certain vitamins.Galacto-oligosaccharides are a substrate for bacteria, such as bifidobacteria and lactobacilli.