As prebiotics exploit the use non-viable dietary components to improve gut health, the range of foods into which they can be added is much wider than that for probiotics, where culture viability needs to be maintained. This has the advantage that heat stability, or exposure to oxygen is not an issue. As such, virtually any carbohydrate containing food is susceptible to supplementation. Examples are shown in Table 1. On the contrary, it may be possible to intake prebiotics more naturally through the diet.
Examples are onion, garlic, banana, asparagus, leek, and Jerusalem artichoke.
However, the likely situation is that levels are too low to have any significant effect. Hence, there exists much value in the approach of dietary fortification. However, it is important to ensure that the prebiotic effect is maintained in the food product. The nature of the trial was a crossover approach in that volunteers took active and placebo shortbread, but neither they nor the investigators were aware of which was ingested. The data clearly show that the use of FOS exerted a profound effect upon bifidobacteria.