Probiotics are supplements you will have come across I'm sure. They are sold in various forms such as capsules, powders, liquids and added to foods such as yogurts and yogurt drinks. They are often described as 'friendly bacteria' and advertised as a remedy for bloating. The aim of taking a probiotic is to rebalance the bacteria of the gut after a course of anti-biotics, for example, or where an excess of 'bad bacteria' has resulted in IBS type symptoms.
There seems to be general (if cautious) acceptance for the benefit of probiotics in helping manage IBS symptoms, such as this from NHS Choices;
"Probiotics may help reduce abdominal bloating and flatulence in some people with IBS, and they may help relieve pain and provide general relief. [...] however, we don't yet know the extent of the benefits, nor the most effective probiotic species and strain." (1)
Prebiotics (FOS) are often included in probiotic supplements to provide a food source for these good guys, which seems reasonable, but it's possible they also feed the bad bacteria. As I found out, most of the studies into the benefits of prebiotics for gut health have been carried out on healthy people, not people with IBS. In fact, Kevin Whelan of King's College, London reports that "in Crohn's disease and irritable bowel syndrome there is evidence that some prebiotics in high doses worsen functional symptoms." (2)
Well, as you can see in the photos below, the amount of prebiotics in supplements varies drastically. In fact I was surprised by just how much they vary. The first picture is of a bottle of probiotic capsules containing 100mg of FOS per capsule, whereas the second picture is of a psyllium husk (fibre) supplement which contains 1620mg per serving. Quite a difference yet you might notice that the probiotic content of each is pretty similar.
And here's that contradiction - the prebiotic Fructo-Oligosaccharides (FOS) are high FODMAP. Surely if you are reducing your FODMAP intake by limiting your diet to 'safe' foods, it doesn't make sense to add them back via prebiotic supplements, especially at the higher doses? Chances are that you are already getting sufficient prebiotics through everyday (low-FODMAP) foods anyway.
"If you are following a strict low–FODMAP diet, you can obtain prebiotics from non–FODMAP foods such as bananas, kale, chard, brown rice and oatmeal." (3)
Having discovered that I am sensitive to Fructo-oligosaccharides (including wheat, onions, garlic and cashews) I'm inclined to steer clear of probiotics which have added FOS altogether. Of course, if you can tolerate FOS (something you will discover from your low-FODMAP diet) then prebiotics probably aren't going to cause you problems either.