The Daily Mail have just published an article that involved hydrogen breath tests:
Although this was about somebody who was feeling bloated and tired because her system could not cope with the sugar created by eating a lot of fruit, it might be interesting for those who suffer from chronic dumping syndrome with a sugar:insulin imbalance / spikes for that reason. The case study, which needless to say did not involve an oesophagectomy, was concerned with fructose malabsorption and the article describes how excess sugar that is not digested starts to ferment and feed gut bacteria that can lead to bloating and diarrhoea. There is also a bit about low FODMAP diets, and glucose, lactose and fructose.
One always has to be careful about reading too much into these things but it might help some people that have been trying to eat healthily but keep on getting problems.