Probiotic supplements are of no use to healthy people and may harm people who have impaired immune systems, UPI quoted a British microbiologist as saying. British consumers spend tens of millions of dollars a year on unregulated probiotic supplements because of some "instinctive sense" it will make them healthier, said Michael Wilson, a microbiologist at London's University College. Diarrhea caused by antibiotics can be reduced by "topping up on good bacteria" found in probiotics, such as yogurts, Wilson said. Overall, however, evidence regarding probiotics is "shaky" and needs thorough investigation, Wilson told The Daily Telegraph in a story published Saturday. "No bacterium is totally innocuous," he said. "If you are healthy there is probably no harm in taking probiotics, but there is also no benefit. But to increase the bacterial burden if you are immuno-compromised is asking for trouble," he said. Spokesmen for probiotic makers Yakult and Danone said the companies stand behind the health benefits of their products.