Consumers canfind probioticsupplements with such brand names as "Nature's Bounty," "Healthy Origins and "Garden of Life" on store shelves. They claim torestore balance tothebacteriathatnor- mally live in the intestinal tract, thereby keeping your digestive system healthy and happy. Sceptics say many probiotics disappear after entering the digestive system. They affect different people in different ways. They note that research about the products hasn't been done, hasn't backed up manufacturers claims or might not be reliable because it was paid for or conducted by the manufacturers themselves. Linda Lee, a gastroenterologist at Johns Hopkins Hospital in Baltimore, says she is often asked for advice about probiotics. Leenotes that probiotics, which are live bacteria delivered through a pill, drink or powder, don't affect all of us equally Patients often trythese things based on what friends or family members have told them and they have had a great result, Lee says. "So they think they should try it But we cannot predict who is going to respond to a par ticular probiotic strain Oluf Pedersen, a professor of medicine at the University of Copenhagen and director of the Novo Nordisk Foundation Centre for Basic Metabolic Research, and colleagues looked at someof the evidence. In a study published in May in the journal "Genome Medicine', the researchers narroweddown thehundreds of studies to seven that fit certain criteria: They used healthy adults and included a control group and a DNA based identification of the various bacterial strains Pedersen's group found that some probiotics work for irritable bowel syndrome, ulcerative colitis and trav ellers diarrhoea. With these ailments, the varietyofnor mally occurring bacteria called the microbiotic "flora may be disturbed or knocked out of balance But for healthy people seeking to stay that way, for get Only one of the seven trials showed any difference in the bacteria in the gut, as measured in the study par ticipants' waste.