Unlike infectious diarrhoea, diarrhoea caused by high amounts of vitamin C or magnesium is not generally accompanied by other signs of illness; the same is true when the problem comes from sorbitol or fructose. In these cases, avoiding the offending supplement or food brings rapid relief. Drinking several cups of coffee per day causes diarrhoea in some people. People with chronic diarrhoea who drink coffee should avoid all coffee for a few days to evaluate whether coffee is the culprit. Allergies and food sensitivities are common triggers for diarrhoea. For example, some infants suffer diarrhoea when fed cow’s milk-based formula but improve when switched to soya-based formula. People with chronic diarrhoea not attributable to other causes should discuss the possibility of food sensitivity with a doctor. Nutritional supplements that may be helpful: Acute diarrhoea can damage the lining of the intestine. Folic acid can help repair this damage. In one preliminary trial, supplementing with very large amounts of folic acid (5 mg three times per day for several days) shortened the duration of acute infectious diarrhoea by 42% in a preliminary study. However, a double-blind trial failed to show any positive effect with the same level of folic acid. Therefore, evidence that high levels of folic acid supplementation will help people with infectious diarrhoea remains weak. Brewer’s yeast has been shown to alter the immune system or the flora living in the intestine and may relieve infectious diarrhoea. Three capsules or tablets of brewer’s yeast three times per day for two weeks was reported to be helpful in three cases of infectious diarrhoea caused by Clostridium difficile. Animal research has confirmed that brewer’s yeast helps fight this unfriendly bacterium. Note that real brewer’s yeast is not identical to nutritional, or torula, yeast and that when asking for brewer’s yeast in health food stores, people are often directed toward these other products. Real brewer’s yeast is bitter, whereas other health food store yeasts have a more pleasant taste. An organism related to brewer’s yeast, Saccharomyces boulardii (Sb) , is sometimes available as a supplement and is widely used in Europe to prevent antibiotic-induced diarrhoea. Animal research with Sb shows interference with Clostridium difficile, a common cause of diarrhoea.