According to the Journal Clinical and Translational Gastroenterology, consuming too much of probiotics can cause brain fogginess and disorientation, as well as rapid belly bloating. In a study of 30 patients, researchers found that 22 who reported problems like confusion and difficulty concentrating, in addition to their gas and bloating, were all taking probiotics, some several varieties. The researchers claimed that when they looked further, they found large colonies of bacteria breeding in the patients' small intestines, and high levels of D-lactic acid being produced bu the bacteria lactobacillus' fermentation of sugars in their food.
While probiotics can be beneficial in some scenarios, like helping a person restore his gut bacteria after taking antibiotics, researchers advised caution against its excessive and indiscriminate use. According to the researchers, probiotics should be treated as a drug, not as a food supplement. D-Lactic acid is known to be temporarily toxic to brain cells, interfering with cognition, thinking and sense of time. They found some patients had two to three times the normal amount of D-lactic acid in their blood. Some said their brain fogginess, lasted for about a half hour to many hours after eating.
The researchers claimed that what they know is that probiotic bacteria have the unique capacity to break down sugar and produce D-lactic acid. So, if you inadvertently colonise your small bowel with probiotic bacteria, then you have set the stage for potentially developing lactic acidosis and brain fogginess.
Short bowel syndrome results in many undigested carbohydrates that are said to cause small intestinal bacterial overgrowth, and the high levels of D-lactic acid. Severe liver and kidney problems can produce similar problems.
Movement of food through the gastrointestinal tract was slow in one third of the brain foggy patients and one fourth of the other group. Slower passage, as well as things like obesity surgery, can increase the chance of bacterial buildup, or small intestinal bacterial overgrowth.
Good food sources of probiotics include yogurt, sauerkraut, kimchi, kefir and dark chocolate, which are generally safe because of the small amounts of bacteria present.