Gut: The Inside Story of Our Body’s Most Underrated Organ

by Giulia Enders

Fructose intolerance can also affect our mood. Sugar helps the body absorb many other nutrients into the bloodstream. The amino acid tryptophan likes to latch on to fructose during digestion, for example. When there is so much fructose in our gut that most of it cannot be absorbed into the blood and we lose that sugar, we also lose the tryptophan attached to it. Tryptophan, for its part, is needed by the body to produce serotonin—a neurotransmitter that gained fame as the happiness hormone after it was discovered that a lack of it can cause depression. Thus, a long-unrecognized fructose intolerance can lead to depressive disorders. General practitioners and family doctors are only now beginning to include this knowledge in their diagnostic toolkit.

Serotonin not only puts us in a good mood, it is also responsible for making us feel pleasantly full after a meal.

The vagus nerve is the fastest and most important route from the gut to the brain. It runs through the diaphragm, between the lungs and the heart, up along the esophagus, through the neck to the brain. Experiments on humans have shown that people can be made to feel comfortable or anxious by stimulating their vagus nerve at different frequencies. In 2010, the European Union approved a medical treatment that uses stimulation of the vagus nerve to help patients suffering from depressive disorders.

The risk of being involved in a traffic accident is higher among toxoplasma carriers, especially when the infection is in the active early stage rather than the later dormant stage.

Severe toxoplasma infection in conjunction with a particular blood group (rhesus negative) turned out to be the highest risk factor.