Treating diarrhea: Bland foods such as apple sauce and bananas are recommended for diarrhea treatment. Electrolytes like potassium are lost in large quantities during bouts of diarrhea and may make those affected feel weak. Bananas can help to promote regularity and replenish potassium stores. Preserving memory and boosting mood: Bananas also contain tryptophan, an amino acid that studies suggest plays a role in preserving memory and boosting your mood.